National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

Natural Resource Condition Assessment

Horseshoe Bend National Military Park

Natural Resource Report NPS/SECN/NRR—2015/981
ON THE COVER

Photo of the Tallapoosa River, viewed from Horseshoe Bend National Military Park

Photo Courtesy of Elle Allen
Natural Resource Condition Assessment

Horseshoe Bend National Military Park

Natural Resource Report NPS/SECN/NRR—2015/981

JoAnn M. Burkholder, Elle H. Allen, Stacie Flood, and Carol A. Kinder

Center for Applied Aquatic Ecology

North Carolina State University

620 Hutton Street, Suite 104

Raleigh, NC 27606

June 2015 

U.S. Department of the Interior

National Park Service

Natural Resource Stewardship and Science 

Fort Collins, Colorado
ii

The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, 

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report in a format optimized for screen readers, please email irma@nps.gov.

Please cite this publication as:

Burkholder, J. M., E. H. Allen, S. Flood, and C. A. Kinder. 2015. Natural resource condition 

assessment: Horseshoe Bend National Military Park. Natural Resource Report NPS/SECN/NRR—

2015/981. National Park Service, Fort Collins, Colorado.

NPS 407/128933, June 2015
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Contents

Page

Figures..................................................................................................................................................vii

Tables....................................................................................................................................................xi

Plates..................................................................................................................................................xvii

Appendices.........................................................................................................................................xvii

Acknowledgments...............................................................................................................................xix

Abbreviations......................................................................................................................................xxi

Executive Summary...........................................................................................................................xxv

1. NRCA Background Information ....................................................................................................1

2. Introduction and Setting .................................................................................................................5

2.1. Introduction........................................................................................................................5

2.2. Enabling Legislation and Potential for Expansion.............................................................8

2.3. Geographic Setting.............................................................................................................8

2.4. Demographics..................................................................................................................12

2.5. Visitation Statistics ..........................................................................................................15

2.6. Watersheds.......................................................................................................................16

2.7. GIS Data Layers...............................................................................................................18

2.7.1. Data Selection and Acquisition ..........................................................................18

2.7.2. Data Oversight and Database Management........................................................18

2.7.3. Map Generation ..................................................................................................19

3. Natural Resources Inventory ........................................................................................................21

3.1. Climate.............................................................................................................................21

3.1.1. Temperature........................................................................................................23

3.1.2. Precipitation........................................................................................................25

3.1.3. Moisture..............................................................................................................27

3.1.4. Phenology (Growing Degree Days)....................................................................29

3.1.5. Extreme Weather Events....................................................................................33

3.2. Air Quality .......................................................................................................................36

3.2.1. Federal Criteria for Major Air Pollutants, and a Federal Index Scale ................36
iv

3.2.2. National Park Service Indices for Air Quality....................................................40

3.2.3. Air Quality in the Park and Vicinity...................................................................42

3.3. Soundscape ......................................................................................................................50

3.3.1. Some Definitions and Interpretations.................................................................50

3.3.2. The Horseshoe Bend Soundscape.......................................................................51

3.4. Lightscape ........................................................................................................................52

3.5. Geology and Soils............................................................................................................56

3.5.1. Geologic Resources............................................................................................56

3.5.2. Soils and Erosion................................................................................................58

3.6. Water Resources ..............................................................................................................61

3.6.1. Surface Water .....................................................................................................62

3.6.2. Groundwater.......................................................................................................84

3.7. Biological Resources and Management...........................................................................89

3.7.1. Attributes Used in Assessment...........................................................................89

3.7.2. Horseshoe Bend Biota Assessment – Overview.................................................91

3.7.3. Vascular Flora.....................................................................................................95

3.7.4. Fish .....................................................................................................................99

3.7.5. Herpetofauna ....................................................................................................101

3.7.6. Birds..................................................................................................................106

3.7.7. Mammals..........................................................................................................107

3.7.8. Species of Special Management Concern.........................................................109

3.7.9. Exotic/Invasive Species....................................................................................110

3.7.10. Management Actions........................................................................................114

3.8. Synopsis of Stressors to Horseshoe Bend Natural Resources........................................117

4. Indicators to Assess Natural Resource Conditions.....................................................................119

4.1. Management Directives and Planning Guidance ...........................................................119

4.2. Study Scoping and Design .............................................................................................124

4.3. Climate Change..............................................................................................................127

4.4. Watershed/Landscape Dynamics...................................................................................129

4.4.1. Human Population in the Surrounding Area ....................................................129
v

4.4.2. Visitors - Human Population Within the Park..................................................134

4.4.3. Land Use/Land Cover.......................................................................................136

4.5. Air Quality .....................................................................................................................142

4.6. Soundscape ....................................................................................................................145

4.7. Lightscape ......................................................................................................................147

4.8. Soil and Streambank Erosion.........................................................................................148

4.9. Surface Water Hydrology ..............................................................................................150

4.10. Surface Water Quality....................................................................................................153

4.11. Biological Resources .....................................................................................................155

4.11.1. Vascular Plant Flora, Compromised by Exotic/ Invasive Species ...................156

4.11.2. Fish ...................................................................................................................157

4.11.3. Herpetofauna ....................................................................................................157

4.11.4. Birds..................................................................................................................159

4.11.5. Mammals..........................................................................................................161

4.11.6. Species of Special Management Concern (SSMCs).........................................162

5. Discussion ..................................................................................................................................165

5.1. Summary of Natural Resource Conditions in Horseshoe Bend.....................................165

5.2. Remaining Major Knowledge Gaps and Next Steps .....................................................173

6. Literature Cited...........................................................................................................................175

vii

Figures

Page

Figure 1. Maps showing the location of HOBE....................................................................................6

Figure 2. Map showing features of the battle at Horseshoe Bend (1814) within the park....................7

Figure 3. Map of land use/land cover (2011 NLCD in GIS, first available in 2014) in the 

Middle Tallapoosa sub-basin (#03150109) that includes HOBE (red outline)....................................11

Figure 4. Interactive map for GIS files and metadata, created by the Environmental 

Research and Mapping Facility (ERMF 2007) at the University of Tennessee -

Chattanooga. ........................................................................................................................................12

Figure 5. The Middle Tallapoosa River basin human population. Map shows the sparse 

population as of 2010 (black dots), Horseshoe Bend National Military Park (red), and the 

only population center near the park (Alexander City)........................................................................14

Figure 6. Visitation statistics for total recreationists per year in the park (NPS 2015i)......................15

Figure 7. Visitors to the Park for recreation or use of the boat ramp (2003–2011)............................16

Figure 8. Map of the Tallapoosa River watershed showing the various locks and dams

(National Atlas of the United States 2006). .........................................................................................17

Figure 9. Weather stations near Horseshoe Bend National Military Park, Alabama (from 

Wright 2011)........................................................................................................................................22

Figure 10. Mean annual temperature in the Division 5 area of Alabama, including 

Horseshoe Bend National Military Park, from 1895 to 2013, hereafter referred to as 

NOAA NWS (NOAA 2015)................................................................................................................23

Figure 11. Increasing trend in mean annual temperature in Division 5 of Alabama, 

including Horseshoe Bend National Military Park, from 1960 to 2013 ..............................................24

Figure 12. Increasing trend in mean summer temperature in Division 5 of Alabama, 

including Horseshoe Bend National Military Park, from 1960 to 2012 ..............................................24

Figure 13. Increasing trend in the mean summer temperature in Division 5 of Alabama, 

including Horseshoe Bend National Military Park, from 2004 to 2012 ..............................................25

Figure 14. Increasing trend in mean annual precipitation within the Division 5 area of 

Alabama, including Horseshoe Bend National Military Park, from 1895 through 2012 ....................26

Figure 15. Mean summer precipitation (June through August) in the Division 5 area of 

Alabama during 2003 to 2012 showing a decrease of 23.27 cm, or -9.16 inches................................27

Figure 16. PDSI values for the Division 5 area of Alabama over nine-year periods from 

1896 through 2012 ...............................................................................................................................28

Figure 17. PDSI values for the Division 5 area of Alabama from 1896 to 2012................................30

Figure 18. PDSIs over the past decade (2003-2012) in the Alabama Climate Division 5, 

showing a decrease ..............................................................................................................................31
viii

Figures (continued)

Page

Figure 19. The GDDs per year for the Division 5 area of Alabama from 1930 through 

2012......................................................................................................................................................32

Figure 20. Approximate date when 1200 GDD was reached for each year in the Division 

5 area of Alabama in 1930 through 2012.............................................................................................32

Figure 21. Map showing tracks of 24 tropical storms (1930–2012) that passed within 161 

km (100 miles) of Alexander City, Alabama (NOAA 2015b).............................................................34

Figure 22. The total number of major and minor storms per month (1930 to 2012) that 

occurred within 161 km (100 miles) of Alexander City, Alabama......................................................35

Figure 23. The number of storms per decade (1930 to 2009 - the latest year for which 

complete data were available) that occurred within 161 km (100 miles) of Alexander 

City, Alabama. .....................................................................................................................................35

Figure 24. Map of power plants in Alabama (data from EISPC 2014)...............................................45

Figure 25. Map of total sulfur (S) and total nitrogen (N) emissions (both oxidized forms 

as nitrogen oxides and reduced forms as ammonia) by county as of 2002 in the vicinity of 

HOBE (star; and black line ≡ portion of the SECN boundary delineation).........................................47

Figure 26. Evaluation of air quality conditions (2005–2009) at HOBE (NPS 2014a)........................49

Figure 27. Influence of A- and C-weighting curves on the relationship between dB and 

frequency (pitch, Hz; modified from http://www.sengpielaudio.com/calculator-dbaspl.htm, last accessed in May 2015). ...................................................................................................50

Figure 28. Artificial night sky brightness due to light pollution in the 1950s, 1970s, 1997, 

and projected to 2025...........................................................................................................................53

Figure 29. Map of the geology of the general Park area (star - HOBE, including 

quartzite, mica schist, and gneiss; green lines - faults)........................................................................56

Figure 30. Map of simplified geology of the Park showing granodiorite, schist, and mica 

schist ....................................................................................................................................................58

Figure 31. Simplified map of 21 soils in the Park (blue - most abundant) .........................................60

Figure 32. Map of streams in the Park (boundary in white), which are intermittent except 

for those indicated by numbers............................................................................................................63

Figure 33. USGS stream gaging stations in and near the Park ...........................................................64

Figure 34. Daily flow in 2010 (blue line), median monthly flow (dots 2010 data), and 

interquartile range (error bars) for the Tallapoosa River at Wadley (upper panel) and New 

Site (nearest HOBE - lower panel). .....................................................................................................68
ix

Figures (continued)

Page

Figure 35. Daily flow in 2012 (blue line), historical median monthly flow (dots - 2012 

data), and interquartile range (error bars) for the Tallapoosa River near Wadley (upper 

panel) and near New Site (Horseshoe Bend; lower panel) ..................................................................71

Figure 36. Map of wetland locations in the park ................................................................................74

Figure 37. Water temperature and turbidity (upper and lower panels, respectively) in the 

Tallapoosa River at HOBE (Boat Ramp station, January 2000 - February 2007) from a 

monthly sampling program by volunteer citizens in the Alabama Water Watch (AWW). .................81

Figure 38. Water pH, alkalinity, and hardness (upper, middle, and lower panels, 

respectively) for the Tallapoosa River at HOBE (Boat Ramp station, January 2000 -

February 2007) from a sampling program by volunteer citizens in the AWW. ..................................82

Figure 39. DO as concentration and percent saturation (upper and lower panels, 

respectively) for the Tallapoosa River at HOBE (Boat Ramp station, January 2000 -

February 2007) from a sampling program by volunteer citizens in the AWW. ..................................83

Figure 40. The Piedmont and Blue Ridge Aquifer System: Crystalline-rock aquifers 

underlie the rolling hills of the Piedmont physiographic province and the rugged 

mountains of the Blue Ridge physiographic province in a band that extends from eastcentral Alabama northeastward through western South Carolina. From Miller (1990), 

with permission....................................................................................................................................86

Figure 41. Map showing the locations of the USGS monitoring wells (black dots; USGS 

well numbers) near HOBE (orange dot) ..............................................................................................88

Figure 42. Mean depth to water level (feet - NGVD 1929) over time (1973-2011) for the 

well nearest Horseshoe Bend National Military Park (#334207084254801; blue line) 

within the Piedmont and Blue Ridge Aquifer System, showing the substantial decrease...................88

Figure 43. Relationship between land area (in hectares) and species richness, excluding 

exotic (introduced) species, among 16 parks within the Southeast Coast Network of the 

NPS, including HOBE (red dot), showing the strong positive linear relationship between 

(log-transformed) land area and species richness ( P = 0.001)..........................................................102

Figure 44. Spatially balanced, random sampling locations at HOBE in the 2009 studies 

of vocal anuran amphibians and birds. From Byrne et al. (2011a), modified by the NPS 

SECN (2014)......................................................................................................................................103

Figure 45. Map of survey sites for mammals in HOBE during August - October 2003 

study...................................................................................................................................................108

Figure 46. Map of the three longleaf pine restoration sites (shaded areas with red stars) at 

HOBE, also showing fire boxes (blue triangles)................................................................................117

Figure 47. Conceptual model of the HOBE ecosystem, used as a general framework to 

select indicators of natural resource health for the park ....................................................................126
x

Figures (continued)

Page

Figure 48. The color-coded “stoplight report card” system used to succinctly convey the 

status of HOBE natural resources. .....................................................................................................126

Figure 49. A schematic of possible relationships between human population density and 

biodiversity, especially focusing on the negative impacts of human population growth ..................131

Figure 50. Map showing the population density of the State of Alabama as of 2010 

(upper panel: Au-OpMA in pink box, and a magnified view of the Au-OpMA in 2004 

(lower panel; Wikipedia Commons 2006).........................................................................................133

Figure 51. A widely used Impervious Cover Model (ICM) of stream quality and 

macroinvertebrate community response to urban development as the percentage of 

impervious cover in a given watershed or sub-watershed .................................................................138

Figure 52. Previous widely accepted conceptual model of the response of stream biota to 

urban development - now questioned ................................................................................................139

Figure 53. Left: Response of EPT species (Ephemeroptera - mayflies, Plecoptera -

stoneflies, and Trichoptera - caddisflies) to urbanization in the Atlanta area (IC ≡ 

impervious cover) ..............................................................................................................................140

Figure 54. The extreme “hydro-peaking” effects from regulation of discharge at the 

Harris Lake outflow, downstream at the Wadley USGS gaging station............................................152

Figure 55. Relationship between land area (in hectares) and species richness, excluding 

exotic introduced) species, among 16 parks within the Southeast Coast Network of the 

NPS, including HOBE. Modified from Tuberville et al. (2005) to show apparent breaks in 

the data...............................................................................................................................................158
xi

Tables

Page

Table 1. Previous land use/land cover, 10-15 yr ago: As of 2001 and 2006, area and 

percent cover of each land use class in the middle Tallapoosa sub-basin (#03150109), 

from analysis by the NCSU CAAE........................................................................................................9

Table 2. Land use/land cover information...........................................................................................10

Table 3. Location of relevant weather stations near HOBE, station network affiliation 

and additional metadata for weather stations used in this report .........................................................22

Table 4. Palmer Drought Severity Index (PDSI) scale. From Dai et al. (2004)..................................28

Table 5. The Saffir/Simpson Hurricane Scale (SSHS - Blake et al. 2007). ........................................33

Table 6. National ambient air quality (AQ) standards (NAAQS, 40 CFR part 50), set by 

the EPA (October 2011) for six principal (“criteria”) pollutants considered harmful to 

public health and the environment.......................................................................................................37

Table 7. EPA’s Air Quality Index (AQI) criteria (modified from GA DNR 2007b, EPA 

2009) ....................................................................................................................................................38

Table 8. The Air Quality Index (AQI) of the EPA (1994) translated into actions that 

citizens can take to protect their health from potentially harmful levels of major air 

pollutants..............................................................................................................................................39

Table 9. The NPS ranks for ozone concentrations to protect human health in air quality 

condition assessment (NPS 2011)........................................................................................................40

Table 10. The NPS ranks for ozone concentrations to protect sensitive plant species in air 

quality condition assessment. (NPS 2011)...........................................................................................41

Table 11. The NPS ratings for wet deposition of nitrogen (N) or sulfur (S) in air quality 

condition assessment, in order to protect park ecosystems (NPS 2011)..............................................41

Table 12. The NPS ratings for visibility in air quality condition assessment. (NPS 2011). ...............42

Table 13a. The overall Air Quality Index (AQI) percentage levels for Alexander City, 

Alabama (Homefacts 2015a,b) ............................................................................................................43

Table 13b. The 2014 Air Quality Index (AQI) for Alexander City, Alabama, also 

showing levels of the top six criteria pollutants...................................................................................43

Table 13c. The 2013 Air Quality Index (AQI) for Alexander City, Alabama, also 

showing levels of the top six criteria pollutants...................................................................................43

Table 14. Air Quality Index (AQI) and Air Pollution Index (APl; pounds in parentheses) 

for Montgomery and Birmingham, Alabama in 2012, also showing the statewide and 

national averages (Areavibes.com 2015).............................................................................................44

Table 15. The Bortle Dark-Sky Scale for assessing artificial light pollution......................................54
xii

Tables (continued)

Page

Table 16a. Indicators of Hydrologic Alteration Metrics and Environmental Flow 

Components, including potential ecosystem influences modified from the IHA User’s 

manual (The Nature Conservancy 2009). ............................................................................................66

Table 16b. Indicators of Environmental Flow Components, including potential 

ecosystem influences modified from the IHA User’s manual (The Nature Conservancy 

2009). ...................................................................................................................................................66

Table 16c. Indicators of Hydrologic Alteration Metrics, including potential ecosystem 

influences modified from the IHA User’s manual (The Nature Conservancy 2009). .........................67

Table 17. Monthly median and low flow magnitudes (in cfs) for the two USGS gaging 

stations nearest HOBE during 2010.....................................................................................................69

Table 18. Extreme flow magnitudes (cfs, 1-day to 90-day) at the two upstream USGS 

gaging stations nearest HOBE during 2010.........................................................................................69

Table 19. EFCs (The Nature Conservancy 2009) for flows (in cfs) at the USGS gaging 

stations nearest HOBE during 2010.....................................................................................................69

Table 20. Monthly median flow magnitudes (in cfs) for the Tallapoosa River in 2012, 

upstream from HOBE at the two USGS gaging stations.....................................................................72

Table 21. The 1- to 90-day extreme flow magnitudes (USGS data, cfs) for the Tallapoosa 

River in 2012, upstream from HOBE at the two nearest USGS gaging stations.................................72

Table 22. Environmental Flow Components for flows (in cfs) for the Tallapoosa River in 

2012, upstream from HOBE at the two nearest USGS gaging stations...............................................72

Table 23. In-stream water quality standards for non-coastal surface waters with 

designated use as Fish and Wildlife (ADEM 2013b). .........................................................................75

Table 24a. Summary of Alabama state standards for acceptable water quality in waters 

classified as Fish and Wildlife designated use, and of conditions for acceptable water 

quality recommended by other sources (ADEM 2013b). ....................................................................76

Table 24b. Summary of Alabama state standards for acceptable water quality for toxic 

metals in waters classified as Fish and Wildlife designated use, and of conditions for 

acceptable water quality recommended by other sources (ADEM 2013b)( U.S. EPA 

2000, 2002d).........................................................................................................................................77

Table 25. Dates of water quality sampling, and parameters sampled in surface waters of 

the park, considering information from 2000 - present .......................................................................80

Table 26. Water quality conditions during the past decade based on data collected by 

ADEM: Parameters measured at the boat ramp station in HOBE (ADEM #3952 -

Tallapoosa River; lat. 32.97734, long. -85.73968) (sampling dates per year ranged from 8 

to 13)a...................................................................................................................................................84
xiii

Tables (continued)

Page

Table 27. Alpha-diversity indices for species richness (data: observations identified to 

the species-level) used by the Network; notes also add interpretations from other sources 

as indicated...........................................................................................................................................90

Table 28. Species of concern (SoCs) reported to occur in HOBE (Alabama Natural 

Heritage Program 2011, NPS 2013b). .................................................................................................92

Table 29. Other plant SoCs reported to occur in Tallapoosa County (Alabama Natural 

Heritage Program 2012, Appendix 3), but not found in HOBE according to the NPS 

Certified Species List (2013b) and other information.* ......................................................................93

Table 30. Alpha-diversity estimates for vocal anuran amphibians at HOBE based on 

SECN monitoring in 2009 (Byrne et al. 2011a).................................................................................104

Table 31. Bird alpha-diversity estimates at HOBE based on 2009 data ...........................................107

Table 32. Exotic/ invasive taxa in HOBE, also indicating (*) Top 10 status on the 

Alabama Exotic Pest Plant Council (2015) Category #1 status, and Category #1 Alert 

status of the Alabama List of Exotic and Invasive Plants; and the NPS Top Ten Species 

List for national parks in the Southeast region (NPS 2015b). ...........................................................112

Table 33. Current and potential stressors that are affecting or may affect HOBE (ND ≡ 

no data to make judgment; NP ≡ not a problem;-- ≡ not applicable; EP ≡ existing 

problem; PP ≡ potential or pending problem)....................................................................................118

Table 34. Vital signs identified by the SECN for its inland parks including HOBE ( ≡ 

Vital Sign for which the SECN will develop protocols and implement monitoring;  ≡ 

Vital Sign that is monitored by a network park, another NPS program, or another federal 

or state agency;  ≡ monitoring deferred). Modified from DeVivo et al. (2008). ...........................121

Table 35. Overall scores for climate change, based on the six selected indicators. ..........................129

Table 36. Evaluation of Climate Change Condition in HOBE, based on five Climate 

Indicators............................................................................................................................................129

Table 37a. Five Population Condition Indicators, and the Present status of Surrounding 

Population Condition in impacting or potentially impacting the park...............................................134

Table 37b. Paramerters used to rate the Five Population Condition Indicators in HOBE................134

Table 37c. Overall evaluation for the Five Population Condition Indicators in HOBE....................134

Table 38a. Visitation Condition in HOBE, based on three Visitation Indicators. ............................136

Table 38b. Overall evaluation of Visitation Condition in HOBE, based on three 

Visitation Indicators...........................................................................................................................136

Table 39a. Land Use/ Land Cover Condition surrounding the park, based on evaluation 

using two indicators. ..........................................................................................................................142
xiv

Tables (continued)

Page

Table 39b. 5-10 year overall evaluation for Land Use/ Land Cover Condition 

surrounding the park, based on evaluation using two indicators. ......................................................142

Table 40a. Evaluation of overall Air Quality Condition in HOBE, based on the AQI (Air 

Quality Index of the U.S. EPA...........................................................................................................144

Table 40b. Evaluation of 2005-2009 Air Quality Condition in HOBE, based on the AQI 

(Air Quality Index of the U.S. EPA, and seven NPS indicators (ozone concentration that 

protects human health, ozone concentration that protects plant health [2 indicators], N 

deposition, S deposition, Visibility, and Acidification).....................................................................144

Table 40c. Paramerters used to rate NPS Air Quality Condition in HOBE......................................145

Table 40d. Overall evaluation of NPS Air Quality Condition in HOBE. .........................................145

Table 41a. The three Soundscape Indicators, and present Soundscape Condition in 

HOBE.................................................................................................................................................146

Table 41b. Paramerters used to rate Soundscape Condition in HOBE. ............................................146

Table 41c. Overall Soundscape Condition in HOBE. .......................................................................147

Table 42a. Evaluation of the Lightscape Condition at HOBE, using the Bortle Dark-Sky 

Scale...................................................................................................................................................147

Table 42b. Paramerters used to rate Lightscape Indicators in HOBE...............................................148

Table 43a. Evaluation of present Soil Condition in HOBE, based on four Soil and 

Streambank Erosion Indicators - erodibility; visible evidence of erosion along trails and 

roadways; visible evidence of streambank erosion; and soil acidification potential. ........................149

Table 43b. Paramerters used to rate Soil Condition Indicators in HOBE.........................................150

Table 43c. Overall evaluation of present Soil Condition in HOBE, based on four Soil and 

Streambank Erosion Indicators - erodibility; visible evidence of erosion along trails and 

roadways; visible evidence of streambank erosion; and soil acidification potential. ........................150

Table 44a. Present Hydrologic Condition in HOBE, evaluated using the HydroMAG and 

HydroFLASH Indicators. .......................................................................................................................153

Table 44b. Evaluation of Present Hydrologic Condition, non-storm conditions, in 

HOBE, evaluated using the HydroMAG and HydroFLASH Indicators. ..................................................153

Table 45a. The present Surface Water Quality Condition in HOBE, based on seven 

Water Quality Indicators (see Table 24 for references). ....................................................................154

Table 45b. Paramerters used to rate Surface Water Quality Condition Indicators in 

HOBE.................................................................................................................................................154

Table 45c. Overall evaluation of Surface Water Quality Condition in HOBE, based on 

seven Water Quality Indicators (see Table 24 for references)...........................................................155
xv

Tables (continued)

Page

Table 46a. Evaluation of present Vascular Flora Condition in the park, based on two 

Terrestrial and two Wetland Indicators..............................................................................................156

Table 46b. Paramerters used to rate Vascular Flora Indicator Condition Indicators in 

HOBE.................................................................................................................................................156

Table 46c. Overall evaluation of Vascular Flora Indicator Condition Ratings for HOBE. ..............157

Table 47. Fish Condition in HOBE, based on two Fish Indicators. ..................................................157

Table 48a. Herpetofauna Condition in HOBE, based on three indicators. .......................................158

Table 48b. Overall evaluation of Herpetofauna Condition in HOBE...............................................159

Table 49. Breeding Bird Survey results for BBS Route 02209- Wedowee, Ala., the route 

closest to HOBE, ~20 km (12.5 miles) northeast of the park. ...........................................................160

Table 50a. Bird Fauna Condition in HOBE, based on evaluation using five indicators...................161

Table 50b. Overall Evaluation of Bird Fauna Condition in HOBE. .................................................161

Table 51. The present Mammalian Fauna Condition in HOBE, based on evaluation using 

three indicators...................................................................................................................................162

Table 52a. Present condition of Species of Special Management Concern (SSMCs) in 

HOBE, based on four indicators. .......................................................................................................163

Table 52b. Evaluation of overall condition of Species of Special Management Concern 

in HOBE.............................................................................................................................................163

Table 53. Overall Report Card of Natural Resource Conditions in HOBE.......................................166

Table 54. Summary of Natural Resource Conditions in HOBE, including 16 separate 

categories that were evaluated using the 59 listed indicators. ...........................................................167

xvii

Plates

Page

Plate 1. The tranquil present-day setting of the bloody Battle at Horseshoe Bend........................ 7

Plate 2. Left: Fire from a prescribed burn, moving through litter layers along the park ........... 116

Appendices 

Page

Appendix 1. GIS Data Used for Assessing Conditions .....................................................................203

Appendix 2. Lists of the Biota Reported from Horseshoe Bend .......................................................215

Appendix 3. Conservation Ranking Systems Used in Assessing Natural Resource 

Conditions..........................................................................................................................................241

Appendix 4. Definitions of Federal and State Species Status (Alabama Natural Heritage 

Program 2012) ...................................................................................................................................245

Appendix 5. “Shortcut” Programs in SAS to calculate GDD and PDSI............................................247

xix

Acknowledgments

This study was funded by the National Park Service, Southeast Coast Network (SECN). In addition 

to the individuals listed as interviewed, we thank our project manager and SECN Coordinator Joe 

DeVivo of the National Park Service, for his tireless and excellent efforts in facilitation, counsel, and 

helpful review comments.

We thank Horseshoe Bend Superintendent Mr. Doyle Sapp for his helpful counsel, and Mr. Jim 

Cahill, Chief Ranger, for his insights. In addition, we are grateful to the following colleagues: Sara 

McCort and Brent Blankley at the NPS, who provided GIS shapefiles for Horseshoe Bend

boundaries, hydrology, trails, and places; and Christina Wright, who provided the available NPS 

species lists of flora and fauna in the park.

Consuelo Arellano of the Department of Statistics, North Carolina State University, counseled us in 

designing the automated program for computing the date when the growing degree day’s threshold is 

reached, and the severity of drought over seven moisture classes. Eric Reutubuch, a research 

associate at the Department of Fisheries and Allied Aquaculture at Auburn University, provided a 

link to water quality information for the Tallapoosa River (Lake Watch of Lake Marting 2015). 

These data, the only recent water quality data available for park waters until 2010, were collected as 

part of a volunteer monitoring effort called Alabama Water Watch (Alabama Water Watch 

Association 2015). Nutrient data (2004-2006) from the Tallapoosa River near the Boat Ramp site, 

were collected as part of Auburn University’s Tallapoosa Watershed Project (Alabama Water Watch 

Association 2015).

xxi

Abbreviations

ADEM – Alabama Department of Environmental Management

Ala. – Alabama

API – Air Pollution Index (kilograms or pounds; calculated as total pounds of the six most hazardous 

air pollutants (arsenic, benzene, carbon tetrachloride, lead, and mercury)

AQI – Air Quality Index (of the EPA; scale from 0 to 500, with higher numbers indicating poorer air 

quality)

AWW – Alabama Water Watch (volunteer program of Auburn University)

ARD – automated recording device (for a study of anuran amphibians)

ASABE – American Society of Agricultural and Biological Engineers 

Au-OpMA – the Auburn-Opelika metropolitan area (in adjacent Lee County)

Bd – Batrachochytrium dendrobatidis (chytrid fungal pathogen of amphibians)

BDSS – the Bortle Dark-Sky Scale

BMP – best management practices

cfs – cubic feet per second

cfu – colony forming units

CI – confidence interval (in statistics)

cm – centimeter

cms – cubic meters per second

CO – carbon monoxide

CO2 – carbon dioxide, a major greenhouse gas contributing to global warming

dB(A) – A-weighted decibels, wherein a decibel is a unit of sound production; decibel(A) refers to 

sound production level on an A-weighted scale according to sound frequency

DO – dissolved oxygen

EFC – Environmental Flow Component

EPA –United States Environmental Protection Agency 

EPMT – Exotic Plant Management Team (of the NPS)

ERMF – Environmental Research and Mapping Facility (of the University of Tennessee)

ft – feet

Ga. – Georgia

GDD – growing degree days

GIS – Geographic Information System

GeRI – Geologic Resources Inventory

GRD – Geologic Resources Division (of the NPS)

GRI – Groundwater Resources Inventory

HOBE – Horseshoe Bend National Military Park

hr – hour

Hz – cycles per second, a measure of pitch in noise analysis

I&M Program – Inventory and Monitoring Program (of the NPS)

IHA – Indicators of Hydrologic Alteration (software from the Nature Conservancy)

in – inch
xxii

IPCC –Intergovernmental Panel on Climate Change (of the United Nations)

IRMA – Integrated Resource Management Applications (National Park Service portal)

kHz (or KHz) – kilohertz, unit of alternating current or electromagnetic wave frequency equal to one 

thousand hertz (Hz)

km – kilometer

km2– square kilometer

L – liter(s)

lat. – latitude

long. – longitude

m – meter

μg/L – micrograms per liter 

mile2– square mile

mg/L – milligrams per liter 

mgd – million gallons per day

mya – million years ago

N – nitrogen (nutrient; excessive enrichment can degrade water quality)

NAAQS – National Ambient Air Quality Standards (of the EPA)

NADP – National Atmospheric Deposition Program (of the EPA)

NCSU CAAE – North Carolina State University Center for Applied Aquatic Ecology

NH4

+N – ammonium (inorganic form of nitrogen, ionized from ammonia; excessive enrichment can 

degrade water quality)

NLCD – National Land Cover Database

NOAA – National Oceanic and Atmospheric Organization

NO3

–

+ NO2

–

– nitrate + nitrite (inorganic forms of nitrogen; excessive enrichment can degrade water 

quality)

NOx – nitrate + nitrite (inorganic forms of nitrogen; excessive enrichment can degrade water quality)

NPC – Not possible for the National Park Service to control

NPDES – National Pollutant Discharge Elimination System

NPS – National Park Service

NRC – Natural Resource Condition

NRCA – Natural Resource Condition Assessment

NRS – National Resource Strategy (of parks in the NPS)

NTU – nephelometric turbidity units

NWI – National Wetlands Inventory

NWS – National Weather Service (of NOAA)

O3 – ozone

P – Phosphorus (nutrient; excessive enrichment can degrade water quality)

Pa – Pascal, a unit of pressure: 1 Pa = the pressure of 1 newton per square meter

PDSI – Palmer Drought Severity Index (PDSI, a scale ranging from -3 to +3; sometimes called the 

Palmer Drought Index)

PM2.5 – particulate matter, diameter < 2.5 μm (air pollutant)

PM10 – particulate matter, diameter < 10 μm (air pollutant)
xxiii

ppb – parts per billion 

ppm – parts per million 

RSS – Resource Stewardship Strategy 

SECN – Southeast Coast Network (of the National Park Service)

SSHS – Saffir/Simpson Hurricane Scale

SO2 – sulfur dioxide (air pollutant)

SoC – species of concern (endangered, threatened, etc. - federal and/or state)

SOP – standard operating procedure

spec. cond. – specific conductivity

SSHS – Saffir/Simpson Hurricane Scale

STORET – Storage and Retrieval Environmental Data System (of the EPA)

TD – tropical depression

TDS – total dissolved solids

TKN – total Kjeldahl nitrogen

TMDL – total maximum daily load

TN – total nitrogen

TP – total phosphorus

TS – Tropical storm

TSS – total suspended solids

TWP – Tallapoosa Watershed Project (of Auburn University)

UC – unacceptable condition (referring to water quality)

USDA – United States Department of Agriculture

USDI – United States Department of the Interior

USGS – United States Geological Survey

VCP – variable-circular plot technique (for studying bird communities)

VES – visual encounter survey (in amphibian and reptile studies)

yr – year

≡ – is (or are) defined as

xxv

Executive Summary

The two major goals of this report were (i) to inventory the natural resources of Horseshoe Bend 

National Military Park (HOBE, or the park) in eastern Alabama, including synthesis of available 

information and collection of geospatial data layers and maps; and (ii) to develop a set of indicators, 

quantitative insofar as possible, for natural resource conditions that can be tracked over time. The 

natural resources that were evaluated include climate, air quality, geology and soils, groundwater, 

surface water, terrestrial and wetland biota, and species of special concern.

Horseshoe Bend is a small park (8.3 square kilometers [km2], or 2,040 acres) in Tallapoosa County 

within the middle Tallapoosa River basin. Its natural resources include mixed hardwood/pine forests 

mixed with grassy fields, two perennial streams, several intermittent streams, and wetlands that 

mostly occur as narrow fringes of swamp forest along the Tallapoosa River. An approximately 6-km 

(3.7-mile) segment of that river flows through the park and is its most prominent natural feature; 

indeed, the park is named for a “horseshoe-like” bend in the river. Horseshoe Bend has excellent 

soundscape and lightscape features and is described by park staff as minimally affected by noise or 

light pollution. The airshed has moderate ozone levels that may adversely affect both human health 

and the park vascular plant communities. Visibility is poor because of compromised air quality, and 

the park also lies in an area that is especially prone to acid deposition by nitrogen and sulfur species.

The Middle Tallapoosa River basin is predominantly rural with mostly forested land cover. 

Unfortunately, Tallapoosa County has a relatively high poverty level, and the park is also threatened 

by rapid population growth of the Auburn-Opelika metropolitan area in adjacent Lee County. 

Horseshoe Bend is a popular park that was visited by approximately100,000 people in 2012, 

comparable to or lower than the number of visitors estimated for previous years. Park trails are wellused; in 2012 there were an average of 17 visitors per km of trail per day (27 visitors per mile of trail 

per day). Although more than half of the soil categories in Horseshoe Bend are moderately eroded, 

there is little evidence of soil erosion along the trails, or of streambank erosion.

The Tallapoosa River segment that traverses Horseshoe Bend lies between dams and hydropower 

facilities at two run-of-river impoundments, ~32 km (20 miles) upstream, and ~40 km (25 miles) 

downstream. Since the upstream dam was installed in 1982, the river segments downstream have 

been subjected to changes in river flow from as low as zero to 45.3 cubic meters per second (m3/sec; 

or 16,000 cubic feet per second, cfs). River flow is routinely extreme and is regulated by the 

Alabama Power Company on a daily basis. The upper Tallapoosa River system also has been 

targeted as a potential source of potable water for Atlanta, Ga. Water quality of the river in HOBE is 

characterized by ample dissolved oxygen and desirable pH to support beneficial aquatic life, but high 

turbidity and moderate nutrient levels are suggestive of land disturbance and nutrient pollution from 

upstream watershed development.

The terrestrial and aquatic biota of Horseshoe Bend are not well known other than species lists. 

Based on the available lists, the park contains rich vascular plant floras, with 230 and 227 taxa in 

terrestrial and wetland/aquatic habitats, respectively. However, the natural floras are being 

compromised by exotic/ invasive species including six highly invasive terrestrial species 
xxvi

(Bermudagrass - Cynodon dactylon, Chinese lespedeza - Lespedeza cuneata, Chinaberry - Melia 

azedarach, Chinese yam - Dioscorea oppositifolia, kudzu - Pueraria montana var. lobata, and 

mimosa - Albizia julibrissin) and three highly invasive wetland species (Chinese privet - Ligustrum 

sinense, Japanese honeysuckle - Lonicera japonica, and Aleppo milletgrass - Sorghum halepense). A 

total of 251 taxa of vertebrate fauna have been reported to occur in the park. With 66 native 

herpetofauna species, Horseshoe Bend leads other SECN parks in amphibian and reptile species 

richness. Its bird fauna are also species-rich, slightly higher than the number of species reported for 

another SECN park that is a globally Important Bird Area. In fact, 16 taxa identified as priority 

species in the South Atlantic Migratory Bird Initiative Implementation Plan were recently found in 

Horseshoe Bend. The mammalian fauna species list, in contrast, includes only 22 documented native 

species, although 10-11 more are suspected to occur in the park; and at least 16% of the total 

mammalian fauna taxa (5 species) are exotic/invasive.

Aside from invasive exotic taxa, park staff has identified several species of special management 

concern. Prescribed fires at five-year intervals are being used to encourage re-establishment of 

longleaf pines along the ridgeline for a more balanced ecosystem. Recently invasive coyotes may be 

adversely affecting other predators in the park such as gray foxes. Wild turkeys and white-tailed deer 

appear to be over-populated in the park north of the river, but over-hunted in the area south of the 

river. Unfortunately, none of these species has been quantified or assessed for health and stressors.

The larger Mobile River watershed, which contains the Tallapoosa River and Horseshoe Bend, 

historically was home to many endemic species including fishes, mussels, aquatic snails, turtles, 

aquatic insects and crustaceans. During the past two centuries, watershed development has led to 

species extinctions at a rate unparalleled elsewhere in the mainland U.S. and various aquatic and 

wetland species are now threatened or endangered. The habitat fragmentation imposed by the Harris 

and Lake Martin dams, along with two other dams on the lower Tallapoosa River, have affected 

faunal diversity, species distributions, and fisheries. The river serves as a transportation corridor for 

exotic/ invasive species. In contrast, various endemic species appear to have been locally extirpated, 

including most fish species of concern that are sensitive to extreme artificial hydrologic fluctuations 

and/or degrading water quality. Thus, only 25 native species are listed as presently still occurring in 

Horseshoe Bend, and these species are broadly tolerant of disturbance and other human impacts.

Present natural resource concerns are higher sedimentation to surface waters from increased 

upstream clear-cutting, pollution from agriculture and silviculture, and atmospheric deposition of 

pollutants from larger cities in the state and from the Atlanta metropolitan area of Georgia. While the 

middle Tallapoosa sub-basin, at present, is only about 5% urbanized, the combined pressures of 

anticipated increased development in both the upper and middle basins are expected to increase land 

disturbance and water pollution including excessive suspended sediments, nutrients, fecal bacteria, 

and toxic substances. Although the overall potential for nonpoint source impairment in the middle 

sub-basin has been evaluated as low, more than half of the sub-watersheds in this sub-basin were 

estimated by the state environmental agency to have moderate potential of nonpoint source 

impairment because of runoff from forestry practices, clear-cutting, and sedimentation.
xxvii

In selecting the suite of indicators that were developed for natural resource status at Horseshoe Bend, 

a foremost consideration was to ensure insofar as possible that the indicators are scientifically sound, 

clear to the general citizenry, and logistically assessable for park personnel with minimal time and 

additional resources required. We also strived to ensure that the indicators meet the specific needs of 

this park as described by park staff. A total of 58 indicators were used to evaluate the 16 categories 

of natural resources for which sufficient information was available to allow some level of 

assessment. The overall condition of five categories were rated as good; six were evaluated to be in 

fair condition; and five were in poor condition, as shown by the Report Card for Natural Resource 

Conditions in Horseshoe Bend:

Natural Resource Category Indicator(s) HOBE Grades

Climate 5 poor

Human Population Surrounding the Park 5 poor

Visitation - Human Population in the Park 3 fair

Land Use / Land Cover 2 good

Air Quality 8 fair

Soundscape 3 good

Lightscape 1 good

Soil and Streambank Erosion 4 fair

Surface Water Hydrology 2 poor

Surface Water Quality 7 fair

Vascular Flora 4 fair

Fish 2 poor

Herpetofauna 2 good

Birds 5 good

Mammals 1 poor

Species of Special Management Concern 4 fair

The Report Card is evenly distributed with good (5), fair (6), and poor (5), rating an overall “C.” 

Importantly, of these 16 categories of natural resources, most are not possible for the National Park 

Service to control. Only a few categories, within the park biota, can be even partly controlled by park 

staff.

Major knowledge gaps prevented or seriously restricted evaluation of the present condition of several 

natural resource categories. These gaps, and efforts needed to fill them, include:

 Streambank Erosion - A study should be conducted to develop a channel stability index for the 

Tallapoosa River in the park.

 Surface Water Hydrology - The RSS planned for Horseshoe Bend is expected to identify 

additional hydrologic targets, such as an indicator for tracking undesirable high water conditions 

over time, and an indicator to assess changes in flows of the springs in the park.
xxviii

 Groundwater Supply - A monitoring well is needed near Horseshoe Bend within the Piedmont 

aquifer that underlies the park, to provide the data needed to assess aquifer drawdown over time.

 Surface Water Quality - Data for the parameters selected as indicators should be collected at least 

monthly to enable reliable assessment of water quality conditions over time, from one station on 

each stream in the park. In addition, data are needed for fecal coliform bacteria and chlorophyll a

(suspended algal biomass in the Tallapoosa River within Horseshoe Bend).

 Stream Sediment Quality - Information is needed to enable assessment of the quality of stream 

sediments in Horseshoe Bend, focusing on toxic substances such as mercury and PCBs, to 

address an identified concern of park staff.

 Groundwater Quality - Information is lacking on groundwater quality in or near the park. 

Monthly sampling at least every other year is needed to characterize the pH and track 

concentrations of contaminants such as nitrate+nitrite, sulfide, and metals (e.g., iron, aluminum, 

manganese).

 Stream Macroinvertebrate Communities - Stream macroinvertebrates should be assessed at fiveyear intervals as an important biological component of Horseshoe Bend.

 Ecological Studies - Concerted studies of key vascular plant communities and key species of 

interest are needed, including quantitative abundance data and maps. The species-level studies 

should emphasize the dominant terrestrial and wetland vascular plants in each of the general 

habitat types found in the park; the common Category #1 and Category #1 Alert invasive 

vascular plants of most concern to park staff; and any other exotic/invasive fauna of major 

concern to park staff.

 Population Studies - Species of special management concern, including wild turkeys, coyotes, 

and white-tailed deer, should be assessed for food availability, hunting/ poaching pressure, 

disease, and effects on the park ecosystem.

 Updated Biota Surveys - Vouchered species lists should be updated on a decadal basis to assist in 

tracking the biological resource conditions in the park.

 Analysis Over Time of the Cumulative and Synergistic Effects of Pressures from Climatic, Land 

Use, and Exotic/Invasive Species Changes - The rate of climate warming in this century is 

projected to be from 2.5- to 5.8-times higher than the rate measured during the 1900s. 

Temperatures are expected to increase by 2.58°C to 4.58°C. Watershed development is 

expected to accelerate; for example, an average 255% increase in housing density is projected 

by 2100 in lands surrounding national parks throughout the nation. The Au-OpMA, near the 

park, is rapidly growing. Exotic/invasive species generally are favored by disturbances such as 

these. The cumulative, synergistic effects of such changes are predicted to dramatically impact 

ecosystem function and biodiversity in national parks. In fact, it has been estimated that 30% of 

the parklands may lose their present biomes by as early as 2030. 

We have recommended various additional efforts by the Southeast Coast Network which, 

together with the present and planned I&M Program protocols, will greatly strengthen 

understanding about how each of these pressures affects Horseshoe Bend natural resources. The 

resulting databases will make it possible for the Network to consider climatic, land use, and 

exotic/invasive species changes more realistically – through integrative rather than separate 
xxix

analyses of cumulative/ synergistic impacts over time. Ultimately, that approach offers the best 

hope of restoring and protecting the natural resources of Horseshoe Bend.

1

1. NRCA Background Information

Natural Resource Condition Assessments (NRCAs) evaluate current conditions for a subset of 

natural resources and resource indicators in National Park units, hereafter “parks.” NRCAs also 

report on trends in resource condition (when possible), identify critical data gaps, and characterize a 

general level of confidence for study findings. The resources and indicators emphasized in a given 

project depend on the park’s resource setting, status of resource stewardship planning and science in 

identifying high-priority indicators, and availability of data and expertise to assess current conditions 

for a variety of potential study resources and 

indicators.

NRCAs represent a relatively new approach to 

assessing and reporting on park resource 

conditions. They are meant to complement – not 

replace – traditional issue- and threat-based 

resource assessments. As distinguishing 

characteristics, all NRCAs:

 are multi-disciplinary in scope;

1

 employ hierarchical indicator frameworks;

2

 identify or develop reference 

conditions/values for comparison against 

current conditions;

3

 emphasize spatial evaluation of conditions and GIS (map) products;

4

 summarize key findings by park areas;5and

 follow national NRCA guidelines and standards for study design and reporting products.

 

1

The breadth of natural resources and number/type of indicators evaluated will vary by park.

2

Frameworks help guide a multi-disciplinary selection of indicators and subsequent “roll up” and reporting of data for measures, 

conditions for indicators, and condition summaries by broader topics and park areas.

3 NRCAs must consider ecologically-based reference conditions, must also consider applicable legal and regulatory standards, 

and can consider other management-specified condition objectives or targets; each study indicator can be evaluated against one 

or more types of logical reference conditions. Reference values can be expressed in qualitative to quantitative terms, as a single 

value or range of values; they represent desirable resource conditions or, alternatively, condition states that we wish to avoid or 

that require a follow-on response (e.g., ecological thresholds or management “triggers”).

4 As possible and appropriate, NRCAs describe condition gradients or differences across a park for important natural resources 

and study indicators through a set of GIS coverages and map products.

5

In addition to reporting on indicator-level conditions, investigators are asked to take a bigger picture (more holistic) view and 

summarize overall findings and provide suggestions to managers on an area-by-area basis:1) by park ecosystem/habitat types or 

watersheds, and 2) for other park areas as requested.
2

Although the primary objective of NRCAs is to report on current conditions relative to logical forms 

of reference conditions and values, NRCAs also report on trends, when appropriate (i.e., when the 

underlying data and methods support such reporting), as well as influences on resource conditions. 

These influences may include past activities or conditions that provide a helpful context for 

understanding current conditions, and/or present-day threats and stressors that are best interpreted at 

park, watershed, or landscape scales (though NRCAs do not report on condition status for land areas 

and natural resources beyond park boundaries). Intensive cause-and-effect analyses of threats and 

stressors, and development of detailed treatment options, are outside the scope of NRCAs.

Due to their modest funding, relatively quick timeframe for completion, and reliance on existing data 

and information, NRCAs are not intended to be exhaustive. Their methodology typically involves an 

informal synthesis of scientific data and information from multiple and diverse sources. Level of 

rigor and statistical repeatability will vary by resource or indicator, reflecting differences in existing 

data and knowledge bases across the varied study components.

The credibility of NRCA results is derived from the data, methods, and reference values used in the 

project work, which are designed to be 

appropriate for the stated purpose of 

the project, as well as adequately 

documented. For each study indicator 

for which current condition or trend is 

reported, we will identify critical data 

gaps and describe the level of 

confidence in at least qualitative 

terms. Involvement of park staff and 

National Park Service (NPS) subjectmatter experts at critical points during 

the project timeline is also important. 

These staff will be asked to assist with the selection of study indicators; recommend data sets, 

methods, and reference conditions and values; and help provide a multi-disciplinary review of draft 

study findings and products.

NRCAs can yield new insights about current park resource conditions but, in many cases, their 

greatest value may be the development of useful documentation regarding known or suspected

resource conditions within parks. Reporting products can help park managers as they think about 

near term workload priorities, frame data and study needs for important park resources, and 

communicate messages about current park resource conditions to various audiences. A successful 

NRCA delivers science-based information that is both credible and has practical uses for a variety of 

park decision making, planning, and partnership activities.

However, it is important to note that NRCAs do not establish management targets for study 

indicators. That process must occur through park planning and management activities. What an 

NRCA can do is deliver science-based information that will assist park managers in their ongoing, 

long-term efforts to describe and quantify a park’s desired resource conditions and management 
3

targets. In the near term, NRCA findings assist strategic park resource planning6and help parks to 

report on government accountability measures.7In addition, although in-depth analysis of the effects 

of climate change on park natural resources is outside the scope of NRCAs, the condition analyses 

and datasets developed for NRCAs will be useful for park-level climate change studies and planning 

efforts.

NRCAs also provide a useful complement to rigorous NPS science support programs, such as the 

NPS Natural Resources Inventory & Monitoring (I&M) Program.8For example, NRCAs can provide 

current condition estimates and help establish reference conditions, or baseline values, for some of a 

park’s vital signs monitoring indicators. They can also draw upon non-NPS data to help evaluate 

current conditions for those same vital signs. In some cases, I&M data sets are incorporated into 

NRCA analyses and reporting products.

Over the next several years, the National Park Service plans to fund a NRCA project for each of the 

approximately 270 parks served by the NPS I&M Program. For more information on the NRCA 

program, visit http://nature.nps.gov/water/nrca/index.cfm.

 

6 A NRCA can be useful during the development of a park’s Resource Stewardship Strategy (RSS) and can also be tailored to act 

as a post-RSS project.

7 While accountability reporting measures are subject to change, the spatial and reference-based condition data provided by 

NRCAs will be useful for most forms of “resource condition status” reporting as may be required by the National Park Service, 

the Department of the Interior, or the Office of Management and Budget.

8

The I&M program consists of 32 networks nationwide that are implementing “vital signs” monitoring in order to assess the 

condition of park ecosystems and develop a stronger scientific basis for stewardship and management of natural resources across 

the National Park System. “Vital signs” are a subset of physical, chemical, and biological elements and processes of park 

ecosystems that are selected to represent the overall health or condition of park resources, known or hypothesized effects of 

stressors, or elements that have important human values.

5

2. Introduction and Setting

2.1. Introduction

Horseshoe Bend National Military Park (HOBE), located in east-central Alabama in Tallapoosa 

County, is a small park (826 hectares, or 2,040 acres; Figures 1 and 2) traversed by the Tallapoosa 

River, a tributary of the Mobile River. It is about 32.2 kilometers (km; or 20 miles) downstream from 

the Harris Dam at the outflow of the Harris Lake impoundment, and about 9.7 km (6 miles) upstream 

from the Lake Martin impoundment. The park is easily accessible from State Highway 49, 8 km (5 

miles) south of New Site (population ~765 as of 2012) and 19.3 km (~12 miles) north of Dadeville 

(population ~4,300). The largest nearby human population center is Alexander City (population 

~16,000) about 13 miles west, adjacent to Lake Martin. Birmingham (metropolitan area population 

1,136,650 as of 2012; Godwin 2013) lies about 145 km (90 miles) northwest, Montgomery 

(metropolitan area population 377,149 as of 2012) is about 113 km (70 miles) southwest, and 

Atlanta, Georgia is about 177 km (110 miles) northeast.

Horseshoe Bend lies at the southern end of the Piedmont Plateau, in a transitional area between the 

Piedmont and Coastal Plain physiographic provinces, but is characterized mostly by Piedmont 

geology and hydrology (Rasmussen et al. 2009). Its low, rolling hills reach an elevation from ~183-

217 m (600-711 ft.) above mean sea level. Its soils are clay-rich, and its major surface water body is 

the Tallapoosa River. The park area (~826 hectares or 2040 acres) consists mostly of mixed 

hardwood forest uplands (83%, or 688 hectares [1,700 acres]); the remainder is ecologically 

disturbed (mowed battlefield area and recovering farmlands, ~55 hectares or 136 acres), and 

wetlands (10% of the park area, or 88 hectares [204 acres]; Rasmussen et al. 2009; Plate 1). Much of 

the park area was farmed for more than 100 years, and various open fields are sites of historic battles.

Horseshoe Bend is under the jurisdiction of the National Park Service and is one of the four 

dedicated War of 1812 parks in the NPS system along with Fort McHenry National Monument in 

Baltimore, Perry’s Victory & International Peace Memorial in Ohio, and Chalmette National 

Battlefield in New Orleans. The park is the site of the Battle of Horseshoe Bend, where Major 

General Andrew Jackson’s forces annihilated about 900 of 1,000 Creek Native Americans on 27 

March 1814. The Creek War began as a civil war within the Creek (Muscogee) Native American 

nation, between the Upper Creeks who wished to strike against U.S. expansionists and return to a 

traditional way of life and the Lower Creeks who sought not to aggravate the U.S. government and 

attempted to assimilate themselves into white culture. In February 1813, friction among the Creeks 

intensified when a group of Upper Creeks, known as the Red Sticks, killed seven frontier families 

after being told erroneously that the United States and the Creek Nation were at war. After a Creek 

tribal council tried and executed the Creeks responsible for the killings, angered Red Sticks set out to 

destroy white settlements and opposing Creeks. Several months later at Burnt Corn Creek in 

Alabama, Red Sticks retaliated against a group of American soldiers and plundered their munitions. 

This exchange broadened the Creek Civil War to include American forces. Incited to fight, William 

Weatherford, a Red Stick leader, ordered his warriors to assault an American stockade, Fort Mims, 

on the Alabama River on 30 August 1813. Although Weatherford attempted to restrain his warriors, 

the Red Sticks killed about 500 people.
6

Figure 1. Maps showing the location of HOBE. (Left – black dot ≡ park location in Alabama; middle –

middle Tallapoosa River watershed or sub-basin [park boundary in black]; and right – close-up of park) in 

east-central Alabama between Harris Lake and Lake Martin (direction of water flow is from north to south. 

From the NPS SECN (2014).

Jackson, an expansionist who saw the opportunity to secure Creek land, demanded “retaliatory 

vengeance” (Schafer 2003). In November of 1813, Jackson led an advance on the Creeks, and ~500 

Creeks were killed during the battles of Tallushatchee and Talladega in Alabama (Figure 2).

Although the Creeks defeated Tennessee militiamen in three minor engagements in January 1814, 

they finally were overcome in the Battle of Horseshoe Bend. In DeVivo (2004), it was stated that, 

“Never before or since in the history of the United States have so many Native Americans lost their 

lives in a single battle. This battle ended, for all time, the power of the lands Creek Nation.” The 

Creek Confederacy was broken. Its defeat opened the way for settlement in Alabama and other parts 

of what historically was referred to as “the old Southwest.” Creek lands were subsequently were 

added to the United States and opened for settlement.

The National Park Service currently maintains a Visitors Center and museum, a 4.5-km (2.8-mile) 

nature trail, a 4.8-km (3-mile) tour road, picnic areas, and the battlefield. Grasslands and cleared 

grass fields associated with battlefields and park facilities can be found in the central regions of the 

park; the “Battlefield Area” has large open areas of well-mowed grasses interspersed with patches of 

mixed forest. In the visitor’s area, a paved road can be used to reach various observation posts; there 

is also a Battlefield Hiking Trail and a Nature Hiking Trail. A network of several miles of service 

roads traverses the non-visitors area.
7

Figure 2. Map showing features of the battle at Horseshoe Bend (1814) within the park. The green border 

shows the boundaries of the present-day park. Other park features are also shown (NPS 2015e).

Plate 1. The tranquil present-day setting of the bloody Battle at Horseshoe Bend. Approximately 900 of 

1,000 Creek Native Americans were annihilated here by Jackson’s forces on 27 March 1814 (NPS 

2015e).
8

Enabling Legislation and Potential for Expansion

As early as August 1907, Alabama state legislature voted to petition the U.S. Congress to establish 

Horseshoe Bend Battle Park to memorialize a battle site of “great patriotic and educatory value” 

(Cummings and Gebhard 1996). Congress voted in April 1914 to appropriate $5,000 to erect a small 

stone monument on the battleground, but petitions to establish a military park at the site were 

rejected in 1909, 1911, 1913, and 1914 because the “national significance” of the event was in doubt 

(Cummings and Gebhard 1996). Also during this period, a controversy erupted over who owned the 

battle site and who would control the region's emerging hydroelectric technology. Benjamin Russell, 

a local industrialist, began to build his own dam near Alexander City. In 1911, the Alabama Power 

Company, which planned to build its own dam on the river at Cherokee Bluff, brought suit against 

Russell and was successful at having construction stopped. In 1923, the Alabama Power Company 

purchased Horseshoe Bend from Russell. The company’s president, Thomas Martin, whose greatgrandfather had fought with Jackson’s army in 1814, recommended to the Power Company’s board 

of directors that no action on a dam should be taken until every effort to win congressional approval 

for a national park had been expended (Martin 1959).

After much research, Martin succeeded in convincing Congress of the significance of the battle. A 

Congressional Act approved on 25 July 1956 (70 Stat. 651 - first section, 16 U.S.C. § 430ff) 

provided that when at least 2.02 square kilometers (km2; or 500 acres) of non-Federal lands known as 

the Horseshoe Bend Battle Ground had been acquired and transferred to the Federal Government, the 

area would be dedicated as the Horseshoe Bend National Military Park. On 11 June 1957, in accord 

with the second section of that act (16 U.S.C. § 430gg), the Secretary of the Interior approved a map 

of 8.26 km2(2,040 acres) on the Horseshoe Bend Battleground for the park. The Alabama state 

legislature provided $150,000 to purchase part of the area, and the remaining ~2.27 km2(560 acres) 

were donated by the Alabama Power Company. The deeds for the land were presented to the 

Secretary of the Interior on 24 April 1959 (Cummings and Gebhard 1996). With the requirements of 

both sections of the Act having been met, on 11 August 1959 President Eisenhower issued 

Proclamation No. 3308 (73 Stat. c72, 16 U.S.C. 430 ii 24 F.R. 6607) to establish the park. HOBE 

was dedicated March 27, 1964 on the 150th anniversary of the Battle of Horseshoe Bend, thus 

culminating more than 50 years of effort.

2.2. Geographic Setting

The park elevation ranges from 165 meters (m; or ~540 feet, ft.) to more than 183 m (600 ft.) on river 

hills (Dusi and Dusi 1997). Land use within park boundaries is primarily forested by upland and 

floodplain mixed hardwoods and pines. The Tallapoosa River basin is characterized by high 

physiographic diversity. It flows 415 km from the Piedmont uplands in western Georgia and eastern 

Alabama, crosses the Fall line in another set of large falls prior to impoundment, and continues 

across the Coastal Plain, joining with the Coosa River to form the mainstem Alabama River. The 

Middle Tallapoosa sub-basin, which includes Horseshoe Bend, has an area of 1,527.3 km2(589.7 

square miles, mi2) and includes all lands and surface waters that drain to the Tallapoosa River 

between the confluence of the Tallapoosa and Little Tallapoosa Rivers and Martin Dam (Figure 1; 

CH2MHill 2005).
9

The North Carolina State University Center for Applied Aquatic Ecology (NCSU CAAE) analyzed 

land use/land cover in the Middle Tallapoosa River sub-basin (Hydrologic Unit Code [HUC] 

#03150109), which includes Horseshoe Bend, using the most recent National Land Cover (NLCD) 

data, from 2011 (the most recent data available), for comparison with land use/land cover in 2001

and 2006 (Tables 1 and 2). The CAAE also generated a new land use-land cover map for this subbasin using the following procedure: The sub-basin boundary (HUC) Geographic Information 

System (GIS) data layer was provided by the US Geological Survey (USGS), and NLCD for 2006 

were downloaded from the USGS Seamless Data Distribution System (USGS 2015b). Using the 

Spatial Analyst extension of ArcGIS 9.1, the land use classification system was modified to include 

eight general categories: (1) urban areas, (2) row crop agriculture, (3) animal agriculture, (4) forests, 

(5) grasslands, (6) water, (7) wetland, and (8) barren/disturbed. Once the grid was reclassified, the 

Spatial Analyst “tabulate area” function was used to calculate the area of each land class within the 

sub-basin surrounding Horseshoe Bend. This analysis indicated that the park is in a mostly rural 

setting, mainly consisting of forested land cover (~70%) which helps to provide favorable conditions 

for good water quality (CH2MHill 2005; Tables 1 and 2, Figure 3). The remainder is mostly 

grassland (~9%), pasture/hay agriculture (~9%), urban development (5%), and water (~5%), with 

wetlands comprising only about 1.4% of the land cover. While the data for percentages of land 

use/land cover categories were similar in 2001 and 2006, in 2011 there was slightly more 

urban/developed land, less pasture/hay and forest versus more grassland, and less barren/rock area. 

This information provided a baseline from which to assess future watershed changes that may affect 

the park’s natural resources. 

Table 1. Previous land use/land cover, 10-15 yr ago: As of 2001 and 2006, area and percent cover of 

each land use class in the middle Tallapoosa sub-basin (#03150109), from analysis by the NCSU CAAE. 

The National Land Cover data (NLCD) for 2001 were downloaded from the United States Geological 

Survey (USGS) Seamless Data Distribution System (USGS 2015b). Note that “forest” here includes 

silviculture.

Land 

Cover 

Type

Urban/

Developed

Pasture/

Hay

Row 

Crops Forest Grassland Water Wetland

Barren/

Rock Total

2001

km2206.3 382.6 0.8 2,835.1 379.8 201.9 58.8 52.10 4,117.4

miles279.7 147.7 0.3 1,094.5 146.7 77.9 22.7 20.2 1,589.7

% of Total 5.0% 9.30% 0.02% 68.88% 9.20% 4.90% 1.40% 1.30% 100%

2006

km2

209 337.4 0.3 2,835.1 379.8 201.9 58.8 52.10 4,117.4

miles280.7 130.2 0.3 1,060.4 211.3 78.2 22 6.6 1,589.7

% of Total 5.10% 8.20% 0.01% 66.70% 13.30% 4.90% 1.40% 0.40% 100%
10

Table 2. Land use/land cover information. As of 2011, area and percent cover of each land use class in 

the middle Tallapoosa sub-basin (03150109), from analysis by the NCSU CAAE. The NLCD for 2011 

were downloaded from the USGS Seamless Data Distribution System (USGS 2015b).

Land 

Cover 

Type 

(2011)

Urban/

Developed

Pasture/

Hay

Row 

Crops Forest Grassland Water Wetland

Barren/

Rock Total

Area (km2) 214.9 331.2 0.3 2,621.1 674.9 202.8 57.0 15.2 4,117.4

Area 

(miles2)

83.0 127.9 0.1 1,012.0 260.6 78.3 22.0 5.8 1,589.7

% of Total 5.22% 8.04% 0.01% 63.66% 16.40% 4.93% 1.38% 0.37% 100%

The Environmental Research and Mapping Facility (ERMF) at the University of Tennessee –

Chattanooga (2007) was retained by the National Park Service to develop and maintain a GIS Base 

Map for Horseshoe Bend (Figure 4). The ERMF conducted data surveys, field data collection, and 

additional file processing and development to derive geospatial files and metadata. Tasks included 

verification of digitized topographical map components and development of distinct data processing 

layers including contours, the river and creeks, structures, paved roads, dirt roads, monuments, and 

the park boundaries. Primary forest distributions were developed. Existing fire management maps 

were digitized to show 26 burn units within the park. Distinct data layers were also developed for the 

visitor center/administration building, maintenance building, three houses, a boat ramp, two picnic 

shelters, three interpretative shelters, a barricade location, water-sewage-electrical lines, hiking trails 

(4.8 km or 3 miles), dirt fire roads (19.3 km or 12 miles), wooden fencing, three drilled water wells, 

USGS boundary markers, and interpretative stops along the main tour road within the park. The 

information, and scanned historic documents are available on an auto-run compact disc application.
11

Figure 3. Map of land use/land cover (2011 NLCD in GIS, first available in 2014) in the Middle Tallapoosa 

sub-basin (#03150109) that includes HOBE (red outline). Map: NCSU CAAE (S. Flood).
12

Figure 4. Interactive map for GIS files and metadata, created by the Environmental Research and 

Mapping Facility (ERMF 2007) at the University of Tennessee - Chattanooga.

2.3. Demographics

The Middle Tallapoosa River basin is sparsely populated (Figure 5). The estimated population of

Tallapoosa County in 2011 was 41,623 people with 71.2% Caucasian, 26.9% African-American, 

0.4% Native American, and 0.5% Asian. About 78% of persons age 25 or older were high school 

graduates; 17.1% had a Bachelor’s degree or higher. The area is economically depressed, with a

median household income of $39,400 (only about 2/3 of the national average). Unemployment is 

high (11.5%; Economic Profile System-Human Dimensions Toolkit [EPS-HDT] 2012), and 17.1% of 

the population (more than 7,000 people) are below poverty level (U.S. Census Bureau 2015) This 

percentage is higher than the national average reported for those years, at 13.8%.

The population density in the county averages 22 people per km2 (58 people per mi2), and 75% of 

the population lives in a rural setting (Advameg, Inc. 2014). The population increased 23% from 

1970 to 2010, but decreased by 0.34% over the past decade (2000-2010; Moonshadow Mobile 2012; 

EPS-HDT 2012). Employment has also been stagnant, increasing by only 1% from 1970 to 2010. A 

landscape dynamics analysis by the NPS (SECN Program Manager Joe DeVivo, pers. comm., 

August 2013) showed that the human population in the 25 km area surrounding the park had a net

increase in the past 20 years of only 1.1%.

Although the immediate area surrounding the park is still rural and low in human population density, 

an identified concern of park staff is the burgeoning population of adjacent Lee County 

(Superintendent Mr. Doyle Sapp, pers. comm., April 2013; and see Chapter 4). Only about 64 km (40 

miles) southeast of the park, the Auburn-Opelika metropolitan area (Au-OpMA) in Lee County 

(population 147,257 as of 2012) is the 11th fastest growing metropolitan area in the nation. The AuOpMA grew 2.6% in human population from July 2011-July 2012 (Alabama Media Group 2015). 

This represented the highest growth anywhere in the state. By comparison, the Montgomery
13

metropolitan area lost 1,413 residents and the Birmingham-Hoover metropolitan area grew only 

slightly. Lee County has a high population density of 91.1 people per km2(236 people per mile2as of 

2011 (Advameg 2015).

It has now become economically advantageous for farmers in eastern Tallapoosa County to sell their 

lands for development. Development was first proposed along the park boundary in 2007. Park staff 

are concerned that the rapid increase in nearby urbanization will result in increased highway traffic; 

increased air, water, land, light, and noise pollution; and other urban sprawl issues (Superintendent

Mr. Doyle Sapp, pers. comm., April 2013; and see NPS 2008). The Strategic Plan for Horseshoe 

Bend (2008-2012; NPS 2012) also identifies the increasing population of neighboring Lee County as 

a threat to the rural setting of the park.
14

Figure 5. The Middle Tallapoosa River basin human population. Map shows the sparse population as of 

2010 (black dots), Horseshoe Bend National Military Park (red), and the only population center near the 

park (Alexander City). Map: NCSU CAAE (S. Flood).
15

2.4. Visitation Statistics

The National Park Service (2008) reported that each year one million travelers on Highway 49 pass 

through the park, on average. The park itself has been estimated to average approximately 100,000 

visitors per year as recreational visitors (Rasmussen et al. 2009). Of that population, about 70,000 

visitors use the Tour Road, Nature Trail and park grounds; 15,000 visitors use the Tallapoosa River 

access; 25,000 people make use of the park’s amenities (visitors center, bookstore, auditorium); and 

an estimated 26,000 people benefit from special events and programs.

The National Park Service has gathered statistics for the number of recreationists in the park, and the 

data show a decrease in recreating visitors during the period from 2001 to 2012 (Figure 6). The 

median number of visitors annually over that period was 71,149. An additional figure provided by 

former Horseshoe Bend Chief Ranger J. Cahill shows the number of visitors who used the boat ramp 

over roughly the same period (2003-2011; Figure 7).

Figure 6. Visitation statistics for total recreationists per year in the park (NPS 2015i).

1960 1970 1980 1990 2000 2010

Number of Visitors

0

100000

200000

300000

400000
16

Figure 7. Visitors to the Park for recreation or use of the boat ramp (2003–2011). Source: former HOBE

Chief Ranger Jim Cahill, 2011.

2.5. Watersheds

Horseshoe Bend is located within the middle Tallapoosa basin (HUC 013150109).The Tallapoosa 

River is a major tributary within the Mobile River basin (113,959 km2, or 44,000 miles2), which is 

the 6th largest river basin in the U.S. (Burkholder and Rothenberger 2010; Figure 8). From its 

headwaters in northwest Georgia (four counties west of the City of Atlanta, Georgia), the Tallapoosa 

River flows 314 km (195 miles) south-southwest through Alabama (16 counties) until it joins the 

Coosa River near Montgomery to form the Alabama River.

In Alabama, the Tallapoosa River basin (12,121 km2or 4,680 miles2) lies within the Piedmont (with 

Horseshoe Bend) and Coastal Plain physiographic provinces. Its physiography reflects a geologic 

history of mountain building in the Appalachian Mountains together with long periods of repeated 

land submergence in the Coastal Plain province 

(https://epd.georgia.gov/sites/epd.georgia.gov/files/related_files/site_page/chapt-21.pdf, last accessed 

in May 2015).. The Piedmont has well-dissected uplands with rounded inter-stream areas to the 

north, and substantial erosional and weathering resistance of underlying geologic units. The stream 

patterns are predominantly dendritic (Journey and Atkins 1996).

40,000

35,000

30,000

25,000

30,000

15,000

10,000

5,000

2003 2004 2005 2006 2007 2008 2009 2010 2011

Recreational Visits

Boat Ramp

40,000

35,000

30,000

25,000

30,000

15,000

10,000

5,000

2003 2004 2005 2006 2007 2008 2009 2010 2011

Recreational Visits

Boat Ramp
17

Figure 8. Map of the Tallapoosa River watershed showing the various locks and dams (National Atlas of 

the United States 2006).
18

2.6. GIS Data Layers

2.6.1. Data Selection and Acquisition

Data files available from NPS GIS personnel were pared down to those relevant to natural resource 

management concerns. An FTP site was set up for file transfer from NPS personnel to the CAAE 

server. Data considered necessary for specific analytical or display purposes, but unavailable from 

NPS files, were obtained from external databases. The databases that provided national or statewide 

data for use in assessing Horseshoe Bend included:

 National Land Cover Database 2006 (NLCD2006) provided through Multi-Resolution Land 

Characterization (MRLC) consortium (USGS 2015a);

 Statewide hydrology, elevation, geographic names and government unit file were obtained from 

the Geospatial Data Gateway (USDA NRCS 2014);

 National Wetlands Inventory (NWI), Critical Habitat, National Wildlife Refuge Boundaries, and 

Wilderness Preserve Boundaries were obtained from U.S. Fish and Wildlife (USFWS 2015);

 Landfill, Land Application Sites and 305(b) and 303(d) waterbody listings for 2010 were 

obtained from Alabama Dept. of Environmental Management (ADEM 2015);

 2010 U.S. Census Population Density data obtained from U.S. Census Bureau (U. S. Census 

Bureau 2015b)

All of the above websites were last accessed in May 2015.

NPScape should also be mentioned here: It is a landscape dynamics monitoring project of the 

National Park Service that produces and delivers to parks a suite of landscape-scale datasets, maps, 

reports, and other products to inform resource management and planning at local, regional, and 

national scales. Initial analyses include six major categories (population, housing, roads, land cover, 

pattern, and conservation status) that broadly address the environmental drivers, natural attributes, 

and conservation context of the parks. In aggregate, these measures contribute to assessments of 

current natural resource status, potential threats, and conservation vulnerability and opportunity (NPS 

2014b).

2.6.2. Data Oversight and Database Management

Each file was accessed and reviewed for spatial reference and availability/correctness of metadata. 

Where necessary, files were copied and post-processed to merge into a cohesive database for acrossthe-board integration in map-making and analyses. Aerial imagery was examined in ArcMap and 

orthorectified where necessary.

Organizational efforts were made to maintain copies of NPS data in an “unadulterated” form digitally 

segregated from data that had been geoprocessed or created by the CAAE, while maintaining a 

logical directory structure. We separately maintained oversight of CAAE GIS systems (software and 

hardware), GIS computer hardware upkeep and maintenance, troubleshooting/updating of ArcGIS 

software, and, as needed, addressed any other database management requirements for spatial data 

amassed by CAAE staff. All of the GIS data we have gathered are listed in Appendix 1.
19

2.6.3. Map Generation

Maps depicting various geographic themes were developed for Horseshoe Bend, including soils, 

geology, hydrology, wetlands, population density, impervious surfaces, urban encroachment and 

social trails, and land use coverage/change in the park, sub-watershed, and/or overall river basin. The 

maps were designed to address points of interest specific to the park, and to illustrate geographic 

positioning of known site localities and/or regional relationships.

21

3. Natural Resources Inventory

3.1. Climate

Climate is defined as the long-term pattern and processes of weather events for a given location 

(UGA 2015). Climate is one of the most significant influences dictating biotic components anywhere 

on Earth.

Weather and climate are key drivers for ecosystem patterns and processes, affecting both biotic and 

abiotic components alike. Understanding the role of climate as a forcing agent for other vital signs 

(e.g., plant and animal communities) is a critical component of network monitoring. Continuous 

weather monitoring is [also] a key factor in separating the effects of climate from the effects of 

human-induced disturbance on plant and animal community and population dynamics (White 2011).

The Tallapoosa watershed has a moist, temperate climate, with mean annual precipitation ranging 

from 124 to 135 cm (49 to 53 inches) per year (USGS 1997, Georgia Environmental Protection 

Division 1998). The state in general has relatively mild winters, hot summers, and year-round 

precipitation (Alabama Humanities Foundation 2012). Precipitation occurs mostly as rainfall that is 

fairly evenly distributed throughout the year except for a distinct dry season from mid-summer to late 

fall (Georgia Environmental Protection Division [GA EPD] 1998). Precipitation typically is highest 

in March and lowest in October. The mean annual temperature is about16.1°C (61°F; GA EPD 

1998).

Summary climate data for Horseshoe Bend are presented in annual reports published by the

Southeast Coast Network, available online in the NPS’s NRInfo portal (http://nrinfo.nps.gov).

Limited climate data, used for these NPS reports (e.g., Wright 2012), are available from three 

stations near Horseshoe Bend (Table 3, Figure 9); much more complete data records are available 

from the National Oceanic and Atmospheric Administration for the City of Montgomery, 113 km (70 

miles) southeast of the park. The location of the state at mid-latitudes near the Gulf of Mexico 

produces the often-turbulent weather patterns that commonly bring tornadoes and hurricanes to the 

state. Evaporation and transpiration account for approximately 76 cm (30 in) of rainfall, resulting in 

about 45.7 cm (18 in) annually available for streamflow and percolation to groundwater. A dry 

season typically occurs from mid-summer to late fall, whereas maximal precipitation and flow occur 

in March. Prevailing winds are from the south in most months, except from the northeast or north 

from September to January. Average wind speed is highest, about13.8 km (8.5 miles) per hour, in 

March.
22

Table 3. Location of relevant weather stations near HOBE, station network affiliation and additional 

metadata for weather stations used in this report. NL indicates information was not listed in the station 

metadata documentation. dd = decimal degrees; RH = relative humidity (from Wright 2012a).

Distance 

(km[mi])

Station 

Name

National 

Network

Station 

ID

Lat 

(dd)

Long 

(dd) County

Elev.

(ft)

Start 

Date

19.0 [11.8] Alexander City COOP 10160 32.95 -85.95 Tallapoosa 640.1 10/1/1969

28.6 [17.8] Lafayette 2W COOP 14502 32.9 -85.4333 Chambers 740.2 6/1/1948

66.6 [41.4] Anniston Metro 

Airport (RH only)

COOP 10272 33.5833 -85.85 Calhoun 594.2 11/1/1928

Figure 9. Weather stations near Horseshoe Bend National Military Park, Alabama (from Wright 2011).
23

3.1.1. Temperature

Data from the National Weather Service of the NOAA provides excellent information on changes in 

temperature, precipitation, and drought conditions over time. Its historic record for the Atlanta area 

covers the period from 1895 to 2012 (NOAA 2015a). The mean annual temperature across that entire 

118-year period was 16.9°C (62.5°F) (Figure 10). The graph shows two periods of temperature 

increase separated by a period of declining temperatures. When the period from the 1960s to the 

present was considered, there was an increase of 0.2°C (+0.3°F) per decade (Figure 11). The mean 

annual temperature was slightly less, 16.3°C (61.4°F). The summer season (June-August) also 

showed an increasing trend in temperature over the period from 1960° through 2012, and over the 

past decade as well (2003-2012; Figures 12 and 13, respectively).

Figure 10. Mean annual temperature in the Division 5 area of Alabama, including Horseshoe Bend 

National Military Park, from 1895 to 2013, hereafter referred to as NOAA NWS (NOAA 2015).
24

Figure 11. Increasing trend in mean annual temperature in Division 5 of Alabama, including Horseshoe 

Bend National Military Park, from 1960 to 2013. From the NOAA NWS.

Figure 12. Increasing trend in mean summer temperature in Division 5 of Alabama, including Horseshoe 

Bend National Military Park, from 1960 to 2012. The overall average was 25.1°C, or 77.2°F (NOAA 

NWS).
25

Figure 13. Increasing trend in the mean summer temperature in Division 5 of Alabama, including 

Horseshoe Bend National Military Park, from 2004 to 2012. From NOAA NWS.

3.1.2. Precipitation

The annual average precipitation from 1895 to 2012 in the Division 5 area of Alabama showed an 

increasing trend (+1.9 cm or +0.73 inches per decade, and +0.23 cm or +0.09 inches per decade, 

respectively; Figures 14 and 15). In the past decade (2003 through 2012), however, mean summer 

precipitation showed a decreasing trend of -23.27 cm (-9.16 inches; Figure 15).

Overall, both annual and summer precipitation are increasing, long-term (1960s on) and within the 

past decade; mean annual precipitation has increased; and summer precipitation is decreasing. 

Collectively, the data suggest that increasing temperatures and decreasing precipitation in the warm 

season will lead to a decrease in available water at Horseshoe Bend and an increase in drying which 

may, in turn, promote more frequent and/or severe drought conditions.
26

Figure 14. Increasing trend in mean annual precipitation within the Division 5 area of Alabama, including 

Horseshoe Bend National Military Park, from 1895 through 2012. The mean annual precipitation was 

135.2 cm (53.21 inches) over that period, suggesting an increase of +1.85 cm (+0.73 inches) per decade 

(NOAA NWS).
27

Figure 15. Mean summer precipitation (June through August) in the Division 5 area of Alabama during 

2003 to 2012 showing a decrease of 23.27 cm, or -9.16 inches). From NOAA NWS.

3.1.3. Moisture

Drought severity in the region of Alabama that includes Horseshoe Bend was assessed (1896 through 

2012) using the PDSI, a scale ranging from -3 to +3, which assesses the duration and intensity of 

long-term drought-inducing circulation patterns (Dai et al. 2004, Dai 2011a,b). Since long-term 

drought is cumulative, the intensity of drought during the present month depends on the present 

weather patterns along with the cumulative conditions for previous months. Palmer Drought Severity 

Index values rank the severity of a given drought (Table 4). The indicated “classes” were used to 

assign a monthly PDSI value from 1930 to 2012, and the proportion of months in each class for each 

9-year period was determined (Figure 16). Drought severity was highly variable over time, but the 

data show a strong increase in the proportion of months that were in the abnormally dry and 

excessively dry classes since 1896.
28

Table 4. Palmer Drought Severity Index (PDSI) scale. From Dai et al. (2004).

Scale Interval Class Description

-3 or less Severely dry

-2 to less than -3 Excessively dry

-1 to less than -2 Abnormally dry

-1 to less than 1 Slightly dry/favorably moist

1 to less than 2 Abnormally wet

2 to less than 3 Wet

3 or greater Excessively wet

Figure 16. PDSI values for the Division 5 area of Alabama over nine-year periods from 1896 through 

2012. Data from the Southeast Regional Climate Center (SERCC).
29

3.1.4. Phenology (Growing Degree Days)

Phenology is the study of the effects of changes in the seasonal variation of temperature and

precipitation on biological processes, reflected in the timing of reproduction, flowering, and the 

length of the growing season (NOAA NWS). We assessed changes in phenology as growing degree 

days (GDDs), defined as the total amount of time in an annual cycle when the temperature is above 

4.4oC (40oF), roughly equivalent to the growing season when non-evergreen plants are able to 

photosynthesize. The monthly mean temperature for Division 5 of Alabama over time (1930 to 2012) 

was used to estimate the approximate number of GDDs per month:

GDD = (Tm – 40) Dm

Where GDD = Growing degree days, Tm = monthly mean temperature, and Dm = number of days in 

month. The GDDs for each month were added to estimate the GDDs per year, and these values were 

plotted over time to assess long-term changes in the numbers of GDDs in the Atlanta area (Figures 

17 and 18). Using the approach of Dorr et al. (2009), we also considered phenology within the 

context of a calendar year by selecting an arbitrary GDD threshold of 1200 and then estimating the 

data at which that number of GDDs was reached. This would be similar to estimating the specific 

date when a phenologic event such as cherry trees flowering in March or April. The total monthly 

accumulated GDD through March 31st was calculated by multiplying the mean daily temperature by 

the number of days in a month, and the difference from 1200 was determined. The number of days 

required to reach the 1200 GDD was estimated as the slope of the line for the approximate month. If 

the difference was positive, the exact date where 1200 was achieved was estimated as the slope of the 

line between the total GDD for March and the total for April. If the difference was negative, the same 

procedure was used between February and March. In this way, the calendar date when the 1200 GDD 

was achieved was calculated for each year (Figure 19). The annual GDDs in the Division 5 area of 

Alabama have decreased since the 1930s. However, the approximate date when 1200 GDD was 

reached for each year since 1930 has increased by several days (Figure 20). Thus, the phenology in 

the Division 5 area may be advancing, but the annual variation for GDD is high so that the R2value 

is weak. The analysis indicates that species found in warmer climates may, in time, be able to expand 

into the region, whereas more northern species may be limited.
30

Figure 17. PDSI values for the Division 5 area of Alabama from 1896 to 2012. Data from NOAA NWS.
31

Figure 18. PDSIs over the past decade (2003-2012) in the Alabama Climate Division 5, showing a 

decrease. Data from NOAA NWS.000
32

Figure 19. The GDDs per year for the Division 5 area of Alabama from 1930 through 2012. The long-term 

mean annual number of GDDs is 5,984 (dashed line). The data suggest that the GDD has decreased 

from 1930-2012, but increased in the past decade (green box). Data from the SERCC.

Figure 20. Approximate date when 1200 GDD was reached for each year in the Division 5 area of 

Alabama in 1930 through 2012. Dashed line = long-term mean approximate date when 1200 GDD was 

reached (5/12). The GDD apparently has increased by several days since the 1930s, but has decreased 

in the past decade (green box). Data from the SERCC.

1930

1934

1938

1942

1946

19501954

1958

1962

1966

1970

1974197819821986

1990

1994

1998

2002

20062010

R2 = 0.031

Trend line

Annual Growing Degree Days - Montgomery, AL

Growing Degree Days / Yr

7000

6500

6000

5500

5000

4500

1930

1934

1938

1942

1946

19501954

1958

1962

1966

1970

1974197819821986

1990

1994

1998

2002

20062010

R2 = 0.031

Trend line

Annual Growing Degree Days - Montgomery, AL

Growing Degree Days / Yr

7000

6500

6000

5500

5000

4500

Date when 1200 GDD was reached - Montgomery

Trend line

6/5

5/31

5/26

5/21

5/16

5/11

5/6

5/1

4/26

4/21

4/16

4/11

1930

1934

1938194219461950

19541958

1962196619701974

1978

198219861990

1994

1998

2002

20062010

Date when 1200 GDD was reached - Montgomery

Trend line

6/5

5/31

5/26

5/21

5/16

5/11

5/6

5/1

4/26

4/21

4/16

4/11

1930

1934

1938194219461950

19541958

1962196619701974

1978

198219861990

1994

1998

2002

20062010
33

3.1.5. Extreme Weather Events

Storm tracks within a 161-km (100-mile) radius of Atlanta were acquired from 1851 to 2012 from 

the NOAA National Weather Service. Each storm was rated as a tropical depression (TD), a tropical 

storm (TS), or a Category 1-4 hurricane. Storms categorized as tropical depressions have maximum 

sustained winds of 61 km/hr (38 miles per hour, mph) or less. Tropical storms have maximum 

sustained winds of 63 to 117 km/hr (39 to 73 mph; U.S. Department of Commerce 2001). The 

Saffir/Simpson Hurricane Scale (SSHS; Table 5) rates and categorizes hurricanes on a scale of 1 to 5 

based on wind speeds (Blake et al. 2007), and a major hurricane is rated as a 3, 4, or 5 on the SSHS. 

Storms that occurred on successive days were combined into one storm event, and the event was 

assigned the most severe storm rating that it received). The data were considered by decade, and also 

by the total per month over the period from 1930 through 2012.

Table 5. The Saffir/Simpson Hurricane Scale (SSHS - Blake et al. 2007).

Typical Characteristics of Hurricanes by Category

Scale Number 

(Category)

Wind Speed 

(mph) Millibars Inches Surge (feet) Damage

1 74 - 95 > 979 > 28.91 4 to 5 Minimal

2 96 - 110 965 - 979 28.50 - 28.91 6 to 8 Moderate

3 111 - 130 945 - 964 27.91 - 28.47 9 to 12 Extensive

4 131 - 155 920 - 944 27.17 - 27.88 13 to 18 Extreme

5 > 155 < 920 < 27.17 > 18 Catastrophe

Of the 24 storms in total from 1930 through 2012, all were tropical depressions and tropical storms

except for two level-1 hurricanes and one level-2 hurricane (Figure 21). Most storms in the Atlanta 

area have occurred during August - September (Figure 22). The total number was similar from the 

1930s through the 1990s, then increased within the past decade (Figure 23).
34

Figure 21. Map showing tracks of 24 tropical storms (1930–2012) that passed within 161 km (100 miles) 

of Alexander City, Alabama (NOAA 2015b).
35

Figure 22. The total number of major and minor storms per month (1930 to 2012) that occurred within 

161 km (100 miles) of Alexander City, Alabama.

Figure 23. The number of storms per decade (1930 to 2009 - the latest year for which complete data 

were available) that occurred within 161 km (100 miles) of Alexander City, Alabama.

Number of Storms

10

8

6

4

2

0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Number of Storms

10

8

6

4

2

0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Number of Storms

10

8

6

4

2

0

1930-1939

1940-1949

1950-19591960-1969

1970-19791980-19891990-19992000-2009

Number of Storms

10

8

6

4

2

0

1930-1939

1940-1949

1950-19591960-1969

1970-19791980-19891990-19992000-2009
36

3.2. Air Quality

3.2.1. Federal Criteria for Major Air Pollutants, and a Federal Index Scale

The EPA maintains NAAQS under the federal Clean Air Act (EPA 2014). The Clean Air Act has set 

standards for six “criteria” pollutants (including two categories for one of these, particulate matter) 

(Table 6). The regulatory air quality standards are health-based, and concentrations above the

standards are considered unhealthy for sensitive groups. For example, the eight-hour ozone standard 

is attained when the average of the fourth highest concentration measured is equal to or below 0.08 

parts per million (ppm; 0.085 ppm with the EPA rounding convention), averaged over three years.

The standards for the six criteria pollutants are fairly straightforward except for the particle pollution 

(PM2.5) standard: To be in compliance with the federal air PM2.5 standard, an area must have an 

annual arithmetic mean concentration of less than or equal to 15 μg PM2.5/m3. An additional 

requirement imposed a stricter standard for fine particulate matter as of 2007, wherein the 98th

percentile 24-hour concentration must be < 35 μg PM2.5/m3to protect sensitive groups (Table 6).

Ozone is monitored in March through October, since that period is when ozone production mostly 

occurs (EPA 2004). This pollutant is a serious health concern because it attacks the mammalian 

respiratory system, causing coughs, chest pain, throat irritation, increased susceptibility to respiratory 

infections, and impaired lung functioning. In fact, moderate ozone levels can interfere with 

performance of normal daily activities by people who have asthma or other respiratory diseases. Of 

more concern than acute affects are chronic effects of repeated exposure to ozone, which can lead to 

lung inflammation and permanent scarring of lung tissue, loss of lung function, and reduced lung 

elasticity. Fine particulate matter (PM2.5) is produced by various sources including industrial 

combustion, residential combustion, and vehicle exhaust, or when combustion gases are chemically 

transformed into particles. Research has indicated that PM2.5 is a human health concern because it can 

penetrate into sensitive areas of the lungs and cause persistent coughs, phlegm, wheezing, more 

serious respiratory and cardiovascular disease, cancers, and premature death at particle levels well 

below the existing standards (Schwela 2000, EPA 1994a). Mounting evidence indicates that PM2.5

enhances delivery of other pollutants and allergens deep into lung tissue where the effects are 

exacerbated. Especially sensitive groups include children, the elderly, and people with cardiovascular 

or lung diseases such as asthma. PM2.5 also impairs visibility and contributes to haze in the humid 

conditions that characterize the eastern Alabama climate (EPA 1994a).
37

Table 6. National ambient air quality (AQ) standards (NAAQS, 40 CFR part 50), set by the EPA (October 

2011) for six principal (“criteria”) pollutants considered harmful to public health and the environment. The 

Clean Air Act identifies two types of national ambient AQ standards: Primary standards provide public 

health protection, including protecting the health of “sensitive” populations such as asthmatics, children, 

and the elderly. Secondary standards provide public welfare protection, including protection against 

decreased visibility and damage to animals, crops, vegetation, and buildings (EPA 2014).

Pollutant 

[Final Rule Cited]

Primary/

Secondary

Averaging 

Time Level Form

Carbon Monoxide 

[76 FR 54294, Aug 31, 2011]

primary 8-hour 9 ppm Not to be exceeded more than once per 

year

1-hour 35 ppm

Lead 

[73 FR 66964, Nov 12, 2008]

primary and 

secondary

Rolling 3 

month 

average

0.15 μg/m 3 (1) Not to be exceeded

Nitrogen Dioxide 

[75 FR 6474, Feb 9, 2010], 

[61 FR 52852, Oct 8, 1996]

primary 1-hour 100 ppb 98th percentile, average over 3 years

primary and 

secondary

Annual 53 ppb (2)Annual Mean

Ozone 

[73 FR 16436, Mar 27, 2008]

primary and 

secondary

8-hour 0.075 ppm (3)Annual fourth highest daily maximum 8-hr 

concentration, averaged over 3 years

Particle pollution 

Dec 14, 2012

PM2.5 primary Annual 12 μg/m3annual mean, averaged over 3 years

secondary Annual 15 μg/m3annual mean, averaged over 3 years

primary and 

secondary

24-hour 35 μg/m398th percentile, average over 3 years

PM10 primary and 

secondary

24-hour 150 μg/m3 Not to be exceeded more than once per 

year on average over 3 years

Sulfur Dioxide 

[75 FR 35520, Jun 22, 2010], 

[38 FR 25678, Sept 14, 1973]

primary 1-hour 75 ppb (4)99th percentile of 1-hour daily maximum 

concentrations, averaged over 3 years

secondary 3-hour 0.5 ppm Not to be exceeded more than once per 

year

1 Final rule signed October 15, 2008. The 1978 lead standard (1.5 μg/m3

as a quarterly average) remains in effect until 1 yr 

after an area is designated for the 2008 standard, except that in areas designated nonattainment, the 1978 standard remains in 

effect until implementation plans to attain or maintain the 2008 standard are approved.

2 The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for the purpose of clearer 

comparison to the 1-hr standard.

3 Final rule, signed March 12, 2008. The 1997 ozone standard (0.08 ppm, annual fourth highest daily maximum 8-hour 

concentration, averaged over 3 yr) and related implementation rules remain in place. In 1997, the EPA revoked the 1-hour 

ozone standard (0.12 ppm, not to be exceeded more than once per yr) in all areas, although some areas have continued 

obligations under that standard ("anti-backsliding"). The 1-hour ozone standard is attained when the expected number of days 

per calendar year with maximum hourly average concentrations higher than 0.12 ppm is 1 day or less.

4 Final rule signed June 2, 2010. The 1971 annual and 24-hour SO2 standards were revoked in that same rulemaking. 

However, these standards remain in effect until 1 yr after an area is designated for the 2010 standard, except in areas 

designated nonattainment for the 1971 standards, wherein the 1971 standards remain in effect until implementation plans to 

attain or maintain the 2010 standard are approved.
38

The EPA’s Air Quality Index (AQI) scale (from 0 to 500 with lower values indicating less pollution) 

was designed to help inform the general citizenry about potential health impacts from air quality 

degradation (Tables 7 and 8). The AQI is designed to provide accurate, timely, easily understandable 

information about daily levels of air pollution with a uniform system for the major air pollutants 

regulated under the Clean Air Act. The index allows the general citizenry to assess whether air 

pollution levels in the location of interest are Good, Moderate, Unhealthy for Sensitive Groups, or 

worse. For example, an AQI value of 50 indicates good air quality with low potential for adverse 

public health effects, whereas an AQI of more than 300 indicates hazardous air quality. An AQI less 

than 100 generally is used as the acceptable level set by the EPA to protect public health (Air Now 

2015). Information is also provided about precautions that should be taken if air pollution levels are 

Unhealthy or worse. It should be noted that the state of Alabama relies on the federal standards for 

air quality (Alabama Department of Environmental Management [AL DEM] 2013a).

Table 7. EPA’s Air Quality Index (AQI) criteria (modified from GA DNR 2007b, EPA 2009)

Maximum Pollutant Concentration

AQI Value

Descriptor 

(color-coded) EPA Health Advisory

PM2.5

(24hr) 

μg/m3

PM10

(24hr)

μg/m3

SO2

(24hr)

ppm

O3

(8hr)

ppm

CO 

(8hr) 

ppm

NO2

(1 hr) 

ppm

< 15.4 < 54 < 0.034 < 0.064 < 4.4 None 0-50 GOOD Air quality satisfactory; little 

or no risk from air pollution

15.5 -

40.4 55-154 0.035 -0.144

0.065 -

0.084

4.5 -

9.4 None 51 - 100 MODERATE

Air quality acceptable, but 

for some pollutants there 

may be a moderate health 

concern for a small number 

of unusually sensitive 

people

40.5 -

65.4

155 -

254

0.145 -

0.224

0.085 -

0.104

9.5 -

12.4 None 101 - 150

UNHEALTHY

for Sensitive 

Groups

Sensitive groups (people 

with lung or heart disease) 

are at greater risk from 

exposure to particulate 

pollution, ozone

65.5 -

150.4

255 -

354

0.225 -

0.304

0.105 -

0.124

12.5 -

15.4 None 151 - 200 UNHEALTHY

Everyone may begin to 

sustain health effects; 

members of sensitive 

groups may experience 

more serious health 

impacts

150.5 -

250.4

355 -

424

0.305 -

0.604

0.125 -

0.374

15.5 -

30.4

0.65 -

1.24 201 - 300

VERY 

UNHEALTHY

AQI values trigger a health 

alert; everyone sustain 

more serious health effects. 

If related to high ozone, If 

related to high ozone, 

restricted to morning or late 

evening to minimize 

exposure

250.5 -

500.4

425 -

604

0.605 -

1.004 None 30.5 -50.4

1.25 -

2.04 301 - 500 HAZARDOUS

AQI values over 300 trigger 

health warnings of 

emergency conditions; the 

entire populace is more 

likely to be affected
39

Table 8. The Air Quality Index (AQI) of the EPA (1994) translated into actions that citizens can take to protect their health from potentially harmful 

levels of major air pollutants. From EPA (2009).

AQI Value

Actions To Protect Your Health 

From Particle Pollution

Actions to Protect Your Health 

From Ozone

Actions To Protect Your Health 

From Carbon Monoxide 

Actions to Protect Your Health 

From Sulfur Dioxide

Good

(0-50) None None None None

Moderate 

(51-100*)

Unusually sensitive people 

should consider reducing 

prolonged or heavy exertion.

Unusually sensitive people 

should consider reducing 

prolonged or heavy outdoor 

exertion.

None None

Unhealthy 

for Sensitive 

Groups 

(101-150)

The following groups should 

reduce prolonged or heavy 

outdoor exertion:

- People with heart or lung 

disease

- Children and older adults 

Everyone else should limit 

prolonged or heavy exertion.

The following groups should 

reduce prolonged or heavy 

outdoor exertion: 

- People with lung disease, 

such as asthma 

- Children and older adults

- People who are active 

outdoors

People with heart disease, such 

as angina, should reduce heavy 

exertion and avoid sources of 

carbon monoxide such as heavy 

traffic.

People with asthma should 

consider reducing exertion 

outdoors.

Unhealthy 

(151-200)

The following groups should 

avoid all physical outdoors: 

- People with heart or lung 

disease 

- Children and older adults 

Everyone else should avoid 

prolonged or heavy exertion.

The following groups should 

avoid prolonged or heavy 

outdoor exertion: 

- People with lung disease such 

as asthma 

- Children and older adults

- People who are active 

outdoors Everyone else should 

limit prolonged outdoor exertion.

People with heart disease, such 

as angina, should reduce 

moderate exertion and avoid 

sources of carbon monoxide 

such as heavy traffic

Children, asthmatics, and people 

with heart disease should reduce 

exertion outdoors

Very 

Unhealthy 

(201-300)

The following groups should 

remain indoors and keep activity 

levels low: 

- People with heart or lung 

disease 

- Children and older adults 

Everyone else should avoid all 

physical activity outdoors.

The following groups should 

avoid all outdoor exertion: 

- People with lung disease, such 

as asthma 

- Children and older adults 

- People who are active 

outdoors 

Everyone else should limit 

outdoor exertion.

People with heart disease, such 

as angina, should avoid exertion 

and sources of carbon monoxide 

such as heavy traffic

Children, asthmatics, and people 

with heart or lung disease should 

avoid outdoor exertion. Everyone 

else should reduce exertion 

outdoors.
40

3.2.2. National Park Service Indices for Air Quality

The National Park Service (2011) has developed guidance for assessing AQ conditions within its 

parks, including information for evaluating O3 as related to plant responses. The Air Resources 

Division of the National Park Service used all available monitoring data over the 2005-2009 fiveyear period to generate interpolations for the parks throughout the continental U.S., including parks 

such as Horseshoe Bend that do not have on-site monitoring. The National Park Service then 

determined an index for each type of air quality data considered, including ozone concentrations and 

exposures (mean annual fourth highest eight-hour [hr] ozone concentrations), nitrogen wet 

deposition, sulfur wet deposition, and visibility condition (Group 50 visibility minus estimated 

annual average natural conditions, where Group 50 is the mean of the 40th to 60th percentiles of 

observed measurements in deciview). Park AQ interpolated values are then assigned to one of three

condition categories for each NPS AQ index:

 Air quality is in good condition

 Air quality is in moderate condition

 Air quality is a significant concern

The following procedures are taken from National Park Service (2011):

3.2.2.1.Ozone Condition:

The O3 human health standard (EPA 2008) requires that the three year average of the fourth highest 

daily maximum eight-hour average ozone concentrations measured at each monitor within the area of 

interest over each year must not exceed 75 parts per billion (ppb). Accordingly, the National Park 

Service assigned five-year average values as in Table 9:

Table 9. The NPS ranks for ozone concentrations to protect human health in air quality condition 

assessment (NPS 2011).

Ozone Condition (Human Health) Ozone Concentration

Significant Concern ≥ 76 ppb

Moderate 61-75 ppb

Good ≤ 60 ppb

Note that the “moderate” and “good” conditions are assigned to parks with average five-year, fourth

highest eight-hour ozone concentrations > 80% of the standard and < 80% of the standard, 

respectively.

The National Park Service has incorporated vegetation sensitivity, as well as human health, into its 

park air quality rating, in consideration of the fact that some plant species have been shown to be 

more sensitive to O3 than humans so use of an O3 standard for humans would not be sufficiently 

protective of those plant species. The National Park Service completed a risk assessment in 2004 that 

rated parks at low, moderate, or high risk for ozone injury to vegetation based on the presence of 

sensitive plant species, O3 exposures, and environmental conditions (especially soil moisture). For O3

condition assessment, parks that were evaluated at high risk are moved into the next worse condition 
41

category. For example, a park with an average O3 concentration of 72 ppb, but evaluated at high risk 

for vegetation injury, would be moved from “moderate condition” to “significant concern.”

The National Park Service also developed a method for rating O3 condition considering only plant 

response, based on the EPA’s proposed approach; use of the metric W126 for a secondary O3

standard designed to protect vegetation. The W126 measures cumulative O3 exposure over the 

growing season and is considered a better predictor of plant response than the eight-hour human 

health standard metric. A similar metric, SUM06, also measures cumulative exposure. The thresholds 

below for both metrics are based on recommendations from an expert workgroup (Table 10): W126 

in the range of 7-13 ppm-hr would protect growth effects to tree seedlings in natural forest stands, 

whereas W126 ranging from 5-9 ppm-hr would protect plants in natural ecosystems from foliar 

injury (Heck and Cowling 1997, EPA 2007).

Table 10. The NPS ranks for ozone concentrations to protect sensitive plant species in air quality 

condition assessment. (NPS 2011).

Ozone Condition (Ecological) Ozone Exposure - W126 Ozone Exposure - SUM06

Significant Concern > 13 ppm-hr >15 ppm-hr

Moderate 7-13 ppm-hr 8-15 ppm-hr

Good < 7 ppm-hr <8 ppm-hr

3.2.2.2.Nitrogen and Sulfur Conditions:

Wet deposition is calculated by multiplying the N or S concentration in precipitation by a normalized 

precipitation amount (note: dry deposition data are not available). Factors considered in rating the 

deposition condition include natural background deposition estimates (~.25 kilograms per hectare per 

year [kg/ha/yr] for either N or S), and deposition effects on ecosystems. Certain sensitive ecosystems 

respond to levels of N or S deposition at ~1.5 kg per ha per hr, whereas information is not available 

indicating that wet deposition of < 1 kg/ha/yr causes ecosystem harm. Therefore, the NPS ranks 

parks with wet N or S deposition as in Table 11: Note that the basis for the level of deposition ranked 

as “significant concern” was not given by the National Park Service (2011). Values for parks with 

ecosystems that are potentially more sensitive to N or S are adjusted up one category.

Table 11. The NPS ratings for wet deposition of nitrogen (N) or sulfur (S) in air quality condition 

assessment, in order to protect park ecosystems (NPS 2011).

Deposition Condition Wet Deposition of N or S (kg/ha/yr)

Significant Concern > 3

Moderate 1-3

Good <1

3.2.2.3.Visibility Condition:

This rating is based on the deviation of the current Group 50 visibility conditions from the estimated 

Group 50 natural visibility conditions, where Group 50 is the mean of the visibility observations 

within the range from the 40th through the 60th percentiles. Current visibility is estimated from 
42

interpolating the five-year averages of the Group 50 visibility. Visibility is expressed in terms of a 

haze index (derived from calculated light extinction - see report #EPA-454/B-03-005), in deciviews 

(dv):

Visibility = present Group 50 ̶ estimated Group 50 visibility

Condition visibility under natural conditions

The dv ranges for these categories were described as somewhat subjective but selected to reflect, 

insofar as possible, the variation in visibility conditions across the monitoring network. The NPS 

criteria for visibility were finalized as shown in Table 12:

Table 12. The NPS ratings for visibility in air quality condition assessment. (NPS 2011).

Visibility Condition

Current Group 50 - Estimated Group 50 

Natural (dv)

Significant Concern > 8

Moderate 2-8

Good < 2

3.2.3. Air Quality in the Park and Vicinity

Based on the AQI, air quality in the Alexander City, Ala. area near Horseshoe Bend was evaluated as 

having good air quality 98.94% of the time (days) in 2013 thus far, and 97.57% of the time in 2012 

(Table 13; Homefacts 2015a). Air quality was moderate, and therefore still acceptable for sensitive 

groups, only 6.94% of the time in 2014, and considering the past decade, the highest percentage of 

moderate air quality days occurred in that year. Of the two largest population centers nearest 

Horseshoe Bend to the west - therefore, potential influences on the park’s air quality - Montgomery 

had better air quality than Birmingham (Homefacts 2015b). Air quality was good in Montgomery

91.82 to 97.05% of the time over the past ~seven years (2008 to 2014), with the remainder of the 

time classified as moderate. In contrast, over the past ~seven years, air quality in Birmingham was 

good 79.10 to92.58% of the time, moderate 7.42 to 20.28% of the time, and unhealthy for sensitive 

groups up to 0.61% of the time. For all three population centers, violations of the priority criteria 

standards occurred for ozone and PM2.5; Birmingham also had a small number of violations of the 

carbon monoxide (CO) and sulfur dioxide (SO2) standards.
43

Table 13a. The overall Air Quality Index (AQI) percentage levels for Alexander City, Alabama (Homefacts 

2015a,b)

Air Quality Index (AQI) Percentage Levels Pie Chart

GOOD 93.06 %

MODERATE 6.94 %

UNHEALTHY FOR.SENSITIVE GROUPS 0.00 %

UNHEALTHY 0.00%

VERY UNHEALTHY 0.00 %

HAZARDOUS 0.00 %

Table 13b. The 2014 Air Quality Index (AQI) for Alexander City, Alabama, also showing levels of the top 

six criteria pollutants. Numbers in the two tables show the number of days violations occurred for each 

priority pollutant (Homefacts 2015a,b)

Pollutant Stat. Lat. & Long. Good % 0-50 51-100 101-150 151-200 201-300

301-

500

Ozone 32.4986, -86.1366 97.21% 209 6 0 0 0 0

CO 33.5653, -86.7964 100.00% 274 0 0 0 0 0

NO2 33.5214, -86.8441 98.90% 270 3 0 0 0 0

SO2 33.5531, -86.815 98.53% 269 4 0 0 0 0

PM10 33.5783, -86.7739 98.88% 265 3 0 0 0 0

PM2.5 33.5531, -86.815 60.00% 135 90 0 0 0 0

Table 13c. The 2013 Air Quality Index (AQI) for Alexander City, Alabama, also showing levels of the top 

six criteria pollutants. Numbers in the two tables show the number of days violations occurred for each 

priority pollutant (Homefacts 2015a,b)

Pollutant Stat. Lat. & Long. Good % 0-50 51-100 101-150 151-200 201-300

301-

500

Ozone 32.4986, -86.1366 97.96% 240 5 0 0 0 0

CO 33.5653, -86.7964 100.00% 365 0 0 0 0 0

NO2 33.5531, -86.815 100.00% 31 0 0 0 0 0

SO2 33.5531, -86.815 99.73% 363 1 0 0 0 0

PM10 32.4071, -86.2564 100.00% 89 0 0 0 0 0

PM2.5 33.2813, -85.8022 84.75% 100 18 0 0 0 0

The AQI for Montgomery in 2012 was evaluated as 9% less than the average AQI for Alabama, and 

56.7% greater than the national average (Area Vibes 2015; Table 14). An air “pollution index” (API) 

was also available for the two larger cities, calculated as the sum of the most hazardous air pollutants 

(arsenic, benzene, carbon tetrachloride, lead, and mercury) in kilograms (pounds). The pollution 
44

indices indicate that Birmingham had ~9.1-fold more air pollution by weight of these hazardous 

substances than Montgomery, ~4.3-fold more air pollution than the average for the state, and 2.9-fold 

more air pollution than the national average.

Table 14. Air Quality Index (AQI) and Air Pollution Index (APl; pounds in parentheses) for Montgomery 

and Birmingham, Alabama in 2012, also showing the statewide and national averages (Areavibes.com 

2015). 

Location AQI

Median API in 

kg (lbs)

Days Measured

(for AQI) Evaluation

Montgomery 38 939,911

(2,072,150)

246 209 - good

37 - moderate

0 - Other

Birmingham 58 8,617,439 336 118 - good

202 - moderate

16 - poor for sensitive groups

Alabama

(mean)

42 2,025,117

(4,464,618)

-- --

National

(mean)

37 3,004,568

(6,623,939)

-- --

The Birmingham area has improved in air quality after years of violations. There are no coal-fired 

power plants in the vicinity of Horseshoe Bend, but several lie to the west (Southern Alliance for 

Clean Energy 2002; Figure 24). In 1999, Alabama ranked third in the U.S. in per capita premature 

deaths attributable to PM10 and PM2.5 from power plants, and Birmingham was among the top ten 

cities for highest death rates in the U.S. from power plant fine particulate matter air pollution. The 

Birmingham and Montgomery metropolitan areas were both in violation of the national health 

standard for ground level ozone (Southern Alliance for Clean Energy 2002). Montgomery has since 

made progress, and in January 2013 the EPA reported that for the first time in 30 years, Birmingham 

met federal air quality standards.

Acid deposition is another air quality issue of concern for SECN parks to the east in the Atlanta, Ga.

area. Acid precipitation can adversely affect or kill aquatic life and harm human health (Abelson 

1987, Herlihy et al. 1991, Baker and Christensen 1992), and can act synergistically with ozone to 

harm human health as well (Abelson 1987). The major pollutants from coal-fired power plants, 

including those involved in acid deposition (SO2, mostly from coal-fired power plants, and NOx from 

coal-fired power plants, car exhausts and other sources) can be transported long distances across 

airsheds (Schwela 2000).
45

Figure 24. Map of power plants in Alabama (data from EISPC 2014).
46

Sullivan et al. (2011) assessed the threat of acid deposition to national parks across the nation, 

including Horseshoe Bend. First, they compiled and mapped data for total sulfur and total nitrogen 

emissions from the EPA (2002 National Emissions Inventory dataset - tons per mile2per year); from 

the NADP for wet deposition (2001-2003 - kg/hectare/yr); and from the 12-km Community 

Multiscale Air Quality (CMAQ) Model projections for dry deposition for 2002. Then, they ranked 

the 32 NPS networks and also the individual parks within each network considering four metrics (not 

further defined or explained): Pollutant Exposure, Ecosystem Sensitivity, Park Protection, and an 

overall metric, Summary Risk to acid deposition. This analysis indicated that the Network ranked at 

the top of the second highest quintile in Pollutant Exposure among the NPS networks. Emissions and 

deposition of S and N within the Network were evaluated as fairly high. The SECN Ecosystem 

Sensitivity ranking was Very Low, in the bottom quintile among the networks, and at the bottom of 

the second lowest quintile in Park Protection because it has only limited amounts of protected lands. 

The Network’s overall Summary Risk ranking was relatively low among the networks.

More specifically, Horseshoe Bend lies along the area of outermost influence from the Birmingham 

metropolitan area and other sources of air pollution to the north/northwest and east. As of 2001, the 

area including the park was estimated to have sustained >5 to < 10 kg/hectare/yr of total sulfur 

emissions and total nitrogen emissions (Figure 25). Sullivan et al. (2011) ranked Horseshoe Bend

High (second highest ranking of five) for Pollutant Exposure, and Moderate (third highest ranking) 

for Ecosystem Sensitivity, Park Protection, and overall Summary Risk from acid deposition.
47

Figure 25. Map of total sulfur (S) and total nitrogen (N) emissions (both oxidized forms as nitrogen oxides 

and reduced forms as ammonia) by county as of 2002 in the vicinity of HOBE (star; and black line ≡ 

portion of the SECN boundary delineation). The data are given in units of tons per square mile per year 

(a,b) versus units of kilograms per hectare per year (c,d). Data source for a and b: National Emissions 

Inventory (EPA 2010). Data source for c and d: Wet deposition values were derived from interpolated 

measured values from NADP (3-yr average centered on 2002); dry deposition values were derived from 

12-km CMAQ model projections for 2002. From Sullivan et al. (2011) - but note that although this 

document was recently published, the data used for the publication were from 2002. In the ensuing 

decade, two major point sources of air pollutants significantly reduced their emissions.
48

Air quality is a concern in the park. Horseshoe Bend is within a Class II airshed under the Clean Air 

Act, wherein modest increases in air pollution are allowed beyond baseline levels for particulate 

matter, sulfur dioxide, nitrogen and nitrogen dioxide, provided that the NAAQS, established by the

EPA, are not exceeded. Although the cities to the west have improved in air quality within the past 

few years, in 2008 the federal ozone primary standard was lowered to 0.075 ppm for the eight-hour

averaging time, fourth maximum value, averaged over three years (Federal Register, Vol. 63, No. 

60). Because of that change imposing stricter requirements, there is concern that the Birmingham 

area may not remain in compliance.

Not surprisingly, several air quality issues were identified for Horseshoe Bend by DeVivo et al. 

(2008), including potential aerial deposition of (toxic) metals, high risk of foliar injury based on air 

quality conditions, and Sum06 and W126 indices that frequently or consistently surpassed the NPS 

air quality thresholds identified in Tables 9-12. Overall, the National Park Service has evaluated the 

air quality of Horseshoe Bend to be of significant concern based on the four NPS indices (Figure 26).

It should also be noted that the park occasionally can be affected by smoke from wildland fires 

considerable distances away. For example, in 2007 the National Weather Service reported that 

significant wildland fires which developed across southern Georgia and northern Florida in midApril through May of 2007 pushed a smoke plume into central Alabama. The resulting hazy and 

smoky conditions lasted several days.
49

Figure 26. Evaluation of air quality conditions (2005–2009) at HOBE (NPS 2014a). Air quality condition is 

represented by color: Good = Green, Moderate = Yellow and Significant Concern = Red.
50

3.3. Soundscape

3.3.1. Some Definitions and Interpretations

Sound is defined as an auditory sensation perceived by humans, and created by pressure variations 

that move in waves through a medium such as air or water (NPS 2015e). Sound is measured in terms 

of frequency and amplitude. Noise is defined as sound(s) that is unwanted or inappropriate in an 

environment. Frequency (sometimes referred to as pitch; units, hertz [Hz]) is the number of times per 

second that a sound pressure wave repeats itself. Humans with normal hearing can hear sounds 

ranging from 20 to 20,000 Hz; bats can hear up to 120,000 Hz. Amplitude is defined as the relative 

strength of sound waves (or transmitted vibrations), perceived as loudness or volume. Amplitude, or 

the sound pressure level (intensity), is measured in decibels (dB). The terms dB(A) or dB(C) 

designate two frequency-response functions (weighting characteristics) that filter sounds detected by 

a microphone in a sound level meter. Each emphasizes or de-emphasizes sounds of certain pitches 

relative to others (Figure 27).

Figure 27. Influence of A- and C-weighting curves on the relationship between dB and frequency (pitch, 

Hz; modified from http://www.sengpielaudio.com/calculator-dba-spl.htm, last accessed in May 2015).

The “A” weighting, germane to Horseshoe Bend, filters out the low frequencies and slightly 

emphasizes upper-middle frequencies at ~2 to 3 kilohertz (kHz). A-weighting, used to assess noise 

impacts on wildlife, measures hearing risk and compliance with Occupational Safety and Health 

Administration and Mine Safety and Health Administration regulations that specify permissible noise 

exposures as a time-weighted average sound level or daily noise “dose” that can be tolerated without 

appreciable health risks. Thus, the World Health Organization has recommended that outdoor 

environmental noise should not exceed 55 dB(A) and 40 dB(A) for daytime and nighttime activity, 
51

respectively, to prevent potential adverse psychosocial and physiological effects. For perspective, the 

lower threshold of human hearing is 0 dB; moderate sound levels (e.g. normal speaking voice) are 

less than 60 db; a typical suburban area is ~50-60 dB(A); thunder is ~100 dB(A); and a military jet 

flying at ~100 m above ground level is ~120 dB(A; NPS: see above website, and Crocker 1997).

Because dB are on a logarithmic scale, an increase of 10 dB causes a doubling of perceived loudness 

and represents a ten-fold increase in sound level. Sound levels adjusted for human hearing are 

expressed as dB(A). “Soundscape” is used here in accord with the NPS definition, that is, the human 

perception of these physical sound resources. The acoustical environment is the combination of all of 

the acoustic resources within a given area, including both natural and non-natural (human-caused) 

sounds. Thus, it is important to consider the entire acoustical environment in efforts to protect natural 

sounds.

Sound is an important component of natural park ecosystems; the acoustical environment influences 

a wide array of animal behavior, such as finding desirable habitat and mates, avoiding predators, 

protecting young, and establishing territories (Lynch et al. 2011, and references therein; NPS 2015c).

National parks in all regions of the U.S. are under increasing noise pressure from ground 

transportation, air transportation, and other human activities (Monroe et al. 2007, Lynch et al. 2011). 

For example, noise levels in park transportation corridors are ~1,000-fold higher than natural sound 

levels (Barber et al. 2009). Noise from airplanes can cause as much as a 70% reduction in the size of 

the hunting area where predatory animals are able to hear their prey (Barber et al. 2009, Bell et al. 

2009). There is no question that parks are becoming noisier from human activities, even in remote 

areas, in conflict with the fact that ~70% of Americans have indicated that one of the most important 

reasons for preserving national parks is to provide opportunities to experience natural peace and the 

sounds of nature (Haas and Wakefield 1998). The problem is growing to the extent that national 

parks are presently sustaining what has been described as “an ongoing acoustic assault” by humanrelated noise (see above website). Thus, the National Park Service has determined that “Increasingly, 

careful consideration of the impacts of human-generated noise on wildlife is a critical component of 

management for healthy ecosystems in our parks (NPS 2015c).”

Wildlife, like humans, is stressed by the increasing noise and must adapt. As examples, robins in 

suburban and urban environments are now singing at night in order to be heard by other members of 

their population (Fuller et al. 2007); males of at least one frog species have adapted to traffic noise by 

calling at a higher pitch, although females have been shown to prefer lower-pitched calls which 

apparently are indicative of larger, more “fit” males; bats avoid hunting in areas with road noise 

(Barber et al. 2009, Parris et al. 2009). Noise stress can exacerbate the impacts of other stressors in 

national parks, with important ramifications for wildlife populations.

3.3.2. The Horseshoe Bend Soundscape

Human-related environmental noise reaches Horseshoe Bend from sources such as aircraft, 

construction, trains, and road traffic. The NPS Management Policies and Director’s Order #47, Sound

Preservation and Noise Management, call for and direct the protection of the natural ambient 

soundscape so as to minimize and optimally manage noise, defined as unwanted sound, especially 

dissonant human-caused sounds. However, most noise sources measured in national parks (e.g.,
52

highways, airplane traffic) originate outside park boundaries, beyond NPS management jurisdiction 

(Lynch et al. 2011). The National Park Service recognizes that no single metric is adequate to 

characterize acoustic resources; thus, the Natural Sounds and Night Skies Division of the National 

Park Service works with several metrics and considers SPL data, spectral data, audibility data, source 

identification data, and meteorological data (Lynch et al. 2011). Horseshoe Bend is a predominantly 

rural area, with generally minor noise pollution. Data on the soundscape of Horseshoe Bend are not 

available, but Superintendent Doyle Sapp (pers. comm., April 2013) described human-related 

environmental noise (e.g. from Highway 49) as minimal, and stated that the park is generally very 

quiet.

3.4. Lightscape

Light pollution is considered here as the upward “spill” of light that is scattered and reflected by 

water vapor, dust, and other particles to create “sky glow” (NPS 2007; NPS 2014c). The National 

Park Service uses the term “natural lightscape” to describe resources and values that exist in the 

absence of human-caused light at night.

The 2006 NPS Management Policies directs the NPS to conserve natural lightscapes, in part because 

protection of natural darkness is important for ecological integrity and sustainability - that is, the 

natural lightscape is critical for maintaining nocturnal habitat. Light from cities can be visible from

more than ~322 km (200 miles) away (NPS 2007, and references therein). Thus, to maintain a natural 

nocturnal lightscape, it is essential to minimize the sky glow from artificial light. There is clear 

evidence that human health is adversely impacted by artificial light at night. Although research on 

light pollution’s effect on wildlife is relatively sparse, the available studies suggest that artificial light 

also adversely affects the natural environment and the biological rhythms of flora and fauna. 

Nocturnal predators are especially affected, with “cascading” effects on prey species. Many bird 

species migrate at night and, thus, are prone to disorientation by artificial lights. Some biomes are 

more sensitive than others, such as wetlands, ponds, and shorelines.

The National Park Service is committed to minimizing light from park facilities at night, and to 

restricting the use of artificial light insofar as possible. As with noise pollution, the problem of 

artificial light pollution at night is caused by sources beyond National Park Service control. The 

burgeoning light pollution of the eastern U.S. has been increasing over time (Figure 28), although 

Horseshoe Bend thus far is at sufficient distance from urban centers to remain somewhat insulated 

from light pollution impacts. This observation has been made by park staff, unfortunately with little 

quantitative data. Although various instruments are available for measuring light in the night sky 

(NPS 2012b), few such data have been collected as of yet for national parks in much of the SECN. 

As an alternative for providing baseline information, here we consider the Bortle Dark-Sky Scale 

(BDSS, range 1-9). It was developed to assess light pollution using a numerical scale that is easily 

understood by the general citizenry, policymakers, etc. (Table 15). Truly dark skies typically have a 

BDSS of 7.1 to 7.5. According to Superintendent Doyle Sapp (30 April 2013), Horseshoe Bend is 

minimally impacted by light pollution, and its habitat generally is equivalent to typical, truly dark 

skies.
53

Figure 28. Artificial night sky brightness due to light pollution in the 1950s, 1970s, 1997, and projected to 

2025. Modified from Cinzano et al. (2001).
54

Table 15. The Bortle Dark-Sky Scale for assessing artificial light pollution. The column labeled “Naked-eye Limiting Magnitude” indicates the dimmest stars visible under each class of light 

pollution. The larger the magnitude number, the dimmer the star. Each whole number represents a factor of 5 in brightness - thus, a magnitude-5 star appears to be five-fold brighter than a 

magnitude 6 star, whereas a magnitude-4 star appears to be ten-fold brighter than a magnitude-6 star (see Bortle 2001a,b; Big Sky Astronomy Club 2014).

Class

Color 

Key

Naked-eye 

Limiting 

Magnitude

Sky 

Description

Milky 

Way

(MW) Astronomical Objects

Zodiacal 

Light/

Constellations

Airglow 

and

Clouds

Night 

Time 

Scene

1 7.6 - 8.0 Excellent, 

truly 

dark 

skies

MW shows great detail and light 

from the Scorpio/Sagittarius region 

- casts obvious shadow on the 

ground

M33 (Pinwheel Galaxy) is an 

obvious object

Zodiacal light has an obvious 

color and can stretch across the 

entire sky

Bluish airglow is visible 

near the horizon and 

clouds appear as dark 

blobs against the backdrop 

of the stars

The brightness of Jupiter and 

Venus is annoying to night 

vision; ground objects are 

barely lit and trees and hills 

are dark

2 7.1 - 7.5 Typical, 

truly 

dark skies

Summer MW shows great detail 

and has veined appearance

M33 is visible with direct 

vision, as are many globular

clusters

Zodiacal light bright enough to 

cast weak shadows after dark 

and has an apparent color

Airglow may be weakly 

apparent and clouds still 

appear as dark blobs

Ground is mostly dark, but 

objects projecting into the 

sky are discernible

3 6.6 - 7.0 Rural 

sky

MW still appears complex, dark 

voids and bright patches and 

meandering outline are all visible

Brightest Globular Clusters 

are distinct, but M33 only 

visible with averted vision; 

M31 (Andromeda Galaxy) 

obviously visible

Zodiacal light is striking in spring 

and autumn, extending 60 

degrees above the horizon

Airglow is not visible and 

clouds are faintly 

illuminated, except at the 

zenith

Some light pollution evident 

along the horizon; ground 

objects are vaguely apparent

4 6.1 - 6.5 Rural/ 

suburban 

transition

Only well above the horizon does 

the MW reveal any structure; fine 

details lost

M33 is difficult to see, even 

with averted vision; M31 still 

readily visible

Zodiacal light is clearly evident, 

but extends less than 45 

degrees after dusk

Clouds faintly illuminated 

except at the zenith

Light pollution domes are 

obvious in several directions; 

sky is noticeably brighter 

than the terrain

5 5.6 - 6.0 Suburban 

sky

MW appears washed out overhead 

and is lost completely near the 

horizon

The oval of M31 is 

detectable, as is the glow in 

the Orion Nebula

Only hints of zodiacal light in 

spring and autumn

Clouds are noticeably 

brighter than the sky, even 

at the zenith

Light pollution domes are 

obvious to casual observers; 

ground objects are partly lit

6 5.1 - 5.5 Bright 

suburban

sky

MW only apparent overhead and 

appears broken as fainter parts are 

lost to sky glow

M31 is detectable only as a 

faint smudge; Orion Nebula 

is seldom glimpsed

Zodiacal light is not visible; 

constellations are seen and not 

lost against a starry sky

Clouds anywhere in the sky 

appear faintly bright as 

they reflect back light

Sky from horizon to 35 

degrees glows with grayish 

color; ground is well lit

7 4.6 - 5.0 Suburban/ 

urban 

transition

MW is totally invisible or nearly so M31 and the Beehive 

Cluster are rarely glimpsed

The brighter constellations are 

clearly recognizable

Clouds brilliantly lit Entire sky background 

appears washed out, with a 

grayish or yellowish color
55

Table 15 (continued). The Bortle Dark-Sky Scale for assessing artificial light pollution. The column labeled “Naked-eye Limiting Magnitude” indicates the dimmest stars visible under each class of 

light pollution. The larger the magnitude number, the dimmer the star. Each whole number represents a factor of 5 in brightness - thus, a magnitude-5 star appears to be five-fold brighter than a 

magnitude 6 star, whereas a magnitude-4 star appears to be ten-fold brighter than a magnitude-6 star (see Bortle 2001a,b; Big Sky Astronomy Club 2014).

Class

Color 

Key

Naked-eye 

Limiting 

Magnitude

Sky 

Description

Milky 

Way

(MW) Astronomical Objects

Zodiacal 

Light/

Constellations

Airglow 

and

Clouds

Night 

Time 

Scene

8 4.1 - 4.5 City 

sky

MW is not visible at all The Pleiades Cluster is 

visible, but very few other 

objects can be detected

Dimmer constellations lack key 

stars

Clouds brilliantly lit Entire sky background has 

an orangish glow and it is 

bright enough to read at 

night

9 4.0 at best Inner

city 

sky

MW is not visible at all Only the Pleiades Cluster is 

visible to all but the most 

experienced observers

Only the brightest constellations 

are discernible and they are 

missing stars

Clouds brilliantly lit Entire sky background has a 

bright glow, even at the 

zenith
56

3.5. Geology and Soils

3.5.1. Geologic Resources

The information for Section 3.5.1 of this Natural Resources Inventory is largely taken from the 

scoping summary document (KellerLynn 2013), along with Miller (1990) and Rasmussen et al. 

(2009). Horseshoe Bend is located in a transitional area where the eastern Blue Ridge physiographic 

province meets the Northern Piedmont Upland physiographic province, in the immediate vicinity of 

the Brevard Zone which is a large strike-slip fault zone that was last active ~325 million years ago 

(mya; KellerLynn 2013). Horseshoe Bend is on the northwest side of the Brevard Zone (Figure 29). 

The Piedmont province is characterized by complex sequences of igneous and metamorphic rocks, 

collectively called crystalline rocks, of Paleozoic to Precambrian age (Journey and Atkins 1996, 

USGS 1997; Appendix 1). The bedrock materials are granite, gneiss, and schists. The metamorphic 

rocks, which originally were sedimentary, volcanic and volcaniclastic, have been altered by several 

stages of regional metamorphism to slate, phyllite, schist, gneiss, quartzite, and marble. They are 

extensively folded and faulted. The igneous rocks are intrusive, comprised mostly of granites with 

lesser amounts of diorite and gabbro. These rocks are characterized by a complex outcrop and 

subsurface distribution pattern.

Figure 29. Map of the geology of the general Park area (star - HOBE, including quartzite, mica schist, 

and gneiss; green lines - faults). Modified from Miller (1990).
57

The Piedmont contains major fault zones that generally trend northeast-southwest and form the 

boundaries between the major rock groups (Journey and Atkins 1996, GA EPD 1998). The 

crystalline igneous and metamorphic rocks mostly are covered by a layer of weathered rock and soil 

called regolith, which ranges from about a meter to more than 45.7 m (a few feet to more than 150 ft) 

in thickness, depending on the type of parent rock, the topography, and the hydrogeologic history. 

From the land surface, the regolith consists of a porous, permeable soil zone that grades downward 

into a clay-rich, relatively impermeable zone that overlies and grades into porous, permeable 

saprolite. This formation is often referred to as a transition zone (Heath 1989), and it, in turn, grades 

downward into unweathered bedrock. The massive granite and gabbro rocks generally are poorly 

fractured and have a thin soil cover, whereas the schists and gneisses are moderately to highly 

fractured. Weathering of the rocks is erratic and usually deep (Journey and Atkins 1996).

The Geologic Resources Inventory (GeRI), administered by the NPS GRD, recently completed a 

geologic scoping meeting and summary document for Horseshoe Bend, along with a digital geologic 

map and a Geologic Resources Inventory report. Jacksons Gap Group (phyllite, schist, and quartzite) 

is part of the Brevard Zone (Szabo et al. 1988). Emuckfaw Group (schist and gneiss) and Kowaliga 

Gneiss are part of the Blue Ridge province. Zana Granite intruded the Kowaliga Gneiss in the 

vicinity of the park. The Emuckfaw Zana Group was named for exposures along Emuckfaw Creek, 

northwest of Horseshoe Bend. The Brevard Zone contains many different rock types juxtaposed by 

numerous faults. The underlying bedrock consists of a complex mix of metamorphic and igneous 

rocks, mainly gneiss and schists (the latter mostly characterizing Horseshoe Bend; Figure 30) but 

extremely fine-grained rocks such as phyllite and metamorphosed volcanic tuff, ash, and flows are 

common in some areas, and locally quartzite and marble are also present (Rasmussen et al. 2009). As 

examples, the Katy Creek and Abanda faults bound the Jacksons Gap Group of rocks (Steltenpohl et 

al. 1990). The Jacksons Gap Group contains phyllite, schist, and quartzite. Quartzite, which is very 

resistant to weathering, forms distinctive ridges such as Cherokee Ridge in the area. Phyllite, which 

is more easily eroded than quartzite, forms ravines. Movement along faults in the Brevard Zone 

caused the rocks of the Blue Ridge, such as the Emuckfaw Group and Kowaliga Gneiss, to rise up in 

the Horseshoe Bend area. These units slope to the east, with the Emuckfaw Group overlying the 

Kowaliga Gneiss (Neathery and Reynolds 1975).
58

Figure 30. Map of simplified geology of the Park showing granodiorite, schist, and mica schist. From the 

NCSU CAAE (S. Flood).

All rocks within the park are Paleozoic in age (542 to 251 mya). Most metamorphic rocks were once 

sediments; some were originally igneous or volcanic, and some contain ore-bearing mineralized 

zones (Rasmussen et al. 2009). All of the metamorphic rocks have been intruded by igneous rock that 

varies from felsic (light in color, with large quantities of silica) to mafic (dark in color, with large 

amounts of ferromagnesian minerals). Large igneous intrusions consist of granite, quartz monzonite, 

and gabbro. Smaller intrusions such as dikes and sills consist of both felsic and mafic rocks, 

including syenite, andesite, diabase, and pegmatite. The rocks are displaced by several major fault 

zones as mentioned, some of which extend for hundreds of kilometers. Shearing along large fracture 

zones has also produced siliceous, intensely fractured rocks such as mylonite or phyllonite.

Horseshoe Bend contains one rock shelter, Wilson’s Rock, which occurs in overhanging bedrock on 

the western side of the park. Rock shelters usually form from weathering of crystalline bedrock. 

There is occasional seismic activity in the general area, such as an earthquake of magnitude 2.3 on 

the Richter scale that occurred on 15 October 2012 ~100 km (60 miles) north of the park (USGS 

2013b). Mining activities have not been conducted in the park, except for gravel that previously was 

mined from a pit to supply road materials. The pit, not used for many years, has mature trees growing 

on it. Any fossils that may occur in the park are Quaternary in age (past 2.6 million years) and 

associated with Tallapoosa River deposits. If present, these fossils (algal cysts, pollen, leaves, wood 

etc.) could be used for paleoclimatological and paleoecological studies (Tweet et al. 2009).

3.5.2. Soils and Erosion

The Piedmont province includes soils that have been derived in place through weathering of the 

varied igneous and metamorphic rocks; and floodplains or recently deposited soils of stream bottoms.

Soils form 93.7% and water forms 6.3% of the park area, and consist mainly of well-drained reddish 

loams and clays.

The clay-rich soils of the Tallapoosa watershed are almost entirely within the southern Piedmont 

major land-resource area (previously called a soil province; Appendix 1). The soils developed mostly 
59

from gneiss schist, mica schist, and phyllite. The soils have a gravelly sandy loam surface layer and a 

yellowish red to red, loamy to clayey subsoil, with higher mica content than typical for the southern 

Piedmont (Journey and Atkins 1996, GA EPD 1998). Most of the area has slopes of less than 10%, 

but the slopes cover a wide range. The dominant soils have deep red clay subsoil and occur mostly on 

the broader ridges. Steeper hillsides are mostly shallow soils overlying soft bedrock of mica schist 

and phyllite, and these soils have a gravelly fine sandy loam surface layer and yellowish red loamy 

subsoil.

Three soils comprise more than 40% of the total area with soil coverage. These include ToA, the 

Toccoa fine sandy loam (0-2%, occasionally flooded = 18.4%); PrDZ, the Pacolet-Rion complex (15-

25% slopes, moderately eroded, stony = 13.5%), and PrEZ, the Pacolet gravelly sandy loam (6-15% 

slopes, moderately eroded = 11.7%; Figure 31). Of the 21 soil types included in Horseshoe Bend, 12 

(57%) are characterized as moderately eroded, and six (29%) are described as rarely to frequently 

flooded. The soils of the floodplains province represent stream bottomland recently deposited from 

overflow water. This soil material has been washed from contiguous upland areas, and there is 

considerable textural variation in these soils (Smith and Avery 1910).
60

Figure 31. Simplified map of 21 soils in the Park (blue - most abundant). From the NCSU CAAE.
61

3.5.2.1.General Soil Erodibility:

At present the banks along the Tallapoosa River within the park are minimally disturbed by natural 

streambank erosion or sloughing (KellerLynn 2013). The stream bank along the river at the 

Tohopeka Village site appears less stable than other areas and may be related to removal of trees 

(Brown et al. 2004). As mentioned above, however, more than half of the soils in the park are 

characterized as moderately eroded, and nearly a third are occasionally to frequently flooded, 

indicating that water levels commonly change (and see Section 3.6 of this Report). Both 

characteristics typify the three most abundant soils in Horseshoe Bend (ToA, PrDZ, and PrEZ).

Streambank erosion occurs when stream channels widen to accommodate and transport 

increased, sudden (“flash-flood” or “flashy”) runoff and higher stream flows from developed areas 

with elevated impervious area (GA DNR 2001). The runoff events scour and undercut the lower 

areas of the streambank, causing steeper banks to “slump” and collapse during moderate and major 

storms. The soil loss from eroded banks contributes to already-high sediment loads, much of which is 

deposited during larger storms. Trees along the streambanks become weakened as the erosion 

progresses, so that some of their major roots are exposed and they can be more easily uprooted and 

washed away, further destabilizing the streambank. The floodplain elevation for the stream 

commonly increases as the watershed is developed, due to higher peak flows. This problem is 

exacerbated by building and filling in floodplain areas. Thus, over time as the upper and middle 

Tallapoosa River watershed continue to sustain activities such as silviculture, clear-cutting, and other 

land disturbance for development, streambank erosion along the Tallapoosa River is expected to 

increase.

3.6. Water Resources

The middle Tallapoosa River drains mostly rural and forested lands between dams and hydropower 

facilities at two run-of-river impoundments: Harris Lake is 32 km (20 miles) upstream near Linville, 

AL, built and operated by the Alabama Power Company), and Lake Martin’s dam near Alexander 

City, ~40 km (25 miles) downstream. The Alabama Power Company regulates water release and 

river flow entirely for electrical purposes at Harris Dam, 56 km (35 miles) above the park boundary. 

The present water release regime causes extreme river fluctuations, typically more than 1 m (several 

ft.) per day (NPS 2008). More specifically, peak power generation activities at the R.L. Harris Dam 

has been described to result in two high water events per day, causing river levels to fluctuate as 

much as 1.5- 1.8 m (5-6 ft.; DeVivo 2004). Thus, since the upstream dam was constructed in 1980, 

the river segments downstream, including the park area, have been subjected to changes in river flow 

from as low as zero to 453 cubic meters per second (cms; or 16,000 cubic feet per second, cfs). The 

park has no control over this highly regulated, often-extreme artificial flow regime. The dam likely is 

also partially responsible for increased flooding during heavy rains, when the captured water of 

Harris Lake is released too rapidly to the downstream Tallapoosa River (NPS 2008). Such severe 

floods threaten the natural lowland ecosystems of the park, as well as the stability of its roads, trails, 

and cultural resources (NPS 2008). Because of this highly stressed situation, the Tallapoosa River 

was in the Top Ten Most Endangered Rivers in America for 2003 (American Rivers 2012).
62

The upper Tallapoosa River system additionally has been targeted as a potential source of potable 

water for Atlanta, Ga. through interbasin transfer (GA DNR EPD 1998). The ongoing “water wars” 

between Georgia, Alabama, and Florida create what the Horseshoe Bend Strategic Plan (NPS 2008) 

described as “a tremendous unknown to the flow quantity of the Tallapoosa River as it traverses the 

park.”

A 5.9-km (3.7-mile) segment of the Tallapoosa River flows through Horseshoe Bend. In this area the 

river is a relatively deep channel marked by several shoals, habitat features that characteristically 

support high faunal diversity (Irwin and Freeman 2002). The horseshoe-like bend in the Tallapoosa 

River is an entrenched (incised) meander that cut into phyllite bedrock as the channel shifted over 

time. The meander likely formed under conditions of rapid vertical uplift or lowering of base level 

(Neuendorf et al. 2005). The park also contains a small spring-fed perennial and several intermittent 

streams that only flow during flood events. Nevertheless, park staff has expressed concerns about 

runoff problems from springs that affect a parking lot near the battlefield (Rasmussen et al. 2009). 

The park’s wetlands have not been well characterized, but they were recently delineated using GIS 

and occur as narrow fringes of swamp forest mostly along the river.

The town of New Site now supplies water for the park. The water is chlorinated and, thus, is not a 

risk from fecal bacteria. Groundwater resources in the park appear to be plentiful, but data are not 

available to assess groundwater quantity or quality.

3.6.1. Surface Water

3.6.1.1.Hydrology:

Hydrologic features such as stream flow characteristics provide what have been described as:

“some of the most appropriate and useful indicators for assessing aquatic ecosystem integrity, and for 

monitoring environmental changes over time.[They] also provide key support data for other vital 

signs indicators including water quality, threatened and endangered aquatic species, wetlands, and 

riparian habitat. The hydrologic output of a watershed is a function of land characteristics, human 

use, weather and climate conditions, urbanization, and soil characteristics. Hydrologic variation plays 

a key part in structuring the biotic diversity within river ecosystems by controlling critical habitat 

conditions within the river channel, the floodplain, and hyporheic zones...” (Gregory et al. 2012).

The Tallapoosa River, the major perennial water body within Horseshoe Bend, is a fifth-order stream

with a rock, silt, sand and gravel bottom interspersed with patches of organic matter (Burkholder and 

Rothenberger 2010). Some riffle areas occur, as well as areas of woody debris. Its flow is controlled 

mainly by water released by the R.L. Harris Dam below Lake Wedowee to the north. Other surface 

water resources in the park include two small springs: One emerges from a hill about 0.8 km (0.5 

mile) from the top of Battlefield Hill, to the east (Figure 32, #1). A second small spring originates 

from a series of seeps near the second hill of the battlefield, and then becomes a small perennial 

stream (sometimes called Whale Creek; Jones et al. 2010) near visitor’s Stop 1 (Figure 32, #2). 

ERMF (2007) mapped the locations of various intermittent streams in the park (Figure 32).
63

Figure 32. Map of streams in the Park (boundary in white), which are intermittent except for those 

indicated by numbers. Modified from NPS SECN (2014); and see Appendix 1.

A comprehensive analysis of surface water quantity is lacking for HOBE (Jones et al. 2010). USGS 

gaging station 02414715 on the Tallapoosa River in HOBE (drainage area 5,330 km2or 2,058 miles2) 

is listed by the USGS as located at the small community of New Site, Alabama (Figure 33). This 

station has been in operation since 1985, unfortunately post-construction of the Harris Dam. The next

closest USGS gaging station upstream from the park is at Wadley, Alabama (#02414500; drainage 

area 4,338 km2or 1,675 miles2), more than 30 km (19 miles) distant. This station has valuable 

historic information pre-dam construction, as it has been in operation since 1923. Therefore, Jones et 

al. (2010) considered both stations in their hydrologic analysis, summarized as follows.

1

2
64

Figure 33. USGS stream gaging stations in and near the Park. From the NPS SECN (2014).
65

Prior to construction of the Harris Dam, maximum discharge at the Wadley USGS station was 

~1,897 cms (~67,000 cfs). Since the dam has been in place, maximum discharge greater than 2,832 

cms (100,000 cfs) has been recorded (in May 2003). Maximum discharge at Horseshoe Bend also 

exceeded 2,832 cms in May 2003. Flow duration curves indicate that prior to dam construction, there 

was a less than-1% probability that average daily flow would exceed 1,133 cms (40,000 cfs), and 

there was a greater than-50% probability that the average daily flow would be less than ~142 cms 

(5,000 cfs). Post-dam construction, there was a less than-1% probability that the average daily flow 

would exceed 567 cms (20,000 cfs), and there was a greater than-50% probability that the average 

daily flow would be less than 142 cms (5,000 cfs). However, high flow events may occur at higher 

probabilities than indicated, since the data fell above the predicted distribution of high flow return 

frequency (log Pearson III analysis). Although the two USGS stations were somewhat similar in their 

recordings of flow events, the land area drained at New Site near Horseshoe Bend is ~1,000 km2

(~385 miles2) more than at the Wadley station. Thus, high flow events during 1987-1991 reached a 

maximum of ~1,700 cms (60,000 cfs) at Wadley, versus 2,265 cms (80,000 cfs) at New Site/

Horseshoe Bend (Jones et al. 2010).

The NPS Vital Signs Monitoring Program evaluated stream flow variation and the magnitude and 

timing of specific flow at both USGS gaging stations on the Tallapoosa River during 2010. Flow 

patterns were characterized within the context of USGS stream flow, the Nature Conservancy’s 

(2009) Indicators of Hydrologic Alteration (IHA) software, and program Flow (Dowd 2011; Table 

16). The IHA software used single-period daily values in cfs to calculate nonparametric and 

parametric statistical metrics including mean monthly flow values and extreme event characterization

and timing. IHA was also used to calculate EFCs, used to characterize natural flow and departures 

from natural conditions. EFCs characterize flow events that have become typical (over a long period 

such as many years) since perturbations such as diversions or development occurred (Table 16). The 

EFC procedure used by Gregory et al. (2012) set initial high flows as 75% of daily flows for the 

period of record used, and included the following three definitions:

 small floods ≡ events with a two-year return interval;

 large floods ≡ events with a 10-year return interval; and

 extreme low flows ≡ less than 10% of all flows for the period.
66

Table 16a. Indicators of Hydrologic Alteration Metrics and Environmental Flow Components, including 

potential ecosystem influences modified from the IHA User’s manual (The Nature Conservancy 2009).

Parameter Type Definition Potential Ecosystem Influences

Median Monthly 

Flow Conditions 

Median daily value 

for each calendar 

month

• Habitat availability for aquatic organisms

• Soil moisture availability for plants

• Availability of water for terrestrial animals

• Availability of food/cover for furbearing mammals

• Reliability of water supplies for terrestrial animals

• Access by predators to nesting sites

• Water temperature, oxygen levels, photosynthesis in water column

Extreme Flow 

Conditions 

1 to 90 day 

minimum and 

maximum flows

• Balance of competitive, ruderal, and stress- tolerant organisms

• Creation of sites for plant colonization

• Structuring of aquatic ecosystems by abiotic vs. biotic factors

• Structuring of river channel morphology and physical habitat 

conditions

• Soil moisture stress in plants

• Dehydration in animals

• Anaerobic stress in plants

• Volume of nutrient exchanges between rivers and floodplains

• Duration of stressful conditions such as low oxygen and concentrated 

chemicals in aquatic environments

• Distribution of plant communities in lakes, ponds, floodplains

• Duration of high flows for waste disposal, aeration of spawning beds 

in channel sediments

Magnitude of

Extreme Flow 

Conditions

Magnitude of 1 to 90 

day high and low 

• Compatibility with life cycles of organisms

• Predictability/avoidability of stress for organisms

• Access to special habitats during reproduction or to avoid predation

• Spawning cues for migratory fish

• Evolution of life history strategies, behavioral mechanisms

Table 16b. Indicators of Environmental Flow Components, including potential ecosystem influences 

modified from the IHA User’s manual (The Nature Conservancy 2009).

Parameter Type Definition Potential Ecosystem Influences

Monthly Low Flows 

Median low flow 

daily value for each 

calendar month

• Provide adequate habitat for aquatic organisms

• Maintain suitable water temperatures, dissolved oxygen, and water 

chemistry

• Maintain water table levels in floodplain, soil moisture for plants

• Provide drinking water for terrestrial animals

• Keep fish and amphibian eggs suspended

• Enable fish to move to feeding and spawning areas

• Support hyporheic organisms (living in saturated sediments)
67

Table 16c. Indicators of Hydrologic Alteration Metrics, including potential ecosystem influences modified 

from the IHA User’s manual (The Nature Conservancy 2009).

Extreme Low Flow 

and Low Flow 

Pulses 

Frequency, duration 

and timing of low 

flows and low flow 

pulses

• Enable recruitment of certain floodplain plant species

• Purge invasive, introduced species from aquatic and riparian 

communities

• Concentrate prey into limited areas to benefit predators

High Flow Pulses 

Frequency, duration 

and timing of high 

flow pulses

• Shape and physical character of river channel, including pools and 

riffles

• Determine size of streambed substrates (sand, gravel, cobble)

• Prevent riparian vegetation from encroaching into channel

• Restore normal water quality conditions after prolonged low flows, 

flushing away waste products and pollutants

• Aerate eggs in spawning gravels, prevent siltation

• Maintain suitable salinity conditions in estuaries

• Influences bedload transport, channel sediment textures, and duration 

of substrate disturbance high pulses

Small Floods Frequency, duration 

and timing of small 

floods 

• Provide migration and spawning cues for fish

• Trigger new phase in life cycle (i.e., insects)

• Enable fish to spawn in floodplain, provide nursery area for juvenile 

fish

• Provide new feeding opportunities for fish, waterfowl

• Recharge floodplain water table

• Maintain diversity in floodplain forest types through prolonged 

inundation (i.e., different plant species have different tolerances)

• Control distribution and abundance of plants on floodplain

• Deposit nutrients on floodplains

The algorithm makes three passes through the data: The 1st pass each day is assigned to either low 

flow or high flow initial event types; on the 2nd pass all days initially assigned as high flows are reassigned to 1, 2, or 3 high flow classes (small floods, high flow pulses etc.); and for the 3rd pass, 

some of the initial low flow days are re-assigned to the extreme low flow class (the Nature 

Conservancy 2009 - IHA User’s Manual). Annual stream flow features were described within 

historical flow context using the Flow program (Dowd 2011) which produces daily flow graphs 

(median monthly flow, interquartile range, and daily flow. Data were also interpreted within the 

context of existing resource data as defined by Horseshoe Bend staff.

3.6.1.2.Flow Conditions at the Wadley Gaging Station, Baseline Year 2010:

From a special “baseline” study during 2010, Gregory et al. (2012) reported that as would be 

expected, flow was highest in winter and early spring (especially February-March, due to late winter/ 

early spring rains), and lowest during late summer through early autumn (Figure 34). Based on IHA 

analysis, monthly median flow and low flow ranged from 6.9 cms (245 cfs - September) to 143.7 

cms (5,080 cfs – February; Table 17). Low flow ranged from 11.3 cms (398 cfs - September) to 83.8 

cms (2,960 cfs – February; Table 17). The minimum 1- to 90-day extreme flow ranged from 4.9 cms 

(173 cfs - 1 day) to 16.3 cms (575.3 cfs - 90 day; Table 18). The maximum 1- to 90-day extreme 

flow ranged from 192.3 cms (6,792 cfs - 90 day) to 512.5 cms (18,100 cfs - 1 day; Table 18). The 

peak extreme low flow condition (5.5 cms or 193 cfs - 13 events) lasted 1 day, whereas the peak in 

high flow pulse (148.1 cms or 5,230 cfs - 10 events) lasted 4 days (Table 19). Two small floods 

lasting 11.5 days occurred in March-April, with peak flow at 494.1 cms (17,450 cfs; Table 19). The 
68

park plans to build upon these data in subsequent years in order to better characterize hydrologic 

conditions in Horseshoe Bend.

Figure 34. Daily flow in 2010 (blue line), median monthly flow (dots 2010 data), and interquartile range 

(error bars) for the Tallapoosa River at Wadley (upper panel) and New Site (nearest HOBE - lower panel).
69

Table 17. Monthly median and low flow magnitudes (in cfs) for the two USGS gaging stations nearest HOBE during 2010. Metrics were calculated 

using the IHA (The Nature Conservancy 2009) from daily data. Darker blue indicates higher flow magnitude; ** ≡ missing data.

Flow 

Magnitude USGS ID Jan Feb Mar April May June July Aug Sept Oct Nov Dec

Median

2414500 4,420 5,080 4,980 1,910 2,310 1,725 1,000 399 245 680 1,160 1,050

2414715 5,580 6,730 6,570 3,000 3,430 2,460 1,480 561 357 544 1,140 1,190

Low

2414500 2,635 2,960 2,690 1,780 2,045 1,600 1,150 502 398 663 1,160 1,035

2414715 3,570 ** 3,790 2,895 2,740 2,160 1,480 561 399 615 1,140 1,160

Table 18. Extreme flow magnitudes (cfs, 1-day to 90-day) at the two upstream USGS gaging stations nearest HOBE during 2010. These metrics 

were calculated using IHA software (The Nature Conservancy 2009).

Flow 

Magnitude USGS ID 1-day 3-day 7-day 30-day 90-day

Minimum

02414500 173 177 203 386.9 575.3

02414715 249 257 269 461.4 675.8

Maximum

02414500 18,100 17,600 15,300 8,709 6,792

02414715 32,400 27,330 21,540 11,160 8,821

Table 19. EFCs (The Nature Conservancy 2009) for flows (in cfs) at the USGS gaging stations nearest HOBE during 2010. Timing refers to the 

date of the first peak event.

USGS ID

Extreme Low Flow High Flow Pulses Small Flood

FrequencyPeak (cfs)

Duration 

(days)TimingFrequencyPeak (cfs)

Duration 

(days)TimingFrequencyPeak (cfs)Duration (days)Timing

02414500 13 193 1 5-Sep 10 5,230 4 10-May 2 17,450 11.5 8-Apr

02414715 6 283.5 1.5 26-Sep 11 5,950 3.5 4-May 1 32,400 17 12-Mar
70

3.6.1.3.Flow Conditions at the New Site Station Nearest Horseshoe Bend, Baseline Year 2010:

The flow pattern is similar at New Site as at Wadley, although usually much greater in magnitude 

(Figure 33). In 2010 the flow at New Site was highest in winter (especially February-March), and 

lowest during late summer through early autumn (Table 17, Figure 34). Based on IHA analysis, 

monthly median flow and low flow ranged from 10.1 cms (357 cfs - September) to 190.6 cms (6,730 

cfs – February; Table 17). Low flow ranged from 11.3 cms (399 cfs - September; identical to that at 

the Wadley gaging station) to 107.3 cms (3,790 cfs - March; Table 17; note that February data were 

not available). The minimum 1- to 90-day extreme flow ranged from 7.1 cms (249 cfs - 1 day) to 

19.1 cms (675.8 cfs - 90 day; Table 18). The maximum 1- to 90-day extreme flow ranged from 249.8 

cms (8,821 cfs - 90 day) to 917.5 cms (32,400 cfs - 1 day; Table 18). The peak extreme low flow 

condition (8.0 cms or 283.5 cfs) lasted 1.5 days, whereas the peak in high flow pulse (168.5 cms or 

5,950 cfs) lasted 3.5 days (Table 19). One small flood lasting 17 days occurred in March, with peak 

flow at 917.5 cms (32,400 cfs, almost double that at the Wadley station; Table 19).

3.6.1.4.Flow Conditions at the Two Upstream USGS Stations Nearest Horseshoe Bend, 2012:

Data for these EFCs were collected again at the two USGS stations in 2012 (Jones and Gregory 

2013, NPS 2013a). Major findings were generally consistent with the 2010 baseline year, except that 

March, rather than February, had the highest median monthly flow, and August, rather than 

September, had the lowest median monthly flow (Figure 35, Table 20; note that low flow monthly 

conditions were not available in the two cited documents). In the drier year of 2012, the minimum 1-

to 90-day extreme flows at the two stations were much lower (40% and 50% less at the Wadley and 

New Site stations, respectively) than in the 2010 baseline year (Tables 18 and 21). Maximum 1- to 

90-day extreme flows during 2010 and 2012 were fairly comparable at the Wadley station (1 day -

2012: 512.6 cms or 18,100 cfs vs. 2012: 436.1 cms or 15,400 cfs).
71

Figure 35. Daily flow in 2012 (blue line), historical median monthly flow (dots - 2012 data), and 

interquartile range (error bars) for the Tallapoosa River near Wadley (upper panel) and near New Site 

(Horseshoe Bend; lower panel). From Jones and Gregory (2013).

However, the maximum 1- to 90-day extreme flow in 2012 (1 day - 424.8 cms or 15,000 cfs) was 

less than half that during baseline year 2010 (917.5 cms or 32,400 cfs; Tables 18 and 21). The peak 

extreme low flow condition at the New Site station (424.8 cms or 15,000 cfs) was less than half that 

during baseline year 2010 (917.5 cms or 32,400 cfs; Tables 18 and 21). The peak extreme low flow 

condition at the New Site station nearest Horseshoe Bend (6.9 cms or 243 cfs) lasted 3 days; thus, 

02414500 TALLAPOOSA RIVER AT WADLEY AL -- 2012

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Discharge - cfs 15,000

14,000

13,000

12,000

11,000

10,000

9,000

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

02414715 TALLAPOOSA RIVER NR NEW SITE, AL.(HORSESHOE BEND) -- 2012

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Discharge - cfs 15,000

14,000

13,000

12,000

11,000

10,000

9,000

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0
72

this EFC was both lower than in baseline year 2010 and lasted twice as long (Tables 19 and 22). In 

contrast, the peak high flow pulse (328.5 cms or 11,600 cfs) during 2012 was about double that in 

2010 (168.5 cms or 5,950 cfs) and lasted about a third longer (3.5 days in 2010 vs. 5 days in 2012). 

The frequency of extreme low flows and of high flow pulses differed from those in the baseline year 

especially at the New Site station (Table 22). In 2012, extreme low flows occurred 11 times at 

Wadley (USGS gaging station #02414500) and 18 times at New Site nearest Horseshoe Bend (USGS 

gaging station #02414715). The duration of high flow pulses was longest at the New Site station, as 

expected. Overall, daily flows were generally below the median for most of 2012, and were below 

the 25th percentile in April and much of August-October.

Table 20. Monthly median flow magnitudes (in cfs) for the Tallapoosa River in 2012, upstream from 

HOBE at the two USGS gaging stations. Median flow was calculated with IHA (The Nature Conservancy 

2009) using daily USGS data. Darker blue color indicates higher flow magnitude. From NPS (2013) and 

Jones and Gregory (2013).

USGS ID Jan Feb Mar April May June July Aug Sept Oct Nov Dec

2414500 2,300 2,270 4,490 313.5 442 641.5 397 152 261 301 545.5 1,440

2414715 1,950 2,230 3,280 729 572 622.5 335 201 227 269 630 1,090

Table 21. The 1- to 90-day extreme flow magnitudes (USGS data, cfs) for the Tallapoosa River in 2012, 

upstream from HOBE at the two nearest USGS gaging stations. Metrics were calculated using Indicators 

of Hydrologic Alteration software (The Nature Conservancy 2009).

Flow 

Magnitude USGS ID 1-day 3-day 7-day 30-day 90-day

Minimum

2414500 104 128 135.4 234 314.8

2414715 123 133.3 141.9 216.5 275.4

Maximum

2414500 15,400 13,970 10,740 5,266 3,914

2414715 15,000 13,670 9,847 4726 3,644

Table 22. Environmental Flow Components for flows (in cfs) for the Tallapoosa River in 2012, upstream 

from HOBE at the two nearest USGS gaging stations. Timing refers to the average date (i.e., average of 

Julian dates) of a peak event if more than one occurred (NC ≡ timing was not calculated due to the 

distribution of Julian dates). From NPS (2013a) and Jones and Gregory (2013).

USGS ID

Extreme Low Flow High Flow Pulses Small Flood

FrequencyPeak (cfs)

Duration 

(days)TimingFrequencyPeak (cfs)

Duration 

(days)TimingFrequencyPeak (cfs)Duration (days)Timing

02414500 11 159 2 9/1 12 4480 1 NC 0 NC NC NC

02414715 18 243 3 10/19 5 11600 5 NC 0 NC NC NC
73

3.6.1.5.Wetlands:

Wetlands are defined as transitional lands between terrestrial and permanent (deeper) standing-water 

habitats (Cowardin et al. 1979). The water table in wetlands is at or near land surface, or the land is 

covered at times by shallow water. In the Tallapoosa River basin, most wetlands are forested 

floodplain systems, maintained by the natural flooding regime of rivers and streams (CH2MHILL 

2005). This description is characteristic of the woody wetlands in Horseshoe Bend, which occur as 

narrow fringes along the Tallapoosa River (Figure 36). More than 20% of the vegetative cover in 

these wetlands consists of forest or shrub vegetation (Burkholder and Rothenberger 2010). The 

wetlands have not been well characterized, but a recent survey of plant species indicates that there is 

a rich diversity of wetland and aquatic plant species in the park (below).
74

Figure 36. Map of wetland locations in the park. Map also shows the Tallapoosa River (‘riverine,’ in blue; 

USFWS 2011).

3.6.1.6.Surface Water Quality Criteria:

Following the Clean Water Act (33 U.S.C. 1251 et seq., the Federal Water Pollution Control Act as 

amended through P.L. 107-303, November 27, 2002), the state of Alabama has developed various 

standards (criteria) applicable to the surface waters of Horseshoe Bend with designated use for Fish 

and Wildlife (ADEM 2008b, 2013b). The description for the Fish and Wildlife use classification 

states that the “best usage of waters [is for] fishing, propagation of fish, [other] aquatic life, and 

wildlife, and any other usage except for swimming and water contact sports or as a source of water 

supply for drinking or food-processing purposes” (ADEM 2013b). For this designated use, the state 
75

has ambient water quality standards for common water quality parameters such as dissolved oxygen 

(DO), pH, turbidity, fecal bacteria, and enterococci bacteria (Table 23).

Other recommended guidelines for acceptable water quality have been published by the U.S. EPA 

(2000, 2002), Mallin (2000), and Mallin et al. (2006; e.g. Table 24). The Clean Water Act requires 

the U.S. EPA to develop criteria (or recommendations) for water, designed to protect aquatic life. 

The criteria are supposed to reflect accurately the up-to-date scientific knowledge. Whereas the State 

of Alabama has imposed regulations, a U.S. EPA water quality criterion is not a regulation; it does 

not impose legally binding requirements on the U.S. EPA or the states. States have discretion to 

adopt approaches that differ from the U.S. EPA water quality criteria, but these criteria are meant to 

provide useful guidance.

Table 23. In-stream water quality standards for non-coastal surface waters with designated use as Fish 

and Wildlife (ADEM 2013b).

Parameter Acceptable Conditions

Temperature Maximum shall not exceed 90°F [32°C]; maximum in-stream temperature rise above 

ambient due to the addition of artificial heat by a discharger shall not exceed 5°F.

DO For a diversified warm water biota, including game fish, daily concentrations shall not 

be less than 5 mg/L at all times, except that under extreme conditions due to natural 

causes, it may range between 5 mg/L and 4 mg/L, provided that water quality is 

favorable in all other parameters.

pH Sewage, industrial wastes, or other wastes shall not cause the pH to deviate more than 

one unit from the normal or natural pH. The pH should be greater than 6.0 and less 

than 8.5.

Turbidity There shall be no turbidity of other than natural origin that causes substantial visible 

contrast with the natural appearance of waters or interfere with any beneficial uses. In 

no case shall turbidity exceed 50 Nephelometric units [NTU] above background. 

Background is interpreted as the natural condition of the receiving waters, without 

influence of human or human-induced causes.

Fecal Coliform

Bacteria

Shall not exceed a geometric mean (g.m.) of 1,000 colonies [cfu] per 100 mL, nor 

exceed a maximum of 2,000 colonies per 100 mL in any sample. The geometric mean 

shall be calculated from no less than five samples collected over a 30-day period at 

intervals not less than 24 hours. For incidental water contact during June through 

September, water quality is acceptable when a survey by controlling health authorities 

reveals no source of dangerous pollution and when the geometric mean fecal coliform

densities do not exceed 200 colonies per 100 mL. 

Toxic, color-producing, 

odor-producing, and 

other deleterious 

substances from wastes

Only such amounts, whether alone or in combination with other substances or wastes, 

as will not cause acute or chronic toxicity to fish, wildlife, and [other] aquatic life, as 

demonstrated by effluent toxicity testing or by application of numeric criteria given in 

Rule 335-6-10-.07, or adversely affect the aesthetic value of the water.
76

Table 24a. Summary of Alabama state standards for acceptable water quality in waters classified as Fish 

and Wildlife designated use, and of conditions for acceptable water quality recommended by other 

sources (ADEM 2013b).

Parameter ADEM

Other Recommendation(s) 

or Guideline(s) HOBE

DO > 5 mg/L; or >

4 m/L in 

extreme 

conditions

> 4 mg/L (U.S. EPA 2000) .Limited data - some 

violations (down to 3.4 

mg/L)

pH > 6.0, < 8.5 > 6.5, and < 9.0 (U.S. EPA 2000) Limited data - pH as low as 

6.0

Turbidity < 50 NTU 

above 

background

5.7 NTU (25th percentile, all streams; all 

seasons for Level III .Nutrient Ecoregion 

IX, sub-ecoregion #45 (U.S. EPA 2000)

44% of samples were in 

.compliance (2010-2011 

data)

Escherichia coli < 548 cfu/100 

mL (g.m.);< 

2,507 cfu/100 

mL 

in any sample

235 cfu/100 mL for data collected with 

insufficient frequency .to calculate g.m.s 

by the State's criteria (general 

recreational .use; U.S. EPA 2003)

Data not available

Nutrients ----- 25th percentiles, all streams, all 

seasons for Level III Nutrient .Ecoregion 

IX, sub-ecoregion #45; 30 μg TP/L, 234 

μg TKN/L, .177 μg NOx/L, 411 μg TN/L 

(calculated as TKN + NOx; U.S. EPA 

.2000)a

84% of NOx, 100% of TP, 

and .53% of TKN samples 

would .conform (2010-2011 

data)

Chlorophyll a .(chla, 

corrected)

----- 25th percentile, all streams, all seasons 

for Level III Nutrient .Ecoregion IX, subecoregion #45: 3.3 μg chla/L (F)a,b or 

.3.5 μg chla/L (S)a,b

84% of samples would 

conform .(2010-2011 data)

Biochemical Oxygen 

Demand .(BOD)

----- < 3.0 mg/L as the 5-day BOD 

(BOD5).(Mallin et al. 2006)

Data not available

Total suspended 

solids (TSS)

----- < 25 mg/L; and < 10 mg/L increase from 

a sudden spike (U.S. EPA 2000)

Limited data - TSS < 25 

mg/L

a

 U.S. EPA’s (2000b) recommendation for acceptable conditions for nutrients, turbidity, and suspended algal 

biomass as chlorophyll a concentration (corrected for pheopigments), for streams within level III nutrient 

ecoregion IX, sub-ecoregion #45, which includes HOBE. These recommendations were based on the 25th

percentile of all available streams data for the previous decade; alternatively, if reference (minimally impacted) 

streams were available, U.S. EPA (2000) recommends use of the 75th percentile of the data from those streams. 

Note that TP ≡ total phosphorus, TN ≡ total nitrogen, and TKN ≡ total Kjeldahl nitrogen.

b

 F ≡ fluorometric technique; S ≡ spectrophotometric technique.

c

 Dissolved concentrations; equations express the total recoverable concentration depending on the water 

ardness or pH. Please note that this historic procedure for calculating heavy metals concentrations in 

developing freshwater criteria have been replaced by use of the Biotic Ligand Model (BLM), wherein he 

available toxicity data, when evaluated using the procedures described in the Guidelines for eriving Numerical 

National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses, indicate that freshwater 

aquatic life should be protected if the 24-hr average and 4-day average concentrations do not respectively 

exceed the acute and chronic criteria concentrations calculated by the BLM (see 

http://water.epa.gov/scitech/swguidance/standards/criteria/current/index.cfm#mm , last accessed in August 

2013).

d

 Water quality guidelines (reference condition, 25th percentile – also see Byrne 2004). CMC ≡ the criterion 

maximum concentration; CCC ≡ the criterion continuous concentration, within a pH range of 6.5-9. 
77

Table 24b. Summary of Alabama state standards for acceptable water quality for toxic metals in waters 

classified as Fish and Wildlife designated use, and of conditions for acceptable water quality 

recommended by other sources (ADEM 2013b)( U.S. EPA 2000, 2002d).

Toxic metals (μg/L) ADEM

Other Recommendation(s) 

or Guideline(s) HOBE

Aluminum Equationsc CMC 750 CCC 87 Data not available

Cadmium Equationsc CMC 2 CCC 0.25 Data not available

Chromium III Equationsc CMC 570 CCC 74 Data not available

Chromium IV Equationsc CMC 16 CCC 11 Data not available

Copper Equationsc CMC 13 CCC 9 Data not available

Lead Equationsc CMC 65 CCC 2.5 Data not available

Mercury Equationsc CMC 1.4 CCC 0.77 Data not available

Nickel Equationsc CMC 470 CCC 52 Data not available

Zinc Equationsc CMC 120 CCC 120 Data not available

a

 U.S. EPA’s (2000b) recommendation for acceptable conditions for nutrients, turbidity, and suspended algal 

biomass as chlorophyll a concentration (corrected for pheopigments), for streams within level III nutrient 

ecoregion IX, sub-ecoregion #45, which includes HOBE. These recommendations were based on the 25th

percentile of all available streams data for the previous decade; alternatively, if reference (minimally impacted) 

streams were available, U.S. EPA (2000) recommends use of the 75th percentile of the data from those streams. 

Note that TP ≡ total phosphorus, TN ≡ total nitrogen, and TKN ≡ total Kjeldahl nitrogen.

b

 F ≡ fluorometric technique; S ≡ spectrophotometric technique.

c

 Dissolved concentrations; equations express the total recoverable concentration depending on the water 

ardness or pH. Please note that this historic procedure for calculating heavy metals concentrations in 

developing freshwater criteria have been replaced by use of the Biotic Ligand Model (BLM), wherein he 

available toxicity data, when evaluated using the procedures described in the Guidelines for eriving Numerical 

National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses, indicate that freshwater 

aquatic life should be protected if the 24-hr average and 4-day average concentrations do not respectively 

exceed the acute and chronic criteria concentrations calculated by the BLM (see 

http://water.epa.gov/scitech/swguidance/standards/criteria/current/index.cfm#mm , last accessed in August 

2013).

d

 Water quality guidelines (reference condition, 25th percentile – also see Byrne 2004). CMC ≡ the criterion

maximum concentration; CCC ≡ the criterion continuous concentration, within a pH range of 6.5-9. 

3.6.1.7.Potential Pollution Sources:

The Middle Tallapoosa River basin includes a total of 153 point source (National Pollutant Discharge 

Elimination System, NPDES) dischargers (133 industrial, 20 municipal; ADEM 2013c). Data are not 

available for the current permitted flows. There are also 15 active minor NPDES discharges into the 

Tallapoosa River above Lake Martin. The only NPDES point source above Horseshoe Bend is ~40 

river km (25 river miles) upstream and poses no immediate threat to the park. Nevertheless, sewage 

spills have affected tributaries close by in the sub-basin (see Burkholder and Rothenberger 2010). 

ADEM monitors some sites along the Tallapoosa River, although not near the park, for mercury 

content in fish and occasionally has reported fish consumption advisories.

Nonpoint source pollution from airsheds and land occurs from human activities such as urban 

development, agriculture, silviculture, various other industries, and other land use practices. It is the 

major source of pollution in many U.S. watersheds, and can carry toxic substances, suspended 

sediments, excessive nutrients, and microbial pathogens into receiving waters (e.g. U.S. EPA 2001, 
78

Burkholder et al. 2006). Local nonpoint pollution sources in the watershed include suburban/urban 

runoff and air pollution from the small population centers and agricultural and silvicultural 

operations upstream from the park. The upper watershed has been used for agriculture, industrialized 

animal production (mainly poultry), gold mining and, more recently, for timber production and 

harvest (CH2MHill 2005). Concern has been raised that water quality in the Middle Tallapoosa subbasin may be adversely affected by agricultural runoff from upstream livestock and chicken 

production (DeVivo 2004, CH2MHill 2005, ADEM 2006).

In addition to nonpoint water and air pollution from local sources, toxic contaminants, 

dust/particulates, and other pollutants may be carried into the park area and upstream Tallapoosa 

waters from larger cities in the state, and from Atlanta, Ga., by prevailing winds. The risk of foliar 

ozone injury to plants at Horseshoe Bend has been evaluated as moderate, and is considered to affect 

both wetland and terrestrial species (see Figure 26). Other air pollution, notably N and S deposition, 

have been assessed as being of significant concern for park natural resources, and these pollutants 

would also affect Horseshoe Bend surface waters (NPS 2014d. They can cause acidification (both N 

and S), over-fertilization of soils (N), and over-enrichment of surface waters (N; process known as 

eutrophication). These air pollutants can help to drive natural land and water ecosystems out of 

balance, causing shifts from beneficial to undesirable flora and fauna such as microbial pathogens 

and exotic/invasive species (Burkholder and Glibert 2013). Air pollutants such as S and N can also 

adversely affect essential ecosystem services such as air and water purification, decomposition and 

detoxification of waste materials, climate regulation, regeneration of soil fertility, production, and 

biodiversity (NPS 2012).

About 15 years ago, the overall potential for nonpoint source impairment in the Middle Tallapoosa 

River sub-basin was evaluated as low, based on estimates of sedimentation rates, animal unit 

densities, and pasture land (ADEM 2000). However, pollution from increased industrial development 

of the Tallapoosa watershed is a park concern, as is clear-cutting for timber and for development 

(Burkholder and Rothenberger 2010). Other concerns about pollution sources have been expressed 

by Horseshoe Bend staff as follows (Rasmussen et al. 2009):

 Possible contamination of the Tallapoosa River by the upstream and downstream hydroelectric 

power plants;

 Significant agriculture upstream from the park that contributes substantial suspended sediments 

and other pollutants to the river;

 Septic drain fields, including four housing units that feed into a septic tank and drainage field, 

and a septic tank for the maintenance building; and

 Two aboveground storage tanks at the maintenance building, still in Horseshoe Bend although 

others have been removed.

The Tallapoosa River Basin Management Plan (CH2MHILL 2005) described water quality and 

general habitat concerns identified by stakeholders for various segments of the Tallapoosa River and 

certain tributaries within the Middle Tallapoosa watershed, including microbial pathogen 

contamination, erosion and siltation, clay turbidity, nutrient over-enrichment, excessive 
79

phytoplankton biomass (as chlorophyll a) in impoundments. Water quality and habitat integrity 

measures within the Middle Tallapoosa sub-basin were evaluated as generally achieving use 

classification standards (CH2MHILL 2005), likely reflecting the fact that the land is mostly forested. 

However, supporting data for this evaluation are, and were, extremely sparse. The results from a 

Tallapoosa River basin surface water quality assessment (ADEM 2000), now dated by nearly a 

decade, rated the overall potential for nonpoint pollution source impairment as low, based on 

estimates of sedimentation rates, animal unit densities, and pastureland. One smaller watershed 

within the middle Tallapoosa sub-basin (03150109040, located above Horseshoe Bend) was listed as 

a priority NPS-watershed because of only a “fair” assessment rating due to erosion and sedimentation 

from silvicultural practices (CH2MHILL 2005).

Overall, based on a recent watershed condition assessment, present water quality concerns in 

Horseshoe Bend include sedimentation from increased clear-cutting, pollution from agriculture and 

silviculture, and atmospheric deposition of dust/particulates, toxic contaminants, and other pollutants 

from larger cities to the west (Montgomery, Birmingham) and from Atlanta, Ga. (Burkholder and 

Rothenberger 2010). Although the Middle Tallapoosa River watershed is only ~5% urbanized at 

present, the combined pressures of anticipated increased development in the upper and middle basins 

are expected to increase land disturbance and water pollution including excessive suspended 

sediments, nutrients, fecal bacteria, and toxic substances. The present overall potential for nonpoint 

source impairment of surface waters in the area has been evaluated as low, but more than half of the 

sub-watersheds in this sub-basin were considered by ADEM to have moderate potential for nonpoint 

source impairment due to runoff from forestry practices, clear-cutting, and sedimentation.

3.6.1.8.Surface Water Quality at Horseshoe Bend:

The park’s sewage is treated on-site with septic tanks. Park sewer lines for septic tanks, which 

previously caused problems from leakage, recently were replaced and aboveground storage tanks 

were replaced with double-wall containers.

The Tallapoosa River Basin Management Plan (CH2MHill 2005) described water quality and general 

habitat concerns identified by stakeholders for various segments of the Tallapoosa River and certain 

tributaries within the Middle Tallapoosa watershed, including microbial pathogen contamination, 

erosion and siltation, clay turbidity, nutrient over-enrichment, excessive phytoplankton biomass (as 

chlorophyll a) in impoundments. Water quality and habitat integrity measures within the Middle 

Tallapoosa sub-basin were evaluated as generally achieving use classification standards (CH2MHill 

2005), likely reflecting the fact that land use is mostly forested. However, supporting data for this 

evaluation are, and were, extremely sparse. The results from a Tallapoosa River basin surface water 

quality assessment (ADEM 2000), now dated by nearly a decade, rated the overall potential for 

nonpoint pollution source impairment as low, based on estimates of sedimentation rates, animal unit 

densities, and pastureland. One smaller watershed within the middle Tallapoosa sub-basin 

(03150109040, located above Horseshoe Bend) was listed as a priority NPS-watershed because of a 

“fair” assessment rating caused by erosion and sedimentation from silvicultural practices (CH2MHill 

2005).
80

Recent water quality data for Horseshoe Bend, taken within the past ~15 years (since 2000), are 

sparse for parameters other than temperature but, nevertheless, the available data include most of the 

past ~15 years (2000-2007 and 2010-2011; Table 25). The older data taken during that period 

indicate that, except for several violations of the pH criterion, parameters were at acceptable 

conditions (Figures 37-39). Recent data from ADEM (April through October 2011) indicate that 

some conditions were unacceptable on several dates, including turbidity, chlorophyll a, NOx, TKN, 

total dissolved solids (TDS), and TSS (Table 26). Data are not available for algal 

abundance/composition, fecal bacteria, or toxic substances.

Table 25. Dates of water quality sampling, and parameters sampled in surface waters of the park, 

considering information from 2000 - present. For older data, see Burkholder and Rothenburger (2010).

Station Duration n Parameters

Alabama Water Watch (AWW)

Boat Ramp, site #07001001

Jan 2000 -

Feb 07*

127 Water temperature, salinity, alkalinity, hardness, 

turbidity, pH, DO

Tallapoosa Watershed Project 

(TWP)

Just downstream from Boat Ramp 

station - Auburn Univ.

Feb 04 -

Dec 05

29 TP, soluble reactive phosphorus (SRP), TN, TSS

ADEM - boat ramp Apr 10 -

Oct 11

19-

337

Temperature, turbidity, Specific Conductance, pH, 

DO, chla, NOx, NH4

+N, TKN, TP, SRP, BOD5,

chloride, total dissolved solids (TDS), TSS, 

alkalinity

* The dataset was initiated in June of 1993, but this Report emphasizes data from 2000 on.
81

Figure 37. Water temperature and turbidity (upper and lower panels, respectively) in the Tallapoosa River 

at HOBE (Boat Ramp station, January 2000 - February 2007) from a monthly sampling program by 

volunteer citizens in the Alabama Water Watch (AWW).
82

Figure 38. Water pH, alkalinity, and hardness (upper, middle, and lower panels, respectively) for the 

Tallapoosa River at HOBE (Boat Ramp station, January 2000 - February 2007) from a sampling program 

by volunteer citizens in the AWW.
83

Figure 39. DO as concentration and percent saturation (upper and lower panels, respectively) for the 

Tallapoosa River at HOBE (Boat Ramp station, January 2000 - February 2007) from a sampling program 

by volunteer citizens in the AWW.
84

Table 26. Water quality conditions during the past decade based on data collected by ADEM: Parameters 

measured at the boat ramp station in HOBE (ADEM #3952 -Tallapoosa River; lat. 32.97734, long. -

85.73968) (sampling dates per year ranged from 8 to 13)a. Note that UC ≡nd ≡ not detectable. Value 

underlined in bold ≡ in violation of state standard (ADEM 2013b); values shaded in bold ≡ data exceeded 

recommended values for acceptable water quality (EPA 2000).

Parameter Date n Mean (range) Median UC (#)

Temperature (oC) Apr 10 - Oct 11 337 28.9 (14.9 - 32.5) 29.3 3

Turbidity (NTU) Apr 10 - Oct 11 25 6.0 (0.3 - 12.5) 5.8 14

Spec. cond. (μmhos/cm, field) Apr 10 - Oct 11 337 44.1 (33.9 - 48.7) 44 ---

DO (mg/L0 Apr 10 - Oct 11 237 7.3 (6.4 - 10.2) 7.3 ---

pH Apr 10 - Oct 11 337 6.9 (6.5 - 7.2) 6.9 ---

chlorophyll a (mg/m3) Apr 10 - Oct 11 19 1.7 (nd-7.5)

b

0.7 3

NO3

-N + NO2-N (NOx, μg/L) Apr 10 - Oct 11 19 114 (nd - 223)

b

134 3

TKN (μg/L) Apr 10 - Oct 11 19 234 (nd - 625)

b

202 9

TP (μg/L) Apr 10 - Oct 11 19 14 (9 - 21) 13 ---

SRP (μg/L) Apr 10 - Oct 11 19 7 (3 - 19) 6 ---

BOD5 (mg/L) Apr 10 - Oct 11 19 all ndc--- ---

Chloride (mg/L) Apr 10 - Oct 11 19 2.5 (1.9 - 3.5) 2.5 ---

TDS (mg/L) Apr 10 - Oct 11 19 36.5 - (4 - 98) 34 ---

TSS (mg/L) Apr 10 - Oct 11 19 2.3 (nd - 9)b1 ---

Alkalinity, carbonate 

as CaCO3 (mg/L) Apr 10 - Oct 11 19 14 (9 - 20.8) 13.4 ---

a More than 50% of samples were below detection or below the reporting limit with the analytical 

technique used; thus, statistical interpretation was not attempted.

b Abbreviations: °C degrees – Celsius; NTU – nephelometric turbidity units; spec. cond. – specific 

conductivity, NOx – nitrate-N + nitrite-N; NH4+N – ammonium-N; TKN – total Kjeldahl nitrogen; TP –

total phosphorus; SRP – soluble reactive phosphorus; BOD5 – 5-day biochemical oxygen demand; 

TDS – total dissolved solids; TSS – total suspended solids; and CaCO3 –calcium carbonate.

c All values reported less than the level of detection or less than the detection limit were replace with 

1/2 the value, following Ellis and Gilbert (1980) and Zirschky et al. (1985), except that TSS mdl – 1.

3.6.2. Groundwater

3.6.2.1.Groundwater Quantity:

Knowledge of groundwater supplies and quality is critically important to enable sound assessment of 

the status of water resources in most ecosystems:

Groundwater level and groundwater quality data are essential for water resource assessment 

and management. Water level measurements from observation wells are the principal source 

of information about the hydrologic stresses on aquifers and how these stresses affect 

groundwater recharge, storage, and discharge. Long-term, systematic measurements of water 

levels provide essential data needed to evaluate changes in the resource over time; develop 

groundwater models and forecast trends; and design, implement, and monitor the 

effectiveness of groundwater management and protection programs (Taylor and Alley, 2001). 

Groundwater quality data are necessary to ensure that public water supplies meet health 

standards; deterioration of groundwater quality may be virtually irreversible, and treatment of 

contaminated groundwater can be expensive (Alley 1993) [in USGS 2008].
85

Unfortunately, however, little is known about groundwater supplies in the park. The regional geology 

controls the aquifer types present, and influences the natural quantity and quality of the groundwater. 

The aquifers underlying the park and vicinity are fairly well known: A surficial aquifer system, not a 

principal aquifer, covers the state (USGS 2008). The important aquifer underlying east-central 

Alabama is the substantial Piedmont-Blue Ridge Aquifer System, which consists of a fractured, 

crystalline-rock aquifer (within metamorphic and igneous rocks) with little or no primary porosity or 

permeability, and overlying unconsolidated material called regolith which generally acts as a porousmedia aquifer (Miller 1990, Chapman and Peck 1997, Rasmussen et al. 2009; Figure 40). In some 

locations a transition zone also occurs, which lies between the regolith and unweathered crystalline 

bedrock (Chapman and Peck 1997). The regolith includes (i) mostly saprolite, a layer of variable 

thickness (up to ~46 m or 150 ft. in places) of earthy, decomposed rock developed by weathering of 

the bedrock, along with (ii) soil that develops on the upper part of the saprolite; and, mainly instream valleys, (iii) overlying alluvium. The mineralogy and texture of the rocks forming the 

Piedmont and Blue Ridge Aquifer System differ, resulting in substantial local differences in the 

occurrence and availability of groundwater. Nevertheless, the overall hydraulic characteristics of the 

aquifers in this system are similar (Miller 1990). Various textural and structural properties in the 

rocks control permeability features, whereas hydraulic head gradients and recharge are influenced by 

topography and climatic factors.

Water levels in the aquifers fluctuate seasonally, and generally rise in winter/spring because of 

increased recharge from precipitation and less evapotranspiration and pumping (Leeth et al. 2005). 

The magnitude of fluctuations varies substantially across seasons and year to year depending on 

climatic conditions and human use, which influences the amount of ground-water in storage and the 

rate of discharge (Taylor and Alley 2001). As storage is depleted within the radius of pumping 

influence from a well, the water level declines and forms a “cone of depression” around the well. In 

areas with high concentrations of wells, multiple cones of depression form and effect water level 

declines across large areas. These declines can change the groundwater flow direction, reduce flow to 

streams, capture water from a stream or adjacent aquifer, and/or alter groundwater quality (USGS 

2008).

As described by Miller (1990), water in the rocks of the Piedmont and Blue Ridge Aquifer System 

generally is unconfined. Locally, artesian conditions exist when wells penetrate deeply buried 

fractures that are hydraulically connected to recharge areas at higher altitudes or in places where the 

regolith is clayey and forms a confining unit. Water enters the ground in recharge areas, which 

generally include all land surfaces except the lower parts of valleys. The water percolates vertically 

downward through the unsaturated zone. Once it reaches the saturated zone (water table), it moves 

laterally to points of discharge as springs, seeps, baseflow to streams, and seepage to lakes. The 

water table is essentially a subdued replica of surface topography; thus, the depth to the water table 

varies, depending largely on topography and less so on precipitation. On hills and steep ridges, the 

water table lays tens to hundreds of meters below land surface. In contrast, in valleys and adjacent to 

lakes, ponds and wetlands, the water table is at or near the land surface. Water movement in the 

bedrock is restricted entirely to flow through fractures.
86

Figure 40. The Piedmont and Blue Ridge Aquifer System: Crystalline-rock aquifers underlie the rolling 

hills of the Piedmont physiographic province and the rugged mountains of the Blue Ridge physiographic 

province in a band that extends from east-central Alabama northeastward through western South 

Carolina. From Miller (1990), with permission.

More specifically to Horseshoe Bend, the two basic types of aquifers in the Tallapoosa River basin 

are porous-media aquifers wherein groundwater can be obtained from the regolith, and fractureconduit aquifers wherein groundwater can be obtained from fractures in the rock (Miller 1990). The 

porous-media aquifers are shallow and typically consist of unconsolidated or poorly consolidated 

sediments (Journey and Atkins 1996, USGS 1997). Most groundwater occurs within soil, alluvium, 

and saprolite derived from rocks of various age, and the water moves through interconnected pore 

spaces between sediment grains. The porous-media aquifers generally are only suitable for domestic 

use. The fracture-conduit aquifers are deeper, and formed in areas of igneous and metamorphic rocks. 

The crystalline rocks formed under intense heat and pressure; thus, they have few primary pore 

spaces, and the porosity and permeability of the unweathered and unfractured bedrock are extremely 

low (Miller 1990). Groundwater mostly moves through fractured or broken rock, and through 

openings between cleavage plains. Contact zones between crystalline-rock types are favorable places 

for the location of wells yielding large volumes of water. Well yields typically vary from 3.8-95 L (1-
87

25 gallons) per minute, but may exceed 1,893 L (500 gallons) per minute. Overall, most groundwater 

storage occurs in the overlying weathered rock (regolith or saprolite), whereas the fracture-conduit 

aquifer usually has low storage capacity (Journey and Atkins 1996). Water levels in fracture-conduit 

aquifers respond rapidly to pumping and seasonal precipitation changes, with lowest annual water 

levels usually in fall after the dry summer, and highest water levels early in spring after recharge 

from winter rains.

Groundwater/surface water interactions within the Tallapoosa River basin are substantial, based on 

information for the Tallapoosa River at the Georgia-Alabama state line (Journey and Atkins 1996): 

The unit area mean annual baseflow due to groundwater discharge is ~0.01 cms per km2(0.902 cfs 

per mile2). The mean annual contribution of baseflow (groundwater) to the total flow in the 

Tallapoosa River was estimated to be ~15.1 cms (534 cfs), or ~51% of the total annual flow. More 

specifically, however, very little is known about groundwater quantity or quality in Horseshoe Bend. 

The park presently has no wells for monitoring. On the grounds there is an inactive well house

(latitude 32.97932, longitude -85.74007) and an inactive PVC well (latitude 32.98077, longitude -

85.73133) that is welded shut but is not capped (Rasmussen et al. 2009). In addition, there is an old, 

capped, sealed well that was previously used for aquaculture, located between the picnic area and 

river/nature trail in what was probably a gravel quarry (latitude 32.97195, longitude -85.73465).

The Monitoring Well Network within the Network includes two wells within 100 km (62 miles) from 

the park in south-central/southeastern Alabama (Figure 41), but both are in the Southeastern Coastal 

Plain aquifer, not the Piedmont and Blue Ridge and, so, are inappropriate for extrapolation to 

conditions in Horseshoe Bend. The closest well to Horseshoe Bend among this network that also lies 

within the Piedmont and Blue Ridge Aquifer System is USGS #334207084254801 (well name, 

10DD02; latitude 33.70194, longitude ̶ 84.43000). The well depth is ~104 m (341 ft.). The well has 

been sampled from 17 November 1973 to the present, and 13,658 observations had been taken 

between the start data and 31 December 2011, the last observation used for analysis by Wright 

(2012). Trend analysis indicated a significant negative trend in groundwater level of the period of 

record (p = 0.0003; Wright 2012; Figure 42). It is important to mention, however, that this well is 

within the influence of the Atlanta, Georgia metropolitan area, and therefore differs substantially 

from the park area in its higher water demand from the much larger surrounding local population.
88

Figure 41. Map showing the locations of the USGS monitoring wells (black dots; USGS well numbers) 

near HOBE (orange dot). Of the three wells, only the well shown in northern Georgia lies in the Piedmont 

and Blue Ridge crystalline-rock aquifers (Miller 1990), as does the park. Yellow arrow ≡ statistically 

significant negative trend in groundwater level over the period of record at that well. Modified from the 

NPS SECN (2014).

Figure 42. Mean depth to water level (feet - NGVD 1929) over time (1973-2011) for the well nearest 

Horseshoe Bend National Military Park (#334207084254801; blue line) within the Piedmont and Blue 

Ridge Aquifer System, showing the substantial decrease. From Wright (2012).
89

3.6.2.2.Groundwater Quality:

Miller (1990, p.4) provided a general description for the Piedmont and Blue Ridge Aquifer System, 

unfortunately dated now by more than 20 years:

“The quality of water from the Piedmont and Blue Ridge aquifers generally is suitable for drinking 

and other uses practically everywhere.”

Concentrations of dissolved constituents except for fluoride, iron, manganese, and, locally, sulfate 

seldom exceed state and federal drinking water standards. Wells yielding water containing large 

concentrations of these constituents possibly penetrate mineralized zones, although large iron 

concentrations may be due to the action of iron-fixing bacteria. Oxidation and filtration usually will 

alleviate problems of large iron and manganese concentrations, and render the water potable. Rarely, 

radioactive minerals occur in concentrations sufficient to create water quality problems.

In 2000, however, the USGS collected limited data on pH in the middle Tallapoosa River basin near 

Horseshoe Bend and reported that, of 38 samples collected, 31 (65%) were in compliance (pH 6.5-

9.0; ADEM 2013b). Thus, up-to-date groundwater quality data are needed for this park. Two

programs were developed by Dr. J. Dowd at the University of Georgia to support groundwater 

analyses of national parks in the Network, and are described in detail in Rasmussen et al. (2009). 

Both save data to Excel spreadsheets. Program GWInput automates input of groundwater data. Users 

first select the park from the drop-down menu NPS ID. Information entered must be keyed to a 

unique well name, beginning with the four-character code for the park. Program UpdateSW was 

designed to assist in management and interpretation of groundwater data, and updates daily or 

realtime USGS streamflow or groundwater data by using the Internet to update selected gage sites. 

This program also can graph the data, and can be used to evaluate temporal trends for each well. 

UpdateSW can be used to download data from the USGS National Water Information Service 

(NWIS) database, the national archive for hydrologic data (USGS 2015c). Groundwater data can be 

accessed from the NWIS database using http://water.usgs.gov/waterwatch/ (USGS 2015c).

3.7. Biological Resources and Management

3.7.1. Attributes Used in Assessment

The NPS Omnibus Management Act of 1998, and other reinforcing policies and regulations, require 

park managers “to establish baseline information and to provide information on the long-term trends 

in the condition of National Park System resources” (Title II, Sec. 204). A first step toward meeting 

that mandate is to inventory the species diversity of park biota. This information is valuable because 

measures of community composition are often good indicators of abiotic variability, disturbance, 

and/or other stressors (Byrne et al. 2011b). Understanding changes in species distributions is integral 

to informed management of species and their habitats - changes in species distributions over time 

provide valuable insights at local and landscape scales about how species respond to influences such 

as changing land use, climate, hydrology, or habitat quality/availability. Climate change, for 

example, influences the distribution, phenology, population demographics, and abundance of 

individual species. In turn, the cascading effects through altered species interactions and altered food 

web structure can impact ecosystem processes (Montoya and Raffaelli 2010). It is also valuable to 
90

capture the number of species (species richness) and their relative abundance (species evenness or 

dominance) within a given community (here, Horseshoe Bend). These two components describe the 

species diversity, often communicated as various diversity indices.

Diversity, defined as “the variety and abundance of species in a defined unit of study” (Magurran 

2004, p.8 in Byrne et al. 2011b), is a community property that is broadly related to trophic structure, 

productivity, stability (McIntosh 1967, McNaughton 1977), immigration/emigration (Colwell and 

Lees 2000), and ecological condition (i.e., ecological integrity as defined by Karr and Chu 1995). 

Diversity indices respond differently to various mechanisms that influence community structure, so 

the National Park Service uses a suite of alpha-diversity indices (the diversity of species within a 

defined area, community or ecosystem - Whittaker 1972) in order to fully characterize diversity in 

SECN parks (Haedrick 1975; Boyle et al. 1984 in Byrne et al. 2011b; Table 27).

Table 27. Alpha-diversity indices for species richness (data: observations identified to the species-level) 

used by the Network; notes also add interpretations from other sources as indicated. Modified from Byrne 

et al. (2011b).

Index Notes

Native Species 

Richness, Sobs

Value is a positive integer that indicates the number of native species in the sample. Intuitive. Good 

discriminant ability if the sampling effort is comparable; sensitive to sample size, occurrence of rare or 

cryptic species (with low detectability); does not account for relative abundances (Chao 1984, 1987).

Chao1 Values indicate an estimate of species richness; abundance-based estimate; works well with dataset 

containing several infrequent observations (Chao 1984, 1987).

Chao2 Values indicate an estimate of total species richness (including species not present in the sample); 

incidence-based estimate; works well with dataset containing several infrequent observations (Chao 

1984, 1987).

Abundance-based 

coverage, ACE

Values indicate an estimate of species richness; abundance-based estimate (Chao and Lee 1992, 

Chazdon et al. 1998).

Incidence-based 

coverage, ICE

Values indicate an estimate of total species richness (including species not present in the sample); 

incidence-based estimate (Lee and Chao 1994, Chazdon et al. 1998).

Jackknife 1, 

Jack1

Values indicate an estimate of total species richness (including species not present in the sample); 

incidence-based estimate; the higher the value, the higher the species richness. This procedure requires 

no assumptions regarding the data distribution (Burnham and Overton 1978, 1979; Heltshe and Forrester 

1983).

Jackknife 2, Jack2 Values indicate an estimate of species richness, incidence-based (Smith and van Belle 1984).

Y, Boot Values indicate an estimate of species richness, incidence-based (Smith and van Belle 1984).

Fisher's α, α Value is a positive integer and indicates a relative estimate of species richness (Fisher et al. 1943); good 

discriminant ability, low sensitivity to sample size, and robust to deviations in the assumed distribution 

(Kempton and Taylor 1974, Wolda 1983, Hayek and Buzas 1997, Kempton 2002); abundance-based 

estimate.

Q static, Q Value is a positive integer and indicates a relative estimate of species richness (Kempton and Taylor 

1974, 1976); good discriminant ability and low bias with small samples (Kempton and Wedderburn 

1978), model fit is irrelevant to index performance (Magurran 1988); value is not weighted toward 

abundant or rare species; abundance-based estimate.

* Community attribute: Richness (Sobs, Chao1, Chao2, ACE, ICE, Jack1, Jack2, Boot, α, Q), 

Evenness (Evar, E1/D, E', EG); and Dominance (DBP).
91

Table 27 (continued). Alpha-diversity indices for species richness (data: observations identified to the 

species-level) used by the Network; notes also add interpretations from other sources as indicated. 

Modified from Byrne et al. (2011b).

Index Notes

Smith and Wilson, 

Evar 

Values range from 0 (no evenness) to 1 (perfectly even and all species exist in relatively equal 

abundance); weighs common species more heavily than rare species (desirable in certain cases; 

Simpson 1949, Smith and Wilson 1996).

Smith and Wilson 

1/D, E1/D 

Values range from 0 (no evenness) to 1 (perfectly even and all species exist in relatively equal 

abundance); weighs rare and abundant species equally (desirable in certain cases; Simpson 1949, Smith 

and Wilson 1996).

Camargo, E' Values range from 0 (no evenness) to 1 (perfectly even and all species exist in relatively equal 

abundance); performs well at estimating intermediate values of evenness in comparison to the other 

indices; weighs rare and abundant taxa equally (desirable in certain cases; Camargo 1992).

Gini, Eg Values range from 0 (no evenness to 1 (perfectly even and all species exist in relatively equal 

abundance; Gini 1912); good discriminant ability and low sensitivity to sample size (Lexerød and Eid 

2006).

Berger-Parker, 

DBP 

Values range from 0 (no single species dominance) to 1 (sample is strongly dominated by a single 

species; Berger and Parker 1970); describes the proportional dominance of the single most abundant 

species; low sensitivity to sample size but poor discriminant ability (Magurran 2004) - not used for 

across-years or across-sites comparisons.

* Community attribute: Richness (Sobs, Chao1, Chao2, ACE, ICE, Jack1, Jack2, Boot, α, Q), 

Evenness (Evar, E1/D, E', EG); and Dominance (DBP).

3.7.2. Horseshoe Bend Biota Assessment – Overview

The biota at Horseshoe Bend are generally known only through species lists. In recognition of this

substantial knowledge gap, the Network has begun to characterize the amphibians, birds, and 

mammals of the park, and also have surveyed for a chytrid fungus (Batrachochytrium dendrobatidis) 

that causes amphibian disease worldwide (Byrne and Moore 2011; Byrne et al. 2011b).

According to the NPS Certified Species List (2013b - modified for vascular plant flora to include 

recent taxonomic changes), a total of 706 taxa have been reported to occur in Horseshoe Bend.

These include 251 fauna (32 amphibians, 39 reptiles, 26 fish, 122 birds, and 32 mammals) and 455

taxa of vascular flora (228 terrestrial plants, 224 wetland plants, and three aquatic plants; Appendix 

2). Note that these total numbers of vascular plant and animal taxa differ markedly from the figures 

given in the Strategic Plan for the park (NPS 2008), which lists the number of known plant species at 

901 and the number of known animal species at 354, for a total of 1,255 species. The reason for these 

considerable discrepancies - almost two-fold higher species numbers in the 2008-2012 Strategic Plan 

than in the NPS Certified Species List for Horseshoe Bend (NPS 2008 and NPS 2013b, respectively) 

- is uncertain but likely is due to the fact that the species lists for the park are mostly unvouchered, 

and/or were compiled from historic as well as present information. Similar discrepancies for the 

vascular flora of two other parks, Kennesaw Mountain National Battlefield Park and Ocmulgee 

National Monument, were reflected in the NPS Certified Species List (2013b) versus vouchered, 

recent lists compiled by Zomlefer et al. (2010, 2013). This information collectively suggests that 

Horseshoe Bend, like other SECN parks, is in need of an updated, vouchered Certified Species List 

for its flora and fauna. A recent, vouchered species list unfortunately is not yet available for 
92

Horseshoe Bend, so at present the best-available information is the NPS Certified Species List 

(2013b). As vouchered, updated species lists for this park become available, the new information 

should replace the summaries given here.

According to the NPS Certified Species List (2013b), six Species of Concern (SoC s): one

amphibian, two reptiles, and three birds) can be found in the park (Table 28). At least 33 other SoCs 

have been reported in Tallapoosa County (Alabama Natural Heritage Program 2012) but not in 

Horseshoe Bend, suggesting that these species may have occurred there historically but were 

extirpated (Table 29). These include 13 plants (12 higher vascular plants + 1 moss), 12 fish, two

amphibians, three reptiles, and three birds. In addition, three mammalian species, the American black 

bear (Ursus americanus), red wolf (Canis rufus), and mountain lion (Puma concolor), likely have 

been extirpated from the park. Black bear sightings have been reported from Tallapoosa County, but 

there apparently is no established, self-sustaining population (Alabama Natural Heritage Program 

2012). Various sensitive macroinvertebrates likely also have been extirpated, such as bivalve 

mollusks and certain crayfish (Table 29).

Table 28. Species of concern (SoCs) reported to occur in HOBE (Alabama Natural Heritage Program

2011, NPS 2013b).

Biota Group Species Common Name Statusa

Amphibians Rana sylvatica Wood frog S2, G5

Reptiles Lampropeltis getula Common kingsnake SP, S4, G5T5b

Masticophis flagellum Coachwhip (snake) SP, S3, G5

Birds Dendroica petechia Yellow warbler SP, S2B, G5

Falco sparverius American kestrel SP, S3B, S5N, G5

Vireo solitarius Solitary vireo SP, S3B, S4N, G5

a State of Alabama: E, endangered; T, threatened; R, rare (Alabama Department of Conservation and 

Natural Resources)

b As Lampropeltis getula getula
93

Table 29. Other plant SoCs reported to occur in Tallapoosa County (Alabama Natural Heritage Program 2012, Appendix 3), but not found in 

HOBE according to the NPS Certified Species List (2013b) and other information.*

Biota Group Scientific Name Common Name

SoC Listing(s)

State Federal Status

Plants (13) Amphianthus pusillus granite pool sprite S1 G2 LT

Baptisia metacarpa Apalachicola wild indigo S2 G2

Cyperus granitophilus granite-loving flatsedge S2 G3G4Q

Cypripedium kentuckiense southern lady's-slipper S1 G3

Hypericum nudiflorum pretty St. John's-wort S2 G5

Isoetes virginica Piedmont quillwort S2 G3

Juncus georgianus Georgia rush S1 G4

Matelea baldwyniana Baldwin's milkvine S1 G3

Phacelia dubia var. georgiana outcrop smallflower phacelia S2 G5T3

Pyrularia pubera buffalo-nut S2 G5

Rudbeckia triloba var. pinnatiloba pinnate-lobed blackeyed Susan S2S3 G5T3

Rhynchospora globularis var. saxicola Stone Mountain beakrush S1 G3Q

Selaginella rupestris ledge spike-moss S2 G5

Fish (12) Crystallaria asprella crystal darter S3 G3 SP

Cyprinella gibbsi Tallapoosa shiner S3 G4

Etheostoma chuckwachatte lipstick darter S2 G2G3 SP

Etheostoma tallapoosae Tallapoosa darter S3 G4

Fundulus bifax stippled studfish S2 G2G3

Hiodon tergisus Mooneye S3S4 G5

Hybopsis lineapunctata lined chub S3 G3G4

Notropsis uranoscopus skygazer shiner S2 G3

Percina palmaris bronze darter S3 G4

* Four invertebrate SoCs were also reported by the Alabama Natural Heritage Program (2012) to occur in Tallapoosa County, including 

Cambarus englishi (Tallapoosa crayfish), Cambarus halli (slackwater crayfish), Pyganodon cataract (easter floater - mussel), and Toxolasma 

parvum (lilliput - mussel). It is not known whether these species occur in HOBE, as the NPS Certified Species List for that park does not 

include invertebrate taxa.
94

Table 29 (continued). Other plant SoCs reported to occur in Tallapoosa County (Alabama Natural Heritage Program 2012, Appendix 3), but not 

found in HOBE according to the NPS Certified Species List (2013b) and other information.*

Biota Group Scientific Name Common Name

SoC Listing(s)

State Federal Status

Fish (12)

(continued)

Percina shumardi river darter S3 G5

Percina smithvanizi muscadine darter S2 G2G3

Polyodon spathula paddlefish S3 G4 CNGF, SP

Amphibians (2) Desmognathus monticola seal salamander S5 G5 SP

Plethodon websteri Webster's salamander S3 G3

Reptiles (3) Graptemys nigrinoda nigrinoda black-knobbed sawback (turtle) S3 G3T3Q SP

Graptemys pulchra Alabama map turtle S3 G4 SP

Plestiodon inexpectatus southeastern five-lined skink S3 G5 SP

Birds (3) Columbina passerine common groung-dove S3 G3 SP

Picoides borealis red-cockaded woodpecker S2 G3 SP

Scolopax minor American woodcock S3B, S5N G5 GB

* Four invertebrate SoCs were also reported by the Alabama Natural Heritage Program (2012) to occur in Tallapoosa County, including 

Cambarus englishi (Tallapoosa crayfish), Cambarus halli (slackwater crayfish), Pyganodon cataract (easter floater - mussel), and Toxolasma 

parvum (lilliput - mussel). It is not known whether these species occur in HOBE, as the NPS Certified Species List for that park does not 

include invertebrate taxa.
95

The larger Mobile River watershed, which contains the Tallapoosa River and Horseshoe Bend, was 

once home to many endemic species including aquatic insects and crustaceans, aquatic snails, 

mussels, fishes, and turtles (Burkholder and Rothenberger 2010, and references therein). During the 

past two centuries, watershed development has led to species extinctions at a rate unparalleled 

elsewhere in the U.S. mainland and various aquatic and wetland species are now threatened or 

endangered. The habitat fragmentation imposed by the Harris and Lake Martin dams, along with two 

other dams on the lower Tallapoosa River, have affected faunal diversity, species distributions, and 

fisheries. For example, shoals of the Tallapoosa River support populations of Cahaba lily 

(Hymenocallis coronaria), which has a limited distribution and requires swift current to flourish. This 

wetland plant has been eliminated from portions of its native range by impoundments, and is not 

listed among the park flora. Two protected mussel species, the finelined pocketbook (Lamsilis atilis) 

and the ovate clubshell (Pleurobema perovatum), are thought to be rare although present within park 

boundaries, but their ability to re-colonize the Tallapoosa, including park waters, is impeded by the 

impoundments along the river. Sensitive macroinvertebrates such as bivalve mollusks are 

“barometers” of aquatic ecosystem health. There is no information on their present status in the park. 

CH2M HILL (2005) reported that native mussels were becoming rare in the middle reach of the 

Tallapoosa mainstem which includes Horseshoe Bend. Three of the four endemic fish species known 

from the Tallapoosa basin are on the park species list, including the lipstick darter (Etheostoma 

chuckwachatte), the Tallapoosa shiner (Cyprinella gibbsi), and the mottled sculpin (Cottus bairdi).

In contrast to the paucity of SoCs in Horseshoe Bend, the park contains 46 exotic/invasive taxa 

comprising 39 vascular plants (23 terrestrial, 16 wetland), and seven vertebrate animal species (one

fish, three birds, three mammals), as well as an unknown number of invertebrate taxa including at 

least two highly damaging species (see Section 3.7.9 below). Major concerns have been expressed by 

park staff about exotic/ invasive species problems.

3.7.3. Vascular Flora

The National Park Service (2012) describes plant communities as:

“The primary drivers for a range of ecological processes...integral to the 

proper function of park ecosystems. They serve as the foundation for food 

webs and wildlife habitat for many species, and function as a carbon sink, 

produce oxygen, cycle nutrients and energy through an ecosystem, influence 

the local climate, improve water quality, and moderate flooding and 

erosion.”

Prior to European settlement, most of the Tallapoosa River basin was forested, but the entire 

watershed has sustained varying degrees of logging and extensive clearing for agriculture 

(Tallapoosa Basin Plan, Section 2 - River Basin Characteristics; see 

https://epd.georgia.gov/sites/epd.georgia.gov/files/related_files/site_page/tallapoosa.pdf, chapter 2, 

and https://epd.georgia.gov/tallapoosa-river-basin-watershed-protection-plan, last accessed in May 

2015). The native forests in the Piedmont were dominated by deciduous hardwoods and mixed stands 

of pines and hardwoods. The wetlands originally were forested as well, and were mostly in the 
96

floodplains of streams and rivers. Those still remaining are maintained by the natural flooding 

regime.

Horseshoe Bend lies near the northern boundary of longleaf pine (Pinus palustris), and historically 

the floodplains and drainages consisted of mixed hardwoods, while patches of longleaf pine grew 

along the ridgetops. The hillsides and ridgelines also had a climax beech (Fagus spp.)-oak (Quercus

spp.)-hickory (Carya spp.) forest, mixed with ash (Fraxinus spp.), walnut (Juglans spp.), and 

chestnut (Castanea spp.; DeVivo 2004). Since the battle of 1814, the vegetation was altered 

extensively by human settlement, logging, and the introduction of exotic species until the park was 

established in 1959 (NPS 2000). Many agricultural fields are now managed in loblolly pine or are 

undergoing ecological succession, and some of the park is also maintained through mowing as open 

grasslands.

Using the NPS Certified Species List as a starting point, we determined terrestrial versus wetland 

status following Godfrey and Wooten (1981a,b), the USDA Plants Database (also called the 

PLANTS Database or National Plants Database) of USDA’s Natural Resources Conservation Service 

(USADA NRCS 2015), and The National Wetland Plant List (Lichvar 2012; USACE 2015). We 

checked all scientific and common names for discrepancies, and indicated the PLANTS Database 

recent changes to scientific names. As mentioned, 431 taxa of vascular flora have been reported from 

Horseshoe Bend, including 216 terrestrial plants, 212 wetland plants (many with broad mesic-hydric 

tolerance), and three aquatic plants (Appendix 2). The Network conducted plant surveys of 

Horseshoe Bend during summer 2011, and the data summary is expected to be available shortly, 

including a vegetation map inventory (NPS 2012). Thus far, however, there has been no ecological 

study of the park flora. Its three general habitat types include woodlands, wetlands, and ongoing 

ecologically disturbed areas, as follows:

3.7.3.1.Woodlands:

As mentioned, most of Horseshoe Bend (83%, or 688 hectares [1,700 acres]) is medium-aged, 

second growth upland mixed hardwood forest (Rasmussen et al. 2009). In many places, pines have 

displaced the climax hardwoods that historically were present (Watson 2005). Thus, the forests that 

cover most of the park have been modified by disturbance into secondary growth hardwoods and 

mixed hardwood-pine growth. Chief Ranger J. Cahill (pers. comm., 2009) described a shift in 

Horseshoe Bend forests from historic [longleaf] pine stands to “takeover” by sweetgum and [other] 

hardwoods. The flora has also been altered by exotic/invasive species (see Section 3.7.9 below). The 

forests of Horseshoe Bend most recently have been described as mostly consisting of mesic beechoak hickory (American beech, Fagus grandifolia; oaks such as the white oak - Quercus alba, the

southern red oak - Q. falcata, and the post oak - Q. stellata; and hickory, Carya alba) with some 

loblolly pine (Pinus taeda; Watson 2005).). Other abundant tree species can include sweetgum 

(Liquidambar styraciflua) and tulip tree (Liriodendron tulipifera; modified from Zomlefer et al. 2010 

based on authors’ observations). Habitats in drier areas and along hilltops are dominated by loblolly 

pine.

The understory vegetation is relatively open, commonly with sapling elms (Ulmus alata - winged 

elm, U. americana - American elm, and U. rubra - slippery elm), blueberries (Vaccinium pallidum -
97

Blue Ridge blueberry), silver bells (Halesia diptera - two-wing silverbell, H. carolina - Carolina 

silverbell), muscadines (Vitis rotundifolia), and ferns (e.g. chainfern - Woodwardia areolata , 

sensitive fern - Onoclea sensibilis, cinnamon fern - Osmunda cinnamomea, royal fern - Osmunda 

regalis). The understory shrubs also include the exotic/invasive species Chinese privet (Ligustrum 

sinense), and Japanese honeysuckle (Lonicera japonica; see below). Common vine species among 

the shrub understory are Carolina coralbead (Cocculus carolinus), wild yam (Dioscorea villosa), 

American ivy (Parthenocissus quinquefolia), greenbriers (Smilax spp.), noxious poison ivy 

(Toxicodendron radicans), and muscadines

The herbaceous layer of the forested areas varies depending on the soil moisture and the season. 

Early spring taxa include spotted geranium (Geranium maculatum), bedstraw (Galium aparine),

littlebrownjug (Hexastylis arifolia), King Solomon’s seal (Polygonatum biflorum), Carolina wild 

petunia (Ruellia caroliniensis), bloodroot (Sanguinaria canadensis), bashful wakerobin (Trillium 

catesbaei), perfoliate bellwort (Uvularia perfoliata), and violets (Viola spp.). Woodland species 

thrive later in the season, especially under canopy openings and along trails, and include mainly 

greater tickseed (Coreopsis major), tickrefoil (Desmodium spp.), panicgrass (Dichanthelium spp.), 

Carolina elephantsfoot (Elephantopus carolinianus), common elephantsfoot (E. tomentosus), 

American pokeweed (Phytolacca americana), blackseed needlegrass (Piptochaetium avenaceum), 

Christmas fern (Polystichum acrostichoides), Canada sanicle (Sanicula canadensis), kidneyleaf 

rosinweed Silphium compositum, and aster (Symphyotrichum spp.) (adapted from Zomlefer et al. 

2010, based on authors’ observations).

3.7.3.2.Wetlands:

The park’s wetlands mostly occur along the Tallapoosa River. Wetlands are defined here according 

to Cowardin et al. (1979), as lands transitional between terrestrial and deeper-water habitats where 

the water table is at or near the land surface, or the land is covered by shallow water. About 10% of 

the park is wetlands, or ~83 hectares (204 acres). As mentioned in the above overview, a total of 212 

taxa of wetland vascular plants, including five wetland ferns, occur in the park, mainly along the 

~6.4- km (4-mile) segment of the Tallapoosa River that flows through Horseshoe Bend (Appendix 

2). These taxa comprise ~50% of the total vascular plant taxa in Horseshoe Bend. Only about 4% of 

the wetland taxa (nine species) are exotic/invasive. Scattered shrubs of buttonbush (Cephalanthus 

occidentalis) are common and grasses, sedges, and rushes predominate (e.g. Carex spp., strawcolored 

flatsedge - Cyperus strigosus, blunt spikerush - Eleocharis obtusa, and Juncus spp.; authors’ 

observations). Horseshoe Bend forested wetlands include both seasonally flooded, mesic lowlands 

and smaller areas with groundwater seepage year-round. Typical swampland trees and shrubs (red 

maple - Acer rubrum, silky dogwood - Cornus amomum, sourwood - Oxydendrum arboretum, and 

poison ivy) characterize the woody margins bordering open wetland areas.

3.7.3.3.Ongoing Ecologically Disturbed Habitats:

Aside from woodlands and wetlands, the remaining 7% of the park area (~58 hectares or 143 acres) 

consists of ongoing ecologically disturbed lands such as cleared fields, mowed battlefield areas, and 

cleared areas around public access sites (roadsides, parking lots, trails; Watson 2005). The flora at 

these sites is variable. Numerous grasses commonly include the exotic/invasive taxa Bermudagrass 
98

(Cynodon dactylon), goosegrass (Eleusine indica), Dallas grass (Paspalum dilatatum), and 

Bahiagrass (Paspalum notatum var. saurae), and native species such as Virginia wild rye (Elymus 

virginicus) and various others. Tree and shrub borders of the cleared fields commonly include species 

such as red maple (Acer rubrum), the exotic/invasive species mimosa (Albizia julibrissin), eastern 

redbud (Cercis canadensis),flowering dogwood (Cornus florida), common honeylocust (Gleditsia 

triacanthos), and exotic/invasive Chinese privet and Chinaberry (Melia azedarach), Arkansas or 

shortleaf pine (Pinus echinata), loblolly pine, and water oak (Quercus nigra) - also with woody vines 

such as common trumpetcreeper (Campsis radicans), poison ivy, and muscadines (modified from 

Zomlefer et al. 2010, based on authors’ observations).

3.7.3.4.Vegetation Community Survey in August 2011: 

As part of the NPS Vital Signs monitoring program, the SECN Inventory & Monitoring Program 

(NPS 2012a) sampled 21 locations at Horseshoe Bend in 2-18 August 2011, including information on 

vascular plant species, frequency of occurrence, percent cover, diversity, and distribution in the 

groundcover, shrub, and canopy strata (Heath et al. 2014a). Vegetation communities were sampled 

within each stratum using hybrid methods following the North Carolina Vegetation Survey nestedsubplot design (Peet et al. 1998) within a circular plot similar to that of the Forest Inventory and 

Analysis protocol described by Bechtold and Patterson (2005).

From the two-week survey, 172 vascular plant taxa were detected (Heath et al. 2014a). Of these, 16 

species and 2 genera (rattlesnake root, Prenanthes, and Heuchera, alum root) were newly detected in 

Horseshoe Bend; another species, (Acer saccharum), was also described as newly reported for the 

park, but it was the only species of the 17 that was included in the NPS Certified Species list as of 

2013 (NPS 2013a). One newly reported taxa, Japanese stiltgrass or Nepalese browntop 

(Microstegium vimineum), is invasive. The newly reported species were added to the NPS Certified 

Species List (Appendix 2).

This survey indicated that Horseshoe Bend had 86.5% vascular plant canopy cover across the park, 

and the canopy cover was fairly uniform (Heath et al. 2014a). Longleaf pine (Pinus palustris) had the 

largest average diameter at breast height of any canopy species in the park where more than two 

individuals were measured. The shrub stratum was dominated by sweetgum (Liquidamber 

styraciflua), which had the highest absolute and relative cover. Red maple (Acer rubrum) had the 

second highest absolute and relative shrub cover, and sweetgum and red maple were the most 

frequently occurring shrub species. Blue Ridge blueberry (Vaccinium pallidum) had the highest 

estimated seedling density at the park. The most frequently occurring species in the groundcover 

stratum were muscadine grape (Vitis rotundifolia), greenbriars (Smilax spp., notably cat greenbriar 

Smilax glauca), and Virginia creeper (Parthenocisus quinquifolia). Muscadine grape and common 

greenbriar (Smilax rotundifolia) had the highest and second highest absolute cover, respectively, in 

the groundcover stratum. Leaf litter was the most frequently occurring ground condition in 

Horseshoe Bend, and also had the highest relative and absolute cover of any ground condition.

3.7.3.5.Vegetation Community Survey in May 2012: 

Using a similar approach, vegetation communities were sampled within each of three strata at 30 

spatially balanced, permanent, random sites in Horseshoe Bend during 9-25 May 2012 (Heath et al. 
99

2014b). The site locations differed somewhat from those surveyed in August 2011, and they were 

selected using the Reversed Randomized Quadrant-Recursive Raster algorithm (Theobald et al. 2007, 

as described by Byrne et al. 2013). All sampling locations were in naturally vegetated areas. 

A total of 196 vascular plant taxa were detected during the May 2012 survey, including 11 newly 

reported species and two newly reported genera (beak sedge – Rhynchospora, and ragworts and 

groundsels – Senecio) for Horseshoe Bend (Heath et al. 2014b). The higher number of taxa detected 

in this survey relative to the August 2011 effort may reflect seasonal differences; in addition, 

different sites were sampled. Although more sites also were sampled in this survey than in the 

previous year, the number of sites examined in August 2011 had been evaluated as sufficient to 

capture the species richness (Heath et al. 2014a). Therefore, theoretically, increasing the number of 

sites should not have increased the species richness. Of the 196 taxa, 11 were newly reported species 

for the park, and 2 others were newly reported genera (species apparently were not possible to 

identify based on the available specimens). The newly reported species were added to the NPS 

Certified Species List (Appendix 2).

The findings from this survey were very similar to those from the August 2011 survey: The absolute 

canopy cover across the park was 87.8%, and the canopy was uniform. Post oak (rather than longleaf 

pine as in the August 2011 survey) had the highest estimated seedling density. In the shrub stratum, 

the highest and second highest relative cover were sweetgum and red maple/Elliott’s blueberry 

(Vaccinium elliotti), respectively. Sweetgum was the most frequently occurring species in the shrub 

substratum as well. A second blueberry species, Blue Ridge blueberry, had the highest estimated 

seedling density in the park. In the groundcover stratum, muscadine grape and roundleaf greenbriar 

had the highest and second highest relative cover, respectively. Muscadine grape also had the highest 

absolute cover, whereas giant cane (Arundinaria gigantea) had the second highest absolute cover. 

The most frequently occurring species in the groundcover stratum were muscadine grape, Virginia 

creekper, cat greenbrier, and poison ivy (Toxicodendron radicans). Leaf litter was the most 

frequently occurring ground condition in Horseshoe Bend, and also had the highest relative and 

absolute cover of any ground condition.

3.7.4. Fish

The middle ~80 km (50-mile) reach of the Tallapoosa River from Harris Dam to the inflow of Lake 

Martin, which includes the section within Horseshoe Bend, is the only remaining Piedmont largeriver habitat remaining in the state of Alabama. It represents one of the longest and highest-quality 

segments of Piedmont River habitat remaining in the Mobile River drainage (Lydeard and Mayden 

1995). Various factors, including a subtropical climate and freshwater habitat diversity, combined to 

make the Mobile River basin what was once one of the most diverse natural faunistic regions 

throughout North America (Meador et al. 2005). Mettee et al. (1996) reported 404 fish species in the 

Mobile River basin and tributaries in Alabama and adjacent states. More specific to Horseshoe Bend, 

the Tallapoosa River basin historically was described as having 114-120 fish species (Williams 1965; 

Rivers of Alabama 2015) last accessed in September 2013). Watershed development and associated 

habitat degradation has led to the decline of fish species richness in these streams (Johnston and 

Maceina 2009).
100

The present NPS Certified Species List (NPS 2013b) indicates that there are only 26 species of fish 

in park waters (Appendix 2). This region of the Tallapoosa River has sustained a decline in some 

species such as the speckled chub (Macryhybobsis aestivalis), bullhead minnow (Pimephales

vigilax), madtom catfish (Noturus spp.), and redhorse sucker (Moxostoma spp.; Freeman et al. 2001). 

According to the NPS Certified Species List, none of these species are present in Horseshoe Bend. 

Three of the four endemic fish species known from the Tallapoosa basin were included in the NPS

Certified Species List for the park several years ago (2008), including the lipstick darter (Etheostoma 

chuckwachatte), the Tallapoosa shiner (Cyprinella gibbsi), and the mottled sculpin (Cottus bairdi). 

These species have since been removed from the NPS Certified Species List for Horseshoe Bend

(NPS 2013b).

Some evidence suggests that the highly artificial flow variation imposed on the Tallapoosa River by 

regulation for hydropower at the Harris Dam may be severely impacting fish populations and other 

aquatic life in the park (NPS 2008). There is no fisheries management plan for the park (DeVivo 

2004), which seems a major oversight given that the Strategic Plan for Horseshoe Bend (NPS 2008) 

describes the Tallapoosa River as the park’s “major ecological resource.” In addition, freshwater fish 

are important ecologically and for recreational uses. The Alabama Department of Conservation and 

Natural Resources conducts annual creel surveys at the Horseshoe Bend boat ramp but, clearly, 

additional efforts are needed to track fish populations and overall fish community health in the 

Tallapoosa River within the park and upstream from it. Saalfeld et al. (2012) noted that “To maintain 

and improve water quality, there is an increasing need to understand relationships between current 

land use practices (e.g., agriculture, forested/silviculture, and urban) and stream ecosystems.” They 

assessed relationships among water quality, habitat composition, fish assemblages, and present land 

use practices in the Tallapoosa River basin in eastern Alabama. For all six streams examined, all fish 

metrics were significantly higher in streams draining forested lands than in streams draining 

agricultural lands. Nutrient pollution (total nitrogen and total phosphorus, TN and TP, respectively) 

were most descriptive of fish biotic integrity, and were negatively related to fish biotic integrity. 

These nutrient concentrations increased as the percentage of land use in agriculture increased. 

Saalfeld et al. (2012) concluded that agricultural land use practices, in particular, appear to be 

negatively impacting stream water quality and biota in the Tallapoosa watershed.

In addition to concerns at the fish community level, an example of the imperiled status of fish 

populations in the Tallapoosa basin is that of the stippled studfish (Fundulus bifax). This species is 

endemic to the Tallapoosa River system, but is not listed as present in Horseshoe Bend. It is widely 

considered to be at risk due to habitat degradation, and its global ranking is N2N3 (NatureServe: 

imperiled/ vulnerable). Its required habitat is clean water over clean sand in small or large streams. 

Therefore, and unfortunately not surprisingly, it apparently has been extirpated in the state of 

Georgia and appears to be increasingly uncommon in Tallapoosa basin waters of Alabama. 

Stallsmith (2013) visited 24 sites in the Alabama portion of the watershed during 2008 in an attempt 

to assess the current status of this killifish. Many of these sites were locations where the species had 

been found in 1980. Stallsmith (2013) found at least one individual from each of six different creek 

systems in four counties including Tallapoosa County, although sites in Horseshoe Bend were not 

sampled. The shrinkage in distribution was attributed to habitat degradation. Genetic analysis 
101

indicated that the existing populations are monophyletic, with low molecular variation. The author 

concluded (p.19) that “the future of the species is in doubt, with the six distinct populations being 

vulnerable to further habitat degradation and diminished gene flow.”

As good news for Horseshoe Bend, wadeable stream habitat monitoring has been planned for the 

park. The Network has developed assessment procedures based on the USGS National Water Quality 

Assessment (NAWQA) program, USEPA wadeable stream assessment program and USDA protocols 

(NPS 2012). A combination of reach- and transect-level flow, geomorphic, and physical in-stream 

and riparian habitat measurements will be included. In addition, large river monitoring is planned for 

implementation in future years, which will utilize bank-to-bank videography along the length of the 

Tallapoosa River in the park. The video will be synced with GPS. From this information, a full-river 

map of potential sites of management concern, such as erosion features, will be generated.

3.7.5. Herpetofauna

Amphibian communities in the southeastern U.S. are widely considered to be among the most 

diverse in the world, and they are a valued resource in SECN parks. Several factors are attributable to 

population declines and localized extinctions [including] disease and anthropogenic stressors such as

habitat loss and degradation, non-native predators, acid precipitation, altered hydrology and 

hydroperiod, ultraviolet radiation, and chemical contaminants (Collins and Storfer 2003). Given their 

habitat requirements, anatomy, and physiology, amphibians are considered good indicators of 

ecological condition...[and] amphibian communities are a priority for SECN monitoring efforts 

(Byrne et al. 2011a).

Amphibian communities in the southeastern U.S. are widely considered to be among the most 

diverse in the world, and they are a valued resource in SECN parks (Byrne and Moore 2011). 

According to the NPS Certified Species List (NPS 2013b), Horseshoe Bend contains 32 native 

species of amphibians and 34 native species of reptiles (Appendix 2). The amphibians include 20 

species of frogs and toads, and 12 species of newts and salamanders. The reptiles include 8 species of 

lizards, 22 snakes, and nine turtles. Three SoCs are present at Horseshoe Bend: the wood frog (Rana 

sylvatica), the common kingsnake, and the coachwhip snake (Table 29). In a comparison of 16 parks 

including Horseshoe Bend, Tuberville et al. (2005) noted that while larger parks had higher species 

richness, Horseshoe Bend had an unusually rich assemblages of herpetofauna considering its small 

size (Figure 43). Horseshoe Bend was considered to have a high diversity of habitat types. Because it 

is located near the Fall line along the boundary between the Piedmont and Coastal Plain, resident 

herpetofauna of this park include species characteristic of both physiographic provinces.

3.7.5.1.National Park Service 2009 Study of Vocal Anuran Amphibians:

An Amphibian Community Monitoring Protocol is being produced for use in all SECN parks. The 

long-term objective is to determine trends in amphibian species occupancy, distribution, diversity, 

and community composition in each park (Byrne et al. 2011a). In the interim, Byrne et al. (2011a) 

described partial implementation and test application of Standard Operating Procedure (SOP) #4 of 

the Protocol, the ARD SOP, to monitor vocal anuran amphibians (frogs and toads) at Horseshoe 

Bend. Data were collected using this SOP from 22 April to 2 May 2009 at 30 spatially balanced, 

random locations in the park (Figure 44). To allow for park-wide inference, the park’s administrative 
102

boundary was used as the sampling frame. The sampling frame was divided into a systematic 0.5-

hectare grid, and the center point of each grid cell was considered the potential sampling site. A 

spatially balanced sample was drawn from the grid using the Reversed Randomized QuadrantRecursive Raster algorithm (Theobald et al. 2007). Alternate points were used when selection criteria 

(i.e., safety and access issues) were not met. A sample size of 30 was chosen after consideration of 

the park’s size, hypothesized variability, and logistical issues.

Figure 43. Relationship between land area (in hectares) and species richness, excluding exotic 

(introduced) species, among 16 parks within the Southeast Coast Network of the NPS, including HOBE 

(red dot), showing the strong positive linear relationship between (log-transformed) land area and species 

richness ( P = 0.001). Modified from Tuberville et al. (2005).

Log Area (hectares)

Log # Species

2.0

1.5

1.0

0.5

0.0

0 1 2 3 4 5

y = 0.274x + 0.722

R

2

= 0.534

Log Area (hectares)

Log # Species

2.0

1.5

1.0

0.5

0.0

0 1 2 3 4 5

y = 0.274x + 0.722

R

2

= 0.534
103

Figure 44. Spatially balanced, random sampling locations at HOBE in the 2009 studies of vocal anuran 

amphibians and birds. From Byrne et al. (2011a), modified by the NPS SECN (2014).
104

A total of 8,960 minutes were recorded by the ARDs when deployed in the park. A total of 29 

samples were taken. ARDs provide only detection versus non-detection information; thus, data on 

abundance could not be obtained with this SOP. The species accumulation curve generated from the 

data was found to asymptote at a higher value than the sample size of 29 - that is, higher than the 

total number of samples collected - so the ARD data alone from this study were evaluated as 

inadequate to characterize amphibian diversity in the park. This was anticipated, as the primary goal 

of the study was to test the ARD technique for the overall Amphibian Community Monitoring 

Protocol, rather than to characterize the entire amphibian community.

In the 2009 study, seven of the 19 vocal anuran species known to occur in the park were detected, all 

native taxa. The most widely detected species was Fowler’s toad (Bufo fowleri). Diversity indices 

were also calculated for these data as reflective of community composition (i.e., number of species 

(Table 30). Confidence intervals for each diversity index were estimated with a bootstrap procedure 

(not further described). The observed species richness (Sobs) was seven (95% CI: 4.19, 9.80). The 

ICE and Boot species richness estimates and confidence intervals were relatively consistent with one 

another. These estimates appeared to perform comparatively well, given the characteristics and 

limitations of the data, and were considered to be better estimates of true species richness than 

Chao2, Jack1, or Jack2 indices because of the uncertainty associated with those estimates as 

indicated by high CIs (Byrne et al. 2011a). The data were viewed as instructive information for when 

baseline values for the entire amphibian community can be generated from planned additional 

monitoring efforts.

Table 30. Alpha-diversity estimates for vocal anuran amphibians at HOBE based on SECN monitoring in 

2009 (Byrne et al. 2011a).

Index Symbol Value

Lower 

95% CI

Upper 

95% CI Value Interpretation

Native Spp. Richness Sobs 7.00 4.19 9.80 Number of native species detected

Chao 2 Chao2 9.89 7.34 30.99 Estimated true species richness (high CI)

Incidence-based Coverage ICE 10.94 8.14 13.74 Estimated true species richness

Jackknife 1 Jack1 9.89 4.23 15.55 Estimated true species richness (high CI)

Jackknife 2 Jack2 12.68 8.25 17.11 Estimated true species richness 

Bootstrap Boot 8.21 6.72 9.70 Estimated true species richness

3.7.5.2.Survey for a Chytrid Fungus Pathogen of Amphibians:

Limited sampling on one date each in spring and fall of 2006 was conducted to assess whether an 

amphibian pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Bd), was present in 

Horseshoe Bend (Byrne and Moore 2011). This fungus has been identified as a cause of localized 

declines and extinctions of amphibian populations worldwide (Fisher et al. 2009). Samples were 

collected throughout the park, specifically in a beaver pond, all insular streams, and at least two 

locations along each stream that originated outside the park.

Two pooled samples were collected in spring of 2006: One pooled sample contained pooled swabs 

from the southern two-lined salamander (Eurycea cirrigera, n = 9) and three-lined salamander 
105

(Eurycea guttolineata, n = 1). The other pooled sample contained swabs from the southern cricket 

frog (Acris gryllus, n = 2), green frog (Rana clamitans, n = 3), and southern leopard frog (Rana 

sphenocephala, n = 3). Both pooled samples tested positive for Bd, but the actual species infected 

could not be determined.

Individual species samples were collected in fall of 2006, but because of the small sample size, low 

confidence was calculated to detect Bd in amphibians other than two species, the southern two-lined 

salamander and the green frog. The fungal pathogen was detected in 15% (4 of 27; 95% CIs, 1.4-

28.2) of green frog samples, and in 42% (21 of 50; 95% CIs, 28.3-55.7) of southern two-lined 

salamander samples. There was no obvious signs of the disease in animals that tested positive for Bd, 

but several of the infected southern two-lined salamanders were lethargic, and their tails detached or 

were crushed during very light handling (Byrne and Moore 2011). In streams where the two species 

co-occurred, some samples from each tested positive for Bd. Positive samples for each species were 

also collected at locations where only one of the two species were detected. Considering the small 

size of the park (~825 hectares), point-pattern analysis was not considered necessary; it was assumed 

that the fungus is evenly distributed across the park.

3.7.5.3.National Park Service 2011 Study of Amphibians and Reptiles:

Efforts to characterize amphibian and reptile communities of Horseshoe Bend were conducted in 

2011, when both ARDs for vocal anuran amphibians (11 March through 31 May) and visual 

encounter surveys (VESs, 2-18 August) for both amphibians and reptiles were used to collect data at 

the 30 spatially balanced random locations in the park (Smrekar et al. 2013). Because of prescribed 

burn activities, ARDs were deployed at 29 of the sites. A total of 135 vocal detections were made 

using the ARD recordings, wherein each detection represented an identifiable observation of a 

species or species group during one night of monitoring at a given sampling site.

This study detected 20 amphibian species, including vocalizations from 13 identifiable anuran 

species. The VESs revealed 61 post-metamorphic amphibians representing 12 species and three more 

taxa identified at the family or genus level, as well as 324 larval-stage amphibians within two taxa. 

Two species, Fowler’s toad (Bufo fowleri) and the spring peeper (Pseudacris crucifer), had the 

highest overall frequency of occurrence, and Fowler’s toad also had the highest relative abundancebased on the VESs. The spring peeper and Cope’s gray treefrog (Hyla chrysoscelis) had the highest 

relative detection frequency of vocalizations during the 77-day ARD recording period. Fowler’s toad, 

the spring peeper and the southern leopard frog, were the most widespread amphibian species in the 

park, found in all four quadrants. Two amphibian species were detected for the first time in 

Horseshoe Bend, the squirrel treefrog (Hyla squirella) and the spotted dusky salamander 

(Desmognathus conanti).

The 2011 VESs also resulted in detection of 261 reptiles within 15 identifiable, all native taxa 

(Smrekar et al. 2013). Two reptilian species were detected for the first time in Horseshoe Bend, the 

southeastern crowned snake (Tantilla coronata) and the smooth earth snake (Virginia valeriae). It is 

noteworthy that shells of the eastern box turtle (Terrapene carolina) occurred at 20 (70%) of the 

sampling sites, but only one live individual was found. The authors of the study suggested that this 

finding may warrant additional surveys to assess the status of this species at Horseshoe Bend.
106

The year 2013 marks a milestone for the National Park Service, which is now concurrently 

publishing both reports on its natural resources, and the data and metadata serving as the basis for the 

reports.

3.7.6. Birds

Birds are an important component of park ecosystems, and their high body temperature, rapid 

metabolism, and high ecological position in most food webs make them a good indicator of the 

effects of local and regional changes in ecosystems. Long-term trends in the community composition, 

relative abundance, distribution, and occurrences of breeding bird populations provide a measure for 

assessing the ecological integrity and sustainability in southeastern systems. Further, long-term 

patterns of these attributes in relation to changes in the structural diversity of vegetation resulting 

from fire and other management practices will improve our understanding of the effects of various 

management actions (Byrne et al. 2011b, p. ix).

As stated, 122 species of birds have been reported from Horseshoe Bend (Appendix 2). Of those, 

11% (13 species) are mostly associated with wetland/aquatic habitats. Some species, such as the 

spotted sandpiper (Actitis macularia) and the Nashville warbler (Vermivora ruficapilla), historically 

have been seen only rarely (once or twice) within park boundaries. The park has three state-listed 

SoCs (Table 32 - the yellow warbler - Dendroica petechia, American kestrel - Falco sparverius, and 

solitary [blue-headed] vireo - Vireo solitarius), and three exotic/invasive species (see Section 3.7.9 of 

this Report). An Avian Conservation Implementation Plan was developed for Horseshoe Bend in 

2005, in association with the North American Bird Conservation Initiative, to help identify and 

prioritize bird conservation opportunities, and to provide counsel about successful implementation of 

needed conservation activities (Watson 2005).

Byrne et al. (2011b) used the Draft SECN Landbird Community Monitoring Protocol to conduct a 

survey of birds in Horseshoe Bend in April and May of 2009. Data were collected at the same 30 

spatially balanced random locations as for the anuran amphibian study (Figure 44). The data were 

collected using an adaptation of the VCP technique with distance estimation. Evaluation of sampling 

effort relative to the number of species detected indicated that the sample adequately characterized 

the bird diversity of Horseshoe Bend. Thus, these data are considered to serve as a baseline for 

comparison with future monitoring efforts for this Vital Sign (see Chapter 4 of this Report).

A total of 845 birds representing 53 species were detected in the spring 2009 study, all native species. 

In general, the data indicated that species were not aggregated and occurred uniformly across the 

Park. Two species were newly reported for the park, Petrochelidon pyrrhonota (cliff swallow) and 

Dendroica petechia (yellow warbler, an SoC). The most widely distributed species were Cardinalis 

cardinalis (northern cardinal) and Parula americana (northern parula), which were found at all 

sampling sites. The second most widely distributed species group consisted of Melanerpes carolinus

(red-bellied woodpecker), Vireo olivaceus (red-eyed vireo), Baeolophus bicolor (tufted titmouse), 

Thryothorus ludovicianus (Carolina wren), and Corvus brachyrhynchos (American crow), which 

were detected at 87-97% of the sampling sites. It is also noteworthy that 16 species identified as 

priority species in the South Atlantic Migratory Bird Initiative Implementation Plan (Watson and 

Malloy 2006) were detected at Horseshoe Bend during the 2009 study (Appendix 2).
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Observed species richness (i.e., Sobs) was 53 (95% CI: 48.36, 56.97; Table 31). Most species richness 

estimators were relatively consistent with one another, ranging from 54.52 to 63.97. The diversity 

indices suggested high bird species diversity at the park (α = 12.56, Q = 14.64). The sample was 

relatively well distributed among species, with four species composing approximately 40% of the 

sample. The consistent performance of the evenness/ dominance indices (i.e., Evar, E1/D, Eg, and DBP) 

suggest varied relative abundances of the species in the sample and, again, a diverse bird community 

at Horseshoe Bend.

Table 31. Bird alpha-diversity estimates at HOBE based on 2009 data. From Byrne et al. (2011b).

Index Symbol Value

Lower 

95% CI

Upper 

95% CI Value Interpretation

Native Spp. Richness Sobs 53.00 48.36 56.97 Number of native species detected

Chao 1 Chao1 54.52 52.95 64.17 Estimated true species richness 

Chao 2 Chao2 57.72 53.86 73.92 Estimated true species richness

Abundance-based Coverage ACE 55.84 53.08 58.60 Estimated true species richness

Incidence-based Coverage ICE 60.53 56.37 64.69 Estimated true species richness

Jackknife 1 Jack1 62.50 54.91 70.09 Estimated true species richness

Jackknife 2 Jack2 63.97 58.46 69.48 Estimated true species richness

Bootstrap Boot 57.75 55.91 59.59 Estimated true species richness

Fisher’s α α 12.56 10.80 14.32 Baseline value, suggests high diversity

Q Statistic Q 14.64 10.73 15.53 Baseline value, suggests high diversity

Smith and Wilson Evar 0.34 0.30 0.38 Species occur in several relative 

abundances –low evenness

Smith and Wilson 1/D E1/D 0.32 0.30 0.37 Species occur in several relative 

abundances –low evenness

Camargo E’ n.a. - - Invalid calculation due to dataset (i.e., too 

many with few detections)

Gini EG 0.35 0.29 0.39 Species occur in several relative 

abundances –low evenness

Berger-Parker DBP 0.12 0.11 0.14 Sample is not dominated by a single 

species, diverse assemblage of species

3.7.7. Mammals

The Network has also taken recent steps to document the mammalian fauna of Horseshoe Bend by 

supporting a study by Webster (2010), which represents the first comprehensive survey of this 

important biological resource (Vital Sign; see Chapter 4 of this report). There had been no effort to 

document the mammalian fauna of Horseshoe Bend since dated checklists of species present or 

potentially present (Freeman et al. 1974, and University of California-Davis 1992, as described in 

Webster 2010). These checklists contained 35 terrestrial species and nine bats. Prior to Webster’s 

(2010) work, 47 species were included on the NPS Certified Species List as assumed to be present in 

Horseshoe Bend, but estimated species richness was as high as 78 (Webster 2010, p.7).

In addition to gathering information from museums in Tallapoosa County and surrounding counties 

in intensive work, sampling in the park was conducted from 13 August through 9
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October 2003, for a total of 15 man-days in the field and 2,350 trap-nights of sampling effort (Figure 

45). Five major habitats were identified for mammals including stream and river edges, bottomland 

forest, upland mixed hardwood/pine forest, upland managed pine forest, and regularly maintained 

road edges and fields. Most of the field work (with Sherman live traps, pitfall traps, and extensive 

groundtruthing for spoor) was conducted in the more remote (gated) northeast quarter of the park, 

which had adequate segments of all of these habitats except for maintained road edges and fields. 

Many other park areas were visited at least once. Unfortunately, bats were not included in the study.

Figure 45. Map of survey sites for mammals in HOBE during August - October 2003 study. From Webster 

(2010).
109

Webster (2010) documented 24 species of terrestrial mammals from Horseshoe Bend, 22 species 

when domestic cattle and horses were omitted. These species have broad habitat tolerances and 

occupy or would be expected to occupy most of all of the five habitats. Also, the Virginia opossum 

(Didelphis virginiana) was found immediately adjacent to the park and was considered to inhabit it. 

An additional 11 species, widely distributed in the Southeast, were not found at Horseshoe Bend but 

were expected to occur there. Thus, overall, Webster’s (2010) final list included 33 species, and 

consisted of 22 species of terrestrial mammals confirmed to inhabit Horseshoe Bend plus 11 more 

species that were considered likely to occur there on a permanent basis, although they were not 

documented during the study (Appendix 2). In addition, the domestic or feral dog (Canis familiaris) 

and striped skunk (Mephitis mephitis) were evaluated as likely occurring in the park on occasion, 

although the study did not reveal evidence of their presence.

Webster’s (2010) list of mammalian species in Horseshoe Bend was comparable to the NPS Certified 

Species List (NPS 2013b) in its inclusion of the Virginia opossum, domestic or feral dog, striped 

skunk, bobcat (Lynx rufus), muskrat (Ondatra zibethicus), eastern harvest mouse (Reithrodontomys 

humulis), and red fox (Vulpes vulpes). With exception of the Virginia opossum, Webster (2010) 

listed these species as “probably present.” The NPS Certified Species List (NPS 2013b) differed, 

however, (i) its inclusion of two bat species (bats were not tracked by Webster 2010, as noted above), 

and (ii) its inclusion of the eastern wood rat (Neotoma floridana). Webster (2010) considered the 

latter species among five species of mammals that “apparently are absent from Horseshoe Bend

because suitable habitat is lacking;” the other four species in this grouping by Webster were the 

eastern fox squirrel (Sciurus niger), oldfield mouse (Peromyscus polionotus), meadow jumping 

mouse (Zapus hudsonius), and eastern spotted skunk (Spilogale putorius).

The NPS Certified Species List (NPS 2013b) also differed in (iii) omission of six species that 

Webster (2010) considered “probably present” - the southern flying squirrel (Glaucomys volans), the 

exotic/invasive house mouse (Mus musculus) and Norway rat (Rattus norvegicus), the long-tailed 

weasel (Mustela frenata), the American mink (Neovision vision), and the swamp rabbit (Sylvilagus 

aquaticus). In addition, the NPS Certified Species List (NPS 2013b) includes the feral horse (Equus 

caballus) as present at Horseshoe Bend. We have removed that species from Appendix 2 as 

requested by park staff. Thus, overall our species list for mammals at Horseshoe Bend includes 32 

species, in accord with the NPS Certified Species List except for omission of the feral horse. All of 

these have broad habitat tolerances and widespread geographic distributions in the eastern U.S. 

(Webster 2010, and references therein). Our species list additionally notes that Webster’s (2010) 

analysis indicated that six others likely are also present. Three mammalian species that historically 

were found throughout the eastern U.S. - the red wolf, American black bear, and mountain lion -

have been extirpated from the Horseshoe Bend area. Feral pigs have not been reported in the park, 

although there is concern that they may establish within the next decade, and beaver damage to trees 

and water flow alteration has been minimal (Chief Ranger Jim Cahill, pers. comm., 2009).

3.7.8. Species of Special Management Concern

An overall National Park Service goal is to manage native species in the park to restore and maintain 

natural community composition, structure, and diversity. Toward that goal, and beyond efforts 
110

regarding SoCs and exotic/invasive taxa, park staff have described several species of special 

management concern (SSMCs), as follows.

A special focus of the park is restoration of longleaf pines (Superintendent Doyle Sapp, pers. comm., 

30 April 2013). Longleaf pine forests once covered 90 million acres from Virginia to Florida, but 

only ~3 million acres of highly fragmented habitat remain (Ford et al. 2010, and references therein). 

This species typically grows in low-nitrogen, well-drained soils; it has seed dispersal timing that is 

fire-dependent, and longleaf pine forests have a relatively thin understory. Longleaf pines are now 

sparse in the park, and a management goal is to restore them along the ridgeline to historic conditions 

at the time of the Revolutionary War.

Information is lacking about several other SSMSc that have raised Horseshoe Bend staff concerns:

 White-tailed deer and wild turkeys appear to be over-populated in the park north of the river

(Chief Ranger J. Cahill, pers. comm., 2009). Burgeoning deer populations consume forest 

understory species, so their grazing can lead to depressed forest regeneration. The large deer 

population in Horseshoe Bend may be increasingly vulnerable to starvation and disease (e.g. 

Davidson 2006). Population census data for these two SSMCs are needed (e.g. Alabama Division 

of Wildlife and Freshwater Fisheries 2008).

 White-tailed deer and wild turkeys may be over-hunted in the park south of the river because of 

illegal poaching and dog hunting (DeVivo 2004). Poaching is strongly suspected but data are not 

available. The park is working with the Alabama Department of Natural Resources on the 

poaching issue. Horseshoe Bend has targeted wild turkeys as a high priority for conservation.

 Coyotes and armadillos are recent (invasive) arrivals at the park (e.g. (Howell 1921 vs. Choate et 

al. 1994), and their respective impacts on Horseshoe Bend ecosystems are unknown. The coyotes 

may suppress fox populations, for example, via competition for food resources, and/or they may 

exert beneficial pressure on the deer population to bring it into balance.

3.7.9. Exotic/Invasive Species

Invasive exotic species fragment native ecosystems, displace native plants and animals, and alter 

ecosystem function. Invasive species are second only to habitat loss as threats to global biodiversity 

(Scott and Wilcove 1998). Such species negatively affect park resources and visitor enjoyment by 

altering landscapes and fire regimes, reducing native plant and animal habitat, and increasing trail 

maintenance needs (Young et al. 2007).

Thus, exotic species are a foremost concern for national parks throughout the U.S., surely including 

the Southeast. As mentioned, there are at least 38 exotic species in Horseshoe Bend on the NPS 

Certified Species List (Table 32); these include 19 terrestrial plant species, 12 wetland plants, one

fish, three birds, and three mammals. Quantitative information and maps of present 

distribution/coverage are lacking, although vegetation maps for the park are in progress.

3.7.9.1.Flora:

The Alabama Invasive Plant Council has ranked the most noxious of the exotic plants in the state as 

the Top 10 (Alabama Invasive Plant Council 2015). Similarly, the National Park Service has a Top 
111

Ten Species List for the Southeast region. Both lists share three plants that are found in Horseshoe 

Bend, including one terrestrial plant (kudzu, Pueraria montana var. lobata) and two wetland plants 

(Chinese privet - Ligustrum sinense, Japanese honeysuckle - Lonicera japonica; Table 32). These 

plants have few natural enemies in the southeastern U.S.; they rapidly overgrow and shade out 

native, beneficial plant species, inhibiting their growth and displacing them in forests, fields, and/or 

wetlands. According to the Alabama Invasive Plant Council (2012), Kudzu has been called “the vine 

that ate the South” (Alabama Invasive Plant Council 2012). It continues to spread along edges of 

forests, pastures, roads, etc. It can grow up to 0.3 m (1 ft.) per day and covers most structures in its 

way, from buildings and fences to trees, road signs, and telephone poles. Chinese privet spreads by 

abundant seeds carried by birds and water, and its infestations grow by prolific root suckering 

(Alabama Invasive Plant council 2012). It tends to invade along fence rows and forested streams, and 

in upland forests. Its dense growth can be up to ~9 m (30 ft.) and prevents regeneration of 

bottomland hardwood as well as upland pine forests. For berry producers such as Chinese privet, the 

berries are less nutritious for wildlife than native species, but this plant has some limited value for 

deer browse and bird habitat. Japanese honeysuckle thrives in a wide range of habitats including 

fields, forests, wetlands, barrens, and various disturbed lands (NPS; see 

http://www.nps.gov/plants/alien/fact/loja1.htm, last accessed in May 2015). This plant has numerous 

growth and dispersal mechanisms, and it kills shrubs and young trees by girdling when vines twist 

tightly around stems and trunks, cutting off water flow through the beneficial plant.
112

Table 32. Exotic/ invasive taxa in HOBE, also indicating (*) Top 10 status on the Alabama Exotic Pest Plant Council (2015) Category #1 status, 

and Category #1 Alert status of the Alabama List of Exotic and Invasive Plants; and the NPS Top Ten Species List for national parks in the 

Southeast region (NPS 2015b).

Biota Group Species Status

Terrestrial Plants (19) *Albizia julibrissin (mimosa, mimosa tree, powderpuff tree) Category #1

Cynodon dactylon (Bermudagrass, chiendent pied-de-poule) Category #2

Dioscorea oppositifolia (Chinese yam) Category #2

Duchesnea indica(India mockstrawberry, Indian strawberry)

Eleusine indica (Goosegrass, crowsfoot grass)

Glechoma hederacea (ground ivy)

Helenium amarum (sneezeweed, bitter sneezeweed, yellowdicks)

Lamium amplexicaule (common henbit, giraffehead, henbit)

*Lespedeza cuneata (Chinese lespedeza, sericea lespedeza) Category #1

*Melia azedarach (Chinaberry, Chinaberry tree) Category #1

Opuntia ficus-indica (Indian fig, Indian fig, tuna cactus)

Paspalum notatum var. saurae (bahiagrass)

Plantago aristata (bottlebrush Indianwheat, largebracted plantain)

Plantago lanceolata (narrowleaf plantain, buckhorn plantain, English plaintain)

Prunus mexicana (Mexican plum)

*Pueraria lobata (Pueraria montana var. lobata; kudzu) Top 10, Category #1, NPS Top Ten Species

Trifolium campestre (field [big-hop] clover, field clover, large hop clover)

Trifolium repens (Dutch clover, ladino clover, white clover)

Verbascum thapsus (big taper, common mullein, flannel mullein)

Wetland Plants (12) Carya illinoinensis (pecan)

Heliotropium indicum (India heliotrope, Indian heliotrope)

Ipomoea hederacea (ivyleaf morningglory, entireleaf morningglory)

*Ligustrum sinense (common Chinese privet, privet) Top 10, Category #1, NPS Top Ten Species

*Lonicera japonica (Japanese [Chinese] honeysuckle) Top 10, Category #1, NPS Top Ten Species

Paspalum dilatatum (Dallas grass, dallis grass, dallisgrass)

Polygonum caespitosum var. longisetum (oriental ladysthumb)
113

Table 32 (continued). Exotic/ invasive taxa in HOBE, also indicating (*) Top 10 status on the Alabama Exotic Pest Plant Council (2015) Category 

#1 status, and Category #1 Alert status of the Alabama List of Exotic and Invasive Plants; and the NPS Top Ten Species List for national parks in 

the Southeast region (NPS 2015b).

Biota Group Species Status

Rumex acetosella (red sorrel, sheep sorrel, common sheep sorrel)

Rumex crispus (curleydock, curly dock, narrowleaf dock)

Sorghum halepense (Aleppo milletgrass) Category #2

Verbena bonariensis (purpletop vervain)

Vitis rotundifolia (muscadine, muscadine grape)

Fish (1) Cyprinus carpio (European [common] carp)

Birds (3) Chaetura pelagica (chimney swift)

Passer domesticus (English [house] sparrow)

Sternus vulgaris (European starling)

Mammals (3) Canis familiaris (domestic dog, feral dog)

Felis catus (feral cat)

Vulpes vulpes (red fox)
114

3.7.9.2.Fauna:

Nearly all emphasis on exotic/invasive taxa has focused on plants and, by comparison, little is known 

about exotic/invasive fauna at Horseshoe Bend. Nevertheless, two of the most destructive 

exotic/invasive species in the park are not on the NPS Certified Species List (NPS 2013b) because it 

does not include insects. The exotic invasive Asiatic clam, Corbicula fluminea, is believed to be 

present in the riverine ecosystem and potentially competing with native mussels (DeVivo 2004). This 

species, with high growth and reproduction rates, has substantially impacted other aquatic food webs 

and displaced native bivalve mollusc species (Stites et al. 1995). It also appears to be more adaptable 

to polluted environments than many native bivalves (Jenkinson 1979).

Considering terrestrial ecosystems, two insect species are high risk taxa with extreme damage 

potential. The southern pine beetle, Dendroctonus frontalis, is regarded as the most destructive forest 

insect pest in the southeastern U.S. (Clarke 1995), and it has killed many trees in the park (Chief 

Ranger J. Cahill, pers. comm., 2009). The red fire ant (Solenopsis invicta) originated in South 

America and was introduced to the U.S. in the 1930s (Porter and Savignano 1990). Since its arrival, 

it has infested more than ~1.2 million km2(~468,625 square miles, or 300 million acres) across the 

southern U.S., despite federal quarantine measures (Hawaii Ant Group 2007; and Defenders of 

Wildlife 2015). The red imported fire ant largely has displaced the two fire ant species native to the 

Southeast, the tropical fire ant (Solenopsis geminata) and the southern fire ant (Solenopsis xyloni; 

Porter and Savignano 1990). Red imported fire ants also threaten human health. In the U.S., millions 

of people are stung each year and more than 80 have died from hypersensitivity to the ant venom. 

Red imported fire ants additionally threaten wildlife, significantly depress biodiversity, and damage 

crops, ornamental plants, and electrical equipment (Porter and Savignano 1990, Wojnik et al. 2001, 

Hawaii Ant Group 2007).

Finally, many wildlife populations have been negatively impacted by predation from feral dogs and 

cats (USDI and NPS 2000, Watson 2005). Their effect on the natural biota of the park is a concern to 

park staff.

3.7.10. Management Actions

3.7.10.1. Exotic/Invasive Species:

Exotic vegetation was described by Chief Ranger J. Cahill as a primary concern for Horseshoe Bend. 

Two species specifically were mentioned: Chinese privet is mechanically removed on a five-year

cycle, mostly within 9.1 m (30 ft) from the river. Each year 0.2 hectare (0.5 acre) of parkland infested 

with Chinese privet is treated to remove it, and an additional 1.2 hectares (3 acres) is treated with 

mechanical or chemical means to reduce growth of targeted invasive plants including Chinese privet, 

mimosa, Japanese honeysuckle, and kudzu. One to two areas of kudzu infestation are targeted for 

removal ever year as well. Cultural resource management at Horseshoe Bend includes removal of 

exotic plant species, as well, from certain areas along with erosion control and trail maintenance.

The National Park Service has created an Exotic Plant Management Team (EPMT) through its Exotic 

Plant Management Program. This program assists parks in preventing introductions of new species, 

reducing existing infestations, and restoring native plant communities and ecosystem functions. The 
115

EPMT visits NPS partner parks on a rotational basis for several days at a time but, as of yet, 

Horseshoe Bend is not listed as a “host and partner park (NPS 2015a)

3.7.10.2. Longleaf Pine Restoration Efforts:

The park’s prescribed fire program was initiated in 2002 by previous Horseshoe Bend Superintendent 

Mr. Mark Lewis, who also authored the park’s first Fire Management Plan in 2003. A fire break was 

constructed along the entire park boundary in fiscal year 2004. Burning was planned to continue in 

winter annually, following the approved fire plan for the park on a five-year cycle. In fiscal year 

2005, a burn plan was approved, but weather conditions delayed the first prescribed burn until 2006 

(NPS 2006; and NPS 2015f).

The major goal of the program is to reduce fuels buildup while allowing for natural regeneration of 

longleaf pine along the ridgeline. A second goal is to manage southern pine beetle-damaged areas to 

establish early successional grassland or shrub scrub habitat. Longleaf pine forests require fire for 

long-term viability, but fires in the Horseshoe Bend area have been rare and management actions 

previously emphasized fire avoidance. In fact, throughout the history of the park until 2006, there 

was no record of a forest fire. Over the past 30 years, there has been a significant increase in 

flammable ground fuels (e.g. plant debris), see the Strategic Management Plan for Horseshoe Bend

(NPS 2015g). Prior to the first prescribed burn at the park, concern was expressed by longleaf pine 

specialists at Auburn University that with excessive duff and forest litter that had accumulated over 

time, longleaf pine feeder roots tend to rise to the surface where they could sustain fire damage 

during prescribed burns. Therefore, the fire plan was slightly modified to reduce fuel loads while also 

removing duff layers surrounding longleaf pine stands.

In mid-April of 2006, 115 hectares (285 acres) in the northwest area of the park were successfully 

burned (Plate 2) with assistance of fire use modules from Cumberland Gap National Historical Park, 

Great Smoky Mountains National Park, an engine crew from Kings Mountain National Military Park, 

local Rural Fire Assistance cooperators, and Clemson University. The management goal for 2008 

was to reduce the forest fuel load in Horseshoe Bend by 40% on at least one burn unit that was 

identified in the 2003 Fire Management Plan. The most recent fire fuel survey at Horseshoe Bend by 

the National Park Service was in summer 2011.

The College of Forestry at Auburn University is an active partner in the park’s longleaf pine 

restoration efforts. In 2009, Auburn University researchers purchased and planted 1,565 

containerized longleaf pine seedlings scattered over 10 small gaps throughout Horseshoe Bend in 

three separate sites designated as Northeast (NE), Northwest (NW), and Southwest (SW; Figure 46).

This planting is a pilot effort to assess the success of planting containerized longleaf in small 

regeneration gaps within a disturbed, previously fire-excluded landscape (NPS 2015d).
116

Plate 2. Left: Fire from a prescribed burn, moving through litter layers along the park. Right: Longleaf pine 

“grass stage” seedling, viable after the fuel reduction burn. NPS: photos by J. Cahill and A. Callis (Forest 

and Rangelands 2006).
117

Figure 46. Map of the three longleaf pine restoration sites (shaded areas with red stars) at HOBE, also 

showing fire boxes (blue triangles). Provided by HOBE Superintendent Doyle Sapp.

3.8. Synopsis of Stressors to Horseshoe Bend Natural Resources

The present and potential stressors that are affecting or may affect Horseshoe Bend are summarized 

in Table 33. Despite the relatively remote and rural location of the park, degraded air quality is 

already a moderate to significant concern, encompassing ozone and particulate pollution,

acidification from N and S chemical species, and reduced visibility. Surface water quality data are 

sparse and indicate fair conditions; groundwater quality data apparently are completely lacking. 

Potential pollution sources in the watershed include point source dischargers and nonpoint sources 

such as clear-cutting and agriculture. For example, agricultural impacts may have resulted in local 

extirpations of herpetofauna (Tuberville et al. 2005). The highly artificial flow regime that has been 

imposed on the middle Tallapoosa River by hydroelectric operations periodically would be expected 

to cause sudden, extreme stress and elimination of aquatic life. The dams have also fragmented the 

natural breeding and migration patterns of fish and mussels. Water demands could be exacerbated in 

the future depending on allocations to population centers such as Atlanta. Neighboring Lee County is 

recruiting retirees, resulting in increased population growth and higher value of rural lands being sold 

for development. If this continues, Horseshoe Bend staff expect increased highway traffic, waste 

product pollution, noise, and other urban sprawl issues (NPS 2008).
118

Other concerns are soil erosion, habitat loss and disruption near the park, and the impacts of 

exotic/invasive plants and animals, which have been evaluated as a major threat to the natural 

ecosystems of Horseshoe Bend (Chief Ranger Jim Cahill, pers. comm., 2009).

Table 33. Current and potential stressors that are affecting or may affect HOBE (ND ≡ no data to make 

judgment; NP ≡ not a problem;-- ≡ not applicable; EP ≡ existing problem; PP ≡ potential or pending 

problem).

Stressor

Surface 

Waters

Groundwater Airshed ForestHuman 

Health

Acidification EP ND PP PP PP

Algal blooms PP --- --- --- NP

Toxic algae ND --- --- --- NP

Encroaching development (clear-cutting. etc.) ND (PP) ND (PP) ND (PP) ND (PP) NP

Erosion (including dust) EP --- --- ND (PP) NP

Excessive nutrients EP ND PP --- NP

Exotic invasive species* EP --- --- EP ND (PP)**

Fecal bacteria, other microbial pathogens ND (PP) ND ND ND PP

Habitat disruption EP ND --- EP ---

Hypoxia EP --- --- --- ---

Light pollution ND (PP) --- --- --- ---

Metals contamination ND (PP) ND (PP) ND (PP) --- ND (PP)

Noise pollution ND (PP) --- --- ND (PP) ND (PP)

Other toxic substances EP ND (PP) EP ND (PP) PP

Ozone pollution --- --- EP EP EP

Particulate matter pollution EP ND EP --- EP

Sedimentation EP ND EP --- ---

Trash/refuse pollution ND (PP) ND (PP) ND (PP) ND (PP) ---

Visibility (air pollution) --- --- EP PP EP

Water demand PP PP --- --- PP

* Suspected for aquatic resources; known for terrestrial resources.

** Includes consideration of West Nile virus, carried by mosquitoes and known to be in the area.
119

4. Indicators to Assess Natural Resource Conditions

4.1. Management Directives and Planning Guidance

The NPS mission is to "preserve unimpaired the natural and cultural resources and values of the 

National Park System for the enjoyment, education, and inspiration of this and future generations”

(NPS 2013c). About 15 years ago the NPS (1999) developed an action plan, the Natural Resources 

Challenge, for preserving the natural resources of the national parks (see Carter 2007), and the 

agency has been engaged in many efforts to carry out that plan.

Horseshoe Bend was listed on the National Register of Historic Places in 1976. Thus, the entire area 

was to be “managed with preservation and interpretation of cultural values as the central focus.” The 

park does not have a General Management Plan Environmental Assessment, but it does have a fiveyear Strategic Plan (2008-2012; NPS 2008). According to the present Strategic Plan for Horseshoe 

Bend, the overarching charge for the National Park Service is to preserve “outstanding

representations of America’s natural, cultural, and recreational resources of national significance...” 

and make them available to visitors. The Strategic Plan was written to fulfill requirements of Section 

104 of the National Parks Omnibus Management Act of 1998, consistent with the Government 

Performance and Results Act of 1993.

A Resource Stewardship Strategy (RSS) has not yet been developed for Horseshoe Bend. Once 

available, the RSS should help to protect the park’s natural resources. The present Strategic Plan for 

Horseshoe Bend (NPS 2008) identified long-term goals and five key factors affecting 

accomplishment of those goals. Four of the five key factors - water resources (severe hydrologic 

fluctuations imposed by the Alabama Power Company on the Tallapoosa River in the park), climate

(major storms causing natural disasters), area population increases, and the local economic situation

- significantly affect the natural resource conditions of the park, and all four are factors that are Not 

Possible for the NPS to Control (NPC). Thus, various indicators developed and described in this 

chapter to evaluate Natural Resource Conditions in Horseshoe Bend over time are related to factors 

that are NPC.

The National Park Service has done considerable work to identify natural resources and indicators 

that are important from the perspective of the NPS I&M Program: Three general properties were 

identified that broadly affect the integrity of ecosystems and natural resources in SECN parks: (a) 

parks are generally surrounded by altered landscapes; (b) the ecosystems of the Network are driven 

to a large extent by natural disturbance process such as hurricanes, flooding, and fire; and (c) the 

SECN region is increasingly subject to human development, resulting in diverse anthropogenic 

effects on park resources (DeVivo et al. 2008).

The NPS I&M Program was created as part of the National Park Service’s efforts to improve park 

management through greater reliance on scientific knowledge. The Network developed a suite of 

conceptual models to support and guide development of a monitoring program for the parks, using 

General Ecosystem Model as a template for specific models of the six dominant ecosystem types 

found in SECN parks. Horseshoe Bend has three of these - Upland Forests, Bottomland Hardwoods, 

and Streams. Each model includes a set of system drivers, local drivers, and park resources. 
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Importantly as well, the Network identified 25 Vital Signs, most of which are being/planned to be 

monitored as part of the I&M Program (Table 34). The ecosystem-centered Vital Signs span all 

categories of the Ecological Monitoring Framework: Air & Climate, Geology & Soils, Water, 

Biological Integrity, Human Use, and Ecosystem Patterns and Processes. Most - Air Quality, 

Climate, Geology & Soils, Water, and Biological Integrity (Biological Resources) have been 

discussed in Chapters 2 and 3 of this Report. The Inventory also covers Ecosystem Patterns (land 

use/land cover) and various aspects of Human Use. Many of the Measures were on our preliminary 

list of potential indicators for Horseshoe Bend. For many of these parameters, however, information 

for Horseshoe Bend is not yet available, underscoring the importance of the I&M Program to 

establish present natural resource conditions in the park and track them over time to assess park 

ecosystem health.
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Table 34. Vital signs identified by the SECN for its inland parks including HOBE ( ≡ Vital Sign for which the SECN will develop protocols and 

implement monitoring;  ≡ Vital Sign that is monitored by a network park, another NPS program, or another federal or state agency;  ≡ 

monitoring deferred). Modified from DeVivo et al. (2008).

Ecological Monitoring 

Framework Categories Network 

Level 1 Level 2 Level 3 Vital Sign Measures Status

Air & Climate Air Quality Ozone Air Quality Atmospheric ozone concentration, damage to 

sensitive vegetation 

Wet and Dry 

Deposition

Wet and Dry 

Deposition

Wet and dry sulfate and nitrate deposition 

Visibility and 

Particulate Matter

Visibility and 

Particulate Matter

IMPROVE suite for visibility and fine 

particulates, particle size analyses: pm 10, pm 

2.5, haze index



Air Contaminants Air Contaminants Concentration of mercury, semi-volatile 

organic compounds, acidic components of 

contaminants



Weather & 

Climate

Weather and 

Climate

Weather and 

Climate

Air temperature, precipitation, relative 

humidity, tides, location and magnitude of 

extreme weather events



Geology and Soils Geomorphology Coastal/Oceanographic Features 

and Processes

Coastal Shoreline 

Change

Shoreline position

Salt Marsh 

Elevation

Sediment elevation, salinity

Stream/River 

Channel 

Characteristics

Stream/ River 

Channel 

Characteristics

Percent cover of coarse woody debris, 

detritus, distribution and extent of geomorphic 

features (runs, riffles, pools); grain size 

distribution; distribution, extent, and rate of 

change of erosion features



Water Hydrology Groundwater 

Dynamics

Groundwater 

Dynamics

Water table levels for freshwater and saltwater 

Surface Water 

Dynamics

Surface Water 

Dynamics

Discharge, magnitude and duration of flooding 

events 

Water Quality Water Chemistry Marine Water 

Quality

pH, temperature, dissolved oxygen, turbidity, 

salinity, concentrations of chlorophyll a, TDN, 

TIN, TDP, TIP, metals, and volatile organic 

compounds
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Table 34 (continued). Vital signs identified by the SECN for its inland parks including HOBE ( ≡ Vital Sign for which the SECN will develop 

protocols and implement monitoring;  ≡ Vital Sign that is monitored by a network park, another NPS program, or another federal or state agency; 

 ≡ monitoring deferred). Modified from DeVivo et al. (2008).

Ecological Monitoring 

Framework Categories Network 

Level 1 Level 2 Level 3 Vital Sign Measures Status

Water 

(continued)

Water Quality

(continued)

Water Chemistry

(continued)

Riverine Water 

Quality

pH, temperature, dissolved oxygen, specific 

conductance, turbidity, trace ions, nutrient 

concentrations



Biological Integrity Invasive Species Invasive/Exotic 

Plants

Invasive/ Exotic 

Plants

Occurrence of invasive plant species 

Focal 

Species 

or 

Communities

Marine 

Invertebrates

Marine 

Invertebrates

Occurrence of selected marine Invertebrate 

species

Fishes Fish Communities Fish community diversity, relative abundance, 

Index of Biotic Integrity, percentage of nonnative species, number of crevice spawner 

species



Amphibians and 

Reptiles

Amphibians Species occurrence, diversity, percent area 

occupied, disease incidence 

Birds Breeding Forest 

Birds

Species occurrence, diversity, relative 

abundance 

Mammals Small Mammals Species occurrence, diversity, percent area 

occupied, relative abundance 

Focal species 

or communities 

cont.

Vegetation 

Complex

Plant Communities Plant species occurrence, diversity; percent 

cover by herbaceous, shrub and overstory; 

rooting by feral hogs and armadillos; 

occurrence of disease, occurrence of insect 

outbreaks, occurrence of non-native species; 

NVCS class


123

Table 34 (continued). Vital signs identified by the SECN for its inland parks including HOBE ( ≡ Vital Sign for which the SECN will develop 

protocols and implement monitoring;  ≡ Vital Sign that is monitored by a network park, another NPS program, or another federal or state agency; 

 ≡ monitoring deferred). Modified from DeVivo et al. (2008).

Ecological Monitoring 

Framework Categories Network 

Level 1 Level 2 Level 3 Vital Sign Measures Status

Bioligical Integrity 

(continued)

At risk Biota T&E Species and 

communities

Shorebirds Number and location of piping plover, red knot, 

Wilson’s plover, American oystercatcher

T&E Species and 

communities

T&E Species Abundance, distribution, and recruitment of 

rare species such as sea beach amaranth, 

beach mouse, sea turtles, red-cockaded 

woodpeckers



Human Use Consumptive 

Use

Consumptive Use Fisheries Take Species occurrence, weight, size based on 

compilation of existing data from State and 

other sources

Visitor & 

Recreation Use

Visitor Usage Visitor Use Monthly and annual visitor attendance 

compiled from existing Park and other sources 

Landscapes Fire and Fuel 

Dynamics

Fire and Fuel 

Dynamics

Fire and Fuel 

Dynamics

Burn area and extent, down woody debris, duff 

depth 

Landscape 

Dynamics

Landscape 

Dynamics

Land Cover and 

Use

Extent and distribution of land cover and use 

types, fragmentation, extent and distribution of 

management actions (compiled from park 

records)


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4.2. Study Scoping and Design

Program Manager Joe. DeVivo organized an initial workshop for this project in Atlanta, wherein we 

received guidance about the background and foundation of NPS National Resource Condition 

Assessments. We also received counsel about the best NPS specialists to contact about various 

aspects of the project, available NPS data, and NPS websites with important information. This 

meeting addressed all project objectives, especially (ii) - Determine the subset of NPS-identified and 

PI-identified data and information sources that are most pertinent and useful for developing 

indicators and performance measures) and (vi) - Conduct a series of workshops to assist in project 

completion.

In recognition of the fact that park staff have, by far, the most advanced and detailed, comprehensive 

understanding about the natural resources of Horseshoe Bend, we then visited Horseshoe Bend and 

spent several hours with park staff. They graciously took us on an informative tour of the park’s 

natural resources. We also discussed each category of natural resources with them, and learned their 

knowledgeable views about issues for each category that would need to be considered in inventory 

and assessment efforts. Their input was truly essential to enable us to select an optimal set of natural 

resource indicators that would be the most useful to the park staff both short-term and long-term. We 

additionally were given their guidance on which indicators should be emphasized as major priorities 

for the park. We all were in accord that the indicator framework needed for Horseshoe Bend should 

follow an ecosystem approach as in DeVivo et al. (2008).

An extensive, continued effort over the entire span of the project was then conducted to obtain all 

manner of natural resource information pertinent to the park - historic information, reports, books, 

peer-reviewed publications, management plans, GIS data, etc. All of this information was carefully 

considered in writing the final synthesis of the inventory and status of Horseshoe Bend natural 

resources. The findings were presented within an ecosystem framework (Figure 47), considering 

Horseshoe Bend as the ecosystem. Following a hierarchical framework patterned after Unnasch et 

al.’s (2009) Ecological Integrity Assessment Framework, we first considered the overall goal(s) of 

the park staff for the desirable status, i.e., the ecological integrity, of each category of natural 

resources in Horseshoe Bend. Ecological integrity is defined here as the ability of an ecological 

system to support and maintain a community of organisms with species composition, diversity, and 

functional organization comparable to those of the natural/historic habitats in the park. We then 

conducted a macroscale inventory of landscape pattern (land cover/ land use) surrounding the park; 

the “human biological factor,” i.e. human population demographics in the area surrounding 

Horseshoe Bend and visitor statistics within the park; air quality (airshed level), water quality (within 

the park insofar as possible, but considering pollution sources near the park), the soundscape, and the 

lightscape; and stressors on the natural resources within the park. This included a concerted effort to 

gather and organize existing databases for multiple GIS data layers describing Horseshoe Bend

natural resources. Next, we inventoried what is known about the present composition and condition 

of the vegetation, habitat structure, and including the natural communities, SoC, exotic/invasive 

species, and species of special interest for park managers. For each category of natural resources, we 

then identified a suite of indicators and measures for tracking natural resource health in Horseshoe 

Bend. These indicators were carefully selected to be scientifically sound while also providing the 
125

most “user-friendly,” straightforward, and easily accomplished method for evaluation that we could 

find.

Our intentions in meeting the latter requirement were two-fold: First, to provide, insofar as possible, 

a suite of indicators and the methods to assess them that park staff and the National Park Service in 

general will find clear, simple and rapid, and relatively inexpensive to conduct; and second, in this 

world where information must be conveyed in sound bites and one-page bullets, to provide an 

indicator system with powerful messages that are easy/fast to explain to policymakers who often 

have dramatic influence over our nation’s increasingly precious national parks.

As noted by the South Florida Ecosystem Restoration Task Force (2011) from its “System-wide 

Indicators for Everglades Restoration - 2010 Report,” any method of communicating complex 

scientific and findings to non-scientists [for Horseshoe Bend, the general citizenry, visitors to the 

park, and politicians who strongly influence critically needed funding for the park] must (1) be 

developed with consideration for the specific audience, (2) be transparent as to how the science was 

used to generate the summary findings, (3) be easy to follow the simplified results back through the 

analyses and data to see a clear and unambiguous connection to the information used to roll up the 

results, (4) maintain the credibility of the scientific results without minimizing or distorting the 

science, and (5) should not be, or appear to be, simply a judgment call (Norton 1988, Dale and 

Beyeler 2001, Niemi and McDonald 2004, Dennison et al. 2007) [T]he system must be effective in 

quickly and accurately getting-the-point-across to the audience in order for the information to be 

used effectively (Rowan 1991, 1992; Dunwoody 1992; Weigold 2004; Thomas et al. 2006; Dennison 

et al. 2007). For further information, see

http://issuu.com/evergladesrestoration/docs/2014_indicator_report?e=8031892/12097978, last 

accessed in May 2015.

Thus, here we use a “stoplight report card system” approach (e.g. Doren et al. 2009, NPS 2009) of 

good (green), fair (yellow), and poor (red) to summarize our evaluation of present natural resource 

conditions at Horseshoe Bend (Figure 48). This system has been used with great success to assess 

natural resource conditions systems such as Chesapeake Bay and its watershed (Williams et al. 

2007), and the Florida Everglades ecosystem (Ferriter et al. 2007, Doren et al.2008, 2009).

Importantly, we were instructed by the National Park Service to design indicators that were 

quantifiable insofar as possible, and supported by peer-reviewed science literature. We therefore 

carefully clarify, with supporting scientific basis, any suggested indicators for which quantitative 

information for the park was not available. Because this stipulation, while logical, greatly restricted 

the suite of indicators that could be proposed, in Chapter 5 we also include discussion of data gaps 

that we view as especially important to fill so that certain much-needed indicators can be developed. 

Finally, to ensure that the data used to develop the indicators and assessment were of acceptable 

quality, we restricted our inventory and this analysis to reliable sources (e.g. NPS, peer-reviewed 

literature, quality assured/ quality controlled water quality data, etc.), and to data collected by those 

sources within the past decade.
126

This indicator framework and suite of indicators for Horseshoe Bend support the identified goals of 

the National Park Service to “develop service-wide products that improve management of biological 

resources in parks, and maintain a broad ecosystem-based framework for park management” 

(Unnasch et al. 2009).

Figure 47. Conceptual model of the HOBE ecosystem, used as a general framework to select indicators 

of natural resource health for the park. Modified from DeVivo et al. (2008, Appendix: Conceptual 

Ecological Models; examples of stressors are shown).

good fair poor

Figure 48. The color-coded “stoplight report card” system used to succinctly convey the status of HOBE 

natural resources. Adapted from Ferriter et al. (2007).
127

4.3. Climate Change

Issue: Climate change is rapidly advancing in the Southeast, manifested through warming 

temperatures, altered patterns and amounts of precipitation (droughts, floods), and the storm 

frequency. These changes will dramatically impact Horseshoe Bend natural resources.

Baron et al. (2008) described climate change as already redefining U.S. national parks, and advised 

park managers to begin to include climate change considerations into all activities and plans. Not 

surprisingly, species richness, extirpations, and introductions in national parks in other nations, as 

well as the U.S., have been found to be strongly related to climate, more so than to any other factor 

(Rivard et al. (2000). To increase the resilience of the natural biota to the many changes resulting 

from climate change, Baron et al. (2008) recommended reducing habitat fragmentation and loss, 

invasive species, and pollution; protecting important ecosystem and physical features; restoring 

damaged systems and natural processes; and reducing the risks of catastrophic loss through 

establishing refugia, relocating valued species, replicating populations and habitats, and attempting to 

maintain representative examples of beneficial species populations. The extent to which these goals 

can be done for Horseshoe Bend is unclear, especially for the wetland/aquatic ecosystems of the park 

because of the extreme hydrologic fluctuation that has caused dramatic adverse alterations.

The IPCC 2007 has projected that temperature in the Southeast will increase 2.2 to 5.0oC (4 to 9oF) 

by 2080 (Karl et al. 2009). Since 1970, average annual temperatures in this region have increased by 

~1.1oC (~2oF), and winters in particular are warming: The average number of freezing days has 

declined by four to seven days per year (Karl et al. 2009). Most areas are also becoming wetter, 

especially in the autumn; in contrast, during the spring and summer seasons, areas affected by 

moderate to severe droughts have increased (Karl et al. 2009). It is uncertain whether precipitation 

will increase or decrease, but models suggest that there will be heavier downpours interspersed with 

increased droughts between storm events. Thus, both the risk of flooding and the risk of drought are 

expected to increase. Coastal areas are expected to sustain stronger hurricanes, accelerated sea level 

rise, and larger storm surges (Karl et al. 2009). The IPCC also has projected that flow seasonality 

will increase in rain-dominated regions such as the U.S. Southeast, resulting in higher flows during 

the peak flow season and lower flows during low flow seasons and/or longer dry periods 

(Kundzewicz et al. 2007). Future floods and droughts likely will not occur at historic rates because 

climate change is expected to be a major force controlling the frequency and timing of flow 

seasonality (Brekke et al. 2009). Projections about smaller-scale, regional and subregional impacts 

have high uncertainty, such that accurate assessment of climate change effects on flow and water 

supply will require long-term monitoring (Knowles et al. 2006, Brekke et al. 2009).

The historic and present climatic conditions at Horseshoe Bend, and the significance of changes in

these conditions, were described in Chapter 3 of this Report in terms of five parameters that are 

recommended here as indicators: air temperature, precipitation, moisture (the PDSI and the number 

of dry months), phenology, and extreme weather events. In fulfilling the “easy and straightforward” 

criterion, the data for temperature, precipitation, and PDSI are easily plotted online from the NOAA 

NWS. Other climate information may require assistance from knowledgeable state and federal 

personnel. Evaluation considers trends in the six indicators over the past decade (Table 46):
128

 Summer Average (Mean) Air Temperature: poor = increasing;

 Summer Average (Mean) Precipitation: poor = decreasing;

 Moisture: poor = increasing dryness (lower PDSI, more dry months);

 Annual GDD: poor = increasing; and

 Number of Major Storms: poor = increasing.

As mentioned, an important feature of the selected indicators is that they are easy to assess. Detailed 

climatic data for these indicators are easily available from NOAA (see Chapter 3).

However, we initially encountered difficulty in (1) determining the date when the 1200 GDD 

threshold is reached, and (2) using the PDSI data to rank the severity of drought over seven 

“moisture classes” ranging from excessively wet to severely dry (Chapter 3, Table 4). Therefore, 

with assistance from the Department of Statistics at NCSU, we wrote two straightforward, userfriendly programs for the National Park Service, which automate the computations (Appendix 3). 

Both programs use data that are routinely supplied to end users by the SERCC.

The first program uses GDD data to calculate the date where the 1200 GDD threshold is 

reached. The computation involves finding the calendar date when the 1200 GDD threshold is 

reached for each year in the dataset, by summing the monthly values until the sum is greater than 

1200 and then calculating the slope of the line between that month and the month preceding to 

determine the exact date on which 1200 would occur. Typically, the value 1200 is achieved between 

April and May, but occasionally it occurs between March and April, or between May and June, 

depending on the temperature. The second program uses the PDSI data to rank the severity of 

drought over the seven moisture classes. The computation involves calculating the proportion of the 

number of monthly observations in each drought class for every nine-year period.

The “keystone” indicator of climate change is temperature, as it strongly influences all four other 

indicators. Therefore, an overall score of 0 to only 1 poor evaluation among the five indicators is 

good, unless the poor score is for temperature wherein the overall score is fair. The four possible 

evaluation scenarios are shown in Table 35.

For Horseshoe Bend, rapidly rising average summer temperatures over the past decade have been 

accompanied by a striking decrease in average summer precipitation during the same period, as well

as a strong increase in the proportion of months that have been abnormally dry and excessively dry, 

and a striking decrease in PDSI values. The annual GDD has decreased from the 1930s - 2012, but 

appears to have increased in the past decade, and the approximate date when 1200 GDD was reached 

for each year since 1930 has also increased by several days. The number of storms has increased 

each decade since the 1980s. All of these conditions are undesirable. Thus, all five indicators for 

Climate Change Condition are poor, leading to an overall average evaluation of poor (Table 36).

These indicators are all NPC for the National Park Service. The Network has worked to develop a 

Climate Science Strategy in an attempt to prepare for and mitigate the adverse impacts of global 

warming on all of the national parks in the region (DeVivo et al. 2011).
129

Table 35. Overall scores for climate change, based on the six selected indicators.

Indicators, Evaluations Status

Overall 

Score

Scenario 1

Summer average air temperature Good ,↔ or good

Other indicators ,< 1 poor, < 2 fair, > 3 good

Scenario 2

Summer average air temperature (TEMPSUM), poor poor fair

Other indicators ,< 1 poor, > 4 good or fair

Scenario 3 ,> 3 indicators poor poor

Table 36. Evaluation of Climate Change Condition in HOBE, based on five Climate Indicators.

Climate Change Indicators Trend at HOBE Rating

Summer Average Air Temperature (TSUM) ↑ poor

Summer Average Precipitation (Ppt) ↓ poor

Moisture - PDSI, # of Dry MonthsDry ↓ , ↑ poor

Phenology (GDDANNUAL) ↓ poor

Number of Major Storms (STORMSMAJOR) ↑ poor

Evaluation (each indicator = 1 point).

good = 0 poor or only 1 poor (not T) 

fair = 1 (T) or 2 indicators (not T) poor

poor = 3-5 poor

OVERALL-poor

4.4. Watershed/Landscape Dynamics

4.4.1. Human Population in the Surrounding Area

Issue: Population size and rate of growth have been strongly linked to adverse ecosystem impacts. 

Horseshoe Bend is threatened by a relatively high surrounding poverty level, and its rural setting is 

also threatened by rapid population growth in adjacent Lee County.

Human-related land transformation is the primary driving force in the loss of biological diversity

worldwide (Vitousek et al. 1997). The size, density, and rate of growth of the human population in a 

given area have been strongly linked to rapidly escalating environmental disruption (Ehrlich and 

Holdren 1971) and exotic plant species diversity and abundance (McKinney 2001). As noted by 

Meyer and Turner (1992), “population remains one of the few candidate driving forces that is readily 

measured and for which statistical associations have been found with ecosystem decline.” The human 

population size, growth, and density surrounding national parks are unquestionably major influences 

on the park ecosystems. Thus, Rivard et al. (2000) found that species richness, extirpations, and 

alterations within other national parks were all strongly related to characteristics of the lands 

surrounding the parks. In addition, species invasions and introductions were more frequent in parks 

that were subject to the most human influence.
130

Although the science literature is replete with reports about environmental degradation linked to 

increasing human population density (HPD), information is mostly lacking about the quantitative 

level of HPD that acts as a threshold triggering significant damage to the adjacent natural ecosystem. 

Luck (2007) summarized the issue as follows: “...clear and predictable links between human 

population dynamics and environmental change remain elusive largely because of the complexity of 

the human enterprise and its many and varied impacts on nature” (Figure 49). Viewed from a 

quantitative standpoint, impacts of high HPD can extend many kilometers beyond city boundaries 

(Myers 1994, Repetto 1994), but the effects can vary from minor to major in areas of lower HPD, 

largely depending on the main land use (Luck 2007, and references therein).

Context is also important: For example, a marked increase in HPD near a wilderness reserve would 

be expected to have quite different impacts than if the increase occurred near a city park. This 

difference is especially true of the rate of change: Non-native species introductions (McKinney 2001) 

and species extinctions (Balmford 1996) have occurred faster in more rapidly growing areas with 

lower human population than in highly populated areas. Socioeconomics can also be an important 

influence on the degree of environmental impact, which has been shown to be higher per capita in 

economically depressed areas for reasons ranging from limited economic means to protect natural 

resources, to environmental injustice (Blaikie and Brookfield 1987, Durning 1989, Allen and 

Hoekstra 1991).

Regardless of these complexities, we felt it important to represent HPD and human population 

growth (HPG) as indicators of natural resource health in Horseshoe Bend, to account for the fact that 

human population impacts on adjacent natural resources are not fully captured by related indicators 

such as land use (Figure 49). In addition, it generally can be stated with confidence that HPG results 

in increasing land changes and exotic species introductions; and that land protected for conservation 

is often greatly reduced near human population centers (Luck 2007).
131

Figure 49. A schematic of possible relationships between human population density and biodiversity, 

especially focusing on the negative impacts of human population growth. The evidence for each of these 

relationships varies in the literature. The diagram includes biodiversity feedback loops, but not 

interconnections between energy availability, exotic species establishment, land transformation and 

socio-economic factors. From Luck (2007), with permission.

Our evaluation system for human population indicators in Horseshoe Bend considered the following 

information:

 Tallapoosa County has a small human population, only ~41,600 as of 2012. The population 

density (HPD) of Tallapoosa County is also low, only 22.4 people per km2(58 people/mile2). By 

comparison, the national average HPD in the past decade (2001-2010) was ~31.4 people per km2

(~81.3 people per mile2).

 Over the past ~decade (2000-2010), the population of the county increased by only 0.34%, and 

the population declined by ~1.1% in 2012-2013. By comparison, the national average over the 

~same decadal period was a 9.71% increase in HPG, or about 1% increase per year.

 Tallapoosa County is economically depressed; median household income is only about twothirds of the national average; unemployment is high; and 17.1% of the population (based on data 

from 2007-2011) is below the poverty level, versus a national average of 13.8%.

 In contrast to the profile of Tallapoosa County, less than 64 km (40 miles) away is the AuOpMA, the 11th fastest growing metropolitan area in the nation, with 2.6% increase in population 

from July 2011-July 2012 (from 143,580 people to 147,257 people, respectively; most recent 

available data; Figure 50). In 2010 the population density of Lee County, which includes the Au-
132

OpMA, was 91 people per km2(236 people per mile2). In 2009, U.S. News and World Report 

ranked Auburn in its top ten list of Best Places to Live in the U.S., enhancing the popularity of 

the Au-OpMA (U. S. News and World Reports 2009).

 The State of Alabama had a population of 4,822,023 as of 2012, up ~1% from 2011. The total 

surface area of the state if 135,765 km2(52,419 miles2); thus, the average statewide population 

density in 2011 was 35.5 people per km2(92 people per mile2).

 As an historic “reference” condition, about 500 years ago the HPD of the area was 0.9 people per 

km2(2.3 people per mile2; area of the Southeast Region from Burkett et al. 2001; number of 

Native Americans there from Fagan 1995, Smith 2000).

 Analysis of 24 present-day wilderness areas revealed that all had population densities of < 5 

people per km2(12.8 people per mile2; Mittermeier et al. 2003). It would be expected that 

present-day conditions, even in areas considered somewhat “remote,” would have substantially 

higher HPD than did the southeastern U.S. about 500 years ago.

 Considering this information collectively, for HPG we centered the middle evaluation category, 

fair, around the ~+1% per year national average (0.8 to 1.2% increase per year).

For HPD we set the good category cutoff at < 5 people per km2(~13 people per mile2), comparable 

to present-day conditions near the above-mentioned wilderness areas. Fair was set to the high end of 

the range of the average for Alabama excluding population centers, based on Figure 50 - upper panel 

(20 people per km2, or 50 people per mile2). The evaluation of the five selected human population 

indicators in relation to Horseshoe Bend is shown in Table 37. One of the five indicators yielded a 

good evaluation, one was fair, and three were poor; thus, the overall evaluation of Surrounding 

Human Population Impact Condition affecting Horseshoe Bend is POOR.
133

Figure 50. Map showing the population density of the State of Alabama as of 2010 (upper panel: AuOpMA in pink box, and a magnified view of the Au-OpMA in 2004 (lower panel; Wikipedia Commons 

2006). Note that the population of Auburn in particular is rapidly “sprawling” north toward HOBE.
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Table 37a. Five Population Condition Indicators, and the Present status of Surrounding Population 

Condition in impacting or potentially impacting the park. Note that for this indicator, good ≡ minimal 

adverse impact, whereas poor ≡ maximal adverse impact.

Population Impact Indicators Condition at HOBE Rating

Human Population Growth within a 5-

km (3.1-mile) radius (HPG5-km) ↓ -1.1% per yr for Tallapoosa County good

Human Population Growth within an 80-

km (50-mile) radius (HPG80-km) 

↑ +2.6%/yr (Au-OpMA, Lee County), comparable 

to.growth in the Atlanta, Ga. metropolitan area poor

Human Population Density within a 5-

km radius (HPD5-km)

Tallapoosa County: 22.4 people/km2(58 people/mile2) fair

Human Population Density within an 80-

km radius (HPD80-km)

Lee County: 91 people/km2(236 people/mile2); this.high 

density is ~48 km (~30 miles) from HOBE poor

Poverty surrounding the park (POV)

Tallapoosa County: 17.1% of population is 

below.poverty level poor

Table 37b. Paramerters used to rate the Five Population Condition Indicators in HOBE.

Indicator good fair poor

HPG5-km < 0.8%/yr > 0.8 to 1.2%/yr > 1.2%/yr

HPG80-km same same same

HPD5-km < 5 people/km2

(13/mile2)

> 5 to 20/km2

(13 to 50/mile2)

> 20 per km2

(> 50/mile2)

HPD80-km same same same

POV < 5% of the population 5-10% >10%

Table 37c. Overall evaluation for the Five Population Condition Indicators in HOBE. 

Evaluation (decadal basis - 5 indicators) Rating

good: HPG5-km, HPD5-km both good, < 2 others good, < 1 fair, 0 poor

OVERALLpoor

fair: > 2 fair, < 1 poor

poor: > 2 poor

4.4.2. Visitors - Human Population Within the Park

Issue: Although the National Park Service mission is partly centered on excellence in service for park 

visitors, visitors have been shown to negatively impact another key portion of the agency’s mission, 

to protect natural and cultural resources.

Visitors’ impacts are identified by the National Park Service as among the Top Ten Issues for 

National Parks (National Geographic 2015; Buckley 2003, Taylor and Knight 2003, Park et al. 

2008). The two central portions of the National Park Service mission statement are in conflict 

especially when visitor pressure is high.

Although ~1 million travelers on Highway 49 pass through the park, on average, each year, the actual 

number of visitors is about 10% of that number, or 100,000. Of these, ~70,000 visitors were reported 

to use the Tour Road, Nature Trail, and park grounds. Additional statistics were not available to gain 
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further insights about use of the Nature Trail, for example. Park staff have not expressed concerns 

about parking, however. Our evaluation of Visitation Condition is based on three indicators:

 Visitor Number (annual total, March-October season total, and trend over time);

 Visitor Number per Area (season from March-October, 245 days); and

 Visitor Pressure on Trails (growing season total).

The annual Visitor Number per Area was estimated by dividing the number of visitors by the total 

park area. This approach tacitly assumes that visitors use all areas of the park equally, but is 

unrealistic because many visitors concentrate in certain areas such as trails. Therefore, the approach 

underestimates Visitor Pressure in the highly used areas, but enables a straightforward calculation of 

Visitor Pressure for the park. The growing season total was estimated based on the fact that 

according to NPS statistics, ~75% of visitors come to the park in March - October (NPS 2015h). The 

final indicator, Visitor Pressure on Trails, would be more realistic than Visitor Number per Area 

(because people do concentrate in trail areas) except for the fact that the Tour Road and park grounds 

were combined with the Nature Trail in the available park statistics. A similar approach was followed 

as for Visitor Number per Area, using trail length rather than area. For these calculations, we 

conservatively assumed that one-third of the 70,000 visitors per year use the Nature Trail. Evaluation 

of overall Visitation Condition in Horseshoe Bend is outlined in Table 38. It should be noted that this 

Visitation Condition is intended to serve as a “place holder” until park staff can develop a RSS, 

including a targeted recreational carrying capacity for Horseshoe Bend. This target could be 

developed, for example, following Cole and Thomas (2010). It would also be helpful for park staff to 

collect data on trail damage and trash left in the park to strengthen the Visitation Condition index.
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Table 38a. Visitation Condition in HOBE, based on three Visitation Indicators.

Visitation 

Indicators Visitation Condition in HOBE Rating

Trend in Number 

of Visitors/Yr 

(VIS)

HOBE had 58,668 visitors in 2012 (NPS statistics), comparable to/or lower than 

in previous years. good

Visitor Pressure 

Per Unit Area 

(VP-ASEAS)

Total park area is 826 hectares (2,040 acres). HOBE has an average of 91 

visitors/hectare/peak season (March-October), or 0.4 visitor/hectare/day (37 

visitors/acre/peak season, or 0.15 visitor/acre/day).

good

Visitor Pressure 

on Trails 

(VP-TSEAS)

HOBE has ~4.8 km (3 miles) of Nature Trail and Battlefield Hiking Trail. 

Growing season basis (214 days): HOBE has.3,645 visitors/km/peak season, or 

~15 visitors/km of trail/day (5,833 visitors/mile of trail/peak season, or ~24 

visitors/mile of trail/day)

poor

Table 38b. Overall evaluation of Visitation Condition in HOBE, based on three Visitation Indicators.

good fair poor Rating

VIS trend ↓ or -- VP-ASEAS < 10 visitors/hectare/day VP-TSEAS < 5 visitors/km of 

trail/day

OVERALLfair

VIS trend ↓ VP-ASEAS > 10 to 25 VP-TSEAS > 5 to < 15

VIS trend -- or ↑ VP-ASEAS > 25 VP-TSEAS > 15 

> 2 indicators good, 0 poor > 2 indicators fair or good, 1 poor > 2 indicators poor

4.4.3. Land Use/Land Cover

Issue: Watershed land use /land cover has been shown to strongly affect the habitat quality and 

integrity of terrestrial and aquatic communities. Horseshoe Bend is in an area that likely will be 

increasingly be targeted for development due to sprawl from the Au-OpMA.

Changes in the composition and configuration of different land cover types within and adjacent to 

national parks has been shown to greatly affect biological and physical processes within those parks, 

such as habitat availability, animal movements, potential for invasion by non-native plants, water 

quality, and in-stream habitat for fish and other aquatic life (NPS 2012). Information about changes 

and trends in landscape-scale indicators in and around parks can help park managers anticipate, plan 

for, and manages associated effects to park resources.

4.4.3.1.Agriculture and Urbanization:

Changes in land use/land cover over time, especially loss of “green” or natural categories through 

increase in two land use/land cover categories - urbanization and agriculture - are increasingly used 

as broad-scale predictors of watershed conditions and ecosystem health (King et al. 2005, 

Rothenberger et al. 2009). Nonpoint source pollution - especially from urban/ suburban areas, 

croplands (including silviculture), and industrialized animal production - has been identified as 

the greatest threat to water quality in the U.S. (U.S. EPA 1994b). Major changes resulting from 

conversion of natural lands to agricultural use include soil erosion, chemical contamination of those 

lands and receiving waters, and increased water demands. Chemical contaminants - pesticides, 

fertilizers, heavy metals from animal feeds, etc. - cause diverse acute and chronic impacts on water 
137

quality and quantity, soil quality, air quality, pollination by beneficial fauna, seed dispersal, 

biodiversity, and habitat loss (Pickett et al. 2001, and references therein). Confined swine and poultry 

operations of industrialized agriculture, found mostly upstream from Horseshoe Bend in the upper 

Tallapoosa River watershed and in sub-watersheds of several streams in the middle watershed 

(CH2MHill 2005), produce extremely high quantities of manure, which are applied to small land 

areas that cannot accommodate the massive wastes (Burkholder et al. 2007, and references therein).

Although agricultural land use has been clearly related to environmental degradation, thresholds in 

the percent land use linked to significant change in ecosystem health are seldom reported, likely 

because adverse impacts occur at very low levels of natural land conversion to agriculture. Thus, 

Hagen et al. (2010) documented major impacts on streams at a level of “light” (percentage 

undefined) agricultural land use in cropland. Industrialized swine production agriculture can cause 

extreme impacts to sub-watershed airsheds, soils, surface waters, and groundwaters from only one 

operation (Mallin 2000, Burkholder et al. 2007, and references therein). As another example, 

Cuffney et al. (2005) assessed invertebrates and algae in-stream sites across a gradient of agricultural 

land use. The data suggested a threshold response with precipitous declines in biological metrics at 

low levels of agricultural intensity.

Entire ecosystems, including all components from soil, air, and water to biota, have been “drastically 

modified” (wording from Pickett et al. 2001) by watershed urbanization, in comparison to 

ecosystems in watersheds dominated by natural land cover or cropland cultivation (Paul and Meyer 

2001). In the U.S. and other industrialized nations, conversion of land to urban/suburban 

development is growing more rapidly than the populations in urban areas, leading to increased urban 

sprawl and fragmentation of remaining green spaces (Makse et al. 1995). Urbanization severely 

degrades aquatic communities and terrestrial ecosystems (Garie and McIntosh 1986, Pickett et al. 

2001, and references therein, Center for Watershed Protection 2003). More specifically germane to 

Horseshoe Bend, in a study now more than 30 years old of 21 watersheds in the Atlanta area, Benke 

et al. (1981) found a negative relationship between benthic macroinvertebrate species richness and 

the degree of watershed urbanization. Increased urbanization promotes an increase in avian biomass 

but a reduction in species richness, and selection for omnivorous, granivorous, and cavity-nesting 

species (Chace and Walsh 2004). Analogous findings have been reported for a wide array of aquatic 

and terrestrial biota.

4.4.3.2.Impervious Cover:

The percentage of impervious cover (IC) in particular - roads, parking lots, building roofs, etc. - has 

been a reliable “barometer” for ecosystem health in urbanizing areas. IC blocks water and associated 

pollutants from being able to percolate through soil, resulting in rapid transport of much higher 

volumes and pollutant loads directly to receiving surface waters. As a typical example, the total 

volume of pollutant-laden runoff from a 0.4-hectare (1-acre) parking lot was ~16-fold more than the 

runoff from an undeveloped meadow (Schueler 1994, U.S. EPA 2001). IC thresholds have been 

developed for ecological damage, especially focusing on stream ecosystems. In fact, the term “urban 

stream syndrome” has been used to describe the state of ecological degradation common for “city 

streams” worldwide (Meyer et al. 2005). Key features are low species diversity, dominance of 
138

pollution-tolerant taxa, poor water quality, and degraded physical habitat (Schueler et al. 2009, and 

references therein). Schueler et al. (2009) developed an empirical impervious cover model (ICM; 

Figure 51) that is improved over Schueler (1994), which is much more often cited; Schueler (1994) 

set a threshold of 10% as the initial IC at which adverse impacts on stream biota occur, but it turns 

out that that threshold was too high to protect sensitive aquatic life from urbanization impacts,

explained as follows.

Figure 51. A widely used Impervious Cover Model (ICM) of stream quality and macroinvertebrate

community response to urban development as the percentage of impervious cover in a given watershed 

or sub-watershed. Modified from Schueler et al. (2009).

Schuler et al (2009) based his refined empirical ICM on data for many streams which indicated that 

detectable stream degradation generally occurs - sometimes described as “greatly depressed 

ecosystem health” - when the IC of a given watershed is ~7 to 10% (overall range 2-15%; e.g. Booth 

and Reinelt 1993; Booth and Jackson 1994; Shaver et al. 1994, 1995; Booth and Jackson 1997, 

Mallin et al. 2000; Wang 2011). The IC thresholds in these ICMs depended on the specific biological 

indicator, the ecoregion, and the history of watershed land use: Lower IC thresholds were found for 

streams in watersheds that had extensive forests or natural vegetation cover prior to urban 

development. Higher IC thresholds characterized streams in watersheds that had extensive prior 

disturbance (e.g., croplands) prior to urbanization (Harding et al. 1998, Ourso and Frenzel 2003, 

Cuffney et al. 2005) because the macroinvertebrate communities had already lost sensitive species to 

stressors from the pre-urban agricultural land use (Coles et al. 2012).

An underlying, widely accepted assumption in efforts to determine the first threshold for decline of 

stream biota in response to urbanization is that the “biological communities are resistant to change at 

low levels of urban development. Then, as levels of urban development increase, a period of rapid 

degradation occurs in the community condition, ending in a period of exhaustion when no further 
139

change occurs” (Coles et al. 2012; Figure 52). However, a detailed recent analysis conducted by the 

USGS, involving multiple study regions across the nation, found evidence of neither a resistance 

threshold nor an exhaustion threshold. Instead, beneficial macroinvertebrate communities declined in 

response to very low levels of urbanization; for example, in the Atlanta and Boston study regions, 

stream macroinvertebrates showed a linear rather than threshold response to urbanization (Figure 53; 

also documented elsewhere, e.g. Moore and Palmer 2005). The authors concluded that stream 

macroinvertebrate communities are much more sensitive to urbanization than previously thought 

(Coles et al. 2012). In fact, at 10% IC, the macroinvertebrate community composition had already 

decreased by ~25%. The lack of an exhaustion threshold was also considered important, because it 

indicates that stream rehabilitation efforts have a high probability of improving biological condition 

(Coles et al. 2012). In other words, the data from this study indicate that, if given a chance, many 

streams can recover from “urban syndrome.”

Figure 52. Previous widely accepted conceptual model of the response of stream biota to urban 

development - now questioned. Modified from Coles et al. (2012).

Invertebrate community 

composition

Urban Development (%)

0 20 40 60 80 100

Resistance

Maximum rate

of decline

Exhaustion

Invertebrate community 

composition

Urban Development (%)

0 20 40 60 80 100

Resistance

Maximum rate

of decline

Exhaustion
140

Figure 53. Left: Response of EPT species (Ephemeroptera - mayflies, Plecoptera - stoneflies, and 

Trichoptera - caddisflies) to urbanization in the Atlanta area (IC ≡ impervious cover). Many of these 

species are sensitive to contaminants, changes in-stream flow, and other stressors caused by 

urbanization, and have been lost from streams in the Atlanta area. Right panel: Generalized schematic 

from the USGS (Coles et al. 2012). Right: Similar response of invertebrate communities to urban 

development in the Boston area: Note that at 10% impervious cover (= less than 20% urban 

development), the community composition had declined by ~25%. Modified from Coles et al. (2012).

Number of EPT Species

25

20

15

10

5

0

Atlanta Study Area

Community Composition

4

3

2

1

0

Urban Development (%)

0 20 40 60 80 100 10 % IC

25% change in

community composition

Number of EPT Species

25

20

15

10

5

0

Atlanta Study Area

Community Composition

4

3

2

1

0

Urban Development (%)

0 20 40 60 80 100 10 % IC

25% change in

community composition
141

This background information is included here because IC thresholds to protect ecosystem health have 

mostly been based on the ICM approach, using a first threshold of ~10% IC as good, and a second 

threshold of ~20-25% as fair. The approach recently was re-evaluated as insufficiently protective, 

both the formerly accepted 10% IC primary threshold and the 20-25% IC secondary threshold (Coles 

et al. 2012). Regarding the latter, 20-25% IC would protect only highly tolerant biota from stress, 

disease and death due to urbanization impacts (Weaver and Garman 1994). Stream biological metrics 

were described as consistently shifting to poor condition at ~20-25% watershed IC (Collier and 

Clements 2011, Wang et al. 2011, Cole et al. 2012).

4.4.3.3.Indicators for Land Use/Land Cover Influence:

Horseshoe Bend at present is little influenced by agriculture other than silviculture, which is included 

in the land use/land cover category, “forest.” Land use/land cover has changed by only a few 

percentage points in the past five years, as shown in Section 2.3 of this Report (mainly reflecting 

small shifts in loss of grassland to silviculture-as-“forest” - CH2MHill 2005, p.5-6). Unfortunately, a 

concerted hunt for the proportion of “forest” that is actually silviculture in the Middle Tallapoosa 

River watershed was unsuccessful in finding that information, so it was not possible to assess the 

percentage of silviculture versus natural forest. There also has been very little development near 

Horseshoe Bend to cause urban impacts but, as explained in Section 4.4.1 of this Report, that 

situation likely will change in the coming decade because of rapidly developing Lee County. As 

mentioned, the expected continued sprawl north/northwest from the Au-OpMA has been identified as 

a concern of park staff (NPS 2008).

For the above reasons, the following indicators and ratings were developed without consideration of 

agriculture/silviculture except indirectly through the tacit assumption that loss of 

agricultural/silvicultural lands will occur through urban/suburban development. It is recommended 

that the indicators should be tracked at 10-year intervals (or five-year intervals, if park staff consider 

that more desirable). The indicators describe conditions that are often economically difficult or 

impossible to reverse. Therefore, the good rankings are conservatively defined toward the goal of 

maximizing protection of the park.

Impervious Cover (IC) - Viewed from a resource protection standpoint, as explained above, it is not 

scientifically supported to evaluate a ~25% loss in-stream macroinvertebrate community composition 

with 10% IC in a given watershed as good. Figure 51, a widely accepted ICM, suggests that at 10% 

IC, streams develop “detectable” to “greatly depressed” ecosystem health. Although the lower end of 

range of percentage IC at which ecosystem health is seriously impacted is broad (~2-15%), it also 

seems reasonable to err on the side of caution to afford more protection for the nation’s national 

parks. Other studies have shown that wetlands exhibit signs of adverse impacts when watershed IC 

exceeds 2-4%, or about one house for every 3.2 to 4.0 hectares (8 to 10 acres) of watershed area 

(Hicks and Larson 1997, Reinelt and Horner 1991). The recent USGS analysis (Cole et al. 2012) -

and the central conclusion that stream macroinvertebrate communities, commonly considered a 

major “barometer” of stream ecosystem health, are much more sensitive to urbanization that 

previously thought - also factored heavily in our considerations about the levels of %IC to be 

assigned to good, fair, and poor rankings. These rankings reflect the present status of what is known 

in the science literature about stream macroinvertebrate community response to urbanization.
142

Change in Green Space - The Greenspace Indicator (%GRN) tracks the change in the percentage of 

greenspace land over time, both within a 5-km (~3-mile) radius of the park, and in the middle 

Tallapoosa River watershed. The change is generally as loss, which is surely the situation for 

Horseshoe Bend, although cities such as Atlanta are developing programs to restore some greenspace 

area. It has been demonstrated that only a 12% loss of forest cover in a watershed results in 

detectable adverse impacts on the macroinvertebrate communities of streams draining the area (Klein 

1979). Conversion of a forest to homes on 0.10-hectare (0.25-acre) lots can increase the frequency 

and severity of flooding by 100-fold (basis - Soil Conservation Service 1986; Zielinski 2002; 

Community and Environmental Defense Services 2007). When the land is converted to IC rather than 

open space, impacts are sustained at lower percentages of impervious surface (explained above).

The evaluation format used to assess the Land Use/Land Cover Condition surrounding Horseshoe 

Bend is shown in Table 39. Based on these indicators and this evaluation format, the present overall 

condition of Land Use/ Land Cover surrounding the park is good.

Table 39a. Land Use/ Land Cover Condition surrounding the park, based on evaluation using two 

indicators.

Land Use/

Land Cover Indicators Watershed Surrounding HOBE Rating

Impervious Cover 

(% IC5-km , 5-km radius surrounding 

park, 

decadal basis)

The only population center upstream and near to HOBE, 

New Site, has 764 people. IC in the 5-km radius 

surrounding the park is negligible, < 1% of the. Land

use/land cover

good

Total greenspace loss 

(% GRNWAT, (past 5-10 yr): middle 

Tallapoosa sub-watershed

The entire middle Tallapoosa River watershed had only 

5% developed (urban/suburban) land as of 2006. In the 5 

yr between 2001 and 2006, there was a gain of only 

0.1% in developed land use/land cover. 

good

Table 39b. 5-10 year overall evaluation for Land Use/ Land Cover Condition surrounding the park, based 

on evaluation using two indicators.

good: fair: poor: Rating

IC ≤ 5%, and 

< 1% GRN Loss

IC > 5 to < 10%, and 

≥ 1 to < 5% GRN loss

IC ≥ 10%, and 

≥ 5% GRN loss

OVERALLgood

4.5. Air Quality

Issue: Air pollution is an ongoing, serious problem from urbanized areas mostly west, north/ 

northwest, and south of Horseshoe Bend, and is expected to be adversely impact the park’s natural 

resources. Animals are exposed to air pollutants by inhaling gases or small particles, ingesting 

particles suspended in food or water, or absorbing gases through the skin (soft-bodied invertebrates, 

amphibians with thin, moist skin etc.; U.S. EPA 2008). Ozone, SO2, and NOx mostly affect the 

respiratory system, and animals to with higher respiratory rates (e.g., many birds) are likely to be 

more adversely affected by gaseous pollutant injury. Metals such as mercury in air pollution can 

affect the circulatory, respiratory, gastrointestinal, and central nervous systems. Often organs such as 
143

the kidney, liver, and brain are targeted, and entire populations can be adversely affected with 

damage extending through subsequent generations.

The many impacts of acid deposition on terrestrial and freshwater ecosystems is the subject of an 

exhaustive literature (Tomlinson and Tomlinson 1990, Charles and Christie 1991, Brimblecombe et 

al. 2007, and references therein). In terrestrial ecosystems species such as pines are especially 

sensitive to the elevated nitrate enrichment that results in the soils, and their growth and survival are 

depressed (Aber 1992). Leaves affected by acid deposition are damaged, especially the chlorophyll 

pigment that is vital to photosynthesis. Like many other pollutants, acid deposition depresses 

terrestrial biodiversity as sensitive species are eliminated and more acid-tolerant species can survive. 

Acidification effects in freshwater streams depend on the surrounding geology and soils, which 

determine the capacity of the water to neutralize acids. Streams most susceptible to acidification 

occur in watersheds with granite or gneiss bedrock typical of some soils at Horseshoe Bend, where 

thin soils have insufficient base cations freely available to neutralize incoming H+ions. The effects of 

decreasing pH on aquatic invertebrates and fish have been summarized in National Acid Precipitation 

Assessment Program (NAPAP) reports (e.g. NAPAP 2005) and similar documents from Scandinavia 

where acidification impacts have been extreme: In early stages of acidification, acid-sensitive species 

are replaced by acid-tolerant ones. As the pH continues to decline, toxic metals become more 

bioavailable, and more species are lost until even the microbial consortium of decomposers is 

adversely affected. The worst problems with acid deposition result from acid spates, wherein a “slug” 

or high amount of acid moves into a stream in the early phases of a storm. Larval stages of 

amphibians and fish are eliminated by acid spates over a short period (hours to a few days).

Considering the entire Southeast region, the NPS Air Resources Division (ARD) evaluates 10-year

trends in air quality for parks with on-site or nearby monitoring. Maps in the most recently available 

progress report show trends in ozone, deposition, and visibility that can be used to discern regional 

trends (NPS 2007). For the period 1996 – 2005, ozone concentrations and nitrogen and sulfur 

deposition in the Southeast appear to be decreasing, while visibility is relatively unchanged.

More specific to Horseshoe Bend, as related in Chapter 2 of this Report, the National Park Service

(2011) has developed guidance for assessing the air quality conditions within its parks, focusing on 

five key indicators among the myriad of air pollutants potentially affecting the middle Tallapoosa 

River basin. These indicators include Ozone (with two sub-indicators: human health, and Horseshoe 

Bend flora), N deposition, S deposition, visibility, and acidification (with five sub-indicators: 

Pollutant Exposure, Ecosystem Sensitivity, Park Protection, and overall Summary Risk). For ozone 

the National Park Service included consideration of vegetation sensitivity as well as human health 

because science has shown that some plant species are more sensitive to ozone than humans. 

Thus, use of an ozone standard for humans would not be sufficiently protective of those 

species.

The National Park Service has developed management targets or “thresholds” for these five 

indicators as presented in Section 3.2. of this Report and summarized in Table 40. The 

information and supporting science are given in several agency reports, especially National Park 
144

Service (2011) and Sullivan et al. (2011) where the conditions in Horseshoe Bend are also 

described. All five of the NPS-selected Air Quality Indicators are NPC, not possible for park staff or 

the Network to control. Following the NPS guidance and stoplight system, one of the five indicators, 

Ozone, is Moderate Concern (fair rating in the Stop Light approach); the other four indicators are of 

significant concern (poor rating in the Stop Light approach). Therefore, the present overall Air 

Quality Condition at Horseshoe Bend is evaluated as poor.

Table 40a. Evaluation of overall Air Quality Condition in HOBE, based on the AQI (Air Quality Index of the 

U.S. EPA.

Air Quality Indicators Air Quality Measurements Near HOBE Rating

Air Quality Index (AQI)

for Alexander City, Ala.

(U.S. EPA)

As of 2012-2013*: Ozone "Good" 87.1-94.3% of days; CO, 

NO2, SO2, and PM10 "Good" 100% of days; and PM2.5 "Good" 

81.8-92.6% of days. Overall AQI - good 98.9% of days, 

MODERATE 1.1% of days.

good

Table 40b. Evaluation of 2005-2009 Air Quality Condition in HOBE, based on the AQI (Air Quality Index 

of the U.S. EPA, and seven NPS indicators (ozone concentration that protects human health, ozone 

concentration that protects plant health [2 indicators], N deposition, S deposition, Visibility, and 

Acidification).

Air Quality Indicators Air Quality Measurements Near HOBE Rating

Ozone: Human health (Ozone) 61-75 ppb for the 8-hr averaging time, 4th maximal value fair

Ozone: Flora (W126) 7-13 ppm-hr fair

Ozone: Flora (SUM06) 8-15 ppm-hr fair

Nitrogen Deposition (N-DEP) > 3 kg/ha/yr poor

Sulfur Deposition (S-DEP) > 3 kg/ha/yr poor

Visability (VIS) > 8 dv poor

Acidification (ACID) HOBE ranked as follows:

good

*Pollutant exposure - very high (rank > 23)

*Ecosystem sensitivity - low (rank, 9)

*Park Protection - low (rank, 9)

*Overall risk - low (2.4).
145

Table 40c. Paramerters used to rate NPS Air Quality Condition in HOBE.

NPS INDICATOR 

(2005-2009) 

good

(LOW)

fair

(MODERATE)

poor

(HIGH)

Ozone - human health ≤ 60 ppb 61-75 ppb ≥ 76

Ozone - Plants (W126, 

SUM06)

< 7 ppm-hr, 

< 8 ppm-hr

7-13 ppm-hr, 

8-15 ppm-hr

> 12 ppm-hr, 

> 15 ppm-hr

N-DEP < 1 kg/hectare/yr 1-3 kg/hectare/yr > 3 kg/hectare/yr

S-DEP < 1 kg/hectare/yr 1-3 kg/hectare/yr > 3 kg/hectare/yr

VIS (deciviews, dv) < 2 dv 2-8 dv > 8 dv

ACID: Overall evaluation 

is the Summary Risk 

Index

Pollutant Exposure rank < 13 ≥ 13 to 23 > 23 to 35

Ecosystem 

Sensitivity rank < 15 ≥ 15 to 20 > 20 to 35

Park Protection rank < 15 ≥ 15 to < 23 ≥ 23 to 35

Summary Risk 

Index 

(different scale)

rank ≤ 2.5 ≥ 2.5 to 3.4 > 3.4 to 5

Table 40d. Overall evaluation of NPS Air Quality Condition in HOBE.

good 

(LOW)

fair 

(MODERATE)

poor 

(HIGH) Rating

AQI Good (0-50 for 

≥ 90% of days); 

NPS indicators: 

≥ 5 of 7 Good, ≤ 2 Fair 

(Moderate Concern), 

0 poor (Significant 

Concern)

AQI Good or Fair 

(Moderate), 

≤ 100, for ≥ 90% of 

days; 

NPS indicators: 

≥ 3 Fair, 

≤ 3 poor

AQI Unhealthy 

to hazardous 

(101-500) for 

≥ 10% of days; 

NPS indicators: 

≥ 4 poor

Overall -

fair

4.6. Soundscape

Issue: Noise pollution can adversely affect the physiology, behavior, and survival of fauna

communities. Horseshoe Bend is still within a predominantly rural area and noise pollution generally 

is minor. As stated, human-related environmental noise is minor and the park usually is very quiet 

(Superintendent Doyle Sapp, pers. comm., April 2013). Three Soundscape Indicators were developed 

as follows:

 Proximity to a population center (POPSOUND): good - nearest population center with > 50,000 

people is > 97 km (> 60 miles) distant; fair - nearest population center with > 50,000 people is 16 

to < 97 km (10 to < 60 miles) distant; poor - nearest population center with > 50,000 people is < 

16 km (10 miles) distant.

 Proximity to a major road (state or interstate highway), railroad; and/or to several county roads 

with heavy traffic (here, collectively considered as 1 source); and/or major airport, or to a 

speedway, concert amphitheater as major forms of travel (SOURCESOUND): good - no major 

sound source nearby ( < 16 km [10 mile] radius); fair - 1 major sound source nearby that directly 
146

affects much of the park; poor - > 1 major sound source nearby that directly affects much of the 

park.

 Available data or park staff observations (DATA/OBSSOUND): good - outside noise levels < 24 

dB(A) during daytime periods when human travel is generally heaviest (“rush hours”), and/or 

park staff describe the park as very quiet; fair - outside noise levels 24 to 40 dB(A), and/or park 

staff describe the park as sometimes noticeably noisy ; poor - outside noise levels > 40 dB(A), 

and/or park staff describe the park as commonly having noticeable or substantial noise pollution.

In the overall evaluation, the DATA/OBSSOUND indicator is weighted more heavily than the other two 

indicators (Table 41). However, the other two indicators can be used to evaluate the soundscape if 

data and/or reliable observations are not available.

Table 41a. The three Soundscape Indicators, and present Soundscape Condition in HOBE.

Soundscape 

Indicators Soundscape Condition in HOBE Rating

Proximity to population 

center (POPSOUND)

HOBE is ~64 km (40 miles) from the Au-OpMA (rapidly growing 

population center; population 147,257 as of 2012). fair

Proximity to a major 

mode of travel 

(SOURCESOUND)

State Highway 49 passes through the park, but its traffic is usually light 

so it is considered a minor mode of travel. good

Data or observations 

(DATA/OBSSOUND)

Data not available (n.a.); park staff describe HOBE as usually very quiet. good

Indicators:

Table 41b. Paramerters used to rate Soundscape Condition in HOBE.

Soundscape 

Indicators Definition

POPSOUND good - closest population center has ≤ 50,000 people and is > 80 km (> 50 miles) 

distant.

fair - closest population center has ≥ 50,000 to 100,000 people and is ≥ 16 to 80 

km (10 to 50 miles) distant.

poor - closest population center has > 100,000 people and is < 16 km (< 10 

miles) distant.

SOURCESOUND good - nearest major road or railroad is > 8 km (5 miles) distant; no major airport, 

flyway influence, etc.

fair - 1 major road and/or railroad is nearby, or one railroad, or a major 

airport/airplane flyway.

poor - ≥ 1 major road and/or railroad and/or major airport nearby.

DATA/

OBSSOUND

good - outside noise ≤ 24 dB(A) during daytime when related (noise-generating) 

human activity is greatest; or, observations by park staff as overall very quiet

fair - outside noise > 24 to 55 dB(A) during daytime periods with greatest related 

human activity.

poor - outside noise > 55 dB(A) during daytime periods with greatest related 

human activity.
147

Table 41c. Overall Soundscape Condition in HOBE.

Indicator 

Evaluation Description of Soundscape Condition in HOBE Overall Rating

good DATA/OBSSOUND + 1 other indicator good; 3rd indicator good or fair; or no data 

but the other 2 indicators good

good fair All three indicators fair; or no data but both other indicators fair

poor DATA/OBSSOUND poor; or no data but one or both other indicators poor

4.7. Lightscape

Issue: Light pollution in urbanized or developing areas can adversely affect the physiology, behavior, 

and survival of naturally occurring, beneficial fauna.

The Lightscape Condition for Horseshoe Bend is similar to its Soundscape Condition: Both are NPC, 

but fortunately both noise and light pollution are described by park staff as negligible. Thus, 

Superintendent Doyle Sapp (pers. comm., April 2013) stated that Horseshoe Bend night time habitat 

is equivalent to the Truly Dark Skies of the BDSS. The Lightscape Indictor for Horseshoe Bend uses 

this scale to assess artificial light pollution, as follows:

 good - Class 1 (excellent, truly dark skies) to Class 2 (typical, truly dark skies)

 fair - Class 3 (rural sky - ground objects are vaguely apparent); Class 4 (rural/suburban 

transition - sky is noticeably brighter than the terrain, but ground objects are still fairly obscure)

 POOR - > Class 5 (suburban sky - ground objects are partly lit).

These rankings are based on potential impacts of sufficient light to reveal “ground objects,” meaning 

that sufficient light would be available to alter predator-prey interactions at least in some areas of the 

park. The night sky for Horseshoe Bend is Class 2, as noted above (Truly Dark Skies - the ground is 

mostly dark; only objects projecting into the sky may be discernible). Thus, the overall evaluation of 

the Lightscape Condition in the park is good (Table 42).

Table 42a. Evaluation of the Lightscape Condition at HOBE, using the Bortle Dark-Sky Scale.

Lightscape 

Indicator Lightscape Condition at HOBE Rating

Bortle DarkSky Scale 

(LITEARTIF)

The park at present is still in a predominantly rural setting, and the lightscape is 

described as Class 2, Truly Dark Skies. good
148

Table 42b. Paramerters used to rate Lightscape Indicators in HOBE.

Rating Definition

good Classes 1 to 2 (excellent, truly dark skies; or typical, truly dark skies).

fair Classes 3 to 4 (rural sky - ground objects vaguely apparent; or rural/suburban 

transition - sky noticeably brighter than the terrain, ground objects still fairly 

obscure. 

POOR ≥ Class 5 (suburban sky - ground objects partly lit, to inner city sky.

4.8. Soil and Streambank Erosion

Issue: The soils in the Horseshoe Bend area are moderately to highly erodible, increasing the 

potential for damage along streambanks as well as park roads, trails, and other highly used areas, 

although presently there is minimal streambank erosion along the Tallapoosa River in the park. The 

high acid deposition sustained by the park could decrease the soil pH to conditions that impede the 

metabolism of beneficial microbial consortia while also enhancing solubility of porewater toxic 

metals (Bååth 1989).

There have been no studies of soils, soil erosion, or streambank erosion in Horseshoe Bend, but 

its soils logically would be expected to be similar to those in the general region. Therefore, we 

developed a simple index of Soil Condition for the park as follows:

Soil erodibility of the soil types in Horseshoe Bend (#1, SoilEROD), which has been assessed in the 

published literature, based on the soil erodibility factor, K (Olson and Wischmeier 1963, Daniels 

1987, and USDA Soil Conservation Service maps):

 good - < 10% of the soil types are characterized as eroded to severely eroded

 fair - > 10% to 20% of the soil types are eroded to severely eroded, including one abundant soil

 poor - > 20% of the major soil types are eroded to severely eroded, including > 2 abundant soils

Visual evidence of soil erosion in the park (#2, SoilVIS):

 good - little or no soil erosion evident in the park

 fair - a few areas along roadways and trails show signs of erosion

 poor - severe erosion clearly is common along roadways and trails

Visual evidence of streambank erosion in the park (#3, BankEROD):

 good - little or no streambank erosion is notable in the park

 fair - there are occasional signs of streambank erosion after major rain events in a few reaches

 poor - severe erosion clearly is common along the park’s major stream segments

Soil acidification potential based on air quality in areas such as Horseshoe Bend with poor buffering 

capacity of the mostly clay soils, due to the absence of limestone parent materials (#4, SoilACID):
149

 good - low

 fair - moderate

 poor - high

Soil Indicators 1 and 4 are based on information already provided to the park; indicators 2 and 3 are 

based on surveys that can be conducted within ~two hours. Assessment of these indicators can be 

conducted at intervals deemed appropriate by park staff (e.g., two-year or five-year) using a 

consistent, quantitative approach such as walking three 100-m segments along the Tallapoosa River 

and the smaller streams in the park (e.g. see Gordon et al. 2004), and including photographic 

documentation. It should also be noted that the National Park Service is developing a visual 

technique using a consistent approach with photography over time to document streambank erosion 

in SECN parks, which will strengthen the BankEROD indicator (SECN Coordinator Mr. Joe DeVivo,

pers. comm., April 2013).

To assess the overall Soil and Streambank Erosion Condition in the park, we suggest this evaluation 

system:

 good: > 3 of the four indicators are good, and < 1 indicator is fair.

 fair: > 2 indicators are fair, and < 1 indicator is poor.

 Poor > 2 indicators are poor.

As noted in this Report, more than half (12 of 20) of the soil types found in Horseshoe Bend are 

characterized as moderately eroded. In addition, nearly a third of the soil types are occasionally to 

frequently flooded, including indicating two of the three most abundant soil types (see Section 3.5.2

of this Report). Both features typify the three most abundant soils in Horseshoe Bend (ToA, PrDZ, 

and PrEZ). The soil acidification potential is high, based on the air quality as described in Section 

3.2.3. Thus, two of the four indicators are good but the other two are poor, leading to an overall 

evaluation of Soil and Streambank Condition in Horseshoe Bend as poor (Table 43).

Table 43a. Evaluation of present Soil Condition in HOBE, based on four Soil and Streambank Erosion 

Indicators - erodibility; visible evidence of erosion along trails and roadways; visible evidence of 

streambank erosion; and soil acidification potential.

Soil/Streambank 

Erosion Indicators Soil Condition in HOBE Rating

Erodability of soil 

types.(SoilEROD)

12 of 20 soil types in the park are moderately eroded including two of the 

three most,abundant soils. About 20% of the soil types are occasionally to 

frequently flooded, including one of the three most abundant soils 

poor

Visual evidence of 

soil erosion (SoilVIS)

There is little visual evidence of soil erosion in the park.

good

Visual evidence of 

streambank 

erosion.(BankEROD)

There is little visual evidence of streambank erosion in the park.

good

Soil acidification 

potential ,(SoilACID)

Moderate in HOBE, based on air quality information considered together 

with the ~poor buffering capacity of the mostly clay soils. fair
150

Table 43b. Paramerters used to rate Soil Condition Indicators in HOBE.

Soil/Streambank 

Erosion 

Indicators Rating Definitions

SoilEROD good: < 10% of the soil types are eroded to severely eroded. 

fair: > 10% to 20% of the soil types are eroded to severely eroded, 

including one abundant soil 

poor: > 20% of the major soil types are eroded to severely eroded, 

including > 2 abundant soils 

SoilVIS good: little or no streambank erosion in the park.

fair: a few areas along roadways and trails show signs of erosion

poor: erosion is obvious and common along roadways and trails 

BankEROD good: little or no streambank erosion is evident in the park 

fair: occasional signs of streambank erosion after major rain events 

poor: severe erosion is evident and common along major stream 

segments in the park 

SoilACID good: low (basis: NPS air quality analysis)

fair: moderate

poor: high

Table 43c. Overall evaluation of present Soil Condition in HOBE, based on four Soil and Streambank 

Erosion Indicators - erodibility; visible evidence of erosion along trails and roadways; visible evidence of 

streambank erosion; and soil acidification potential.

Evaluation of Soil/Streambank Erosion Indicators Rating

good: > 2 indicators are good, < 2 indicators are fair, and there is no poor evaluation

OVERALLfair fair: > 2 indicators are fair or good, and < 2 indicators are poor

poor: > 3 indicators are poor

4.9. Surface Water Hydrology

Issue: Extreme, artificial manipulation of discharge to the Tallapoosa River in the park has adversely 

impacted the wetland and aquatic communities of HOBE since the upstream Harris Dam was 

installed in 1982, and has been linked to the loss of sensitive species.

Tracking surface water hydrologic changes over time is important for the natural resources in the 

park, considering that as development around the park increases, the surrounding metropolitan land 

cover will in turn increase flash flooding potential. This problem may be exacerbated by the 

escalating trend in global warming (Richter et al. 1997 Groundwater supply information 

unfortunately is not available for Horseshoe Bend (see Section 3.6.2.1 of this Report)., Kundzewicz 

et al. 2007, Brekke et al. 2009).

The availability of IHA software (see Section 3.6.1.1 of this Report) makes it possible to use the 

hydrologic data provided by the USGS to rapidly assess hydrologic changes affecting other 

Horseshoe Bend natural resources over time. As mentioned, IHA calculates EFCs and IHA. 
151

Unfortunately, 20 years of daily data are recommended for estimating many of the parameters for 

analysis (the Nature Conservancy 2007). Over time, park staff can apply the IHA to conduct a Range 

of Variability analysis (Richter 1997, Mathews and Richter 2007) to quickly identify thresholds in 

biological response within an adaptive framework. Once Horseshoe Bend has a RSS, park staff will 

have developed a plan with strategies for managing the park’s natural (and cultural) resources. That 

plan will include hydrologic indicators and targets. For example, in the RSS for the Chattahoochee 

River National Recreation Area, minimum flows of water in the Chattahoochee River were selected 

as a key indicator of hydrologic conditions. Five management targets were identified based on 

relevance to state standards and recommended flows for rafting, canoeing, and trout fishing and 

fishery condition (Nestler et al. 1986, Gregory et al. 2012).

Until the RSS and hydrologic targets have been developed for Horseshoe Bend, we suggest the 

following interim approach to evaluating the Hydrologic Condition of the park, namely, focus on the 

extremes in stage fluctuation because of upstream reservoir (Harris Lake) management by the 

Alabama Power Company. Water release from the reservoir is controlled entirely for electrical 

purposes, with no consideration for aquatic communities downstream. These communities sustain 

adverse impacts from highly abnormal, extreme river fluctuations. Commonly these fluctuations are 

more than 1 m per day, up to 1.8 m (5 feet), and often there are two such “high water” events per 

day.

Altered flow regime is commonly identified as the single most serious threat to the ecological 

sustainability of rivers and associated floodplain wetlands (e.g. Naiman et al. 1995, Sparks 1995, 

Lundquist 1998, Ward et al. 1999; and see the excellent review by Poff et al. 1997). Karr (1999, 

p.225) described a fundamental disconnect in present-day policy and management that have 

sanctioned extreme hydrologic alterations such as the flow regime sustained by the middle 

Tallapoosa River including the Horseshoe Bend segment:

Society, oblivious either to human health risks or to the ecological risks of radically altering rivers, 

has chronically undervalued rivers’ biological components. We have behaved as if we could repair or 

replace any lost or broken parts of regional water resource systems, much as we replace toasters, 

cars, jobs, and even hearts or livers. This disregard has only worsened the lack of coherence in water 

law and in regulations regarding water use. The result in the U.S.A. is a body of federal, state, and 

local law that fails to make the connections between water quality and quantity, surface water and 

groundwater, headwater streams and large rivers, and the living and non-living components of 

aquatic ecosystems.

The extreme hydrologic regime imposed on the Tallapoosa River results in reduced and artificially, 

“rapidly repeated” seasonality because the natural flow conditions are literally lost, leading in turn to 

depressed reproduction and recruitment of various aquatic species and, eventually, to their loss from 

the system (Karr and Dudley 1981). Low flows become more extreme; indeed, as previously noted 

(see Section 3.6 of this Report, since installation of the Harris Dam in 1982, downstream river 

segments (including Horseshoe Bend) have sustained flows as low as zero, and as high as 453 cms 

(16,000 cfs). The hydrologic connectivity between the river channel, floodplain, and groundwater 

largely structures spatial and temporal features of floodplain habitats (Ward and Stanford 1995, Ward 
152

et al. 1999). Flow regulation by dams commonly results in reduced connectivity and altered 

succession in river floodplains, and reduced biodiversity (Ward and Stanford 1995). Sudden flooding 

followed by greatly reduced flow, a pattern sometimes repeated twice daily in the middle Tallapoosa 

River, washes out species and eliminates sensitive species (Poff et al. 1997, and references therein). 

The altered flow regime also can favor proliferation of exotic/ invasive species (Bunn and Arthington 

2002, and references therein).

The Hydrologic Indicators for Horseshoe Bend were developed based on the historic, pre-dam flows 

of the Tallapoosa River at the Wadley, Ala., USGS gaging station which is 22 km (13.7 miles)

downstream from the Harris Dam. As explained previously (see Section 3.6 of this Report), this 

station has historic information available for 58 years prior to installation of the Harris Dam. Despite 

the fact that it is ~30 km (19 miles) upstream from Horseshoe Bend, the present-day flow patterns are 

similar for the Wadley station versus the USGS gaging station that is much closer to Horseshoe Bend

(New Site, Ala.), and historic pre-dam information is not available for the New Site station. The 

Wadley USGS station dataset clearly shows that the present-day flow regime is extreme and highly 

artificial (example shown in Figure 54)

Figure 54. The extreme “hydro-peaking” effects from regulation of discharge at the Harris Lake outflow, 

downstream at the Wadley USGS gaging station. About 75% of the 78-years median discharge was prior 

to installation of the dam (58 years of historic conditions, 1923-1981). The relatively stable historic flow of 

the middle Tallapoosa River in this semi-log plot contrasts starkly with the extreme values imposed daily, 

sometimes twice daily, since the dam was installed (here, represented by the depicted period in 2004). 

From CH2MHill (2005, Exhibit 5-5).

We suggest two Hydrologic Indicators in the interim until a RSS for Horseshoe Bend is available that 

identifies Hydrologic Indicators specific to park waters (Table 44). These recommended interim 

indicators represent discharge magnitude and “flashiness” as follows:

Source: USS 02414500 real-time gage data

Discharge Median daily stream flow based on 78 yr of record.

Apr 10 Apr 17 Apr 24 May 01 2004

Discharge (cfs)

20,000

10,000

1,000

100

Source: USS 02414500 real-time gage data

Discharge Median daily stream flow based on 78 yr of record.

Apr 10 Apr 17 Apr 24 May 01 2004

Discharge (cfs)

20,000

10,000

1,000

100
153

HydroMAG - At a given time interval, the amount of water moving past a fixed location (here, the 

Wadley USGS gaging station) per unit time (Poff et al. 1997). Absent appreciable precipitation:

 good – < 1.5-fold change in discharge (in cfs) under non-storm conditions (defined as > 5 days 

after a < 1.25-cm [0.5-inch] storm at or upstream from Wadley, with no additional storms in the 

interim)

 fair – > 1.5 to < 3-fold change in discharge between storm events

 poor – > 3-fold change in discharge between storm events

HydroFLASH - The rate of change or “flashiness,” that is, how quickly flow changes from one 

magnitude to another (Poff et al. 1997):

 good – discharge varies by < 1.5 over a given 24-hr period during non-storm conditions, defined 

as above.

 fair – discharge varies by > 1.5 to < 3-fold over a given 24-hr period during non-storm 

conditions.

 poor – discharge varies by > 3-fold over a given daily period during non-storm conditions.

These Hydrologic Indicators can be assessed multiple times between storm events over each season.

Table 44a. Present Hydrologic Condition in HOBE, evaluated using the HydroMAG and HydroFLASH

Indicators.

Hydrologic Condition Indicator

Upstream from HOBE (Wadley Station), 

Representing Conditions in the Park Rating

HydroMAG - discharge at the Wadley 

USGS gaging station (in cfs) for 

> 3 days.during non-storm conditions 

The Tallapoosa River at Wadley commonly sustains > 

5-fold change in discharge for > 3 days during non-

.storm conditions

poor

HydroFLASH - discharge at the Wadley 

USGS gaging station (in cfs) within a

24-hr period during non-storm conditions 

The Tallapoosa River at Wadley commonly sustains 

high variation in discharge, ranging from ~5- to 50-.fold, 

over each 24-hr period during non-storm conditions.

poor

Table 44b. Evaluation of Present Hydrologic Condition, non-storm conditions, in HOBE, evaluated using 

the HydroMAG and HydroFLASH Indicators.

Evaluation (non-storm conditions) Rating

Good - HydroMAG (over > 3 days) and HydroFLASH (over 24 hr.) each vary < 1.5-fold

Overallpoor

Fair - HydroMAG (over > 3 days) and HydroFLASH (over 24 hr.) each vary > 1.5-fold to < 3-fold

Poor - HydroMAG (over > 3 days) and HydroFLASH (over 24 hr.) each vary > 3-fold

4.10. Surface Water Quality

Issue: Water pollution is an ongoing problem for the biota of the Tallapoosa River segment in the 

park, caused by upstream land disturbance, silviculture, agriculture, and other development.

Sparse information is available about groundwater quality in or near the park, insufficient for use in 

developing indicators (see Section 3.6.2 of this Report). Therefore, this section focuses on surface 
154

water hydrology. There is a wealth of peer-reviewed literature in support of widely accepted 

parameters indicating the status of surface water quality in freshwaters, and state standards and/or 

federal recommendations for use in interpreting acceptable levels of these parameters (Hynes 1970, 

Whitton 1975, Wetzel 2001, U.S. EPA 2000, 2003; GA DNR 2011). These parameters - pH, 

Dissolved Oxygen (DO), turbidity, nutrients (especially TP and inorganic N as nitrate and/or 

ammonium), suspended algal biomass as chlorophyll a concentration (chla, corrected for 

pheopigments from freshly dead and/or decomposing algae), and various toxic chemical 

environmental contaminants (CECs). We selected the suite of indicators and the evaluation procedure 

shown in Table 45 to assess Surface Water Quality Condition in the park, using the information

contained in Table 26 of this Report. A good evaluation was based on protecting, at least, most 

sensitive aquatic life and sensitive life history stages in park waters.

Table 45a. The present Surface Water Quality Condition in HOBE, based on seven Water Quality 

Indicators (see Table 24 for references).

Surface Water Quality

Indicators NPS Management Target(s) HOBE Rating

pH GA Std: 6.0 - 8.5 100% compliance 

(337 of 337 samples) good

Dissolved Oxygen (DO, mg/L) GA Std: Average 5.0 mg/L; 

minimum 4.0 mg/L

100% compliance 

(237 of 237) good

Biochemical Oxygen Demand 

(BOD5, mg/L) 

Mallin et al. (2006) 

recommendation: 

< 3 mg/L

100% met 

recommendation (19 of 

19)

good

Turbidity (NTU) U.S. EPA recommendation:

5.7 NTU

44% met 

recommendation (11 of 

25)

poor

Total Phosphorus

(TP, μg/L)

U.S. EPA recommendation:

30 μg/L

100% met 

recommendation (19 of 

19)

good

Nitrate + Nitrite

(NOx

-N, μg/L)

U.S. EPA recommendation: 

177 μg/L

84% met 

recommendation (16 of 

19)

fair

Suspended microalgal chlorophyll 

a (Chla; corrected for 

pheopigments; μg/L)

U.S. EPA recommendation:

< 4 μg/L

84% met 

recommendation (16 of 

19)

fair

Table 45b. Paramerters used to rate Surface Water Quality Condition Indicators in HOBE.

Rating pH DO BOD5 Turbidity TP, NOx Chla

good > 90% > 

90% > 90% > 90% > 90% > 90%

fair > 75 to < 90%

> 80 

to < 

90%

> 80 to < 

90% > 75 to < 90% > 75 to < 90%

> 75 to < 

90%

poor < 75% < 

80% < 80% < 75% < 75% < 75%
155

Table 45c. Overall evaluation of Surface Water Quality Condition in HOBE, based on seven Water 

Quality Indicators (see Table 24 for references).

good fair poor

Overall 

Rating

5-7 parameters good < 2 groups poor > 3 groups poor

OVERALLfair 0-2 parameters fair

0 parameters poor

4.11. Biological Resources

Issue: Horseshoe Bend lies within a region that was once among the highest in biodiversity 

nationwide and included many endemic species. Watershed development has led to species 

extinctions at a rate unrivaled across the U.S. mainland. Various species are now threatened, 

endangered, or locally extirpated. Major habitat fragmentation imposed by dams upstream and 

downstream from the park has also adversely affected faunal diversity, species distributions, and 

fisheries, while at the same time the Tallapoosa River has become an important transportation 

corridor for exotic/ invasive species. Exotic/ invasive taxa are a primary concern of park staff, along 

with several SSMCs.

This suite of indicators was especially challenging because there is no quantitative information 

available about species of interest among the biological resources of Horseshoe Bend, a situation 

common to various other parks in the SECN. The information available for all-important plant 

communities at the base of Horseshoe Bend terrestrial and wetland/aquatic food webs is restricted to 

species lists - that is, numbers of species. Based on analyses of SECN parks for which recent, 

vouchered species lists were available for vascular plants, the NPS Certified Species List for 

Horseshoe Bend (NPS 2013b) should be updated and vouchered, as has been planned by the 

Network. This analysis is based on the only information available for Horseshoe Bend, which is the 

present NPS Certified Species List.

Unfortunately, population abundance data are lacking for all species of interest in the park, from 

SoCs to exotic/ invasive taxa to SSMCs. That information is needed to calculate reliable basic 

diversity indices such as Shannon Weaver (Shannon-Wiener; Shannon and Weaver 1949, MacArthur 

and MacArthur 1961, Peet 1974). Other indices that rely solely on species numbers were considered, 

but have major limitations: For example, classic incidence-based indices such as the Jaccard and 

Sørensen Index (J&SI) estimate similarity between two communities, focusing on richness and 

composition. The efficacy of the J&SI in providing a realistic measure of species diversity is in 

debate because the presence/absence data used are neither quantitative nor abundance-based; 

typically a significant under-sampling bias is involved; and there is no accounting for rare species or 

unseen shared species (Gotelli and Colwell 2001, Chao et al. 2006). Because of these significant 

limitations, the J&SI often has been found to yield variable results for the same dataset (Koleff et al. 

2003). The following Biota Indicators were developed within the major constraints imposed by the 

lack of abundance data for species in the park. The suite of available indicators should be modified as 

more information becomes available, especially abundance data for selected species.
156

4.11.1. Vascular Plant Flora, Compromised by Exotic/ Invasive Species

Indicators for this large, important group were developed considering terrestrial and wetland habitats 

separately. For each of the two general habitats, the indicators were based on the proportion of exotic 

taxa and total number of exotic taxa as outlined in Table 58, and on the proportion of invasive taxa. 

Thus, we considered vascular plant communities within the context of alteration by exotic/invasive

plant species.

Exotic/ invasive plants represent ~9% of the terrestrial plant taxa in this park, and less than 5% of the 

wetland flora (Table 46). While these percentages are small in comparison to various other SECN 

parks, Horseshoe Bend is infested with four Category #1 and two Category #2 terrestrial invasive 

plants, and its wetlands contain two Category #1 and 1 Category #2 invasive species. Based on the 

indicators and evaluation format shown in Table 46, the overall Vascular Plant Flora Condition in the 

park is fair.

Table 46a. Evaluation of present Vascular Flora Condition in the park, based on two Terrestrial and two 

Wetland Indicators.

Vascular Flora Indicators Vascular Flora Condition in HOBE Rating

Proportion of exotic terrestrial ,

taxa to total (TERREX)

216 terrestrial vascular plant taxa in the park, including 19 exotic/ 

invasive taxa (9%). fair

Number of highly invasive taxa 

(TERRCAT)

4 Category #1 species + 2 Category #2 species. poor

Proportion of exotic wetland/ 

aquatic taxa (WETEX)

215 wetland/aquatic vascular plant taxa including 10 exotic/ 

invasive (4.7%). Good

Number of highly invasive 

wetland/aquatic taxa.(WETCAT)

2 Category #1 species + 1 Category #2.species. fair

Table 46b. Paramerters used to rate Vascular Flora Indicator Condition Indicators in HOBE.

Vascular Flora 

Indicators Rating Definition

TERREX good < 5% of the terrestrial taxa are exotic/invasive

fair ≥ 5-15% are exotic/invasive

poor > 15% are exotic/invasive

TERRCAT good no Category #1-#4 taxa

fair < 2 Category #1 taxa + some Category #2-#4 taxa

poor 3 or more Category #1 taxa + 1 or more Category #2-#4 taxa

WETEX good < 5% of the wetland taxa are exotic/invasive

fair ≥ 5-15% are exotic/invasive

poor > 15% are exotic/invasive

WETCAT good no Category #1-#4 taxa

fair < 2 Category #1 taxa + > 1 Category #2-#4 taxa

poor 3 or more Category #1 taxa + 1 or more Category #2-#4 taxa 
157

Table 46c. Overall evaluation of Vascular Flora Indicator Condition Ratings for HOBE.

Rating Overall Evaluation of Indicator Ratings

Overall 

Rating

good ≥ 3 indicators good, ≤ 1 indicator fair, 0 poor

OVERALLfair fair ≥ 2 indicators fair, ≤ 1 indicator poor

poor ≥ 2 indicators poor

4.11.2. Fish

In the southern U.S., a pattern has been reported wherein vulnerable fish species at risk of becoming 

threatened or endangered are increasingly more extirpation-prone (Warren et al. 2000). As mentioned 

(see Section 3.7.4), comparison of previous versus present NPS Certified Species Lists suggests that 

species known to have declined in the Middle Tallapoosa River basin (speckled chub, bullhead 

minnow, madtom catfish, redhorse sucker), as well as at least four species known to have been 

endemic to the region (lipstick darter, Tallapoosa darter - Etheostoma tallapoosae, Tallapoosa shiner, 

mottled sculpin), are no longer found in the Middle Tallapoosa River, including the segment within 

Horseshoe Bend - although three of these species were once listed as occurring in Horseshoe Bend. 

The Alabama Natural Heritage Program lists 14 fish species as SoCs within Tallapoosa County; the 

NPS Certified Species List for Horseshoe Bend lists only one species, the blacktail redhorse

(Moxostoma poecilurum), which is not mentioned in the Alabama Natural Heritage Program list 

(Auburn University 2015).

The total Tallapoosa River drainage previously was described to contain 114-120 native fish species, 

yet only ~20% of that number (25 native species) are listed as presently still occurring in Horseshoe 

Bend. The present number of species is low, even if it is assumed that the historic number of fish 

species in the middle Tallapoosa River was only half of the historic total, ~60 species. Based on this 

information, we developed two Fish Indicators and evaluated the Fish Condition in the park as poor

(Table 47). We recommend that fish species in the park should be assessed at five-year intervals or 

more frequently.

Table 47. Fish Condition in HOBE, based on two Fish Indicators.

Fish Indicator HOBE Rating

Fish Species Richness (FISHSPP) 25 native fish species and one exotic/invasive taxon 

have .been reported to occur in the park; declines in 

species .richness have been linked to the extreme, 

artificial .hydrologic regime. 

poor good - > 50 native species

fair - 40-50 native species

poor - < 40 native species

Number of SoCs (FISHSoC) 1 SoC is listed as still occurring in HOBE

poor good - > 10 species

fair - 6-9 species

poor - < 6 species

4.11.3. Herpetofauna

Although the recent surveys of herpetofauna in the park have yielded interesting and helpful 

information, abundance data for the species found are not yet available so that classic species 
158

diversity indices such as the Shannon Weaver cannot be developed (Peet 1974; Magurran 1988, 

2004). Therefore, as first and second indicators of Herpetofauna Condition, we suggest that trends in 

detection of vocal anurans and the data from visual encounter surveys should be tracked over time, 

beginning with the 2011 baseline data. The overall Herpetofauna Condition for Horseshoe Bend is 

good. It should be noted, however, that there is no information on the historic species richness of 

herpetofauna in the park. An assumption used in developing these indicators was that the highest 

species richness for the parks in the Southeast that were assessed by Tuberville et al. (2005) 

represents a good Herpetofauna Condition. Considering the known high diversity of herpetofauna in 

this region together with the high habitat degradation/loss and other negative impacts from watershed 

development, herpetofauna diversity may have been substantially higher.

Figure 55. Relationship between land area (in hectares) and species richness, excluding exotic 

introduced) species, among 16 parks within the Southeast Coast Network of the NPS, including HOBE. 

Modified from Tuberville et al. (2005) to show apparent breaks in the data.

Table 48a. Herpetofauna Condition in HOBE, based on three indicators.

Herpetofauna Indicators HOBE Rating

Vocal Anuran Amphibians (V-Anurans) detected with ARD 

(consistent procedure, .same timing/sites)

March through May 2011 - 13 

vocal anuran amphibian .species 

detected at the 30 established 

sites. good - > 13 vocal anurans detected good

fair - > 10-12 detected (up to 25% fewer)

poor - < 10 detected

# of Species from VES, using consistent procedure, same 

timing/sites (HERPVES)

August 2011 - 15 amphibian and 

reptile taxa detected (same 30 

sites). good - > 15 amphibian & reptile taxa good

fair - 11-14 taxa (up to 25% fewer)

poor - < 11 taxa

GOOD

FAIR

POOR

HOBE

Log Area (hectares)

Log # Species

2.0

1.5

1.0

0.5

0.0

0 1 2 3 4 5

y = 0.274x + 0.722

R

2

= 0.534

GOOD

FAIR

POOR

HOBE

Log Area (hectares)

Log # Species

2.0

1.5

1.0

0.5

0.0

0 1 2 3 4 5

y = 0.274x + 0.722

R

2

= 0.534
159

Table 48b. Overall evaluation of Herpetofauna Condition in HOBE.

Evaluation of Herpetofauna Indicators Rating

good: HERPSPP good, < 2 other indicators good, < 1 other indicator fair

OVERALLgood fair: HERPSPP fair; < 2 other indicators fair, < 1 other indicator poor

poor: < 2 indicators poor

4.11.4. Birds

Horseshoe Bend is listed as having 208 bird species, slightly more than the number of species given 

for an SECN park (Kennesaw Mountain National Battlefield Park - 202 species) that is a globally 

Important Bird Area and has been described as having high bird fauna diversity based on species 

richness. Unfortunately, abundance data are lacking for bird species in Horseshoe Bend, preventing 

calculation of Shannon Weaver or other widely accepted diversity indices for bird diversity. 

Therefore, at present we have based indicators for Bird Fauna Condition in this park on the North 

American Breeding Bird Survey (BBS), and on the baseline survey conducted by Byrne et al. 

(2011b).

The BBS was developed by the U.S. Fish and Wildlife Service in response to the need for a 

continental monitoring program following the widespread use of DDT (dichloro-diphenyl-trichloroethane) and other chlorinated hydrocarbon pesticides, and anecdotal reports about related increased 

mortality of songbirds (Robbins et al. 1986). The program presently represents a cooperative effort 

between the U.S. (USGS), Environment Canada - Canadian Wildlife Service, and the Comisión 

Nacionale para el Conocimiento Uso de la Biodiversidad (CONARIO). The BBS presently includes 

~3,400 randomly located permanent survey routes established along secondary roads. Each route is 

39.4 km (24.5 miles) long and consists of 50 stops spaced at 0.8-km (0.5-mile) intervals. The routes 

are surveyed once each year during the peak of the breeding season. Volunteers experienced in 

identifying birds by sight and sound record all birds detected within 0.4 km (0.25 mile) of each stop 

during a 3-minute observation period (Robbins et al. 1986, Peterson et al. 1995). As a limitation, the 

annual surveys yield what might be more accurately described as a relative abundance index because 

they do not produce a complete counting of the breeding bird populations. In addition, differences in 

experience among volunteers can sometimes cause inconsistencies in the results. Nevertheless, these 

annual surveys have proven valuable in assessments of bird population trends (Link and Sauer 1998, 

Sauer et al. 2003).

BBS summaries of the data by year allow a rapid, user-friendly analysis of trends in the number of 

individuals and the number of species detected over time at a station of interest (USGS 2001b). The 

data are also presented by individual species. For BBS Route 02209 (Wedowee, Ala.), the number of 

species and the number of individuals appear to have remained comparable, given the scatter in the 

data, over the past ~13 years (Table 49).
160

Table 49. Breeding Bird Survey results for BBS Route 02209- Wedowee, Ala., the route closest to HOBE, 

~20 km (12.5 miles) northeast of the park.

Parameter 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Number of 

Species

65 67 ---- 63 60 53 54 49 56 60 51 58 61

Number of 

Individuals

614 579 ---- 588 577 467 474 502 492 511 564 712 767

4 yr average 63 species, 584 individuals 53 species, 483 individuals 57 species, 638 individuals

Three other indicators suggested here for Bird Fauna Condition in Horseshoe Bend were developed 

from the baseline survey conducted in 2009 by Byrne et al. (2011b). They include the observed 

number of species (BIRDOBS SPP), total bird abundance (BIRDABUND, number of individuals), and 

BIRDDIST (the six most widely distributed birds in the park; Table 50). The fifth and final indicator, 

BIRDSoC, is based on the three bird SoCs that were reported for the park in the NPS Certified Species 

List (2013a; Table 61).

Finally, the status of the NPS Certified Species List (2013a) for bird fauna in Horseshoe Bend merits 

mention. This valuable list should be verified at least on a decadal basis. Otherwise, there will be no 

way to track the total number of species that actually can be found in Horseshoe Bend at some time 

during an annual cycle, or the percentage of neotropical migrants, or other important information. At 

present, the total number reported on the list is 208 native species. We did not suggest the total 

number of species on the NPS Certified Species List, tracked over time, as an indicator in 

consideration of the fact that extensive survey of the park over an annual cycle would require a 

major, personnel- and time-intensive effort, but it is important nevertheless.
161

Table 50a. Bird Fauna Condition in HOBE, based on evaluation using five indicators.

Bird Fauna Indicators HOBE Rating

Breeding Birds (BIRDBBS, annual, routinely 

conducted by volunteers for the USGS)

North American BBS in the park area:

2000-2003 - 63 spp., 584 individuals

2004-2007 - 53 spp., 483 individuals

2008-2012 - 57 spp., 638 individuals

The lowest # of species annually over the 2000-

.2012 period was 49 spp. in 2007.

good

good - > 65 native spp.

fair - 55-64 spp.

poor - < 55 spp.

BIRDOBS SPP (assessed at 10-yr intervals, 

same timing/sites as in 2009)

April-May 2009 - 53 native species detected at 

30 established sites.

good

good - > 50 native spp.

fair - 41-49 native spp.

poor - < 41 native spp.

BIRDABUND (# individuals, same assessment) April-May 2009 - 845 individuals detected at 30 

established sites.

good

good - > 800 individuals in total

fair - 700-799 individuals

poor - < 700 individuals

BIRDDIST (most widely distributed, same): April-May 2009 - most widely, distributed taxa: 

northern cardinal, northern parula, red-bellied 

woodpecker, red-eyed vireo, tufted titmouse, 

Carolina wren, and American crow.

good

good - same 7 spp.

fair - 5-6 of the seven spp.

poor - < 4 of the seven spp.

BIRDSoC (assessed at 10-yr intervals in "best" 

locations)

As of 2013 (NPS Certified Species List) - 3 

SoCs: the American kestrel, solitary vireo, and 

yellow .warbler. good - all 3 SoCs observed good

fair - 2 of 3 SoCs observed

poor - < 1 SoC observed

Table 50b. Overall Evaluation of Bird Fauna Condition in HOBE.

Evaluation of Bird Fauna Indicators Rating

good: BIRDBBS or BIRDOBS SPP good, ≥ 2 other indicators good, ≤ 1 other indicator fair, no indicator 

poor OVERALLfair: BIRDSPP or BIRDOBS SPP fair; ≤ 2 other indicators fair, ≤ 1 other indicator poor good

poor: ≥ 2 indicators poor

4.11.5. Mammals

Lacking other helpful information, we based the present form of the mammalian species indicator on 

the proportion of exotic/invasive mammalian taxa relative to the total number of mammalian taxa 

inhabiting Horseshoe Bend (Table 51). Webster (2010) described depauperate mammalian species 

for this park, consisting of 22 documented native taxa. His final list included 11 other species that are 

widely distributed in the Southeast and probably inhabit Horseshoe Bend, but these 11 species were 

not documented there. We recommend that mammalian species should be re-assessed on a five- to 

10-year basis, and that population-level studies should be conducted on mammalian SSMCs, to 

strengthen and improve the Mammalian Indicator in the future.
162

Table 51. The present Mammalian Fauna Condition in HOBE, based on evaluation using three indicators.

Mammalian Fauna Indicators HOBE Rating

Proportion of exotic/invasive species 

(MAMINV - assess every 10 yr)

good - < 5%, none common

fair - 5-10%

poor - > 10%

NPS Certified Species List (2013) - at least ~16% (5 .of 

32) of the mammalian species in the park are 

.exotic/invasive, or recent invasive taxa poor

4.11.6. Species of Special Management Concern (SSMCs)

In addition to the SOCs addressed above in other sections, we developed indicators for the following 

four SSMCs: 

 Longleaf pine natural regrowth and reduced accumulation of materials that act as natural fuels, 

through use of prescribed fires (LLEAF);

 Poaching and other over-hunting of wild turkeys (TURKPOACH);

 Impacts of coyotes that have invaded the park in the past ~decade (COYINV); and

 Stress to deer from over-population or over-harvest (DEERST).

Because quantitative information is not available for any of these species, or for related issues such 

as poaching or disease, the indicators requested by park staff must be qualitative (Table 52). 

Nevertheless, we hope that these straightforward indicators can be used to help leverage support for 

rigorous assessment of the SSMC populations.

It should be noted that we have elected not to develop specific indicators for exotic/ invasive species, 

for two reasons: First, we have already factored exotic/ invasive species into the indicators for 

Vascular Flora and Mammals in this park. The exception was the coyote, in deference to a special 

request from park staff. Second, as Ferriter et al. (2007, p.9-15) wrote,

The indicator[s] for invasive exotics is not similar in nature or context to other indicators 

because nonindigenous [species] in themselves do not make good indicators of ecological 

function, process, or structure....

Based on their extensive experience combating exotic/invasive species in the Florida Everglades, 

Ferriter et al. (2007) suggested use of the following parameters to evaluate and report the status of 

invasive species: the number of different exotic/ invasive species present; the number, abundance, 

and frequency of new exotic/ invasive species in the ecosystem; the number and abundance of extant 

exotic/ invasive species found in new locations; the location and density of invasive exotic species, 

especially in relation to native communities; the rate of invasive species spread; and the effectiveness 

of control actions or programs for exotic/invasive species, generally measured as a decrease in the 

spatial extent of a (plant) species. Very little of any of these types of information is available for 

Horseshoe Bend other than the total number of exotic/ invasive taxa. For example, park staff have 

expressed a desire to manage southern pine beetle-damaged areas so as to replace them by 

establishing early successional grassland or shrub scrub habitat.
163

However, quantitative information is not available as to whether/how much effort has been expended 

to achieve this long-term goal, or measures of progress. An indicator for this effort should be 

developed when this information becomes available.

Overall, the Everglades National Park illustration is apt: Despite major restoration efforts and billions 

of dollars expended over the past decade, that important ecosystem was recently described to be in 

urgent need of work to establish the distributions and biological data for various exotic/invasive 

species (Ferriter et al. 2007). As for the Everglades and many other national parks across the U.S., as 

well as the Southeast, Horseshoe Bend is in urgent need of such work as well.

Table 52a. Present condition of Species of Special Management Concern (SSMCs) in HOBE, based on 

four indicators.

SSMC Indicators HOBE Rating

Re-establishment of longleaf pine habitat 

(LLEAF)

good - prescribed burns at 5-yr intervals.

fair - prescribed burns at 6- to 7-yr intervals.

poor - prescribed burns at > 7-yr intervals.

Prescribed burns were conducted in 2006 and 

2011, and are continuing to be scheduled at 5-yr 

.intervals in an attempt to allow natural regrowth

of longleaf pines.

good

Poaching of wild turkeys (TURKPOACH)

good - no signs of incidents

fair - signs of incidents mainly in 1 area

poor - incidents increasingly reported or signs 

noted, more widespread in the park

Signs/incidents of poaching of wild turkeys, in 

one area of the park, are a concern to park staff.

fair

Recent invasive species (COYINV )

good - none recently detected

fair - 1-2 newly invasive spp. detected

poor - > 2 newly invasive spp. detected

Coyotes recently (past ~decade), increasingly 

noted ; their potential impacts are a concern for 

park staff. fair

Deer over-population stress (DEERST)

good - non-recently detected

fair - occasional signs mainly in 1 area

poor - common signs widespread in park 

Thin animals suggestive of insufficient food have 

been noted in various areas of the park. Staff 

.have expressed concern about potential over-

.population and disease.

poor

Table 52b. Evaluation of overall condition of Species of Special Management Concern in HOBE.

Evaluation of Condition of Species of Management Concern Rating

good: > 3 indicators good, < 1 fair, 0 poor

OVERALLfair fair: > 3 good or fair, < 1 poor

poor: > 2 poor

165 

5. Discussion

5.1. Summary of Natural Resource Conditions in Horseshoe Bend 

This in-depth analysis of the natural resources of Horseshoe Bend considered available information 

for all natural resource categories ranging from climate to SSMCs (Tables 53 and 54). A total of 59 

indicators were used to evaluate the 16 categories of natural resources for which sufficient 

information was available to allow some level of assessment. The overall condition of five categories 

was rated as good; 6 were evaluated to be in fair condition and five were in poor condition. 

The above overall Report Card of Natural Resource Conditions in Horseshoe Bend is evenly 

distributed with good, fair, and poor evaluations, rating an overall “C.” Importantly, of these 16 

categories of natural resources, most are not possible for the National Park Service to control. Only a 

few categories, within the park biota, can be even partly controlled by park staff. For example, park 

staff cannot control the introductions of more exotic/ invasive taxa that have dramatically altered the 

natural communities, because these undesirable taxa can be carried into the park by human visitors, 

birds, wind, water, etc. As another NPC example, the category Human Population Surrounding the 

Park would have rated an overall fair except for two factors, namely, the level of poverty in 

Tallapoosa County, and the looming threat of Lee County population growth and expansion. 

This Report Card can function as a valuable resource for Horseshoe Bend staff and the Network by 

enabling rapid communication to concerned citizens, policymakers in local, state, and federal 

governments, industries etc. about the pressing need to improve protection of the natural (and 

cultural) resources in this valuable park. It is our hope that the many people who depend on 

Horseshoe Bend for recreation and insights about the early history of our nation - and who expect to 

continue to enjoy its natural and cultural resources - will respond to this Report Card by contributing 

more stewardship toward the goal of improving the status and the protection of the natural resource 

conditions in this national park. 
166

Table 53. Overall Report Card of Natural Resource Conditions in HOBE

Natural Resource Category Indicator(s) Rating

Climate 5 poor

Human Population Surrounding the Park 5 poor

Visitation - Human Population in the Park 3 fair

Land Use/Land Cover 2 good

Air Quality 8 fair

Soundscape 3 good

Lightscape 1 good

Soil and Streambank Erosion 4 fair

Surface Water Hydrology 2 poor

Surface Water Quality 7 fair

Vascular Flora 4 fair

Fish 2 poor

Herpetofauna 2 good

Birds 5 good

Mammals 1 poor

Species of Special Management Concern 4 fair
Table 54. Summary of Natural Resource Conditions in HOBE, including 16 separate categories that were 

evaluated using the 59 listed indicators. 

Category Indicators Present Status in HOBE Condition Overall

CLIMATE

TSUM - mean summer 

air temperature

*Mean summer air temperature -

increasing trend.

poor

poor

GDDANN –

phenology;PDSI -

moisture

*Phenology (GDDANNUAL) increasing;

*PDSI decreasing

poor

poor

PPTSUM – mean 

summer precipitation

*Mean summer precipitation –

decreasing trend

poor

Dry - # of dry 

months/yr *Dry - increasing; MSt - increasing: poor

MSt - # of major 

storms

HOBE climate is warming; annual # of 

growing degree days is increasing; 

more dry months/yr, more major 

storms

poor

HUMAN 

POPULATION 

SURROUNDING 

PARK

HPG5-km - human 

population growth 

(5-km radius around 

park)

*Population growth declined in past

decade in Tallapoosa Co. good

poor

HPG80-km - human 

population growth 

(80-km radius)

*High population growth (+2.6%/yr) in

adjacent Lee Co. poor

HPD5-km - human 

population density 

(5-km radius)

.*Moderate population density (5-km 

radius- 22.4 people/km2)

fair

HPD80-km - human 

population density 

(80-km radius)

*High population density (80-km

radius- 91 people/km2)

poor

POV - poverty 

surrounding park

*Tallapoosa Co. - 17.1% of population

is below poverty level poor

VISITATION -

HUMAN 

POPULATION IN 

PARK

VIS - # visitors/yr 

(trend)

*~100,000 visitors (2012), comparable 

or lower than previous years.

good

fair

VP-AGR-SEAS - visitor 

pressure/park area 

(growing season)

*Average of 91 visitors/hectare/growing

seasons, or 0.4 visitor/hectare/day (0.2

visitor/acre/day).

good

VP-TGR-SEAS - visitor 

pressure on trails 

(growing season)

*Avg. of 17 visitors/km of trail/day (27

visitors/mile of trail/day). poor

167
168 

Table 54 (continued). Summary of Natural Resource Conditions in HOBE, including 16 separate 

categories that were evaluated using the 59 listed indicators. 

Category Indicators Present Status in HOBE Condition Overall

LAND USE/LAND 

COVER

%IC5-km - % imperv. 

cover (5-km radius)

*Negligible IC, < 1% land use/land

cover within a 5-km radius of the park.

good good

%GRNWAT -

greenspace (middle 

Tallapoosa subwatershed)

*Entire sub-watershed had only 5%

developed land as of 2006 (most

recent available data). In 2001-2006, 

there was a gain of only 0.1% in 

developed lands.

good

AIR QUALITY

AQI - Air Quality 

Index (U.S. EPA)

*2012-2013: Overall AQI Good 98.9%

of days, Moderate 1.1%. good

fair

O3 - Ozone 

concentration 

(humans); W126, 

SUM06 (plants)

*2005-2009: Ozone 61-75 ppb (8-hr

avg. time, 4th,maximum value); W126, 

7-13 ppm-hr.; SUM06 8-15 ppm-hr.

fair

N-DEP - nitrogen

deposition *2005-2009: N-DEP > 3 kg/ha/yr. poor

S-DEP - sulfur

deposition *2005-2009: S-DEP > 3 kg/ha/yr. poor

VIS - visibility *2005-2009: VIS > 8 dv. poor

ACID - acidification

*Pollutant exposure very high,

ecosystem sensitivity low, Park

Protection low; overall, low risk from 

acidic pollution.

good

SOUNDSCAPE

POPSOUND -

proximity to pop. 

center

*HOBE is ~64 km from the Au-OpMA

(rapidly growing). fair

good

SOURCESOUND -

proximity to major 

source (road, RR, 

etc.)

*State Hwy 49 passes through park,

but its traffic is usually light so it is

considered a minor mode of travel.

good

DATA/OBSSOUND -

noise pollution data 

available for the park

*Data n.a.; parks staff describe HOBE

as usually very quiet. good
169

Table 54 (continued). Summary of Natural Resource Conditions in HOBE, including 16 separate 

categories that were evaluated using the 59 listed indicators.

Category Indicators Present Status in HOBE Condition Overall

LIGHTSCAPE

Bortle Dark-Sky 

Scale - classes:

1-2 (truly dark skies)

3-4 (rural skies)

> 5 (suburban sky, 

ground .objects

partly lit) to 9 (inner 

city sky)

HOBE is still in a predominantly rural 

setting; lightscape is described by park 

staff as Class 2, Truly Dark Skies.

good GOOD

SOIL & 

STREAMBANK 

EROSION

SoilEROD - erodability 

of all soil types

*12 of 20 soil types moderately eroded, 

including two of the three most 

abundant soil types; ~20% of the soil 

types are occasionally to frequently 

flooded, including one of the three most 

abundant soils.

poor

fair

SoilVIS - visual 

evidence of soil 

erosion

*Little evidence of soil erosion in 

HOBE.

good

BankEROD - visual 

evidence of stream-. 

bank erosion

*Little visual evidence of streambank 

erosion in the park...

good

SoilACID - soil 

acidification potential

*Moderate soil acidification potential, 

based on air quality data + poor 

buffering capacity of the mostly clay 

soils.

poor

SURFACE 

WATER 

HYDROLOGY

HydroMAG -

magnitude of 

discharge at the 

Wadley gaging 

station for > 3 days 

(non-storms 

conditions; cfs)

*Tallapoosa River at Wadley 

commonly sustains > 5-fold change in 

discharge for > 3 days during nonstorm conditions.

poor

poor

HydroFLASH -

discharge at the 

Wadley gaging 

station within a 24-hr 

period (non-storm 

conditions; cfs)

*Tallapoosa River at Wadley 

commonly sustains high variation in 

discharge, ranging from ~5- to 50-fold, 

over each 24-hr period during nonstorm conditions.

poor
170

Table 54 (continued). Summary of Natural Resource Conditions in HOBE, including 16 separate 

categories that were evaluated using the 59 listed indicators.

Category Indicators Present Status in HOBE Condition Overall

SURFACE 

WATER QUALITY

pH - 6.0 to 8.5 *pH - 100% compliance (337 samples) good

fair

DO - > 4 mg/L; Avg -

5.0 mg/L *DO - 100% compliance (237 samples) good

BOD5 - < 3 mg/L *BOD5 - 100% met recommendation 

(19 samples)

good

Turbidity - < 5.7 NTU *Turbidity - 44% met recommendation 

(11 of 25 samples) poor

TP - < 30 μg/L *TP - 100% met recommendation (19 

samples) good

NOx

-N - < 177 μg/L *NOx

-N - 84% met recommendation 

(16 of 19 samples)

fair

Chla - < 4 μg/L *Chla - 84% met recommendation (16 

of 19 samples)

fair

VASCULAR 

FLORA

TERREX - # 

Exotics/Total

*9% (19 spp. of 216 total) of the total 

terrestrial taxa are exotic/invasive. fair

fair

TERRCAT - # highly 

invasive taxa

*4 CATEGORY #1 species + 2 

CATEGORY #2 species present in the 

terrestrial vascular flora.

poor

WETEX - # 

Exotics/Total

*19% (42 spp.) of the total wetland 

taxa are exotic/invasive. good

WETCAT - # highly 

invasive taxa

*15% (3 spp.) of CATEGORY #1 taxa 

are wetland and occur in the park, + 2 

CATEGORY #1 Alert taxa + 9 

CATEGORY #2-#4 species. All 5 

CATEGORY #1/CATEGORY #1 Alert 

taxa are common in the park.

fair

FISH

FISHSPP - fish 

species number

*25 native fish species and one 

exotic/invasive species reported in the 

park; declines in species richness have 

been linked to the extreme, artificial 

hydrologic regime.

poor

poor

FISHSoC - number of 

fish SoCs

*Only 1 SoC still listed as occurring in 

HOBE. poor
171 

Table 54 (continued). Summary of Natural Resource Conditions in HOBE, including 16 separate 

categories that were evaluated using the 59 listed indicators. 

Category Indicators Present Status in HOBE Condition Overall

HERPETOFAUNA

HERPSPP - total # of 

species

*2004: 66 native species of

herpetofauna, leading the SECN parks.

good

good V-Anurans - # spp.

detected

*Mar-May 2011: 13 vocal anuran

native spp. detected.

good

HERPVES - # spp. 

detected

*Aug 2011: 15 amphibian and reptile

taxa detected with VES.

good

BIRDS

BIRDBBS - # native 

spp./yr

*68-71 spp. in 2000-2004, 2005-2008,

and 2009-2012; lowest # was 65 spp.

in 2007.

good

good

BIRDOBS SPP - # 

native spp.

*Apr-May 2009: 53 native spp. (30

sites in park).

good

BIRDABUND - # 

individuals *845 individuals. good

BIRDDIST - 6 most 

widely distributed 

spp.

*N. cardinal, northern parula, redbellied woodpecker, red-eyed vireo,

tufted titmouse, Carolina wren, and

American crow.

good

BIRDSoC - SoCs 

observed

*As of 2013, American kestrel, solitary

vireo, yellow warbler. good

MAMMALS MAMINV - #exotic 

spp./total # .

*At least 16% of the mammalian spp.

in the park (5 of 32) are exotic/invasive

taxa, including recent invasives.

poor poor

SSMCs

LLEAF - reestablishment of 

longleaf pine via 

prescribed burns

*Prescribed burns in 2006, 2011;

targeted at 5-yr intervals. good

fair

TURKPOACH -

signs/incidents of 

turkey poaching in 

the park

*Signs/incidents of poaching wild

turkeys in 1 area of park. fair

COYINV - recent 

invasive spp.

*Coyotes recently and increasingly

noted (past ~decade). fair

DEERST - deer overpopulation stress

*Thin animals (suggestive of

insufficient food for deer) commonly 

noted in various areas of park.

poor
172
173 

5.2. Remaining Major Knowledge Gaps and Next Steps 

Major knowledge gaps prevented or seriously restricted evaluation of the present condition of several 

natural resource categories. These gaps, and efforts needed to fill them, include: 

 Streambank Erosion - A study should be conducted to develop a channel stability index for the

Tallapoosa River in the park following the approach used by Heeren et al. (2012). The CSI is a

type of rapid geomorphic assessment (RGA) that provides a quick, straightforward method for

characterizing stream reaches in terms of stability (Simon and Downs 1995). The CSI would be

applicable to Horseshoe Bend because this index was originally designed for areas that are highly

sensitive to erosion. Required measurements include bank height, bank face length, river stage at

baseflow, degree of constriction, and average diameter of streambed sediment, following

guidance on a 2-page sheet. Metrics include representative river stage (water surface height,

measured in the thalweg of the stream, avoiding local scour pools), river channel width at the

cross-section and one fourth of a meander length upstream, measured at the bankfull height; and

degree of constriction (relative decrease in channel width from upstream to downstream). Scores

from several metrics are summed to create an aggregate score, with a higher score indicating

greater instability: < 10 ≡ stable, 10-20.

 Surface Water Hydrology - The RSS in development for Horseshoe Bend is expected to identify

additional hydrologic targets, such as an indicator for tracking undesirable high water conditions

over time, and an indicator to assess changes in flows of the springs in the park.

 Groundwater Supply - A monitoring well is needed near Horseshoe Bend within the Piedmont

aquifer that underlies the park, to provide the data needed to assess aquifer drawdown over time.

 Surface Water Quality - Data for the parameters selected as indicators should be collected at least

monthly to enable reliable assessment of water quality conditions over time, from one station on

each stream in the park. In addition, data are needed for fecal coliform bacteria and chlorophyll a

(suspended algal biomass in the Tallapoosa River within Horseshoe Bend).

 Stream Sediment Quality - Information is needed to enable assessment of the quality of stream

sediments in Horseshoe Bend, focusing on toxic substances such as mercury and polychlorinated

biphenyls (PCBs), to address an identified concern of park staff.

 Groundwater Quality - Information is lacking on groundwater quality in or near the park.

Monthly sampling at least every other year is needed to characterize the pH and track

concentrations of contaminants such as nitrate+nitrite, sulfide, and metals (e.g. iron, aluminum,

manganese), following the approach of Donahue (1998).

 Stream Macroinvertebrate Communities - Stream macroinvertebrates are commonly used to

evaluate habitat conditions, but data for these biota are lacking in or near the park. Stream

macroinvertebrates should be added as an important biological component, and should be

sampled at five-year intervals to assess stream biological condition following well-established

protocols (Barbour et al. 1999, Bowles et al. 2008).

 Ecological Studies to Advance Beyond Species Lists and Presence/Absence Information -

Focused work to characterize key vascular plant communities and key species of interest are

needed, including quantitative abundance data and maps. The species-level studies should
174

emphasize the dominant terrestrial and wetland vascular plants in each of the general habitat 

types found in the park; the common Category #1 and Category #1 Alert invasive vascular plants 

of most concern to park staff; and any other exotic/invasive fauna of major concern to park staff.

 Population Studies - SSMCs, including wild turkeys, coyotes, and white-tailed deer, should be 

assessed for food availability, hunting/ poaching pressure, disease, and effects on the park 

ecosystem.

 Updated Biota Surveys - It would be very helpful to conduct rigorous efforts on a decadal basis to 

track the natural resource conditions of the flora and fauna in Horseshoe Bend. Up-to-date, 

vouchered species lists of vascular flora in terrestrial and wetland habitats are needed. The most 

recent survey of mammals in Horseshoe Bend is already a decade old, and should be updated in 

order to track the condition of this important natural resource category over time.

 Analysis Over Time of the Cumulative and Synergistic Effects of Pressures from Climatic, Land 

Use, and Exotic/Invasive Species Changes - The rate of climate warming in this century is 

projected to be from 2.5- to 5.8-fold higher than the rate measured during the 1900s (Hansen et 

al. 2014, and references therein). Temperatures are expected to increase by 2.58oC to 4.58oC. 

Watershed development is expected to accelerate; for example, an average 255% increase in 

housing density is projected by 2100 in lands surrounding national parks throughout the nation. 

The Au-OpMA, near the park, is rapidly growing. Exotic/invasive species generally are favored 

by disturbances such as these (Ferriter et al. 2007). The cumulative, synergistic effects of such 

changes are predicted to dramatically impact ecosystem function and biodiversity in national 

parks (Hansen et al. 2014). In fact, it has been estimated that ~30% of the parklands may lose 

their present biomes by as early as 2030 (Hansen et al. 2014). 

We have recommended various additional efforts by the SECN which, together with the present and 

planned I&M Program works, will greatly strengthen understanding about how each of these 

pressures affects Horseshoe Bend natural resources. The resulting databases will make it possible for 

the Network to consider climatic, land use, and exotic/invasive species changes more realistically —

through integrative rather than separate analyses of cumulative/synergistic impacts over time. 

Ultimately, that approach offers the best hope of restoring and protecting the natural resources of 

Horseshoe Bend.
175

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203

Appendix 1. GIS Data Used for Assessing Conditions
204

Table A1-1. GIS data used in development of Natural Resource Condition Assessment for Horseshoe Bend National Military Park, Alabama. For 

all data, the projection is UTM Zone 16N and the datum is NAD 83. [Res.=resolution]

File_name Layer_name Category Description Source Scale/Res Metadata

hobe_administrative.s

hp

Current NPS 

Administrative 

Boundary for 

Horseshoe Bend 

National Military Park

Boundary V ector polygon shapefile representing the NPS administrative boundary for 

HOBE. This boundary was originally part of a larger NPS regional dataset and is 

intended for use at the regional level. This boundary is also found in the 

state_regional_gis directory and it may need to be updated as the NPS national 

administrative boundary dataset is updated. 

NPS 1:10,000,0

00

Yes

COUNTY.shp 1990 County and 

Equivalent Area

Counties This dataset contains 1990 County and Equivalent Areas by State equivalent 

code (FIPS) located in the state of Alabama. 

U.S. Census 

Bureau

1:5,000,00

0

Yes - text 

file only

hobe_cities.shp Cities of the United 

States

Cities This map layer includes cities in the United States, Puerto Rico and the U.S. 

Virgin Islands. These cities were collected from the 1970 National Atlas of the 

United States. Where applicable, U.S. Census Bureau codes for named 

populated places were associated with each name to allow additional 

information to be attached. The Geographic Names Information System (GNIS) 

was also used as a source for additional information. This is a revised version of 

the December 2003 map layer. The original dataset was clipped to the county 

boundaries that contain HOBE.

National 

Atlas 

of the 

United 

States

1:2,000,00

0

Yes

hobe_urban_areas.sh

p

Urban Areas of the 

United States

Cities This data set includes a selection of urban areas in the United States derived 

from the urban areas layer of the Digital Chart of the World (DCW). This is a 

revised version of the 1998 data set. The original dataset was clipped to the 

county boundaries that contain HOBE.

USGS 1:2,000,00

0

Yes

dem_mtr (directory) 7.5 Minute Digital 

Elevation Model

Elevation Digital Elevation Model (DEM) is the terminology adopted by the USGS to 

describe terrain elevation data sets in a digital raster form. The7.5-minute DEM 

(30- by 30-m data spacing, cast on a Universal Transverse Mercator (UTM) 

projection) provides coverage in 7.5- by 7.5-minute blocks. The directory also 

contains a park mosaic.

USGS 30 meter Yes - text 

file only

hobe_dem.img National Elevation 

Dataset (DEM)

Elevation The U.S. Geological Survey has developed a National Elevation Dataset (NED). 

The NED is a seamless mosaic of best-available elevation data. The 7.5-minute 

elevation data for the conterminous United States are the primary initial source 

data. NED has been clipped to HOBE surrounding extent. 

USGS 30M Yes
205

Table A1-1 (continued). GIS data used in development of Natural Resource Condition Assessment for Horseshoe Bend National Military Park, 

Alabama. For all data, the projection is UTM Zone 16N and the datum is NAD 83. [Res.=resolution]

File_name Layer_name Category Description Source Scale/Res Metadata

al_plss_utm.shp Public Land Survey 

System of the United 

States

Land Survey This data set portrays the Public Land Surveys of the United States, including 

areas of private survey, Donation Land Claims, and Land Grants and Civil 

Colonies. This is a revised version of the May, 2002 data set. The national 

dataset has been clipped to the state of Alabama.

USGS 1:2,000,00

0

Yes

pipetran (dlg -

directory)

Large-scale Digital Line 

Graph - Pipelines

Transportati

on

Vector polyline shapefiles representing pipeline DLGs in 7.5 minute blocks for 

the extent of HOBE.

USGS 1:24,000 Yes - text 

file only

hobe_railroad.shp Railroads of the United 

States

Transportati

on

This map layer includes railroads in the conterminous United States and Alaska. 

This is a replacement for the December 1998 map layer. The original dataset 

was clipped to the county boundaries that contain HOBE.

National Atlas 

of the United 

States

1:2,000,00

0

Yes

railroad (dlg -

directory)

Large-scale Digital Line 

Graph - Railroads

Transportati

on

Vector polyline shapefiles representing railroad DLGs in 7.5 minute blocks for 

the extent of HOBE.

USGS 1:24,000 Yes - text 

file only

roads.shp Bureau of 

Transportation 

Statistics U.S. Road 

Networks

Transportati

on

This data set portrays a Bureau of Transportation Statistics overview of the road 

networks for all fifty States, the District of Columbia, and Puerto Rico. An extent 

containing HOBE was extracted from the original dataset.

BTS 1:100,000 Yes

ftp_roads Large-scale Digital Line 

Graph - Roads

Transportati

on

Vector polyline shapefiles representing road DLGs in 7.5 minute blocks for the 

extent of HOBE.

USGS 1:24,000 Yes - text 

file only

roads.shp HOBE Roads Transportati

on

The following file represents roads and fire roads located in the Horseshoe 

Bend National Military Park (HOBE). The University of Tennessee at 

Chattanooga Environmental Research and Mapping Facility created these linear 

vector files using handheld and backpack GPS units, aerial photographs, 

preexisting road files, historical documents, and satellite imagery. Features 

classified as roads represent paved or improved surfaces, and "fire roads" 

represent gated solid roadways used for fire and law enforcement access. An 

identical file can be found in the utc_project directory described below.

UTC ERMF unknown Yes
206

Table A1-1 (continued). GIS data used in development of Natural Resource Condition Assessment for Horseshoe Bend National Military Park, 

Alabama. For all data, the projection is UTM Zone 16N and the datum is NAD 83. [Res.=resolution]

File_name Layer_name Category Description Source Scale/Res Metadata

hobe_aquifer.shp Principal Aquifers of the 

48 Conterminous 

United States, Hawaii, 

Puerto Rico, and the 

U.S. Virgin Islands 

Geology This data set contains the shallowest principal aquifers of the conterminous 

United States, Hawaii, Puerto Rico, and the U.S. Virgin Islands, portrayed as 

polygons. The data set was developed as part of the effort to produce the maps 

published at 1:2,500,000 in the printed series "Groundwater Atlas of the United 

States". This is a replacement for the July 1998 data set called Principal 

Aquifers of the 48 Conterminous United States. The original dataset was clipped 

to the county boundaries that contain HOBE.

USGS 1:2,500,00

0

Yes

ssurgo (directory) Soil Survey Geographic 

(SSURGO) database 

for Tallapoosa County, 

Alabama

Soils This dataset is a SSURGO digital soil survey and generally is the most detailed 

level of soil geographic data developed by the National Cooperative Soil Survey. 

The data is divided into spatial files in poly, line, and point formats and 

descriptive attribute files in text and database tabular formats. 

U.S. 

Department of 

Agriculture, 

Natural 

Resources 

Conservation 

Service

1:12,000 Yes

ssurgo_nps (directory) National Park Service -

Soil Survey Geographic 

(SSURGO) database 

for Horseshoe Bend 

National Military Park, 

Alabama

Soils This data set is a digital soil survey and generally is the most detailed lever of 

soil geographic data. Specifically, the data set is identical to the one listed above 

except that it has undergone some additional processing by NPS personnel 

such as clipping the set to the park extent and adding the musym names to the 

attribute table.

NPS - GRD -

SIMP

1:24,000 Yes

SREL_Inv (directory) Herpetofaunal Species 

Locations

Species This directory contains the locations of herpetofauna found in Horseshoe Bend 

National Battlefield Park (HOBE) during a study performed by Tuberville, 

Willson, Dorcas, and Gibbons in conjunction with the Savannah River Ecology 

Laboratory (SREL) between May 2001 and October 2003. Please refer to: 

"Herpetofaunal Species Richness of Southeastern National Parks." 

Southeastern Naturalist 4.3 (2005): 537-569 for more detailed information about 

the study. The data is divided into one spatial file and one tabular file in order to 

provide all of the features found during the study as some of the sampling 

locations were not defined spatially. 

SREL/SECN 1:24,000 Yes
207

Table A1-1 (continued). GIS data used in development of Natural Resource Condition Assessment for Horseshoe Bend National Military Park, 

Alabama. For all data, the projection is UTM Zone 16N and the datum is NAD 83. [Res.=resolution]

File_name Layer_name Category Description Source Scale/Res Metadata

alhuc12_draft.shp The 8, 10, and 12 

hydrologic unit 

boundaries for Alabama

Watershed This dataset is a complete digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for the State of Alabama. This data set consists of 

georeferenced digital data and associated attributes created in accordance with 

the "FGDC Proposal, Version 1.0 - Federal Standards For Delineation of 

Hydrologic Unit Boundaries 3/01/02" 

(http://www.ftw.nrcs.usda.gov/huc_data.html). Polygons are attributed with 

hydrologic unit codes for 4th level subbasins, 5th level watersheds, 6th level 

sub-watersheds, name, size, downstream hydrologic unit, type of watershed, 

non-contributing areas and flow modification. Arcs are attributed with the highest 

hydrologic unit code for each watershed, linesource and a metadata reference 

file. The home directory of this shapefile also contains huc 2,4,6,8, and 10 level 

data but the metadata pertains cheifly to the huc 12 layer.

Alabama 

Natural 

Resources 

Conservation 

Service 

State Office

1:24,000 Yes

wqgis (directory) Horseshoe Bend 

National Military ParkSmall-Scale Base GIS 

Data

WQ GIS The data are comprised of small-scale base GIS data layers, including roads, 

hydrography, political boundaries, trails and other layers as available and 

appropriate, compiled for the purpose of displaying the locations of point-based 

hydrologic features (water quality monitoring stations, stream gages, industrial 

discharges, drinking intakes, and water impoundments) proximate to national 

park units. The data are intended to be used as a set to ensure spatial 

alignment. The accompanying Microsoft Excel file,sources.xls, lists the data 

sources for each data layer.

NPS - WRD varies: 

1:100,000 

or larger

Yes

drg_nad83 (directory) Digital Raster Graphics 

(DRGs)

DRGs This directory contains non-collared digital raster graphics (DRGs), which are 

scanned images of U.S. Geological Survey (USGS) topographic maps that 

cover the extent of HOBE in .tif format. The images inside the map neatline are 

georeferenced to the surface of the Earth. The directory also contains a mosaic 

that joins all of the quads that contain or immediately surround the park.

USGS? 1:24,000? No
208

Table A1-1 (continued). GIS data used in development of Natural Resource Condition Assessment for Horseshoe Bend National Military Park, 

Alabama. For all data, the projection is UTM Zone 16N and the datum is NAD 83. [Res.=resolution]

File_name Layer_name Category Description Source Scale/Res Metadata

hobe_forest_cover.im

g

Forest Cover Types Land Cover This data set portrays general forest cover types for the United States. Data 

were derived from Advanced Very High Resolution Radiometer (AVHRR) 

composite images recorded during the 1991 growing season, with the exception 

of Puerto Rico, for which Landsat Thematic Mapper (TM) data were used. A 

total of 25 classes of forest cover types were interpreted from the AVHRR and 

TM imagery, aided by field observations and refined with ancillary data from 

digital elevation models. The original dataset has been clipped to an unknown 

extent that covers HOBE and the surrounding areas by an unknown source.

USDA Forest 

Service/USGS

1:7,500,00

0

Yes

hobe_2004_partial 

(directory)

2004 IKONOS Imagery Images This base directory contains a jpeg overview image and the 

po_228818_0000000 directory that contains the main 2004 IKONOS imagery 

files. The po_228818_0000000 directory contains 2004 IKONOS imagery in 

GeoTIFF format that covers a portion (eastern half approximately) of HOBE. 

The imagery is projected in both UTM 16N, WGS 84 (original projection) and

NAD 83 (nad_83 folder). The directory contains the standard four bands as well 

as a false color (comp_fc) and natural color (comp_nc) composite. Please refer 

to the individual metadata files for specific process information. 

GeoEye 1 meter Yes - text 

file only

LT_2006 2006 Landsat Imagery Images This directory contains 2006 Landsat 5 Thematic Mapper Imagery in GeoTIFF 

format that covers the extent of HOBE. Specifically, the directory contains the 

seven multispectral bands and three composites that were made by SECN 

personnel (please see COMP_PROC_STEP for composite details). There is a 

somewhat limited text metadata file as well as a technical specification sheet 

that states all of the background imaging data and processes.

USGS 30 meter Yes - text 

file only

hobe_landsat.img WEBMAP.LANDSAT_L

277 (Landsat 

Orthoimagery Mosaic)

Images The Landsat Mosaic orthoimagery database contains Landsat Thematic Mapper 

imagery for the conterminous United States. The more than 700 Landsat scenes 

have been resampled to a 1-arc-second (approximately 30-meter) sample 

interval in a geographic coordinate system using the North American Horizontal 

Datum of 1983. The original image was clipped to include the area containing 

and surrounding the park area. 

USGS 30 meters Yes
209

Table A1-1 (continued). GIS data used in development of Natural Resource Condition Assessment for Horseshoe Bend National Military Park, 

Alabama. For all data, the projection is UTM Zone 16N and the datum is NAD 83. [Res.=resolution]

File_name Layer_name Category Description Source Scale/Res Metadata

hobe_92nlcd.img Alabama Land Cover 

Dataset

Images The National Land Cover Dataset was compiled from Landsat satellite TM 

imagery (circa 1992) with a spatial resolution of 30 meters and supplemented by 

various ancillary data (where available). The original image was clipped to 

include the area containing and surrounding the park. 

USGS 30 meters Yes

hobe_01_nlcd.img National Land Cover 

Database Zone 58 

Land Cover Layer

Images This dataset (NLCD 2001) is an update of the 1992 NLCD described above. The 

extent covers the extent of HOBE and the surrounding areas. 

USGS 30 meter Yes

utc_project (directory) University of 

Tennessee at 

Chattanooga 

Environmental 

Research and Mapping 

Facility (UTC ERMF) 

HOBE Project Files

Park Data This directory contains a number of files that were produced as a part of a park 

inventory and mapping project conducted by the University of Tennessee at 

Chattanooga Environmental Research and Mapping Facility (UTC ERMF) at the 

request of the NPS. The files are found in both decimal degrees and UTM and 

include boundaries, streams, roads, trails, utilities, infrastructure points, fire 

management areas and a natural color IKONOS image among others. The 

directory seems to contain some useful base data and it appears to be well 

documented.

UTC ERMF Varies Yes
210

Table A1-2. Data used in the Natural Resource Condition Assessment for HOBE.

Data Layer_name Source Agency Year Notes 

Current NPS Admininistrative 

Boundary for Horseshoe Bend 

National Military Park

NPS Vector polygon shapefile representing the NPS administrative boundary for HOBE. This boundary was originally part 

of a larger NPS regional dataset and is intended for use at the regional level. This boundary is also found in the 

state_regional_gis directory and it may need to be updated as the NPS national administrative boundary dataset is 

updated. 

1990 County and 

Equivalent Area

U.S. 

Census 

Bureau

1990 This dataset contains 1990 County and Equivalent Areas by State equivalent code (FIPS) located in the state of 

Alabama. 

Cities of the 

United States

National 

Atlas 

of the 

United 

States

revised from 

Dec. 2003 (2010)

This map layer includes cities in the United States, Puerto Rico and the U.S. Virgin Islands. These cities were 

collected from the 1970 National Atlas of the United States. Where applicable, U.S. Census Bureau codes for named 

populated places were associated with each name to allow additional information to be attached. The Geographic 

Names Information System (GNIS) was also used as a source for additional information. This is a revised version of 

the December 2003 map layer. The original dataset was clipped to the county boundaries that contain HOBE.

Urban Areas of the 

United States

USGS revised from 

1998 (2010)

This data set includes a selection of urban areas in the United States derived from the urban areas layer of the Digital 

Chart of the World (DCW). This is a revised version of the 1998 data set. The original dataset was clipped to the 

county boundaries that contain HOBE.

7.5 Minute Digital 

Elevation Model

USGS Digital Elevation Model (DEM) is the terminology adopted by the USGS todescribe terrain elevation data sets in a 

digital raster form. The7.5-minute DEM (30- by 30-m data spacing, cast on a Universal Transverse Mercator (UTM) 

projection) provides coverage in 7.5- by 7.5-minute blocks. The directory also contains a park mosaic.

National Elevation 

Dataset (DEM)

USGS The U.S. Geological Survey has developed a National Elevation Dataset (NED). The NED is a seamless mosaic of 

best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial 

source data. NED has been clipped to HOBE surrounding extent. 

Large-scale Digital Line Graph 

(DLG)

USGS Vector polyline shapefiles representing hydrographic DLGs in 7.5 minute blocks for the extent of HOBE. There is 

also a shapefile that has all of the individual quads merged together in order to form a continuous hydro coverage of 

the park.

Streams and Waterbodies of the 

United States

USGS This dataset portrays the polygon water features of the United States, Puerto Rico and the U.S. Virgin Islands. The 

file was produced by joining the individual State hydrography layers from the 1:2,000,000-scale Digital Line Graph 

(DLG) data produced by the USGS. This data set was formerly distributed as Hydrography Features of the United 

States. This is a revised version of the November 1999 data set. The original dataset was clipped to the county 

boundaries that contain HOBE.

Streams and Waterbodies of the 

United States

USGS This dataset portrays the line water features of the United States, Puerto Rico and the U.S. Virgin Islands. The file 

was produced by joining the individual State hydrography layers from the 1:2,000,000-scale Digital Line Graph (DLG) 

data produced by the USGS. This data set was formerly distributed as Hydrography Features of the United States. 

This is a revised version of the November 1999 data set. The original dataset was clipped to the county boundaries 

that contain HOBE.
211

Table A1-2 (continued). Data used in the Natural Resource Condition Assessment for HOBE.

Data Layer_name Source Agency Year Notes 

Realtime USGS Streamflow 

Stations

USGS This dataset portrays the approximately 5,000 of the 6,900 U.S. Geological Survey sampling stations that are 

equipped with telemetry to transmit data on streamflow, temperature, and other parameters back to a data base for 

real-time viewing via the World Wide Web. A map of the realtime stations is produced every day. The original 

dataset was clipped to the county boundaries that contain HOBE.

Tallapoosa River UTC 

ERMF

fall 2003 -

summer 2004

This vector polygon depicts the Tallapoosa river in Horseshoe Bend National Millitary Park (HOBE). The file was 

created as part of an University of Tennessee at Chattnooga Environmental Research and Mapping Facility (UTC 

ERMF) park inventory and mapping project, started in the fall of 2003 and ending in the summer of 2004. An 

identical file can be found in the utc_project directory described below.

Large-scale Digital Line Graph 

(DLG)

USGS Vector polyline shapefiles representing hypsographic DLGs in 7.5 minute blocks for the extent of HOBE.

National Wetlands Inventory USFWS NWI digital data files are records of wetlands location and classification as developed by the U.S. Fish & Wildlife 

Service. These data are individual NWI quads in polygon and polyline shapefile format that cover the extent of 

HOBE.

Public Land Survey System of 

the United States

USGS revised from May 

2002 (2014)

This data set portrays the Public Land Surveys of the United States, including areas of private survey, Donation Land 

Claims, and Land Grants and Civil Colonies. This is a revised version of the May, 2002 data set. The national 

dataset has been clipped to the state of Alabama.

Large-scale Digital Line Graph -

Pipelines

USGS Vector polyline shapefiles representing pipeline DLGs in 7.5 minute blocks for the extent of HOBE.

Railroads of the 

United States

National Atlas 

of the 

United States

replacement 

for Dec. 1998 

map layer (2010)

This map layer includes railroads in the conterminous United States and Alaska. This is a replacement for the 

December 1998 map layer. The original dataset was clipped to the county boundaries that contain HOBE.

Large-scale Digital Line Graph -

Railroads

USGS Vector polyline shapefiles representing railroad DLGs in 7.5 minute blocks for the extent of HOBE.

Bureau of Transportation 

Statistics U.S. Road Networks

BTS This data set portrays a Bureau of Transportation Statistics overview of the road networks for all fifty States, the 

District of Columbia, and Puerto Rico. An extent containing HOBE was extracted from the original dataset.

Large-scale Digital Line Graph -

Roads

USGS Vector polyline shapefiles representing road DLGs in 7.5 minute blocks for the extent of HOBE

HOBE Roads UTC 

ERMF

The following file represents roads and fire roads located in the Horseshoe Bend National Military Park (HOBE). The 

University of Tennessee at Chattanooga Environmental Research and Mapping Facility created these linear vector 

files using handheld and backpack GPS units, aerial photographs, preexisting road files, historical documents, and 

satellite imagery. Features classified as roads represent paved or improved surfaces, and "fire roads" represent 

gated soild roadways used for fire and law enforcement access. An identical file can be found in the utc_project 

directory described below.
212

Table A1-2 (continued). Data used in the Natural Resource Condition Assessment for HOBE.

Data Layer_name Source Agency Year Notes 

Principal Aquifers of the 48 

Conterminous United States, 

Hawaii, Puerto Rico, and the 

U.S. Virgin Islands 

USGS replacement 

for July 

1998 map 

layer (2010)

This data set contains the shallowest principal aquifers of the conterminous United States, Hawaii, Puerto Rico, and 

the U.S. Virgin Islands, portrayed as polygons. The data set was developed as part of the effort to produce the maps 

published at 1:2,500,000 in the printed series "Ground Water Atlas of the United States". This is a replacement for 

the July 1998 data set called Principal Aquifers of the 48 Conterminous United States. The original dataset was 

clipped to the county boundaries that contain HOBE.

Soil Survey Geographic 

(SSURGO) database for 

Tallapoosa County, Alabama

U.S. Department of 

Agriculture, Natural 

Resources 

Conservation 

Service

This dataset is a SSURGO digital soil survey and generally is the most detailed level of soil geographic data 

developed by the National Cooperative Soil Survey. The data is divided into spatial files in poly, line, and point 

formats and descriptive attribute files in text and database tabular formats. 

National Park Service - Soil 

Survey Geographic (SSURGO) 

database for Horseshoe Bend 

National Military Park, Alabama

NPS - GRD -SIMP This data set is a digital soil survey and generally is the most detailed lever of soil geographic data. Specifically, the 

data set is identical to the one listed above except that it has undergone some additional processing by NPS 

personnel such as clipping the set to the park extent and adding the musym names to the attribute table.

Herpetofaunal 

Species Locations

SREL/SECN May 2001 -

October 

2003

This directory contains the locations of herpetofauna found in Horseshoe Bend National Battlefield Park (HOBE) 

during a study performed by Tuberville, Willson, Dorcas, and Gibbons in conjunction with the Savannah River 

Ecology Laboratory (SREL) between May 2001 and October 2003. Please refer to: "Herpetofaunal Species Richness 

of Southeastern National Parks." Southeastern Naturalist 4.3 (2005): 537-569 for more detailed information about the 

study. The data is divided into one spatial file and one tabular file in order to provide all of the features found during 

the study as some of the sampling locations were not defined spatially. 

The 8, 10, and 12 

hydrologic unit 

boundaries for Alabama

Alabama 

Natural 

Resources 

Conservation 

Service 

State Office

Mar-02 This dataset is a complete digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for the State 

of Alabama. This data set consists of geo-referenced digital data and associated attributes created in accordance 

with the "FGDC Proposal, Version 1.0 - Federal Standards For Delineation of Hydrologic Unit Boundaries 3/01/02" 

Polygons are attributed with hydrologic unit codes for 4th level sub-basins, 5th level watersheds, 6th level 

subwatersheds, name, size, downstream hydrologic unit, type of watershed, non-contributing areas and flow 

modification. Arcs are attributed with the highest hydrologic unit code for each watershed, linesource and a metadata 

reference file. The home directory of this shapefile also contains huc 2,4,6,8, and 10 level data but the metadata 

pertains cheifly to the huc 12 layer.

Horseshoe Bend National 

Military Park-Small Scale Base 

GIS Data

NPS -

WRD

The data are comprised of small-scale base GIS data layers, including roads, hydrography, political boundaries,trails 

and other layers as available and appropriate, compiled for the purpose of displaying the locations of point-based 

hydrologic features (water quality monitoring stations, stream gages, industrial discharges, drinking intakes, and 

water impoundments) proximate to national park units. The data are intended to be used as a set to ensure spatial 

alignment. The accompanying Microsoft Excel file,sources.xls, lists the data sources for each data layer.

Digital Raster Graphics (DRGs) USGS? This directoy contains non-collared digital raster graphics (DRGs), which are scanned images of U.S. Geological 

Survey (USGS) topographic maps, that cover the extent of HOBE in .tif format. The images inside the map neatline 

are georeferenced to the surface of the Earth. The directory also contains a mosaic that joins all of the quads that 

contain or immediately surround the park.
213

Table A1-2 (continued). Data used in the Natural Resource Condition Assessment for HOBE.

Data Layer_name Source Agency Year Notes 

Forest Cover Types USDA 

Forest 

Service/

USGS

This data set portrays general forest cover types for the United States. Data were derived from Advanced Very High 

Resolution Radiometer (AVHRR) composite images recorded during the 1991 growing season, with the exception of 

Puerto Rico, for which Landsat Thematic Mapper (TM) data were used. A total of 25 classes of forest cover types 

were interpreted from the AVHRR and TM imagery, aided by field observations and refined with ancillary data from 

digital elevation models. The original dataset has been clipped to an unknown extent that covers HOBE and the 

surrounding areas by an unknown source.

2004 IKONOS Imagery GeoEye 2004 This base directory contains a jpeg overview image and the po_228818_0000000 directory that contains the main 

2004 IKONOS imagery files. The po_228818_0000000 directory contains 2004 IKONOS imagery in GeoTIFF format 

that covers a portion (eastern half approximately) of HOBE. The imagery is projected in both UTM 16N, WGS 84 

(original projection) and NAD 83 (nad_83 folder). The directory contains the standard 4 bands as well as a false 

color (comp_fc) and natural color (comp_nc) composite. Please refer to the individual metadata files for specific 

process information. 

2006 Landsat Imagery USGS 2006, 2011 This directory contains 2006 and 2011 Landsat 5 Thematic Mapper Imagery in GeoTIFF format that covers the extent 

of HOBE. Specifically, the directory contains the 7 multispectral bands and three composites that were made by 

SECN personnel (please see COMP_PROC_STEP for composite details). There is a somewhat limited text 

metadata file as well as a technical specification sheet that states all of the background imaging data and processes.

WEBMAP.LANDSAT_L277 

(Landsat Orthoimagery Mosaic)

USGS The Landsat Mosaic orthoimagery database contains Landsat Thematic Mapper imagery for the conterminous United 

States. The more than 700 Landsat scenes have been resampled to a 1-arc-second (approximately 30-meter) 

sample interval in a geographic coordinate system using the North American Horizontal Datum of 1983. The orignal 

image was clipped to include the area containing and surrounding the park area. 

Alabama Land Cover Dataset USGS ~1992 The National Land Cover Dataset was compiled from Landsat satellite TM imagery (circa 1992) with a spatial 

resolution of 30 meters and supplemented by various ancillary data (where available). The orignal image was 

clipped to include the area containing and surrounding the park. 

National Land Cover Database 

Zone 58 Land Cover Layer

USGS 2001 This dataset (NLCD 2001) is an update of the 1992 NLCD described above. The extent covers the extent of HOBE 

and the surrounding areas. 

University of Tennessee at 

Chattanooga Environmental 

Research and Mapping Facility 

(UTC ERMF) HOBE Project 

Files

UTC ERMF This directory contains a number of files that were produced as a part of a park inventory and mapping project 

conducted by the University of Tennessee at Chattanooga Environmental Research and Mapping Facility (UTC 

ERMF) at the request of the NPS. The files are found in both decimal degrees and UTM and include boundaries, 

streams, roads, trails, utilities, infrastructure points, fire management areas and a natural color IKONOS image 

among others. The directory seems to contain some useful base data and it appears to be well documented.

215

Appendix 2. Lists of the Biota Reported from Horseshoe 

Bend

Table A2-1 The 228 terrestrial vascular plant taxa (227 species + 1 variety) reported to occur in HOBE.

Note that exotic/invasive taxa are indicated in bold1. This list is modified from the NPS Certified Species 

List (2013a) using taxonomic information from the USDA Plants Database Database 

(http://plants.usda.gov/java/). Exotic/invasive taxa are from information for Tallapoosa County at

http://www.eddmaps.org/tools/countyplants.cfm?id=us_al_01123, and from EDDMapS (2013) at 

http://www.eddmaps.org/. All of these websites were last accessed in May 2015. SoCs are indicated in 

blue*.

Scientific Name Common Name(s)

Acer barbatum a

Southern sugar maple

Achillea millefolium Bloodwort, carpenter's weed, common yarrow

Aesculus pavia Red buckeye

Agrimonia pubescens Groovebur, roadside agrimony, soft agrimony

Albizia julibrissin1 Mimosa, mimosa tree, powderpuff tree1

Allium canadense Canada garlic, meadow garlic, meadow onion

Ambrosia artemisiifolia Annual ragweed, common ragweed, low ragweed

Amphicarpaea bracteata American hogpeanut, hogpeanut

Antennaria plantaginifolia Plantainleaf pussytoes, woman's tobacco

Apocynum cannabinum b

Aristolochia serpentaria b

Asclepias quadrifolia

Indianhemp

Virginia snakeroot

Fourleaf milkweed

Asclepias tuberosa Butterfly milkweed, butterflyweed

Asimina parviflora Smallflower pawpaw

Asplenium platyneuron Ebony spleenwort

Aster pilosus White heath aster, white oldfield aster

Aureolaria flava Smooth yellow false foxglove

Aureolaria virginica Downy yellow false foxglove

Botrychium biternatum Sparselobe grapefern

Botrychium virginianum Rattlesnake fern

Callicarpa americana American beautyberry

Carya alba Mockernut hickory

Carya carolinae-septentrionalis Southern shagbark hickory

Cassia fasciculata Partridge pea, showy partridgepea, sleepingplant

Castanea pumila* Allegeny chinkapin, allegheny chinkapin, chinkapin*

Catalpa speciosa Northern catalpa

Ceanothus americanus Jersey tea, jerseytea, new jersey tea

Celtis occidentalis Common hackberry, hackberry, western hackberry

Centrosema virginianum Butterflypea, spurred butterfly pea

Cerastium glomeratum1 Sticky chickweed1

Cercis canadensis Eastern redbud, Redbud

Chamaecrista nictitans ssp. nictitans var. nictitans c

Sensitive partridge pea
216

Scientific Name Common Name(s)

Cheilanthes lanosa Hairy lipfern

Chimaphila maculata Striped prince's pine, striped prince's-pine

Cimicifuga racemosa Black bugbane

Cirsium discolor Field thistle

Clitoria mariana b

Cnidoscolus stimulosus

Atlantic pigeonwings

Finger rot

Collinsonia serotina Blue Ridge horsebalm

Commelina erecta Erect dayflower, whitemouth dayflower

Conyza canadensis var. canadensis d Canadian horseweed

Coreopsis auriculata Lobed tickseed

Coreopsis major Greater tickseed

Cornus florida Flowering dogwood

Coronilla varia Crownvetch, purple crownvetch, purple crownvetch

Crataegus uniflora Dwarf hawthorn, oneflower hawthorn

Cynodon dactylon1 Bermudagrass, chiendent pied-de-poule, common bermudagrass1

Daucus carota1 Bird's nest, Queen Anne's lace, wild carrot1

Daucus pusillus American wild carrot, rattlesnake carrot, rattlesnake weed

Desmodium lineatum Sand ticktrefoil

Desmodium nudiflorum Barestem tickclover, bare-stemmed tick-treefoil, nakedflower ticktrefoil

Desmodium tenuifolium Slimleaf ticktrefoil

Dichanthelium boscii Bosc's panicgrass

Dichanthelium commutatum Variable panicgrass

Dioscorea oppositifolia1 Chinese yam1

Duchesnea indica1

India mockstrawberry, Indian strawberry1

Elephantopus tomentosus Devil's grandmother, hairy elephantfoot

Eleusine indica1 Goosegrass, crowsfoot grass, goose grass1

Epifagus virginiana Beechdrops

Eragrostis capillaris Lace grass, lacegrass

Erigeron annuus Annual fleabane, eastern daisy fleabane

Erigeron strigosus Daisy fleabane, prairie fleabane, rough fleabane

Euonymus americana Strawberry bush, strawberrybush

Eupatorium glaucescens Waxy thoroughwort

Eupatorium rugosum Richweed, snakeroot, white snakeroot

Euphorbia corollata Flowering spurge, floweringspurge euphorbia

Fagus grandifolia American beech

Fragaria virginiana Virginia strawberry, thickleaved wild strawberry, wild strawberry

Galax urceolata Beetleweed

Gamochaeta purpurea Spoonleaf purple everlasting, spoon-leaf purple everlasting

Geranium maculatum Spotted crane's-bill, spotted geranium, wild crane's-bill

Glechoma hederacea e1 Ground ivy1

Gnaphalium obtusifolium Rabbit-tobacco
217

Scientific Name Common Name(s)

Goodyera pubescens Downy rattlesnake plantain, downy rattlesnake plantain

Halesia carolina Carolina silverbell, silverbell

Helianthus tuberosus Jerusalem artichoke, girasole, Jerusalem sunflower

Helenium amarum1 Sneezeweed, bitter sneezeweed, yellowdicks1

Hepatica nobilis var. acuta f

Sharplobe hepatica

Hepatica nobilis var. obtusa g Roundloabe hepatica

Hexastylis arifolia Littlebrownjug

Hieracium gronovii Gronovis hawkweed, queendevil

Hieracium venosum Rattlesnakeweed

Houstonia longifolia Longleaf bluet, longleaf summer bluet, longleaf summer bluet

Houstonia purpurea Purple bluets, Venus' pride

Hydrangea arborescens Smooth hydrangea, wild hydrangea

Hydrangea quercifolia Oakleaf hydrangea

Hypericum frondosum Cedarglade St. Johnswort

Hypericum gentianoides Orangegrass, pinweed st. johnswort

Impatiens capensis Jewelweed, spotted touch-me-not

Iris cristata Crested iris, dwarf crested iris

Iris verna Dwarf violet iris

Juglans cinerea Butternut

Juglans nigra Black walnut

Juniperus virginiana Eastern redcedar, eastern red cedar, red cedar juniper

Kalmia latifolia Mountain laurel

Lamium amplexicaule1 Henbit, common henbit, giraffehead1

Lechea racemulosa Illinois pinweed

Lepidium virginicum Peppergrass, poorman pepperweed, poorman's pepper

Lespedeza cuneata1 Chinese lespedeza, sericea lespedeza1

Lespedeza procumbens Trailing lespedeza

Lespedeza repens Creeping lespedeza

Liatris squarrosa Scaly blazing star, scaly gayfeather

Luzula multiflora Common woodrush, common woodrush

Lycopodium digitatum Fan clubmoss

Lysimachia quadrifolia b

Magnolia acuminata

Whorled yellow loosestrife

Cucumbertree, cucumbertree

Maianthemum racemosum ssp. 

racemosum h

Feathery false lily of the valley

Malus angustifolia Southern crabapple

Manfreda virginica False aloe

Matelea carolinensis b

Melia azedarach1

Carolina milkvine

Chinaberry, Chinaberry tree, Chinaberrytree1

Melica mutica Oniongrass, twoflower melic, twoflower melicgrass

Menispermum canadense b

Mimosa microphylla

Common moonseed

Littleleaf sensitive-briar, sensitive brier
218

Scientific Name Common Name(s)

Monarda bradburiana Eastern beebalm, wildbergamot beebalm

Monarda punctata Spotted beebalm

Monotropa hypopithys b,i

Morella cerifera

Pinesap

Wax myrtle, waxmyrtle

Nothoscordum bivalve Crowpoison

Nuttallanthus canadensis Canada toadflax, oldfield toadflax, oldfield toadflax

Oenothera biennis Common evening primrose, common eveningprimrose, common evening 

primrose

Oenothera speciosa Pinkladies, Showy evening primrose, showy eveningprimrose

Opuntia ficus-indica1

Indian fig, Indian fig, tuna cactus1

Orbexilum pedunculatum var. 

psoralioides j

Sampson's snakeroot

Ostrya virginiana Eastern hophornbeam, hophornbeam

Oxalis grandis* Great yellow woodsorrel*

Oxalis stricta Common yellow oxalis, erect woodsorrel, sheep sorrel

Oxalis violacea Purple woodsorrel, violet woodsorrel, violet woodsorrel

Packera anonyma Small's ragwort

Parthenocissus quinquefolia American ivy, fiveleaved ivy, Virginia creeper

Paspalum notatum var. saurae1 Bahiagrass1

Passiflora incarnata Purple passionflower

Passiflora lutea b

Penstemon canescens

Yellow passionflower

Eastern gray beardtongue

Phegopteris hexagonoptera Broad beech fern, broad beechfern

Philadelphus inodorus Scentless mock orange

Phlox amoena Hairy phlox

Phlox divaricata Wild blue phlox

Phoradendron leucarpum Oak mistletoe

Physalis pubescens b

Piptochaetium avenaceum

Husk tomato

Blackseed needlegrass, blackseed speargrass

Pityopsis graminifolia b

Pityopsis graminifolia var. graminifolia k

Narrowleaf silkgrass

Narrowleaf silkgrass

Plantago aristata1 Bottlebrush Indianwheat, largebracted plantain1

Plantago lanceolata1 Narrowleaf plantain, buckhorn (English) plantain, lanceleaf 

Indianwheat1

Plantago virginica Paleseed Indianwheat, Virginia plantain

Pleopeltis polypodioides ssp. 

polypodioides l

Resurrection fern

Podophyllum peltatum May apple, mayapple

Polygala curtissii Curtiss' milkwort

Polygala grandiflora Showy milkwort

Polygonatum biflorum Smooth Solomon's seal, King Solomon's seal, Solomon's seal

Polystichum acrostichoides Christmas fern

Porteranthus Indian physic
219

Scientific Name Common Name(s)

Potentilla canadensis Dwarf cinquefoil

Potentilla simplex Common cinquefoil, oldfield cinquefoil, oldfield fivefingers

Prunus americana American plum

Prunus angustifolia Chickasaw plum

Prunus mexicana1 Mexican plum1

Prunus serotina Black cherry, black chokecherry

Prunus umbellata Flatwood plum, hog plum

Pteridium aquilinum Bracken, bracken fern, brackenfern

Pueraria montana var. lobata1 Kudzu, kudzu vine1

Pycnanthemum incanum Hoary mountainmint

Pyrrhopappus carolinianus Carolina desert chicory, Carolina desert chicory, Carolina false dandelion

Quercus alba White oak

Quercus austrina Bastard white oak

Quercus falcata Southern red oak

Quercus marilandica Blackjack oak

Quercus rubra Northern red oak

Quercus stellata Post oak

Quercus velutina Black oak

Rhus copallina Dwarf sumac, shining sumac

Rhus glabra Smooth sumac

Rhus hirta Staghorn sumac

Rubus cuneifolius b

Rubus trivialis b

Rudbeckia hirta

Sand blackberry

Southern dewberry

Blackeyed Susan

Ruellia caroliniensis Carolina wild petunia

Amelanchier arborea b

Salvia lyrata

Common serviceberry

Lyreleaf sage

Salvia urticifolia Nettleleaf sage

Sanguinaria canadensis Bloodroot

Sanicula canadensis Canada sanicle, Canadian blacksnakeroot

Sanicula smallii Small's blacksnakeroot

Sassafras albidum Sassafras

Scrophularia marilandica Carpenter's square, maryland figwort

Selaginella apoda Meadow spike-moss, meadow spike-moss

Silene stellata Whorled catchfly, widowsfrill

Silene virginica Fire pink, firepink

Silphium asteriscus Starry rosinweed

Silphium asteriscus var. laevicaule m

Starry rosinweed

Silphium compositum Kidneyleaf rosinweed

Sisyrinchium fuscatum Coastalplain blue-eyed grass

Smallanthus uvedalius Hairy leafcup
220

Scientific Name Common Name(s)

Solanum carolinense Apple of Sodom, bull nettle, Carolina horsenettle

Solidago caesia Wreath goldenrod

Solidago nemoralis Dyersweed goldenrod, gray goldenrod

Specularia perfoliata Clasping Venus' looking-glass

Spigelia marilandica Indianpink, woodland pinkroot

Spiranthes cernua Nodding ladiestresses, nodding ladies'-tresses, white nodding ladies'-

tresses

Sporobolus indicus var. indicus n1Smut grass1

Stylosanthes biflora Endbeak pencilflower, sidebeak pencilflower

Symphyotrichum divaricatum Southern annual saltmarsh aster

Taraxacum officinale1 Blowball, common dandelion, dandelion1

Tephrosia virginiana Virginia tephrosia

Thalictrum thalictroides o Rue anemone

Thelypteris noveboracensis New York fern

Tilia americana var. heterophylla p

American basswood

Tillandsia usneoides Spanish moss

Tipularia discolor Crippled cranefly

Toxicodendron pubescens Atlantic poison oak, poison oak

Tradescantia radicans Poison ivy

Tradescantia virginiana Virginia spiderwort

Tridens flavus Purpletop, purpletop tridens

Trifolium campestre1

Field (Big-hop) clover, field clover, large hop clover1

Trifolium repens1 Dutch clover, ladino clover, white clover1

Trillium catesbaei Bashful wakerobin

Trillium cuneatum Little sweet Betsy

Trillium underwoodii Longbract wakerobin

Uvularia perfoliata Perfoliate bellwort

Vaccinium arboreum Farkleberry, tree sparkleberry, tree-huckelberry

Vaccinium pallidum Blue Ridge blueberry, Blueridge blueberry

Vaccinium stamineum Deerberry

Verbascum Thapsus1 Common mullein, big taper, flannel mullein1

Viburnum rufidulum b

Viola pedata

Rusty blackhaw

Birdfoot violet

Viola tripartita

q

Threepart violet

Yucca filamentosa Adam’s needle

a Acer barbatum is given as Acer saccharinum var. floridanum (synonym) in the NPS Certified Species List.

b

Newly reported for Horseshoe Bend by Heath et al. (2014a,b).cChamaecrista nictitans ssp. nictitans var. 

nictitans is given as Cassia nictitans (synonym) in the NPS Certified Species List.

d

Conyza canadensis var. canadensis is given as Erigeron canadensis (synonym) in the NPS Certified Species 

List.

e Glechoma hederacea is misspelled as Glecoma hederacea in the NPS Certified Species List.
221

f

Hepatica nobilis var. acuta is given as Hepatica acutiloba (synonym) in the NPS Certified Species List.

g

Hepatica nobilis var. obtusa is given as Hepatica americana (synonym) in the NPS Certified Species List.

h Maianthemum racemosum ssp. racemosum is given as Smilacina racemosa (synonym) in the NPS Certified 

Species List.

I Monotropa hypopithys is given as Hypopitys monotropa (synonym) in Heath et al. (2014b).j Orbexilum 

pedunculatum var. psoralioides is given as Psoralea psoralioides (synonym) in the NPS Certified Species List.

k

Pityopsis graminifolia var. graminifolia is given as Heterotheca graminifolia (synonym) in the NPS Certified 

Species List.

l

Pleopeltis polypodioides ssp. polypodioides is given as Polypodium polypodioides (synonym) in the NPS 

Certified Species List.

m

Silphium asteriscus var. laevicaule is given as Silphium dentatum (synonym) in the NPS Certified Species List.

n

Sporobolus indicus var. indicus is given as Sporobolus poiretii (synonym) in the NPS Certified Species List.

o

Described by Heath et al. (2014b) as newly reported for Horseshoe Bend; was included in the NPS Certified 

Species List as of (NPS 2013a).pTilia americana var. heterophylla is given as Tilia heterophylla (synonym) in the 

NPS Certified Species List.

q

Viola tripartita is given as Viola tripartita var. glaberrima (synonym) in the NPS Certified Species List.

j Pleopeltis polypodioides ssp. polypodioides is given as Polypodium polypodioides (synonym) in the 

NPS Certified Species List.

k Silphium asteriscus var. laevicaule is given as Silphium dentatum (synonym) in the NPS Certified 

Species List.

l

Sporobolus indicus var. indicus is given as Sporobolus poiretii (synonym) in the NPS Certified 

Species List.

m

Tilia americana var. heterophylla is given as Tilia heterophylla (synonym) in the NPS Certified 

Species List.

n

Viola tripartita is given as Viola tripartita var. glaberrima (synonym) in the NPS Certified Species 

List.
222

Table A2-2. Wetland vascular plant taxa in HOBE, modified from the NPS Certified Species List (2013a) 

with some taxonomic changes according to the USDA Plants Database (http://plants.usda.gov/java/, last 

accessed in September 2013). Exotic/invasive species (in bold)1are taken from the same information 

used to compile exotic/invasive taxa in Table A2-1.

Scientific Name Common Name(s)

Acalypha gracilensa

Acer negundo

Slender threeseed mercury

Ashleaf maple, box elder, boxelder

Acer rubrum Red maple

Acer saccharinumb

Silver maple

Agalinis fasciculata Beach false foxglove

Agrimonia parviflora Harvestlice, manyflowered groovebur, southern agrimony, swamp 

agrimony 

Alnus serrulata Alder, brook-side alder, hazel alder

Amianthium muscitoxicum Flypoison

Amorpha fruticosa Desert false indigo, desert indigobush, dullleaf indigo

Andropogon virginicus Broomsedge, broomsedge bluestem, yellow bluestem

Apios americana Apios americana, groundnut, potatobean

Aralia spinosa Angelicatree, devils walkingstick, devil's walkingstick

Arisaema dracontium Green dragon, greendragon

Arisaema triphyllum Indian jack in the pulpit, Jack in the pulpit, Jack in the pulpit

Aristolochia tomentosa Common dutchmanspipe, woolly dutchman's pipe

Arundinaria gigantea Giant cane

Aster lateriflorus Calico aster

Athyrium filix-femina ssp. asplenioides c

Asplenium ladyfern

Betula nigra River birch

Bignonia capreolata Cross vine, crossvine

Boehmeria cylindrica Smallspike false nettle, smallspike false nettle, smallspike falsenettle

Calycocarpum lyonii Cupseed, sasparilla

Campsis radicans Common trumpetcreeper, cow-itch, trumpet creeper

Carex festucacea Fescue sedge

Carex granularis Limestone meadow sedge, limestone meadow sedge

Carex intumescens Greater bladder sedge

Carex leptalea Bristlestalked sedge, bristly-stalk sedge, bristlystalked sedge

Carex lurida Shallow sedge

Carex vulpinoidea Common fox sedge, fox sedge

Carpinus caroliniana American hornbeam, American hornbean

Carya cordiformis Bitternut hickory

Carya glabra Pignut hickory

Carya illinoinensis1 Pecan1

Catalpa bignonioides Southern catalpa

Cephalanthus occidentalis Buttonbush, common buttonbush

Chaerophyllum tainturieri Chervil, hairyfruit chervil, hairyfruit chervil

Chasmanthium latifolium Broadleaf uniola, Indian woodoats, Indian woodoats
223

Scientific Name Common Name(s)

Chasmanthium sessiliflorum Longleaf spikegrass, longleaf woodoats

Chionanthus virginicus Fringetree, white fringetree

Cicuta maculata Common water hemlock, poison parsnip, spotted cowbane

Cirsium horridulum var. horridulum d

Yellow thistle

Clematis glaucophylla Whiteleaf leather flower

Clematis virginiana Devil's darning needles, devil's-darning-needles, Virginia bower

Cocculus carolinus1 Carolina coralbead, Carolina snailseed, redberry moonseed1

Collinsonia canadensis Richweed

Commelina virginica Virginia dayflower

Conoclinium coelestinum Blue mistflower

Cornus amomum Silky dogwood

Cornus foemina Stiff dogwood

Crataegus spathulata Littlehip hawthorn

Cryptotaenia canadensis Canadian honewort, honewort

Cuscuta compacta Compact dodder

Cuscuta gronovii Scaldweed

Cyclospermum leptophyllum Marsh parsley

Cynanchum laeve Climbing milkweed, honeyvine, honeyvine milkweed

Cyperus echinatus Globe flatsedge+B101

Cyperus refractus Reflexed flatsedge

Cyperus strigosus Stawcolored flatsedge, strawcolor flatsedge, strawcolor nutgrass

Decumaria barbara Woodvamp

Dichondra carolinensis a

Diodia teres

Carolina ponysfoot

Poor Joe, poorjoe, rough buttonweed

Diodia virginiana Virginia buttonweed

Dioscorea villosa Wild yam

Diospyros virginiana Common persimmon, eastern persimmon, Persimmon

Dulichium arundinaceum a

Eleocharis obtusa

Three-way sedge

Blunt spikerush, blunt spikesedge

Elephantopus carolinianus Carolina elephantsfoot, leafy elephantfoot

Elymus virginicus Virginia wild rye, Virginia wildrye

Erechtites hieraciifolia American burnweed

Erigeron philadelphicus Philadelphia daisy, Philadelphia fleabane

Eryngium prostratum Creeping eryngo

Eryngium yuccifolium Button eryngo, button snakeroot, Yuccaleaf eryngo

Eupatorium capillifolium Dogfennel

Eupatorium serotinum Late eupatorium, lateflowering thoroughwort

Eutrochium fistulosume

Trumpetweed

Eutrochium purpureumf

Sweetscented joe pye weed

Fraxinus pennsylvanica Green ash

Galium aparine Stickywilly, bedstraw, catchweed bedstraw, cleavers
224

Scientific Name Common Name(s)

Gaylussacia dumosa Dwarf huckleberry

Gelsemium sempervirens Carolina jessamine, evening trumpetflower

Geum canadense White avens

Gleditsia triacanthos Common honeylocust, Honey locust, honeylocust

Halesia diptera Two-wing silverbell, two-wing silverbell

Hamamelis virginiana American witchhazel, witchhazel, witchhazel

Helianthus angustifolius Swamp sneezeweed, swamp sunflower

Heliotropium indicum1

India heliotrope, Indian heliotrope1

Hibiscus moscheutos Crimsoneyed rosemallow, swamp rosemallow

Houstonia caerulea Azure bluet

Hydrocotyle verticillata Whorled marsh pennywort, whorled marshpennywort, whorled 

pennyroyal

Hymenocallis caroliniana* Carolina spiderlily, shoals spiderlily*

Hypericum drummondii Drummond St. Johnswort, nits and lice

Hypericum hypericoides St. Andrews cross, St. Andrew's cross

Hypericum mutilum Dwarf St. Johnswort

Hypericum punctatum Spotted St. Johnswort

Hypoxis hirsuta Common goldstar, eastern yellow star-grass

Ilex decidua Possumhaw

Ilex opaca American holly

Ilex vomitoria Yaupon

Ipomoea hederacea1

Ivyleaf morningglory, entireleaf morningglory, ivyleaf morningglory1

Ipomoea pandurata Bigroot morningglory, bigroot morninglory, man of the earth

Itea virginica Virginia sweetspire

Juncus coriaceus Leathery rush

Juncus effusus Common rush, lamp rush

Juncus validus Roundhead rush

Justicia americana American water-willow, common water-willow, spike justica

Krigia dandelion Potato dwarfdandelion, tuber dandelion, tuber dwarfdandelion

Laportea canadensis Canada lettuce, Canada woodnettle, Canadian woodnettle

Ligustrum sinense1 Chinese privet, common Chinese privet1

Lilium michauxii Carolina lily

Lindera benzoin a

Liquidambar styraciflua

Northern spicebush

Sweetgum

Liriodendron tulipifera Tulip poplar, tuliptree, yellow poplar

Lobelia cardinalis Cardinal flower, cardinalflower

Lobelia puberula Downy lobelia

Lonicera japonica1

Japanese honeysuckle, Chinese honeysuckle1

Lonicera sempervirens Trumpet honeysuckle

Ludwigia palustris Marsh primrose-willow, marsh seedbox

Lycopus virginicus Virginia bugleweed, Virginia bugleweed, Virginia water horehound
225

Scientific Name Common Name(s)

Lysimachia ciliata Fringed loosestrife, fringed yellow-loosestrife

Magnolia grandiflora1 Southern magnolia1

Magnolia virginiana Sweetbay

Malaxis unifolia Green addersmouth orchid, green adder's-mouth orchid

Matelea gonocarpos Angularfruit milkvine

Medeola virginiana Indian cucumber

Melothria pendula

Microstegium vimineum a1

Drooping melonnettle, Guadeloupe cucumber

Japanese stiltgrass, Nepalese browntop1

Mikania scandens Climbing hempvine, climbing hempweed

Mimulus alatus Sharpwing monkeyflower

Mimulus ringens Allegheny monkeyflower, Allegheny monkeyflower, ringen monkeyflower

Mitchella repens Partridgeberry

Morus rubra Red mulberry

Nyssa sylvatica Black gum, black tupelo, blackgum

Onoclea sensibilis Sensitive fern

Ophioglossum petiolatum a

Osmunda cinnamomea

Longstem adderstongue

Cinnamon fern

Osmunda regalis Royal fern

Oxydendrum arboreum Sourwood

Packera glabella Butterweed

Paspalum dilatatum1 Dallas grass, dallis grass, dallisgrass1

Pedicularis canadensis Canadian lousewort, early lousewort+B41

Peltandra virginica Green arrow arum, Virginia peltandra

Penstemon laevigatus Eastern smooth beardtongue

Penthorum sedoides Ditch stonecrop, ditc+B41h-stonecrop, Virginia penthorum

Physalis angulata Cutleaf groundcherry, cutleaf groundcherry, lanceleaf groundcherry

Physostegia virginiana ssp. virginiana g Obedient plant

Phytolacca americana American pokeweed, common pokeweed, inkberry

Plantago rugelii Blackseed plantain, blackseed plantain, Rugel's plantain

Platanthera clavellata Green woodland orchid, small green wood orchid

Platanthera cristata Crested yellow orchid

Platanthera flava var. flava h

Palegreen orchid

Platanus occidentalis American sycamore, sycamore

Pluchea camphorata Camphor pluchea, camphor weed

Poa sylvestris Woodland bluegrass

Polygonum caespitosum var. 

longisetum1

Oriental ladysthumb1

Polygonum punctatum Dotted smartweed

Polygonum virginianum Jumpseed, Virginia smartweed

Polypremum procumbens Juniper leaf

Pontederia cordata Pickerelweed
226

Scientific Name Common Name(s)

Populus deltoides Common cottonwood, cottonwood, eastern cottonwood

Prunella vulgaris1 Common selfheal, heal all, healall1

Quercus laurifolia Laurel oak

Quercus michauxii Swamp chestnut oak

Quercus nigra Water oak

Quercus phellos Willow oak

Quercus prinus Chestnut oak

Ranunculus hispidus Bristly buttercup

Ranunculus recurvatus Blisterwort, littleleaf buttercup

Rhexia mariana Maryland meadowbeauty

Rhexia virginica Common meadowbeauty, handsome Harry

Rhododendron canescens Mountain azalea, Piedmont azalea

Rubus argutus a

Rudbeckia fulgida

Sawtooth blackberry

Orange coneflower

Rudbeckia laciniata Cutleaf coneflower, green-head coneflower

Rumex acetosella1 Red sorrel, sheep sorrel, common sheep sorrel, field sorrel1

Rumex crispus1 Curley dock, curly dock, narrowleaf dock1

Sabatia angularis Rosepink, squarestem rosegentian

Saccharum giganteum a

Sagittaria latifolia

Sugarcane plumegrass

Broadleaf arrowhead, common arrowhead, duck-potato

Salix nigra Black willow

Sambucus canadensis American elder

Saururus cernuus Lizards tail, lizard's tail

Schoenoplectus purshianus Weakstalk bulrush

Scirpus cyperinus Bulrush, woolgrass

Scleria triglomerata a

Scutellaria integrifolia

Whip nutrush

Helmet flower

Scutellaria lateriflora Blue skullcap, mad dog skullcap

Sicyos angulatus Blue-eyedgrass, bur cucumber, burcucumber

Sisyrinchium mucronatum Needletip blue-eyed grass, needletip blue-eyed-grass

Smilax bona-nox Saw greenbrier

Smilax glauca Cat greenbrier

Smilax rotundifolia Bullbriar, common catbriar, common greenbrier

Smilax smallii Lanceleaf greenbrier, small greenbrier

Solidago rugosa Wrinkleleaf goldenrod

Sorghum halepense1 Aleppo milletgrass, herbe de Cuba, Johnson grass1

Sparganium americanum American burreed, American burreed

Staphylea trifolia American bladdernut, American bladdernut

Stenanthium gramineum Eastern featherbells

Styrax americanus American snowbell, snowbell

Symphyotrichum racemosum Smooth white oldfield aster
227

Scientific Name Common Name(s)

Symplocos tinctoria a

Teucrium canadense

Common sweetleaf

American germander, Canada germander, Candad germander

Thalictrum revolutum Waxyleaf meadowrue, waxyleaf meadowrue

Tiarella cordifolia Heartleaf foamflower

Toxicodendron radicans Eastern poison ivy, poison ivy, poisonivy

Trachelospermum difforme a,i

Tradescantia ohiensis

Climbing dogbane

Bluejacket, Ohio spiderwort 

Typha latifolia Broadleaf cattail, cattail, common cattail

Ulmus alata Winged elm

Ulmus americana American elm

Ulmus rubra Slippery elm

Uvularia sessilifolia Sessileleaf bellwort, sessileleaf bellwort

Vaccinium elliottii Elliott's blueberry

Valerianella radiata Beaked cornsalad

Verbena bonariensis1

Tall vervain, pretty verbena, purpletop vervain1

Verbesina alternifolia Wingstem

Verbesina occidentalis Yellow crownbeard

Verbesina virginica Iceweed, Virginia crownbeard, white crownbeard

Vernonia gigantea ssp. gigantea j Giant ironweed

Viburnum nudum a

Vitis baileyana

Possumhaw

Graybark grape

Vitis rotundifolia1 Muscadine, muscadine grape1

Woodwardia areolata Chainfern, netted chainfern

Xanthorhiza simplicissima Yellowroot

Zephyranthes atamasca Atamasco lily

a Newly reported for Horseshoe Bend by Heath et al. (2014).

b Described by Heath et al. (2014a) as newly reported for Horseshoe Bend; was included in the NPS Certified 

Species List as of NPS (2013a).

c

Athryium filix-femina ssp. asplenioides is given as Athyrium asplenioides (synonym) in the NPS Certified 

Species List.

d

Cirsium horridulum var. horridulum is given as Carduus spinosissimus (synonym) in the NPS Certified Species 

List.

e

Eutrochium fistulosum is given as Eupatorium fistulosum (synonym) in the NPS Certified Species List.

f

Eutrochium purpureum is given as Eupatorium purpureum (synonym) in the NPS Certified Species List.

g

Physostegia virginiana ssp. virginiana is given as Dracocephalum virginianum (synonym) in the NPS Certified 

Species List.

h Platanthera flava var. flava is given as Habenaria flava (synonym) in the NPS Certified Species List.

i

Trachelospermum difforme is given as Thyrsanthella difformis (synonym) in Heath et al. (2014b).iVeronia gigantea

ssp. gigantea is given as Veronia altissima (synonym) in the NPS Certified Species List.
228

Table A2-3. Aquatic vascular plant taxa reported to occur in Horseshoe Bend National Military Park 

(HOBE), based on the NPS Certified Species List (2013a).

Scientific Name Common Name

Brasenia schreberi Schreber watershield, watershield

Podostemum ceratophyllum Hornleaf riverweed, threadfoot

Polygonum coccineum Longroot smartweed
229

Table A2-4. List of all exotic/ invasive (non-native) species of vascular plants in HOBE, highlighting 

inclusion (in bold) on the Top Ten Alabama Worst Invasive Plants list (see http://www.seeppc.org/pubs/alabama.pdf). These websites were all last accessed in May 2015.

Group Scientific Name Common Name

Terrestrial Plants (23) Albizia julibrissin Mimosa, mimosa tree, powderpuff tree

Cerastium glomeratum Sticky chickweed

Cynodon dactylon Bermudagrass, chiendent pied-de-poule, 

common bermudagrass

Daucus carota Bird's nest, Queen Anne's lace, wild carrot

Dioscorea oppositifolia Chinese yam

Duchesnea indica India mockstrawberry, Indian strawberry

Eleusine indica Goosegrass, crowsfoot grass, goose grass

Glechoma hederacea Ground ivy

Helenium amarum Sneezeweed, bitter sneezeweed, yellowdicks

Lamium amplexicaule Henbit, common henbit, giraffehead

Lespedeza cuneata Chinese lespedeza, sericea lespedeza

Melia azedarach Chinaberry, Chinaberry tree, Chinaberrytree

Opuntia ficus-indica Indian fig, Indian fig, tuna cactus

Paspalum notatum var. saurae Bahiagrass

Plantago aristata Bottlebrush Indianwheat, largebracted plantain

Plantago lanceolata Narrowleaf plantain, buckhorn plantain, English 

plantain, lanceleaf Indianwheat

Prunus mexicana Mexican plum

Pueraria montana var. lobata Kudzu, kudzu vine 

Sporobolus indicus var. indicus Smut grass

Taraxacum officinale Blowball, common dandelion, dandelion

Trifolium campestre Field (Big-hop) clover, field clover, large hop 

clover

Trifolium repens Dutch clover, ladino clover, white clover

Verbascum thapsus Common mullein, big taper, flannel mullein

Wetland Plants (16) Carya illinoinensis Pecan

Cocculus carolinus Carolina coralbead, Carolina snailseed, redberry 

moonseed

Heliotropium indicum India heliotrope, Indian heliotrope

Ipomoea hederacea Ivyleaf morningglory, entireleaf morningglory, 

ivyleaf morningglory

Ligustrum sinense Chinese privet, common Chinese privet

Lonicera japonica Japanese honeysuckle, Chinese honeysuckle

Magnolia grandiflora Southern magnolia

Microstegium vimineum Japanese stiltgrass, Nepalese browntop

Paspalum dilatatum Dallas grass, dallis grass, dallisgrass
230

Group Scientific Name Common Name

Polygonum caespitosum var. 

longisetum

Oriental ladysthumb

Prunella vulgaris Common selfheal, heal all, healall

Rumex acetosella Red sorrel, sheep sorrel, common sheep sorrel, 

field sorrel

Rumex crispus Curley dock, curly dock, narrowleaf dock

Sorghum halepense Aleppo milletgrass, herbe de Cuba, Johnson 

grass

Verbena bonariensis Tall vervain, pretty verbena, purpletop vervain

Vitis rotundifolia Muscadine, muscadine grape
231

Table A2-5. Fish species reported to occur in Horseshoe Bend National Military Park (HOBE), from the 

NPS Certified Species List (2013a). The exotic/invasive species is indicated in bold and the SoC is in 

blue*.

Scientific Name Common Name

Ameiurus nebulosus Brown bullhead

Campostoma anomalum Central stoneroller

Chaenobryttus gulosus Warmouth

Cottus carolinae Banded sculpin

Cyprinella callistia Alabama shiner

Cyprinus carpio Common carp

Etheostoma stigmaeum Speckled darter

Fundulus olivaceus Blackspotted topminnow

Gambusia affinis Western mosquitofish

Ichthyomyzon gagei Southern brook lamprey

Ictalurus punctatus Channel catfish

Lepomis cyanellus Green sunfish

Lepomis macrochirus Bluegill

Luxilus chrysocephalus Striped shiner

Lythrurus bellus Pretty shiner

Micropterus coosae Redeye bass

Micropterus punctulatus Spotted bass

Moxostoma erythrurum Golden redhorse

Moxostoma poecilurum* Blacktail redhorse*

Notemigonus crysoleucas Golden shiner

Notropis baileyi Rough shiner

Noturus leptacanthus Speckled madtom

Percina caprodes Logperch

Pomoxis annularis White crappie

Pylodictis olivaris Flathead catfish

Semotilus atromaculatus Creek chub
232

Table A2-6. Amphibian taxa reported to occur in HOBE, from the NPS Certified Species List (2013a).

Exotic/invasive amphibian species were not reported. One SoC is indicated in blue*.

Scientific Name Common Name(s)

Acris crepitans Northern cricket frog

Acris gryllus Southern cricket frog

Ambystoma maculatum Spotted salamander

Ambystoma opacum Marbled salamander

Ambystoma talpoideum Mole salamander

Bufo americanus American toad

Bufo fowleri Fowler's toad

Desmognathus conanti Spotted dusky salamander

Desmognathus fuscus Dusky salamander

Eurycea cirrigera Southern two-lined salamander

Eurycea guttolineata Three-lined salamander

Gastrophryne carolinensis Eastern narrowmouth toad, eastern narrow-mouthed toad

Gyrinophilus porphyriticus Spring salamander

Hyla avivoca Bird-voiced treefrog

Hyla chrysoscelis Cope's gray treefrog

Hyla cinerea Green treefrog

Hyla gratiosa Barking treefrog

Hyla squirella Squirrel treefrog

Hyla versicolor Gray treefrog

Notophthalmus viridescens Eastern newt

Plethodon glutinosus Northern slimy salamander, slimy salamander

Pseudacris brachyphona Mountain chorus frog

Pseudacris crucifer Spring peeper

Pseudacris feriarum Southeastern chorus frog, upland chorus frog

Pseudotriton montanus Mud salamander

Pseudotriton ruber Red salamander

Rana catesbeiana Bullfrog

Rana clamitans Green frog

Rana palustris Pickerel frog

Rana sphenocephala Southern leopard frog

Rana sylvatica* Wood frog*

Scaphiopus holbrookii Eastern spadefoot
233

Table A2-7. Reptilian taxa reported to occur in HOBE, based on the NPS Certified Species List (2013a).

Exotic/invasive species were not reported. Two SoCs are indicated in blue*.

Scientific Name Common Name(s)

Agkistrodon contortrix Copperhead

Agkistrodon contortrix contortrix Southern copperhead

Agkistrodon contortrix mokasen Northern copperhead

Agkistrodon piscivorus Cottonmouth

Anolis carolinensis Green anole

Apalone spinifera Spiny softshell, spiny softshell turtle

Apalone spinifera aspera Gulf coast spiny softshell

Carphophis amoenus Eastern worm snake, eastern wormsnake

Carphophis amoenus helenae Midwest worm snake

Chelydra serpentina Snapping turtle

Cnemidophorus sexlineatus Six-lined racerunner

Coluber constrictor Racer

Crotalus horridus Timber rattlesnake

Diadophis punctatus Ringneck snake

Elaphe obsoleta Rat snake, texas ratsnake

Elaphe obsoleta spiloides Gray rat snake

Eumeces egregius Mole skink

Eumeces fasciatus Five-lined skink

Eumeces inexpectatus Southeastern finelined skink

Eumeces laticeps Broadhead skink

Kinosternon subrubrum Eastwern mud turtle

Lampropeltis getula* Common kingsnake*

Masticophis flagellum* Coachwhip*

Nerodia erythrogaster Plainbelly water snake

Nerodia sipedon Northern water snake

Opheodrys aestivus Rough green snake

Pseudemys concinna River cooter

Regina septemvittata Queen snake

Sceloporus undulatus Fence/prairie/plateau lizard

Scincella lateralis Ground skink

Sternotherus minor Loggerhead musk turtle

Sternotherus odoratus Common musk turtle

Storeria dekayi Brown snake

Storeria occipitomaculata Redbelly snake

Tantilla coronata Southeastern crowned snake

Terrapene carolina Eastern box turtle
234

Scientific Name Common Name(s)

Thamnophis sirtalis Common garter snake

Trachemys scripta Slider

Virginia valeriae Smooth earth snake

Table A2-8. Bird taxa reported from HOBE, based on the NPS Certified Species List (2013a). An asterisk 

(*) is used to designated taxa associated with wetland/aquatic habitats; SoCs are indicated in blue1.

Scientific Name Common Name(s)

Accipiter cooperii Cooper's hawk

Actitis macularia * Spotted sandpiper

Agelaius phoeniceus * Red-winged blackbird

Aix sponsa * Wood duck

Anthus rubescens American pipit, buff-bellied pipit

Archilochus colubris Ruby-throated hummingbird

Ardea alba * Great egret

Ardea herodias * Great blue heron

Baeolophus bicolor Tufted titmouse

Bombycilla cedrorum Cedar waxwing

Bubo virginianus Great horned owl

Buteo jamaicensis Red-tailed hawk

Buteo lineatus Red-shouldered hawk

Buteo platypterus Broad-winged hawk

Butorides virescens * Green heron

Caprimulgus carolinensis Chuck-will's-willow

Cardinalis cardinalis Northern cardinal

Carduelis pinus Pine siskin

Carduelis tristis American goldfinch

Carpodacus mexicanus House finch

Carpodacus purpureus Purple finch

Cathartes aura Turkey vulture

Catharus fuscescens Veery

Catharus guttatus Hermit thrush

Ceryle alcyon * Belted kingfisher

Chaetura pelagica Chimney swift

Circus cyaneus Northern harrier

Coccothraustes vespertinus Evening grosbeak

Coccyzus americanus Yellow-billed cuckoo

Colaptes auratus Northern flicker

Colinus virginianus Northern bobwhite

Contopus virens Eastern wood-pewee

Coragyps atratus Black vulture
235

Scientific Name Common Name(s)

Corvus brachyrhynchos American crow

Corvus ossifragus * Fish crow

Cyanocitta cristata Blue jay

Dendroica coronata Yellow-rumped warbler

Dendroica discolor Prairie warbler

Dendroica dominica Yellow-throated warbler

Dendroica fusca Blackburnian warbler

Dendroica magnolia Magnolia warbler

Dendroica palmarum Palm warbler

Dendroica pensylvanica Chestnut-sided warbler

Dendroica petechia1

Yellow warbler1

Dendroica pinus Pine warbler

Dendroica virens Black-throated green warbler

Dryocopus pileatus Pileated woodpecker

Dumetella carolinensis Gray catbird

Egretta caerulea * Little blue heron

Empidonax minimus Least flycatcher

Empidonax virescens Acadian flycatcher

Euphagus carolinus Rusty blackbird

Falco sparverius1

American kestrel1

Gavia immer * Common loon

Geothlypis trichas Common yellowthroat

Guiraca caerulea Blue grosbeak

Helmitheros vermivorus Worm-eating warbler

Hirundo rustica Barn swallow

Hylocichla mustelina Wood thrush

Icteria virens Yellow-breasted chat

Icterus spurius Orchard oriole

Junco hyemalis Dark-eyed junco

Larus delawarensis * Ring-billed gull

Limnothlypis swainsonii Swainson's warbler+B30

Melanerpes carolinus Red-bellied woodpecker

Melanerpes erythrocephalus Red-headed woodpecker

Meleagris gallopavo Wild turkey

Melospiza melodia Song sparrow

Mimus polyglottos Northern mockingbird

Mniotilta varia Black-and-white warbler

Molothrus ater Brown-headed cowbird

Myiarchus crinitus Great crested flycatcher

Oporornis formosus Kentucky warbler

Otus asio Eastern screech-owl
236

Scientific Name Common Name(s)

Parula americana Northern parula

Passer domesticus House sparrow [added]

Passerella iliaca Fox sparrow

Passerina cyanea Indigo bunting

Petrochelidon pyrrhonota Cliff swallow

Pheucticus ludovicianus Rose-breasted grosbeak

Picoides pubescens Downy woodpecker

Picoides villosus Hairy woodpecker

Pipilo erythrophthalmus Eastern towhee, Rufous-sided towhee

Piranga olivacea Scarlet tanager

Piranga rubra Summer tanager

Poecile carolinensis Carolina chickadee

Polioptila caerulea Blue-gray gnatcatcher

Progne subis Purple martin

Protonotaria citrea Prothonotary warbler

Quiscalus quiscula Common grackle

Regulus calendula Ruby-crowned kinglet

Regulus satrapa Golden-crowned kinglet

Sayornis phoebe Eastern phoebe

Seiurus aurocapillus Ovenbird

Seiurus motacilla * Louisiana waterthrush

Seiurus noveboracensis * Northern waterthrush

Setophaga ruticilla American redstart

Sialia sialis Eastern bluebird

Sitta carolinensis White-breasted nuthatch

Sitta pusilla Brown-headed nuthatch

Sphyrapicus varius Yellow-bellied sapsucker

Spizella passerina Chipping sparrow

Spizella pusilla Field sparrow

Stelgidopteryx serripennis Northern rough-winged swallow

Strix varia Barred owl

Sturnella magna Eastern meadowlark

Sturnus vulgaris European starling

Thryothorus ludovicianus Carolina wren

Toxostoma rufum Brown thrasher

Troglodytes aedon House wren

Troglodytes troglodytes Winter wren

Turdus migratorius American robin

Tyrannus tyrannus Eastern kingbird

Vermivora celata Orange-crowned warbler

Vermivora ruficapilla Nashville warbler
237

Scientific Name Common Name(s)

Vireo flavifrons Yellow-throated vireo

Vireo griseus White-eyed vireo

Vireo olivaceus Red-eyed vireo

Vireo solitarius1

Blue-headed vireo, solitary vireo1

Wilsonia citrine Hooded warbler

Zenaida macroura Mourning dove

Zonotrichia albicollis White-throated sparrow
238

Table A2-9. Mammalian taxa reported from HOBE, based on the NPS Certified Species List (2013a).

Scientific Name Common Name

Blarina brevicauda Northern short-tailed shrew

Canis familiaris Feral dog

Canis latrans Coyote

Castor canadensis American beaver

Cryptotis parva Least shrew

Dasypus novemcinctus Nine-banded armadillo

Didelphis virginiana Virginia opossum

Felis catus Feral cat

Lasiurus borealis Eastern red bat

Lontra canadensis North American river otter, northern river otter

Lynx rufus Bobcat

Marmota monax Woodchuck

Mephitis mephitis Striped skunk

Microtus pinetorum Woodland vole

Neotoma floridana Eastern woodrat

Nycticeius humeralis Evening bat

Ochrotomys nuttalli Golden mouse

Odocoileus virginianus White-tailed deer

Ondatra zibethicus Muskrat, common muskrat

Oryzomys palustris Marsh rice rat

Peromyscus gossypinus Cotton mouse

Peromyscus leucopus White-footed mouse

Procyon lotor Common raccoon, northern raccoon

Reithrodontomys humulis Eastern harvest mouse

Scalopus aquaticus Eastern mole

Sciurus carolinensis Eastern gray squirrel

Sigmodon hispidus Hispid cotton rat

Sorex longirostris Southeastern shrew

Sylvilagus floridanus Eastern cottontail

Tamias striatus Eastern chipmunk

Urocyon cinereoargenteus Common gray fox

Vulpes vulpes Red fox

Additional Species Listed by Webster 

(2010) as Probably Present

Glaucomys volans Southern flying squirrel

Mus musculus House mouse

Mustela frenata Long-tailed weasel
239

Scientific Name Common Name

Neovison vison American mink

Rattus norvegicus Norway rat

Sylvilagus aquaticus Swamp rabbit

241

Appendix 3. Conservation Ranking Systems Used in 

Assessing Natural Resource Conditions

Table A3-1. Global conservation ranking system abbreviations.

Global 

Rank Definition

G1 Critically Imperiled - At very high risk of extinction due to extreme rarity (often 5 or fewer populations), 

very steep declines, or other factors.

G2 Imperiled - At high risk of extinction due to very restricted range, very few populations (often 20 or 

fewer), steep declines, or other factors.

G3 Vulnerable - At moderate risk of extinction due to a restricted range, relatively few populations (often 80 

or fewer), recent and widespread declines, or other factors.

G4 Apparently Secure - Uncommon but not rare; some cause for long-term concern due to declines or 

other factors.

G5 Secure - Common; widespread and abundant.

GX Presumed Extinct (species) - Not located despite intensive searches and virtually no likelihood of 

rediscovery. Eliminated (ecological communities) - Eliminated throughout its range, with no restoration 

potential due to extinction of dominant or characteristic species.

GH Of historical occurrence throughout its range. Possibly Extinct (species) - Missing; known from only 

historical occurrences but still some hope of rediscovery. Presumed Eliminated (historic, ecological 

communities) - Presumed eliminated throughout its range, with no or virtually no likelihood that it will be 

rediscovered, but with the potential for restoration (e.g. the American chestnut forest).

GU Unrankable - Currently unrankable due to lack of information or due to substantially conflicting 

information about status or trends.

GNR Not ranked to date.

G#T# Infraspecific Taxon (trinomial) - The status of infraspecific taxa (subspecies or varieties) is indicated by 

a "T-rank" following the global rank for the species. Rules for assigning T-ranks follow the same 

principles outlined above for global conservation status ranks. A T-rank cannot imply that the 

subspecies or variety is more abundant than the species as a whole (e.g. a G1T2 cannot occur). At this 

time, a T-rank is not used for ecological communities.

1 A conservation status rank may not be applicable for some species, including long-distance aerial 

and aquatic migrants, hybrids without conservation value, and non-native species or ecosystems, for 

several [unspecified] reasons.

2

A breeding status is only used for species that have distinct breeding and/or non-breeding 

populations in the state.
242

Table A3-2. State conservation ranking system abbreviations.

State 

Rank Definition

S1 Critically Imperiled - Critically imperiled in Alabama because of extreme rarity (5 or fewer occurrences of 

very few remaining individuals or acres) or because of some factor(s) making it especially vulnerable to 

extirpation from Alabama.

S2 Imperiled - Imperiled in the state because of rarity (6 to 20 occurrences or few remaining individuals or 

acres) or because of some factor(s) making it very vulnerable to extirpation from Alabama.

S3 Vulnerable - Rare or uncommon in Alabama (on the order of 21 to 100 occurrences).

S4 Apparently Secure - Apparently secure in Alabama, with many occurrences.

S5 Secure - Demonstrably secure in Alabama; common, widespread, and abundant in the state.

SX Presumed Extirpated - Species or community is believed to be extirpated from Alabama. Not located 

despite intensive searches of historical sites and other appropriate habitat, and virtually no likelihood that 

it will be rediscovered.

SH Historical (Possibly Extirpated) - Species or community occurred historically in Alabama, and there is 

some possibility that it may be rediscovered. Its presence may not have been verified in the past 20-40 

yr. A species or community could become SH without such a 20-40 yr delay if the only known occurrence 

in the state was destroyed or if it had been extensively and unsuccessfully sought. The SH rank is 

reserved for species or communities for which some effort has been made to relocate occurrences,

rather than simply using this status for all elements not known from verified extant occurrences.

SNR Unranked - State conservation status not yet assessed.

SNA A conservation status rank is not applicable because the species is not a suitable target for conservation 

activities in the state.1

SU Unrankable - Currently unrankable due to lack of information or due to substantially conflicting 

information about status or trends.

SE An exotic species established in Alabama.

1 A conservation status rank may not be applicable for some species, including long-distance aerial 

and aquatic migrants, hybrids without conservation value, and non-native species or ecosystems, for 

several [unspecified] reasons.

2

A breeding status is only used for species that have distinct breeding and/or non-breeding 

populations in the state.
243

Table A3-3. Variant ranks and rank modifiers as applied to Global and State conservation ranking 

system abbreviations.

Rank 

Variants & 

Modifiers Definition

G#G# Range Rank - A numeric range rank is used to indicate the range of uncertainty in the status of a 

species or community (e.g. an element may be given a G-rank of G2G3, indicating global status is 

somewhere between imperiled and vulnerable). Ranges cannot skip more than one rank (e.g. GU 

should not be used rather than G1G4). Also applies to state ranks (e.g. S2S3).

HYB Hybrid

Q Questionable taxonomy - Taxonomic distinctive-ness of this entity at the current level is 

questionable; resolution of this uncertainty may result in a change from a species to a subspecies or 

hybrid, or to the inclusion of this taxon within another taxon, with the resulting taxon having a lower 

conservation priority.

? Inexact Numeric Rank - e.g. G2? .

1 A conservation status rank may not be applicable for some species, including long-distance aerial 

and aquatic migrants, hybrids without conservation value, and non-native species or ecosystems, for 

several [unspecified] reasons.

2

A breeding status is only used for species that have distinct breeding and/or non-breeding 

populations in the state.

Table A3-4. Breeding status qualifiers as applied to State conservation ranking system abbreviations.

Breeding Status Qualifiers2 

B Breeding - Conservation status refers to the breeding population of the species in the state. Regularly 

occurring, usually migratory and may be present only during the breeding season. 

N Non-breeding - Conservation status refers to the non-breeding population of the species in the state. 

Regularly occurring, usually migratory and may not breed in Alabama; this category includes migratory 

birds and bats in inland areas.

M Migrant species occurring regularly on migration at particular staging areas or concentration spots where 

the species might warrant conservation attention. Conservation status refers to the aggregating transient 

population of the species in the nation or state/province.

1 A conservation status rank may not be applicable for some species, including long-distance aerial 

and aquatic migrants, hybrids without conservation value, and non-native species or ecosystems, for 

several [unspecified] reasons.

2

A breeding status is only used for species that have distinct breeding and/or non-breeding 

populations in the state.

245

Appendix 4. Definitions of Federal and State Species Status 

(Alabama Natural Heritage Program 2012)

Federal designations

The U.S. Endangered Species Act (U.S. ESA), administered by the U.S. Fish and Wildlife Service 

for inland areas, is the major legislation providing federal legal protection to threatened and 

endangered species (http://endangered.fws.gov/). “Endangered” is defined as in danger of extinction 

within the foreseeable future throughout all or a significant portion of the species range. 

“Threatened” refers to a species that is likely to become endangered within the foreseeable future 

throughout all or a significant portion of its range.

LE - Listed Endangered: A species in danger of extinction throughout all or a significant portion of 

its range.

LT - Listed Threatened: A species likely to become endangered within the foreseeable future 

throughout all or a significant portion of its range.

PE - Proposed Endangered: A species proposed to be listed as endangered.

PT - Proposed Threatened: A species proposed to be listed as threatened.

PS - Partial Status: An infraspecific taxon or population has federal status but the entire species is in 

only a portion of the species range.

C - Candidate: A species under consideration for official listing for which there is sufficient 

information to support listing. The U.S. Fish and Wildlife Service encourages other agencies to give 

consideration to such taxa in environmental planning.

XN - Experimental Population, Non-essential: Experimental reintroduced population.

SC - Species of Concern: Species that has not been petitioned or been given Endangered, Threatened, 

or Candidate status, but has been identified as important to monitor.

UR - Under Review in the Candidate or Petition Process: A 90-day finding indicated that listing this 

species may be warranted, and a full status review has been initiated to determine if listing is 

warranted.

State status code designations

Alabama does not have a state law equivalent to the federal Endangered Species Act so species do 

not have regulatory protection as state endangered or threatened species. However, some species do 

receive regulatory protection through the Alabama Regulations on Game Fish and Fur Bearing 

Animals published annually. These are the primary regulations affording state protection for some 

species in Alabama, and are administered by the Alabama Department of Conservation and Natural 

Resources (ADCNR - Wildlife & Freshwater Fisheries Division - see 
246

http://www.outdooralabama.com/hunting/regulations/ or the Nongame Species Regulation - Section 

220-2-.92, at http://www.outdooralabama.com/watchable-wildlife/regulations/nongame.cfm).

SP – State Protected: Species protected by Regulation 220-2-.92 (Nongame Species Regulation, pp.

69-71 in the 2010-2011 Regulations), 220-2-.98 (Invertebrate Species Regulation, pp. 65-66), 220-2-

.26(4; Protection of Sturgeon, p. 40), 220-2-.94 (Prohibition of Taking or Possessing Paddlefish, p.

57), or 220-2-.97 (Alligator Protection Regulation, p. 72).

PSM – Partial Status Mussels: All mussel species not listed as a protected species under the 

Invertebrate Species Regulation are partially protected by other regulations of the Alabama Game, 

Fish, and Fur Bearing Animals Regulations. Regulation 220-2-.104 prohibits the commercial harvest 

of all but the 11 mussel species for which commercial harvest is legal.

RT – Regulated Turtle: Species for which the Turtle Catcher/Dealer/Farmer Regulation (Regulation 

220-2-.142) imposes a limit on the number which can be possessed or size limits.

GANOS – Game Animal - No Open Season: Species designated a game animal by Regulation 220-2-

.07, but for which there is no open season.

GA - Game Animal (Managed hunting regulations).

GB – Game Bird (Managed hunting regulations).

GBNOS – Game Bird - No Open Season: Species designated a game bird by Regulation 220-2-.04, 

but for which there is no open season.

GF - Game Fish (Managed Fishing Regulations):

GF-HP – Game Fish – Harvest Prohibited: Species designated a game fish by Regulation 220-2-.34, 

but harvest of the species in the state is prohibited.

CNGF - Commercial or Nongame Fish (Managed Fishing Regulations): Designated a commercial or 

nongame fish by Regulation 220-2-.45 of the Alabama Regulations on Game, Fish, and Fur Bearing 

Animals.
247

Appendix 5. “Shortcut” Programs in SAS to calculate GDD 

and PDSI

These two programs were written with assistance from the NCSU Statistics Department (Dr. 

Consuelo Arellano). Both programs use data requested and received from the Southeast Regional 

Climate Center (SERCC) located in Chapel Hill, NC (Mr. William Schmitz, Service 

Climatologist/Meteorologist).

The first program uses data called Growing Degree Days (GDD) and calculates the date where the 

1200 GDD threshold is reached. The computation involves finding the calendar date when the 1200 

GDD threshold is reached for each year in the dataset. This requires summing the monthly values 

until the sum is greater than 1200 and then calculating the slope of the line between that month and 

the month preceding to determine the exact date on which the 1200 would be achieved. Typically 

the value 1200 is achieved between April and May, but occasionally between March and April, or 

May and June, depending on temperature.

The second program uses Palmer Drought Severity Index data and ranks the severity of drought over 

seven classes ranging from severely dry to excessively wet. The computation involves calculating the 

proportion of the number of monthly observations in each drought class for every nine-year period.

In these programs for Chattahoochee National Recreation Area and the Network, the reference city 

has been set equal to Atlanta.

The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific 

and other information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and 

affiliated Island Communities.

NPS 407/128933, June 2015
National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

1201 Oakridge Drive, Suite 150

Fort Collins, CO 80525

www.nature.nps.gov

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