National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

Plant Community Composition and Structure 

Monitoring for Scotts Bluff National Monument 

2011-2015 Summary Report

Natural Resource Report NPS/NGPN/NRR—2016/1145
ON THIS PAGE

Photograph of riparian cottonwood forest at Scotts Bluff National Monument, 2014.

Photograph courtesy of the National Park Service.

ON THE COVER

Photograph of Scotts Bluff National Monument, 2015.

Photograph courtesy of the National Park Service.
Plant Community Composition and Structure 

Monitoring for Scotts Bluff National Monument 

2011-2015 Summary Report

Natural Resource Report NPS/NGPN/NRR—2016/1145

Isabel W. Ashton

Christopher J. Davis

National Park Service

Northern Great Plains Inventory & Monitoring Network

231 East St. Joseph Street

Rapid City, SD 57701

March 2016

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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This report is available in digital format from the Northern Great Plains Inventory & Monitoring 

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

Please cite this publication as:

Ashton, I. W. and C. J. Davis. 2016. Plant community composition and structure monitoring for

Scotts Bluff National Monument: 2011-2015 summary report. Natural Resource Report

NPS/NGPN/NRR—2016/1145. National Park Service, Fort Collins, Colorado.

NPS 317/131809, March 2016 
iii

Contents 

Page

Figures...................................................................................................................................................iv

Tables....................................................................................................................................................vi

Executive Summary.............................................................................................................................vii

Acknowledgments.................................................................................................................................ix

Introduction............................................................................................................................................1

Methods..................................................................................................................................................2

NGPN and NGPFire Monitoring Plots 2011-2015 ........................................................................2

Other Monitoring Plots (1997-2015)..............................................................................................5

Data Management and Analysis.....................................................................................................6

Reporting on Natural Resource Condition .....................................................................................7

Results and Discussion ..........................................................................................................................9

Status & Trends in Community Composition and Structure of SCBL Prairies .............................9

Species Richness, Diversity, and Evenness.............................................................................11

The Influence of Climate and Fire on Plant Community Structure and Diversity .......................13

Rare Plants....................................................................................................................................17

Golf Course Restoration Project...................................................................................................18

The Status of Riparian Forests in SCBL ......................................................................................20

Exotic Species in Riparian Forests..........................................................................................24

Conclusion ...........................................................................................................................................26

Literature Cited ....................................................................................................................................29

Appendix A: List of plant species found at SCBL 1998-2015 ............................................................32
iv

Figures 

Page

Figure 1. Map of Scotts Bluff National Monument (SCBL) plant community monitoring 

plots, 1997-2015 ....................................................................................................................................3

Figure 2. Long-term monitoring plot layout used for sampling vegetation in Scotts Bluff 

National Monument. ..............................................................................................................................4

Figure 3. The Northern Great Plains Inventory & Monitoring vegetation crew used pointintercept (left and center panel) and quadrats (right panel) to document plant diversity 

and abundance........................................................................................................................................4

Figure 4. Average cover by lifeform of native (green) and exotic (red) plants recorded in 

monitoring plots in Scotts Bluff National Monument (1998-2015) ......................................................9

Figure 5. The average absolute cover of the 10 most common native (green) and exotic 

(red) plants recorded at Scotts Bluff National Monument in 1998-2015.............................................10

Figure 6. Trends in the relative cover of annual bromes in Scotts Bluff National 

Monument from 1998-2015.................................................................................................................10

Figure 7. A photograph of long-term monitoring plot SCBL_FPCM_0039 which has a 

large diversity of native plant species..................................................................................................12

Figure 8. Trends in native species richness and evenness in Scotts Bluff National 

Monument, 1998-2015.........................................................................................................................12

Figure 9. The relationship between native species richness and the relative cover of 

annual bromes in long-term monitoring plots at Scotts Bluff National Monument, 1998-

2015......................................................................................................................................................13

Figure 10. The total annual precipitation anomaly from 1998-2015 for Scott Bluff 

National Monument .............................................................................................................................14

Figure 11. Map of recent fire history (polygons) and relative cover of annual bromes at 

long-term monitoring plots (red) at Scotts Bluff National Monument ................................................15

Figure 12. Native species richness and percent cover of annual bromes across plots with 

different fire histories...........................................................................................................................16

Figure 13. Photographs of two critically imperiled species in Nebraska found in plant 

community monitoring plots at Scotts Bluff National Monument. .....................................................17

Figure 14. Cheatgrass is the dominant species at the long-term monitoring plot, 

LPCM_13, at Scotts Bluff National Monument. .................................................................................19

Figure 15. Map of the plant community types within the riparian area in Scotts Bluff 

National Monument and the location of 20 long-term monitoring plots (yellow)...............................20

Figure 16. Diameter classes of cottonwood (Populus) and willow (Salix) trees in riparian 

forests along the North Platte River in Nebraska in the 1850-1880s...................................................22
v

Figures (continued)

Page

Figure 17. Size-class proportions of cottonwood (Populus) and willow (Salix) trees in 

riparian forests along the North Platte River in Nebraska in the 1850-1880s .....................................23

Figure 18. Perennial pepperweed, an invasive plant that threatens wetlands, marshes, and 

floodplains in the Western US .............................................................................................................25
vi

Tables 

Page

Table 1. Exotic species surveyed for at Scotts Bluff National Monument as part of the 

early detection and rapid response program within the Northern Great Plains Network. .....................5

Table 2. Definitions of state and global species conservation status ranks...........................................7

Table 3. Key to the symbols used in the Natural Resource Condition Table........................................8

Table 4. Average plant species richness in monitoring plots at Scotts Bluff National 

Monument from 1998 to 2015. ............................................................................................................11

Table 5. Rare species occurrence in Scotts Bluff National Monument from 1998-2015....................17

Table 6. Original seed mixture and composition of two restoration plots in Scotts Bluff 

National Monument in 2009, 2013, and 2014. ....................................................................................19

Table 7. Tree and tall shrub occurrence in 2014 at 20 plots in Scotts Bluff National 

Monument............................................................................................................................................21

Table 8. Tree basal area and density by size class for dominant tree and shrub species in 

the riparian forest of Scotts Bluff National Monument .......................................................................21

Table 9. Exotic species detected in 20 riparian plots in Scotts Bluff National Monument 

and their corresponding abundance, cover class, and estimated percent cover. ..................................24

Table 10. Natural resource condition summary table for plant communities in Scotts 

Bluff National Monument (SCBL). .....................................................................................................28
vii

Executive Summary

The Northern Great Plains Inventory & Monitoring Program and Fire Effects Program have been 

monitoring vegetation in Scotts Bluff National Monument for over 18 years. While methods have 

changed slightly, this report summarizes data from over 80 locations from 1998-2015. Below, we 

list the questions we asked using these data and provide a summarized answer. For more details see 

the full report. A summary of the current condition (2011-2015) and trends (based on 1988-2015) in 

plant communities at Scotts Bluff is found in Table ES-1 below. 

1. What is the current status of plant community composition and structure of SCBL 

grasslands (species richness, cover, and diversity) and how has this changed from 1998 to 

2015? 

SCBL plays a vital role in protecting and managing some of the last remnants of native mixedgrass prairie in the area. Native plant diversity is at a moderate level compared to other 

grasslands in the region (Table 10), but diversity is spatially variable. We found no significant 

trends in native diversity or evenness from 1998 to 2015, but both are threatened by the 

increasing cover of annual bromes (Figure 9). There has been an increase in annual brome 

abundance since the 1990s and continued control efforts will be necessary to maintain native 

prairie within SCBL. 

2. How do trends in grassland condition correlate with climate and fire history?

The large variability in SCBL’s climate makes it difficult to discern strong patterns linking 

temperature, precipitation, and plant community structure (e.g. exotic cover, diversity). Native 

diversity increased in plots with longer times since burning. There is an adaptive management 

program planned for 2017 which should provide better guidance to the park on the role of 

prescribed fire in managing annual bromes. 

3. What, if any, rare plants were found in SCBL long-term monitoring plots? 

We identified 35 rare plant species in SCBL between 1998 and 2015; eight of these are 

considered critically imperiled within Nebraska. These plants are found in such low abundance 

and in such few plots, it is unlikely that plant community monitoring will be able to detect any 

trends in rare plant abundance. We recommend more targeted surveys of rare plant species of 

concern be completed when funds are available. 

4. Was the SCBL golf course restoration effective at creating a grassland community 

dominated by native species?

The golf course restoration project had mixed results. While some native grasses were 

established in one of the monitoring plots, establishment was poor in the other. To improve the 

rates of success and the establishment of native species, future projects should include funds to 

cover invasive plant control for many years (~10) after planting.

5. What is the composition and structure of riparian forests at SCBL?

The riparian forest in SCBL is a fairly diverse assemblage of cottonwood, willow species, green 

ash, and box elder. Exotic grasses and forbs are common in the understory of the riparian forest, 
viii

and continuing control efforts will be necessary to prevent their spread. The large abundance of 

green ash and box elder seedlings suggests that a transition to ash-dominated forests is underway.

Table ES-1. Natural resource condition summary table for plant communities in Scotts Bluff National 

Monument (SCBL). Current values are based on data from 2011-2015 and trends are based on data from 

1998-2015.

Indicator of 

Condition

Specific 

Measures

Current

Value 

(mean ± SE)

Reference 

Condition 

and Data 

Source

Condition 

Status/Trend

Rationale for Resource 

Condition

Upland Plant 

Community 

Structure and 

Composition

Native species 

richness (1m2

quadrats) 

4.6 ± 0.3 

species

3-15 

species 

SCBL plays a vital role in 

protecting and managing some of 

the last remnants of native 

mixed-grass prairie in the region. 

The park is characterized by low 

native species richness, but 

average richness is within a 

natural range of variability

(Symstad and Jonas 2014). The 

lowest native diversity is found in 

the prairie dog town and former 

golf course. Native evenness has 

not changed since monitoring 

began in 1998. 

Evenness

(pointintercept 

transects)

0.67 ± 0.014 To be 

determined

Exotic Plant 

Early 

Detection and 

Management

Relative cover 

of exotic 

species 

41.2 ± 2.5% < 10 % 

cover

Many areas of SCBL have a high 

cover of exotic species. Annual 

bromes: cheatgrass and 

Japanese brome present the 

largest challenge to SCBL. Exotic 

cover and annual brome cover 

has shown an increasing trend 

since 1998. More research on 

effective management strategies 

is greatly needed.

Annual brome 

cover 

37.2 ± 2.3% < 10 % 

cover

Riparian 

Forest 

Plains 

cottonwood 

stand seral 

stage

Late seral 

stage

A mix of 

seral 

stages

The riparian forests of SCBL are 

currently a mosaic of areas 

dominated by willow, 

cottonwood, ash, and boxelder 

with an understory of many 

exotic plants. As cottonwood 

forests age in SCBL, green ash 

and box elder are likely to 

become more dominant. Only 2 

of 20 plots had evidence of 

young cottonwoods, but more 

than half the riparian forest in 

SCBL had large densities of 

other native tree and shrub. 

Forest surveys will be repeated 

every 5 years in SCBL and this 

will allow us to detect trends in 

condition. 

Percent of 20 

riparian plots 

with native 

deciduous 

seedlings

60% To be 

determined
ix

Acknowledgments 

We thank the authors of the NGPN Plant Community Monitoring Protocol, particularly A. Symstad, 

for outstanding guidance on data collection and reporting. Thank you to the staff at SCBL, 

particularly R. Manasek, for providing logistical support and performing safety checks. The NGPN

and NGPFire vegetation field crews collected all the data included in this report. We thank D. 

Swanson for providing data on fire history and A. Weaver for helping with the maps for this report.

Comments from R. Manasek, A. Symstad, D.Swanson, C. Thomsen, M. DeBacker, and T. FoltsZettner improved this manuscript. 
1

Introduction 

During the last century, much of the prairie within the Northern Great Plains has been plowed for 

cropland, planted with non-natives to maximize livestock production, or otherwise developed, 

making it one of the most threatened ecosystems in the United States. Within Nebraska, greater than 

77% of the area of native mixed grass prairie has been lost since European settlement (Samson and 

Knopf 1994). The National Park Service (NPS) plays an important role in preserving and restoring 

some of the last pieces of intact prairies within its boundaries. The stewardship goal of the NPS is to 

“preserve ecological integrity and cultural and historical authenticity” (NPS 2012); however, 

resource managers struggle with the grim reality that there have been fundamental changes in the 

disturbance regimes, such as climate, fire, and grazing by large, native herbivores, that have 

historically maintained prairies and there is the continual pressure of exotic invasive species. Longterm monitoring in national parks is essential to sound management of prairie landscapes because it 

can provide information on environmental quality and condition, benchmarks of ecological integrity, 

and early warning of declines in ecosystem health. 

Scotts Bluff National Monument (SCBL), established in 1919 to protect and preserve two iconic 

bluffs and the associated heritage of western expansion, covers 3,003 acres and is dominated by 

mixed-grass prairie with smaller areas of juniper woodlands, badlands, and riparian forests. 

Vegetation monitoring began at SCBL in 1997 by the Heartland Inventory & Monitoring Program 

(James 2010) and the Northern Great Plains Fire Ecology Program (NGPFire; Wienk et al. 2011). In 

2010, SCBL was incorporated into the Northern Great Plains Inventory & Monitoring Network 

(NGPN). At that time, vegetation monitoring protocols and plot locations were shifted to better 

represent the entire park and to coordinate efforts with NGPFire (Symstad et al. 2012b). A total of 34

plots were established by NGPFire and NGPN in SCBL and the combined sampling efforts began in 

2011 (Ashton et al. 2011). In 2014, an additional 20 plots were established in the riparian forest to 

assess forest condition. In this report, we use the data from 2011-2015 to assess the current condition 

of park vegetation and the data from 1998-2015 are used to look at longer-term trends. 

Using 18 years of plant community monitoring data in SCBL, we explore the following questions:

1. What is the current status of plant community composition and structure of SCBL grasslands

(species richness, exotic plant cover, and diversity) and how has this changed from 1998-

2015? 

2. How do trends in grassland condition correlate with climate and fire history?

3. What, if any, rare plants were found in SCBL long-term monitoring plots? 

4. Was the SCBL golf course restoration effective at creating a grassland community dominated 

by native species?

5. What is the composition and structure of riparian forests at SCBL?
2

Methods 

Three different methods and protocols have been used to monitor long-term vegetation plots at SCBL 

since 1997: the NGPN monitoring protocol (Symstad et al. 2012b, a), the Fire Monitoring Handbook

(NPS 2003), and the Heartland Vegetation Monitoring Protocol (James et al. 2009). Below, we 

briefly describe all three methods, but focus on the NGPN monitoring protocol, which is the current 

standard and was used to collect most of the data in this report. For more detail on any of the 

methods, please see the protocol publications (cited above). 

NGPN and NGPFire Monitoring Plots 2011-2015

The NGPN and NGPFire implemented a survey to monitor plant community structure and 

composition in SCBL using a spatially balanced probability design (Generalized Random 

Tessellation Stratified [GRTS]; Stevens and Olsen 2003, 2004). Using a GRTS design, NGPN 

selected 20 randomly located sites within the upland grasslands of SCBL to become Plant 

Community Monitoring plots (PCM plots; Figure 1). The NGPN visits 8 PCM plots every year using 

a rotating sampling scheme where 4 sites were visited in the previous year and 4 sites are new visits. 

After 5 years (2011-2015), most of the PCM plots were visited at least twice during the last two 

weeks of May. When a PCM plot fell within an active burn unit, NGPFire added additional visits 

based on a 1, 2, 5, and 10 year sampling schedule. NGPFire also established and monitored a number 

of new sites focused in active burn units (Fire FPCM plots) using the same GRTS sampling schema.

From 2011-2015, 14 FPCM plots were established. Finally, using the same set of random sites, 

NGPN selected 20 additional PCM plots that fell within the riparian forest along the North Platte 

River. These were monitored in 2014 to assess forest condition. A total of 34 plots were established 

by NGPFire and NGPN in 2011-2015. 

At each of the grassland sites we visited, we recorded plant species cover and frequency in a 

rectangular, 50 m x 20 m (0.1 ha), permanent plot (Figure 2). Data on ground cover and herb-layer (≤ 

2 m) height and plant cover were collected on two 50 m transects (the long sides of the plot) using a 

point-intercept method (Figure 3). At 100 locations along the transects (every 0.5 m) a pole was 

dropped to the ground and all species that touched the pole were recorded, along with ground cover, 

and the height of the canopy (Figure 3). Using this method, absolute canopy cover can be greater 

than 100% (particularly in wet years and productive sites) because we record multiple layers of 

plants. Species richness data from the point-intercept method were supplemented in the 20 NGPN 

plots with species presence data collected in five sets of nested square quadrats (0.01 m2

, 0.1 m2, 1 

m2

, and 10 m2) located systematically along each transect (Figure 2). 

When woody species were also present, tree regeneration and tall shrub density data were collected 

within a 10 m radius subplot centered in the larger 50 m x 20 m plot (Figure 2). Trees with diameter 

at breast height (DBH) > 15 cm, located within the entire 0.1 ha plot, were mapped and tagged. For 

each tree, the species, DBH, status, and condition (e.g., leaf-discoloration, insect-damaged, etc.) were 

recorded. This occurred at only 2 PCM plots in SCBL from 2011-2015. 
3

Figure 1. Map of Scotts Bluff National Monument (SCBL) plant community monitoring plots, 1997-2015. 

Twenty PCM plots (red) were established by the Northern Great Plains Inventory & Monitoring Program 

(NGPN) and 14 (blue) FPCM plots were established by the Fire Effects Program (NGPFire) between 

2011 and 2015. Eleven LPCM plots were established by the Heartland Monitoring Network (pink) 

representing restored and native mixed-grass prairie. In 2014, 20 plots were established by the NGPN to 

monitor riparian forest condition (yellow). An additional 19 FMH plots (green) were monitored from 1997-

2011 by NGPFire. 
4

Figure 2. Long-term monitoring plot layout used for sampling vegetation in Scotts Bluff National 

Monument.

Figure 3. The Northern Great Plains Inventory & Monitoring vegetation crew used point-intercept (left and 

center panel) and quadrats (right panel) to document plant diversity and abundance. 

NGPN completed a survey of riparian forests in SCBL in the last week of August 2014 using a set of 

20 forested sites. In this case, seedlings and poles were measured as described above, but larger trees 

(DBH >15cm) were not tagged and only measured within the 10 m radius subplot. Dead and downed 

woody fuel load data were collected at these forested plots on two perpendicular, 100 ft (30.49 m) 
5

transects with midpoints at the center of the plot (Figure 2), following Brown’s Line methods (Brown 

1974, Brown et al. 1982). These data were not reported because grasses dominated the fuel layer.

At all PCM plots, but not the FPCM plots, we also surveyed the area for common disturbances and 

target species of interest to the park. Common disturbances included such things as prairie dog 

towns, rodent mounds, animal trails, and fire. For all plots, the type and severity of the disturbances 

were recorded. We also surveyed the area for exotic species that have the potential to spread into the 

park and cause significant ecological impacts (Table 1). These species were chosen in collaboration 

with the Midwest Invasive Plant Network, the Exotic Plant Management Team, park managers, and 

local weed experts. For each target species that was present at a site, an abundance class was given 

on a scale from 1-5 where 1 = one individual, 2 = few individuals, 3 = cover of 1-5%, 4 = cover of 5-

25%, and 5 = cover > 25% of the plot. The information gathered from this procedure is critical for 

early detection and rapid response to such threats. 

Table 1. Exotic species surveyed for at Scotts Bluff National Monument as part of the early detection and 

rapid response program within the Northern Great Plains Network.

Scientific Name Common Name Habitat

Alliaria petiolata garlic mustard Riparian

Polygonum cuspidatum; P. sachalinense; P. x bohemicum knotweeds Riparian

Pueraria montana var. lobata kudzu Riparian

Iris pseudacorus yellow iris Riparian

Ailanthus altissima tree of heaven Riparian

Lepidium latifolium perennial pepperweed Riparian

Arundo donax giant reed Riparian

Rhamnus cathartica common buckthorn Riparian

Heracleum mantegazzianum giant hogweed Riparian

Centaurea solstitialis yellow star thistle Upland

Hieracium aurantiacum; H. caespitosum orange and meadow hawkweed Upland

Isatis tinctoria Dyer's woad Upland

Taeniatherum caput-medusae medusahead Upland

Chondrilla juncea rush skeletonweed Upland

Gypsophila paniculata baby's breath Upland

Centaurea virgata; C.diffusa knapweeds Upland

Linaria dalmatica; L. vulgaris toadflax Upland

Euphorbia myrsinites & E. cyparissias myrtle spurge Upland

Dipsacus fullonum & D. laciniatus common teasel Upland

Salvia aethiopis Mediterranean sage Upland

Ventenata dubia African wiregrass Upland

Other Monitoring Plots (1997-2015)

In 1997, NGPFire began monitoring plots within SCBL to evaluate the effectiveness of prescribed 

burns. Starting in 1998, data collection followed the NPS National Fire Ecology Program protocols 

(NPS 2003): in grassland plots vegetation cover and height data were collected using a pointintercept method, with 100 points evenly distributed along a single 30 m transect. In forested sites, 
6

plots are 0.1 ha (20 x 50 m) in size and point-intercept data were collected along the two 50 m sides.

For each live tree with a DBH > 15 cm located within the 0.1 ha plot, the species and DBH were 

recorded. The densities of smaller trees (2.54 cm ≤ DBH ≤ 15 cm) were measured within a subset of 

the plot area. NGPFire plot locations were located randomly within major vegetation types within 

areas planned for prescribed burning (burn units) in the near future. The plots were then sampled 1, 

2, 5, and 10 years after a prescribed burn. The data were not collected using these protocols in 1997 

and 2010, so these years were excluded from analyses. Hereafter, we refer to these plots as Fire 

Monitoring Handbook (FMH) plots. These FMH plots are being retired after the10 year visit (e.g. the 

rebar will be removed) and replaced with the FPCM plots described above. 

The Heartland Inventory & Monitoring Program also established a number of plots in 1997. Plant 

frequency was measured using circular subplots as described in the Heartland Networks’ vegetation 

monitoring protocol (James et al. 2009). The data and a summary of results from these plots are 

described in detail by James (2010). In 2009, 2013 and 2014, a subset of these plots (called Legacy 

Plant Community Monitoring Plots, LPCMs) was revisited by NGPN and point-intercept data was 

also collected using the methods described above. These plots were chosen to revisit because they 

were established to evaluate the effectiveness of a restoration project. In 1989, Scotts Bluff NM 

began a restoration project in a former golf course with a goal of restoring native prairie –these areas 

were planted with native grasses and forbs in 1997 (Huddle et al. 2001), two plots were established 

within the restored area (LPCM_13 and 14) and two plots were established nearby in native prairie 

(LPCM_11 and 12). In this report, we present the point-intercept from the 3 survey years, but do not 

report frequency.

Data Management and Analysis

We used FFI (FEAT/FIREMON Integrated; http://frames.gov/ffi/) as the primary software 

environment for managing our sampling data. FFI is used by a variety of agencies (e.g., NPS, USDA 

Forest Service, U.S. Fish and Wildlife Service), has a national-level support system, and generally 

conforms to the Natural Resource Database Template standards established by the Inventory and 

Monitoring Program. 

Species scientific names, codes, and common names are from the USDA Plants Database (USDANRCS 2015). However, nomenclature follows the Integrated Taxonomic Information System (ITIS) 

(http://www.itis.gov). In the few cases where ITIS recognizes a new name that was not in the USDA 

PLANTS database, the new name was used, and a unique plant code was assigned. This report uses 

common names after the first occurrence in the text, but scientific names can be found in Appendix 

A. 

After data for the sites were entered, 100% of records were verified to the original data sheet to 

minimize transcription errors. A further 10% of records were reviewed a second time. After all data 

were entered and verified, automated queries were used to check for errors in the data. When errors 

were caught by the crew or the automated queries, changes were made to the original datasheets 

and/or the FFI database as needed. Summaries were produced using the FFI reporting and query 

tools and statistical summaries, and graphics were generated using R software (version 3.2.2).
7

Plant life forms (e.g., shrub, forb) were based on definitions from the USDA Plants Database 

(USDA-NRCS 2015). The conservation status ranks of plant species in Nebraska is determined by 

the Nebraska Natural Heritage Program (NENHP). For the purpose of this report, a species was 

considered rare if its conservation status rank was S1, S2, or S3. See Table 2 for a detailed definition 

of each conservation status rank.

Table 2. Definitions of state and global species conservation status ranks*.

Status 

Rank Category Definition

S1/G1 Critically imperiled Due to extreme rarity (5 or fewer occurrences) or other factor(s) making it 

especially vulnerable to extirpation.

S2/G2 Imperiled Due to rarity resulting from a very restricted range, very few populations (often 20 

or fewer), steep declines, or other factors making it very vulnerable to extirpation.

S3/G3 Vulnerable Due to a restricted range, relatively few populations (often 80 or fewer), recent 

widespread declines, or other factors making it vulnerable to extirpation. 

S4/G4 Apparently secure Uncommon but not rare; some cause for concern due to declines or other factors.

S5/G5 Secure Common, widespread and abundant.

S#S#/

G#G#

Range rank

(e.g. S2S3)

Used to indicate uncertainty about the status of the species or community. 

Ranges cannot skip more than one rank.

* Adapted from NatureServe status assessment table (http://www.natureserve.org/conservationtools/conservation-status-assessment)

We measured diversity at the plots in two ways: species richness and Pielou’s Index of Evenness. 

Species richness is simply a count of the species recorded in an area. Peilou’s Index of Evenness, J’, 

measures how even abundances are across taxa. It ranges between 0 and 1; values near 0 indicate 

dominance by a single species and values near 1 indicate nearly equal abundance of all species 

present. Plant richness was calculated for each plot using the total number of species intersected 

along the transects. Average height was calculated as the average height per plot using all species 

intersected on the transects. 

Climate data from the Scottsbluff , Nebraska W.B. Heilig Field Airport weather station 

(GHCND:USW00024028) were downloaded from NOAA’s online database (NOAA 2015). Fire 

history maps were compiled for the park and cross-referenced with plot locations. For each time data 

were collected at a plot (i.e., plot visit), we determined the number of years since the plot had burned 

and the number of fires recorded for that plot. For plots where no burns were recorded, we calculated 

the difference between the year of data collection and the oldest fire recorded in the park. This is 

likely an underestimate of the true time since it burned because fires were infrequent prior to the 

1980s.

Reporting on Natural Resource Condition

Results were summarized in a Natural Resource Condition Table based on the templates from the 

State of the Park report series (http://www1.nrintra.nps.gov/im/stateoftheparks/index.cfm). The goal 

is to improve park priority setting and to synthesize and communicate complex park condition 

information to the public in a clear and simple way. By focusing on specific indicators, such as exotic 
8

species cover, it will also be possible and straightforward to revisit the metric in subsequent years. 

The status and trend of each indicator is scored and assigned a corresponding symbol based on the 

key found in Table 3.

We chose a set of indicators and specific measures that can describe the condition of vegetation in 

the Northern Great Plains and the status of exotic plant invasions. The measures include: absolute 

herb-layer canopy cover, native species richness, evenness, relative cover of exotic species, and 

annual brome cover. Reference values were based on descriptions of historic condition and variation, 

past studies, and/or management targets. Current park condition was compared to a reference value, 

and status was scored as good condition, warrants moderate concern, or warrants significant concern 

based on this comparison (Table 3). Good condition was applied to values that fell within the range 

of the reference value, and significant concern was applied to conditions that fell outside the bounds 

of the reference value. In some cases, reference conditions can be determined only after we have 

accumulated more years of data. When this is the case, we refer to these as “To be determined”, or 

TBD, and estimate condition based on our professional judgment.

Table 3. Key to the symbols used in the Natural Resource Condition Table. The background color 

represents the current status, the arrow summarizes the trend, and the thickness of the outside line 

represents the degree of confidence in the assessment. A symbol that does not contain an arrow 

indicates that there is insufficient information to assess a trend. Based on the State of the Park reports 

(http://www.nps.gov/stateoftheparks/).

Condition Status Trend in Condition

Confidence in 

Assessment

Warrants 

Significant Concern Condition is Improving High

Warrants 

Moderate Concern Condition is Unchanging Medium

Resource is in Good 

Condition Condition is Deteriorating Low
9

Results and Discussion

Status & Trends in Community Composition and Structure of SCBL Prairies

There are 515 plant species on the SCBL species list and we found 250 of these in monitoring plots

from 1998-2015 at SCBL (Appendix A). Graminoids, which includes grasses, sedges, and rushes, 

accounted for most of the vegetative cover at SCBL, but forbs, shrubs and subshrubs (defined as 

low-growing shrubs usually shorter than 0.5m) were also present (Figure 4). We found 40 exotic 

plant species at SCBL, all of which were forbs or graminoids. Exotic graminoids were particularly 

abundant (Figure 4). The shrubs and subshrubs were all native species.

Figure 4. Average cover by lifeform of native (green) and exotic (red) plants recorded in monitoring plots 

in Scotts Bluff National Monument (1998-2015). Absolute cover can be greater than 100% because the 

point-intercept methods records layers of overlapping vegetation. 

Western wheatgrass (Pascopyrum smithii), needle and thread (Heterostipa comata), and threadleaf 

sedge (Carex filifolia) were the most abundant native graminoids and averaged between 15 and 30% 

absolute cover (Figure 5). Cheatgrass (Bromus tectorum) and Japanese brome (B. japonicus) were the 

most pervasive exotics at SCBL. Cheatgrass and Japanese brome are both Eurasian, annual grasses 

that have been a part of the NGP landscape for more than a century, but their invasion in the region 

has accelerated since 1950 (Schachner et al. 2008). The presence of annual bromes in mixed grass 

prairie is associated with decreased productivity and altered nutrient cycling (Ogle et al. 2003). There 

is strong evidence from regions further west that cheatgrass alters fire regimes and the persistence of 

native species (D'Antonio and Vitousek 2003). Our data suggest that the cover of annual bromes has 

been increasing over time (R2

=0.19, F1,121 =36.5 P<0.001; Figure 6). From 1998 to 2015, the average 

relative cover of annual bromes was 27.5 ± 1.8% (mean ± standard error), but the average for the last 

5 years was 37.2 ± 2.3%. While there are many other exotic plants within SCBL, they contribute 

relatively little to cover. The average cover of all exotic species in 2011-2015 was 41.2 ± 2.5 %, 

meaning that over 90% of exotic cover is annual bromes. Clearly, reducing the cover of annual 

bromes presents a major challenge for the park, as it has been for the past 15 years. We are currently 

studying the temporal and spatial abundance of annual bromes in greater depth with a goal of using 

data to help guide management actions.
10

Figure 5. The average absolute cover of the 10 most common native (green) and exotic (red) plants 

recorded at Scotts Bluff National Monument in 1998-2015. Bars represent means ± one standard error.

Figure 6. Trends in the relative cover of annual bromes in Scotts Bluff National Monument from 1998-

2015. Points represent mean ± one standard errors and sample size is to the right of the point. Years with 

fewer than 3 monitoring plots were excluded from the graph. The shaded area highlights the period from 

2011-2015 when sampling methods were consistent and distribution of plots was more even and 

consistent across years. The dashed line represents the maximum and minimum cover values for each 

year. 
11

Species Richness, Diversity, and Evenness 

One of the ways for the NPS to measure effectiveness of actions to achieve its mission of ‘preserving

ecological integrity’ is to examine trends in native plant diversity and evenness within park 

boundaries. Average species richness has been measured by point-intercept since 1998 and in 1 m2

and 10 m2 quadrats since 2011 (Table 4). 

Table 4. Average plant species richness in monitoring plots at Scotts Bluff National Monument from 1998 

to 2015. Values represent means ± one standard error. 

Point-intercept

(1998-2015; n=58)

1 m2 quadrats

(2011-2015, n=38)

10 m2 quadrats

(2011-2015, n=38)

Species richness 11.0 ± 0.6 6.3 ± 0.3 10.0 ± 0.6

Native species richness 8.6 ± 0.5 4.6 ± 0.3 7.7 ± 0.6

Exotic species richness 2.7 ± 0.2 1.6 ± 0.1 2.4 ± 0.2

Graminoid species richness 6.9 ± 0.3 3.7 ± 0.2 4.7 ± 0.2

Forb species richness 3.2 ± 0.2 2.3 ± 0.2 4.4 ± 0.4

While there was some variation across the park, the plots we visited in SCBL tended to have a low 

diversity of native plants compared to other mixed-grass prairies. Species richness in the mixed-grass 

prairie is determined by numerous factors including fire regime, grazing, prairie dog disturbance, and 

weather fluctuations (Symstad and Jonas 2011). In SCBL, there is also a mixed history of past landuse practices that have affected current species richness. While it is difficult to define a reference

condition for species richness, which naturally varies considerably across both space and time, the 

natural range of variation over long-time periods may be a good starting point (Symstad and Jonas 

2014). Long-term records of species diversity in mixed-grass prairie from a relatively undisturbed 

site in Kansas varied between 3 and 15 species per square meter over the course of 30 years 

(Symstad and Jonas 2014). Compared to this, SCBL is within the natural range (5 species) but is on 

the low end of the range, and some sites, such as PCM_0006, 0015, and 0022 [in the northwest 

(0006, 0022) and northeast (0015) portions of the park; Figure 1], fall below this reference condition.

In two of these plots, past and current land use can explain the degraded state: site 0006 falls within 

an active prairie dog town and historic feed lot, and 0015 is within the footprint of a former golf 

course. One of the most diverse plots, SCBL_FPCM_0039 in the north-central part of the park 

(Figure 1), has a mix of native shrub and grassland habitat (Figure 7).

We did not find any trends in species richness or evenness (Figure 8). Native species richness in 1m2

quadrats was consistent from 2011 to 2015 and ranged from a low in 2012 of 4.3 ± 0.7 (a drought 

year) to a high of 5.2 ± 0.6 in 2014 (a wet year). In the longer record from point-intercept data (1998-

2015; Figure 8: top) annual average native richness ranged between 5 and 12 species. Annual 

average evenness ranged from 0.58 to 0.81 during this time period, indicating the plots were not 

strongly dominated by a single species (Figure 8: bottom). There is a great deal of variation in 

species richness and evenness among sites within the park (dashed lines in Figure 8 represent the 

maximum and minimum values) which makes long-term trends in these metrics difficult to detect.
12

Figure 7. A photograph of long-term monitoring plot SCBL_FPCM_0039 which has a large diversity of 

native plant species. 

Figure 8. Trends in native species richness and evenness in Scotts Bluff National Monument, 1998-2015.

Data are means ± one standard error. The dashed line indicates the maximum and minimum values for 

each year.

There is evidence from other regions that annual bromes can affect persistence of native species 

(D'Antonio and Vitousek 2003). In SCBL, there is a negative correlation between the cover of annual 

bromes and native species richness (Figure 9; F1,162=19.3, P<0.0001). If the high cover of annual 
13

bromes in SCBL persists or increases, we expect there will be a corresponding decline in native 

species richness over time. 

Figure 9. The relationship between native species richness and the relative cover of annual bromes in 

long-term monitoring plots at Scotts Bluff National Monument, 1998-2015. 

Disturbance from grazing, prairie dogs, fire, and humans affects plant community structure and 

composition in mixed-grass prairie. We estimated the approximate area affected by natural and 

human disturbances at each site we visited in 2011-2015 by surveying the area for ~ 5 minutes at the 

end of the plot visit. The most common disturbance was from rodents (e.g. pocket gophers) and 

prairie dogs, but there was also evidence of deer trails and grazing. We found no correlation between 

native richness or exotic cover and total disturbance or small or large animal disturbance.

The Influence of Climate and Fire on Plant Community Structure and Diversity

Climate

The Northern Great Plains has a continental climate, with hot summers and very cold winters. The 

30- year normal temperatures at a nearby weather station, Scottsbluff W B Heilig Field airport, 

ranged from average minimum monthly temperatures in December of 12.5° F to maximum monthly 

July temperatures of 89.8° F (based on 1981-2010). The 30-year normal annual precipitation totals 

15.79 inches. Annual precipitation at SCBL in 1998-2015 was variable and ranged between 6.9 and 

22.9 inches, in 2012 and 2015, respectively. There were dry years in the early 2000s, 2006-2008, and 

in 2012-2013 (Figure 10). The last two years have been much wetter than average. The native 

vegetation is adapted to this variation, and productivity responds strongly to decreases in spring and 

summer precipitation (Yang et al. 1998, Smart et al. 2007). Species richness and diversity in regional 

grasslands are also sensitive to temperature and precipitation fluctuation, but the response is complex 

and less predictable (Jonas et al. 2015).
14

Figure 10. The total annual precipitation anomaly from 1998-2015 for Scott Bluff National Monument.

Positive values (blue) represent years wetter than and negative values (red) years drier than the 1981-

2010 average. The anomaly is measured in inches and based on data from a nearby weather station.

At SCBL, the average height of plants increased with increasing precipitation (R2=0.23, P=0.05), but 

did not respond to temperature. There was a marginally significant trend for native species richness 

to increase in years with more precipitation (R2

=0.17, P=0.09), but richness did not correlate with 

temperature. The relative cover of annual bromes did not correlate with total annual precipitation or 

temperature. Because of the large variation in annual temperature and precipitation patterns at SCBL, 

a longer time series of vegetation data is needed to elucidate trends and correlations with climate.

Fire History

Historically, fire was a common disturbance in Northern Great Plains grasslands, with natural fire

return intervals of 9-12 years (Guyette et al. 2015). Natural fires have been suppressed for most of 

the last century, but the use of prescribed burning in Northern Great Plains parks to mitigate the 

effects of the absence of natural fires has increased over time since its start at Wind Cave NP in 1973 

(Wienk et al. 2011). As of 2015, there is a mosaic of recently burned and unburned areas at SCBL 

(Figure 11).
15

Figure 11. Map of recent fire history (polygons) and relative cover of annual bromes at long-term 

monitoring plots (red) at Scotts Bluff National Monument. Larger bubbles indicate higher relative cover of 

annual brome. 
16

Figure 12. Native species richness and percent cover of annual bromes across plots with different fire 

histories. 

The effects of specific prescribed burns on vegetation and fuel loads and more details about fires at 

SCBL can be found in past NGPFire annual reports (see http://www.nps.gov/ngpfire/docs.htm). 

Here, we were interested in determining the relationship between fire history and vegetation. We 

compared two vegetation metrics, native species richness and relative cover of annual bromes, with 

the length of time between the data collection at a plot and the most recent fire at that plot (years 

since fire). For example, a site that burned in the spring and then was visited in the summer would be 

0 years since fire. We excluded plots that had not burned from this analysis, because we do not have 

confidence in the historical fire record (pre-1980s).

We found a positive relationship between native richness and years since fire (Figure 12; F1,136=6.3, 

P=0.0135). There was a lower number of native species in sites that burned more recently. This 

suggests that prescribed fire may reduce native species richness in the short term, but it over time 

mixed-grass prairie recovers. We found no significant relationship between annual brome and years 

since fire (Figure 12; F1,136=0.9, P=0.3325). This implies that in the short-term, prescribed burns are 

not effective at reducing brome. However, unburned plots concentrated in the southwest portion of 

the park had a higher cover of annual bromes than sites that burned more recently (Figure 11). 

Burning this unit of the park may assist in increasing native richness and reducing annual brome 

cover. The increasing trend in annual brome abundance across the park (Figure 6) despite fairly 

frequent prescribed burns suggests that burning alone may not be sufficient. The best approach to 

reducing annual brome abundance in SCBL will likely include burning, targeted herbicides, and 

seeding of native species. Ongoing research on this topic and an upcoming adaptive management 

initiative for annual brome control in NGPN parks should provide more data and guidance to help 

with these management decisions. 
17

Rare Plants 

While repeating rare plant surveys and locating rare species is not the focus of NGPN plant 

community monitoring, we identified 35 rare plant species in SCBL monitoring plots from 1998 to 

2015. Of these species, the critically imperiled species slender wheatgrass (Elymus trachycaulus S1;

Figure 13) was the most abundant with an average cover of 1.52%. Other critically imperiled species 

were observed in low frequencies and abundances, with hairy false goldenaster (Heterotheca villosa

S1) being more common and occurring in nine plots with 0.08% average cover. Other rare species 

abundances are described in Table 5, and 22 vulnerable to secure (S3S5) species observations are 

noted in Appendix A. Most of the rare species we observed are classified as apparently secure or 

secure (G4 or G5) at the global scale, but are rare in Nebraska as a result of these species existing on 

the edge of their global range in the state.

Figure 13. Photographs of two critically imperiled species in Nebraska found in plant community 

monitoring plots at Scotts Bluff National Monument. Left: slender wheatgrass (Elymus trachycaulus S1). 

Right: hairy false goldenaster (Heterotheca villosa S1).

Table 5. Rare species occurrence in Scotts Bluff National Monument from 1998-2015. Status ranks are 

based on Nebraska Natural Heritage Program designations. Plot count is the number of unique plots a 

species was recorded in across all years. Mean cover is the average cover of that species across all 

years in plots where cover measurements were recorded.

Species Common Name

State 

Rank

Global 

Rank

Plot 

Count

Mean Cover 

(%)

Hieracium umbellatum narrow-leaf hawkweed S1 G5 1 0.00

Pseudoroegneria 

spicata bluebunch wheatgrass S1 G5 3 0.08

Astragalus agrestis field milk-vetch S1 G5 2 0.01

Danthonia spicata poverty oatgrass S1 G5 1 0.00

Elymus lanceolatus thickspike wheatgrass S1 G5 2 0.01

Elymus trachycaulus slender wheatgrass S1 G5 44 1.52

Heterotheca villosa hariy goldenaster S1 G5 9 0.02

Senecio integerrimus lambstongue ragwort S1 G3 1 <0.01

Antennaria microphylla little-leaf pussytoes S2S4 G4G5 1 0.00

Fritillaria atropurpurea leopard-lily S2S4 G5 1 0.00

Physaria reediana rock bladder-pod S2S4 G4 1 0.00

Ericameria nauseosa rubber rabbitbrush S2S4 G5 7 0.02

Vicia americana American vetch S2S4 G5 13 0.08
18

Since it has been 20 years since the last rare plant survey was done at SCBL (Rolfsmeier 1996), we 

recommend a survey be redone when funds are available. A full rare plant survey will be more likely 

to accurately quantify the status of rare plants found on the main bluffs, an area with no monitoring 

plots. Any future construction efforts that could disturb native vegetation (e.g. trail building), should 

avoid damaging species considered rare in Nebraska.

Golf Course Restoration Project

Scotts Bluff NM acquired the property of a former golf course in 1973. Just over a decade later, the 

park began to restore the area by removing concrete, planting millet, spraying the area with an 

herbicide, and mowing. In 1997, it was planted with a mix of native grasses including western 

wheatgrass, junegrass (Koeleria macrantha), needle and thread, blue grama (Bouteloua gracilis), 

sideoats grama (B. curtipendula), and buffalograss (B. dactyloides) (Huddle et al. 2001). Sedges 

(Carex filifolia) were transplanted into the restoration area, but most died after one season due to 

drought and exotic species pressures (personal communication, M. DeBacker, B. Manasek). Two

monitoring plots were established within the restored area (LPCM_13 and 14; Figure 1) and two 

plots were established nearby in native prairie (LPCM_11 and 12; Figure 1). An earlier evaluation of 

the restoration project from 1997-2009 found mixed results: this evaluation found that the park was 

successful at creating a community that resembled the native prairie, except that threadleaf sedge,

which is difficult to seed, was absent (Huddle et al. 2001). However, the restored sites did have a 

higher frequency of exotic grasses than the native prairie (James 2010).

NGPN visited the native prairie and restoration sites in 2009, 2013, and 2014. In 2014, many of the 

species originally planted in the restoration area were present in plots LPCM-13 and 14, but only a 

few were common enough to contribute to the plant cover as measured by the point-intercept method

(Table 6). LPCM-13 had a high cover of western wheatgrass and trace amounts of sideoats and blue 

grama. The native grasses in LPCM-14 were more successful and junegrass was the only species 

missing from the area in 2014. However, native grasses remained in low abundance and blue grama, 

buffalo grass, and junegrass did not establish well in either plot.

The two restored plots differ from one another (Table 6), and neither closely resembles the nearby 

native prairie. LPCM_13 is characterized by lower native species richness and a much higher cover 

of annual bromes (close to 75% cover; Figure 14) than the control plots (which in 2014 averaged 6 

native species and 12.8% cover of annual brome). LPCM-14 has a high diversity of native plants, but 

also has a very high cover of annual bromes (close to 50% cover). To improve the rates of success 

and the establishment of native species, future projects should include funds to cover weed control 

for many years (~10) after planting. 
19

Table 6. Original seed mixture and composition of two restoration plots in Scotts Bluff National Monument

in 2009, 2013, and 2014. 

Seed

(% of mix)

% Cover

in restored plot LPCM-13

% Cover

in restored plot LPCM-14

1997 2009 2013 2014 2009 2013 2014

Western wheatgrass 58 44 19 22 13 4 3

Needle and thread 23 0 0 0 51 30 36

Sideoats grama 7 0 0 0 11.5 7 5

Blue grama 6 1 0 0 1.5 0 3

Buffalo grass 5 0 0 0 0 0 0

Junegrass trace 0 0 0 0 0 0

Native species 

richness

- 5 2 3 13 8 10

Relative cover of 

annual bromes

- 36.9 71.7 71.9 10.5 39.4 48.9

Figure 14. Cheatgrass is the dominant species at the long-term monitoring plot, LPCM_13, at Scotts Bluff 

National Monument.
20

The Status of Riparian Forests in SCBL

In 2014, the NGPN established 20 plots in the forested area along the North Platte River to monitor 

status and trends in lowland riparian forest condition (Figure 15). The 2014 data provide a baseline 

dataset for future surveys; we plan to revisit the same plots every five years (e.g. 2019, 2024, etc.).

The riparian lowland forest in Scotts Bluff NM is small (~ 60 acres), and comprises only about 2% of 

the park. The forest is fairly open and dominated by plains cottonwood (Populus deltoides), 

peachleaf willow (Salix amygdaloides ), and green ash (Fraxinus pennsylvanica) (TNC 1998). There 

are also large areas of shrubland (Figure 15, light green and pink) and exotic-species-dominated

grassland (Figure 15, green). The 20 monitoring plots were chosen randomly within the riparian 

corridor and fall in all of the dominant community types with the exception of narrowleaf willow (S. 

exigua) shrubland.

Figure 15. Map of the plant community types within the riparian area in Scotts Bluff National Monument

and the location of 20 long-term monitoring plots (yellow). Vegetation classification is based on the NPS 

Vegetation Mapping Program report (TNC 1998).

In 2014, we found nine species of tree or tall shrub in 19 riparian forest plots at SCBL (Table 7). One

plot (S-0899) did not have any tree or tall shrub species present. Our data were consistent with the 

1990’s vegetation map and the most common tree species were cottonwood, peachleaf willow, and 

green ash (Table 7). The density of large trees was similar across these three species (Table 8), but 

we found many fewer cottonwood seedlings compared to other species. Mature box elder (Acer 

negundo) trees occurred in only four plots (Table 7), but the average density was high (Table 8). As 

riparian forests along the North Platte age, cottonwood and willow forests are most often replaced 

with green ash and box elder forests (Johnson 1994). In 2014, we found numerous poles and 

seedlings of green ash and box elder but a few sites still have cottonwood and willow seedlings and 

poles present. Future monitoring is needed to determine if these stands will soon become dominated 

by green ash and box elder.
21

Table 7. Tree and tall shrub occurrence in 2014 at 20 plots in Scotts Bluff National Monument.

Species Name Common Name

Number of plots 

with trees

(DBH > 15 cm)

Number of plots 

with poles

(2.5 cm ≤ DBH ≤ 15 

cm)

Number of plots 

with seedlings

Salix amygdaloides peachleaf willow 8 0 2

Populus deltoides plains cottonwood 7 1 2

Fraxinus pennsylvanica green ash 6 2 9

Acer negundo boxelder 4 3 6

Juniperus scopulorum Rocky Mountain juniper 1 1 0

Shepherdia argentea silver buffaloberry 1 0 0

Prunus virginiana chokecherry 0 1 4

Salix interior sandbar willow 0 1 2

Ulmus americana American elm 0 0 2

Table 8. Tree basal area and density by size class for dominant tree and shrub species in the riparian 

forest of Scotts Bluff National Monument. (Values: mean across 20 riparian forest monitoring ± standard 

error of the mean)

Species Indicator Value

Willow species Basal Area (m2/ ha) 3.4 ± 1.7

Tree Density (stems/ha) 14 ± 5

Pole Density (stems/ha) 53 ± 38

Seedling Density (stems/ha) 5282 ± 3728

Snag Density (stems/ha) 0

Plains cottonwood Basal Area (m2/ ha) 3.4 ± 1.6

Tree Density (stems/ha) 18 ± 10

Pole Density (stems/ha) 6 ± 6

Seedling Density (stems/ha) 103 ± 102

Snag Density (stems/ha) 3 ± 3

Green ash Basal Area (m2/ ha) 0.7 ± 0.3

Tree Density (stems/ha) 15 ± 7

Pole Density (stems/ha) 8 ± 6

Seedling Density (stems/ha) 1973 ± 1070

Snag Density (stems/ha) 5 ± 3

Box elder Basal Area (m2/ ha) 1.6 ± .08

Tree Density (stems/ha) 28 ± 15

Pole Density (stems/ha) 21 ± 14

Seedling Density (stems/ha) 535 ± 273

Snag Density (stems/ha) 3 ± 2

Since the mid to late 1880’s, riparian forests have expanded along the North Platte as a result of the 

construction of dams and the resulting changes in water flow (Johnson 1994). Willows and 

cottonwoods have thrived because low flows in June allow for sufficient recruitment and lower peak 
22

flows and reduced ice scour reduce tree mortality. We compared our 2014 data to forest composition 

in the late 1850s to late 1880s (from Johnson 1994). The data from the late 1850s to late1880s 

encompasses a greater area, but the comparison shows large willows occurring in SCBL in 2014 but 

not historically, but also many more of the very smallest size classes (Figure 16, black bars). 

Cottonwoods also comprise a smaller proportion of the forest community (Figure 16, white bars),

and there has been a decrease in the proportion of cottonwoods in smaller diameter classes and an 

increase in the large diameter classes (Figure 17) . This suggests that new cottonwoods are no longer 

being established at the same extent or rate as they were 150 years ago. A metric developed to 

classify cottonwood stand successional status indicates that SCBL riparian areas are primarily

composed of late seral stage cottonwood stands, also suggesting a lack of cottonwood seedling 

recruitment (Uresk 2015). If the goal is to maintain cottonwood forests along this section of the 

North Platte, management interventions such as watering and fencing around existing cottonwood 

saplings could ensure that the young trees survive to maturity. 

Figure 16. Diameter classes of cottonwood (Populus) and willow (Salix) trees in riparian forests along the 

North Platte River in Nebraska in the 1850-1880s (bottom panel; from Johnson 1994) and along the same 

river but only in Scotts Bluff National Monument in 2014 (top panel). Class categories indicate upper limits 

of each range (e.g. diameter class 10 includes individuals >5 cm and ≤10 cm). 

Late 1800’s

2014
23

Figure 17. Size-class proportions of cottonwood (Populus) and willow (Salix) trees in riparian forests

along the North Platte River in Nebraska in the 1850-1880s (bottom panels; from Johnson 1994) and 

along the same river but only in Scotts Bluff National Monument in 2014 (top panel). Labels in wedges 

indicate diameter-at-breast-height (DBH) class categories, and each number is the upper limit of that

range (e.g. diameter class 10 includes individuals >5 cm and ≤10 cm). 
24

Exotic Species in Riparian Forests

The understory of the riparian forests in SCBL is a mix of native and exotic plants. The focus of the 

2014 survey was woody species, but field crews also surveyed for the presence of exotic species of 

management concern (e.g. musk thistle, poison hemlock) and potential early invaders (Table 1). 

Musk thistle and cheatgrass were found in a majority of the 20 plots (Table 9). On average, 3 exotic 

species were found in each plot. The only early detection we made was of perennial pepperweed 

(Lepidium latifolium); a number of plants were found in two plots in the center of the riparian 

corridor: SCBL_PCM_0963 and SCBL_PCM_1141 (Figure 15). Perennial pepperweed is an 

invasive plant that threatens wetlands, marshes, and floodplains in the Western US (Figure 18). It is 

common in Wyoming, but still relatively rare in Nebraska. 

The NGP Exotic Plant Management Team (EMPT) is aware of the high density and cover of exotic 

plants in the riparian forest and much of their control efforts were concentrated in this area during the 

2015 field season (Hauk 2016). The EPMT focused on the control of musk thistle (Carduus nutans), 

Canada thistle (Cirsium arvense), and poison hemlock (Conium maculatum). The NGP Exotic 

Management Team was notified of the perennial pepperweed, but there has not been a concerted 

effort at eradication. Unfortunately, the large seed bank and moist conditions will be challenging for 

continued control and eradication efforts of exotic species in this area. Moreover, the river continues 

to provide and an avenue for infestation. A more efficient use of resources may be in control efforts 

focused in upland areas with intact native communities (e.g. FPCM_0039, Figure 7) and rare plants 

(Rolfsmeier 1996).

Table 9. Exotic species detected in 20 riparian plots in Scotts Bluff National Monument and their 

corresponding abundance, cover class, and estimated percent cover. 

Species Common Name

Number

of Plots

Average

Cover Class

Estimated

Cover (%)

Carduus nutans musk thistle 17 2.4 ± 0.2 <5

Bromus tectorum cheatgrass 12 4.3 ± 0.3 5-25

Verbascum thapsus common mullein 8 2.0 ± 0.3 <1

Cirsium arvnese Canada thistle 6 2.0 ± 0.0 <1

Cynoglossum officinale houndstongue 6 1.7 ± 0.3 <1

Phalaris arundinacea reed canarygrass 5 4.6 ± 0.4 5-25

Marrubium vulgare horehound 4 2.0 ± 0.0 <1

Bromus inermis smooth brome 3 3.0 ± 0.6 <5

Conium maculatum poison hemlock 3 2.3 ± 0.3 <5

Lepidium latifolium perennial pepperweed 2 2.0 ± 0.0 <1
25

Figure 18. Perennial pepperweed, an invasive plant that threatens wetlands, marshes, and floodplains in 

the Western US. For more information an early detection flyer on riparian invaders can be found on the 

NGPN website and on the NPS IRMA Portal: https://irma.nps.gov/App/Reference/Profile/2208790/ )
26

Conclusion

The Northern Great Plains Inventory & Monitoring Program and Fire Effects Program have been 

monitoring vegetation in Scotts Bluff National Monument for over 18 years. While methods have 

changed slightly, this report summarizes data from over 80 locations from 1998-2015. Below, we 

list the questions we asked and provide a summarized answer, for more details see the Results and 

Discussion section. We conclude with a Natural Resource Condition Table (Table 10) that 

summarizes the current status and trends in a few key vegetation metrics. 

1. What is the current status of plant community composition and structure of SCBL 

grasslands (species richness, cover, and diversity) and how has this changed from 1998 to 

2015? 

SCBL plays a vital role in protecting and managing some of the last remnants of native mixedgrass prairie in the area. Native grasses, such as western wheatgrass, and native sedges, such as 

threadleaf sedge, are abundant and still the dominant component of many sites. Native plant 

diversity is at a moderate level compared to other grasslands in the region (Table 10), but 

diversity is spatially variable. As expected, areas with historical and current disturbances, such as 

the prairie dog town and former golf course, have fewer native plants than other sites. 

We found no significant trends in native diversity or evenness from 1998 to 2015, but both are 

threatened by the increasing cover of annual bromes (Figure 9). Annual bromes are the most 

abundant exotic plant species in SCBL and present the largest challenge to SCBL. There has 

been an increase in annual brome abundance since the 1990s and continued control efforts will be 

necessary to maintain native prairie within SCBL. 

2. How do trends in grassland condition correlate with climate and fire history?

Native diversity tended to increase in wet years. The large variability in SCBL’s climate makes it

difficult to discern strong patterns linking temperature, precipitation, and plant community 

structure (e.g. exotic cover, diversity). A longer time series of vegetation data will make it easier 

to elucidate trends in the future. 

SCBL has been using prescribed burning as a management tool since the 1980s. There was a 

lower number of native species in sites that burned more recently suggesting that prescribed fire 

can benefit the mixed-grass prairie in SCBL, but it may take time to see the positive effects. We 

found no significant relationship between annual brome and years since fire. There is an adaptive 

management program planned for 2017 which should provide better guidance to the park on how 

to manage annual bromes. Ongoing research is looking at treating areas with a range of annual 

brome abundance with a combination of prescribed fire, herbicide, and native grass drill seeding 

to see which combination of treatments is most effective in reducing annual brome cover.

3. What, if any, rare plants were found in SCBL long-term monitoring plots? 

We identified 35 rare plant species in SCBL between 1998 and 2015; eight of these are 

considered critically imperiled within Nebraska. These plants are found in such low abundance 

and in such few plots, it is unlikely that plant community monitoring will be able to detect any 
27

trends in rare plant abundance. We recommend more targeted surveys of rare plant species of 

concern be completed when funds are available. 

4. Was the SCBL golf course restoration effective at creating a grassland community 

dominated by native species?

The golf course restoration project had mixed results. While some native grasses were

established in one of the monitoring plots, establishment was poor in the other. The project area 

now has a very high relative cover of annual bromes (>45%). To improve the rates of success and 

the establishment of native species, future projects should include funds to cover invasive plant

control for many years (~10) after planting.

5. What is the composition and structure of riparian forests at SCBL?

The riparian forest in SCBL is a fairly diverse assemblage of cottonwood, willow species, green 

ash, and box elder. Seedlings are common (Table 10) and cottonwoods of all age classes are 

present. Exotic grasses and forbs are common in the understory of the riparian forest, and 

continuing control efforts will be necessary to prevent their spread. While there are fewer young 

cottonwood trees compared to surveys done in the late 1800s, some young cottonwoods have 

successfully established. However, the large abundance of green ash and box elder seedlings 

suggests that a transition to ash-dominated forests is underway.
28

Table 10. Natural resource condition summary table for plant communities in Scotts Bluff National 

Monument (SCBL). Current values are based on data from 2011-2015 and trends are based on data from

1998-2015. 

Indicator of 

Condition

Specific 

Measures

Current

Value 

(mean ± SE)

Reference 

Condition 

and Data 

Source

Condition 

Status/Trend

Rationale for Resource 

Condition

Upland Plant 

Community 

Structure and 

Composition

Native species 

richness (1m2

quadrats) 

4.6 ± 0.3 

species

3-15 

species

SCBL plays a vital role in 

protecting and managing some of 

the last remnants of native 

mixed-grass prairie in the region. 

The park is characterized by low 

native species richness, but 

average richness is within a 

natural range of variability

(Symstad and Jonas 2014). The 

lowest native diversity is found in 

the prairie dog town and former 

golf course. Native evenness has 

not changed since monitoring 

began in 1998. 

Evenness

(pointintercept 

transects)

0.67 ± 0.014 To be 

determined

Exotic Plant 

Early 

Detection and 

Management

Relative cover 

of exotic 

species 

41.2 ± 2.5% < 10 % 

cover

Many areas of SCBL have a high 

cover of exotic species. Annual 

bromes: cheatgrass and 

Japanese brome present the 

largest challenge to SCBL. Exotic 

cover and annual brome cover 

has shown an increasing trend 

since 1998. More research on 

effective management strategies 

is greatly needed.

Annual brome 

cover 

37.2 ± 2.3% < 10 % 

cover

Riparian 

Forest 

Plains 

cottonwood 

stand seral 

stage

Late seral 

stage 

Mix of seral 

stages

The riparian forests of SCBL are 

currently a mosaic of areas 

dominated by willow, 

cottonwood, ash, and boxelder 

with an understory of many 

exotic plants. As cottonwood 

forests age in SCBL, green ash 

and box elder are likely to 

become more dominant. Only 2 

of 20 plots had evidence of 

young cottonwoods, but more 

than half the riparian forest in 

SCBL had large densities of 

other native tree and shrub. 

Forest surveys will be repeated 

every 5 years in SCBL and this 

will allow us to detect trends in 

condition. 

Percent of 20 

riparian plots 

with native 

deciduous 

seedlings

60% To be 

determined
29

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32

Appendix A: List of plant species found at SCBL 1998-2015

Below is a list of all the plant species found in SCBL long-term plant community monitoring plots. 

The species are grouped by plant family. An “X” in the exotic column means that species is not 

native to the park or, in the case where only the genus was identified, there are some species within 

that genus that are exotic. Species considered to be rare in Nebraska are marked in the final column 

and the state conservation ranks are provided. Conservation rank definitions are in Table 2 of the 

report. 

Family Code Scientific Name Common Name Exotic Rare

Aceraceae ACNE2 Acer negundo boxelder S3S5

Agavaceae YUGL Yucca glauca soapweed yucca

Amaranthaceae AMARA Amaranthus pigweed X

AMRE Amaranthus retroflexus redroot amaranth

Anacardiaceae RHAR4 Rhus aromatica fragrant sumac

RHTR Rhus trilobata skunkbush sumac

TORA2 Toxicodendron radicans eastern poison ivy

TORY Toxicodendron rydbergii western poison ivy

Apiaceae COMA2 Conium maculatum poison hemlock X

CYGL99 Cymopterus glomeratus plains springparsley

PASA2 Pastinaca sativa wild parsnip X

Asclepiadaceae ASCLE Asclepias spp. milkweed

ASPU Asclepias pumila plains milkweed

ASSP Asclepias speciosa showy milkweed

ASVE Asclepias verticillata whorled milkweed

ASVI Asclepias viridiflora green comet milkweed

Asteraceae AGGL Agoseris glauca pale agoseris S1

AMPS Ambrosia psilostachya Cuman ragweed

ANMI3 Antennaria microphylla littleleaf pussytoes S2S4

ANTEN Antennaria spp. pussytoes

ARCA12 Artemisia campestris field sagewort S3S5

ARDR4 Artemisia dracunculus tarragon

ARFI2 Artemisia filifolia sand sagebrush

ARFR4 Artemisia frigida fringed sagewort

ASTER Aster spp. aster

BREU Brickellia eupatorioides false boneset

CANU4 Carduus nutans musk thistle X

CIAR4 Cirsium arvense Canada thistle X

CICA11 Cirsium canescens prairie thistle

CIOC2 Cirsium ochrocentrum yellowspine thistle

CIRSI Cirsium spp. thistle X

COCA5 Conyza canadensis horseweed

DICA18 Dieteria canescens hoary tansyaster S2S4

DYPA Dyssodia papposa fetid marigold

ERCA4 Erigeron canus hoary fleabane

ERFL Erigeron flagellaris trailing fleabane S3
33

Family Code Scientific Name Common Name Exotic Rare

ERNA10 Ericameria nauseosa rubber rabbitbrush S2S4

GRSQ Grindelia squarrosa curlycup gumweed S1

GUSA2 Gutierrezia sarothrae broom snakeweed

HEAN3 Helianthus annuus common sunflower

HELIA3 Helianthus spp. sunflower

HEPE Helianthus petiolaris prairie sunflower

HEVI4 Heterotheca villosa hairy false goldenaster S1

HIUM Hieracium umbellatum narrowleaf hawkweed S1

HYFI Hymenopappus filifolius fineleaf hymenopappus

HASP3 Haplopappus spinulosus lacy tansyaster X

LASE Lactuca serriola prickly lettuce X

LIPU Liatris punctata dotted blazing star

LOAR5 Logfia arvensis field cottonrose X

LYJU Lygodesmia juncea rush skeletonplant

MAPI Machaeranthera pinnatifida lacy tansyaster

MUOB99 Mulgedium oblongifolium blue lettuce

NOCU Nothocalais cuspidata prairie false dandelion

PACA15 Packera cana woolly groundsel

PAPL12 Packera plattensis prairie groundsel

RACO3 Ratibida columnifera upright prairie coneflower

SEIN2 Senecio integerrimus lambstongue ragwort S1

SENEC Senecio spp. ragwort

SERI2 Senecio riddellii Riddell's ragwort

SOCA6 Solidago canadensis Canada goldenrod S3S5

SOLID Solidago spp. goldenrod

SOMI2 Solidago missouriensis Missouri goldenrod

SOMO Solidago mollis velvety goldenrod

SONCH Sonchus spp. sowthistle X

SONE Solidago nemoralis gray goldenrod

SYER Symphyotrichum ericoides white heath aster S3S5

SYMPH4 Symphyotrichum aster

TAOF Taraxacum officinale common dandelion X

THME Thelesperma megapotamicum Hopi tea greenthread

TRDU Tragopogon dubius yellow salsify X

XASP99 Xanthium spinulosum lacy tansyaster

Boraginaceae CRCA8 Cryptantha cana mountain cryptantha

CRCE Cryptantha celosioides buttecandle

CRTH Cryptantha thyrsiflora calcareous cryptantha S3S5

CYOF Cynoglossum officinale houndstongue X

LAOC3 Lappula occidentalis flatspine stickseed

LIIN2 Lithospermum incisum narrowleaf stoneseed

Brassicaceae ALDE Alyssum desertorum desert madwort X

BRASS2 Brassica mustard X

CAMI2 Camelina microcarpa littlepod false flax X

DEPI Descurainia pinnata western tansymustard S3S5

DESCU Descurainia spp. tansymustard X
34

Family Code Scientific Name Common Name Exotic Rare

DESO2 Descurainia sophia herb sophia X

DRRE2 Draba reptans Carolina draba

ERAS2 Erysimum asperum western wallflower

ERCA14 Erysimum capitatum sanddune wallflower

LEDE Lepidium densiflorum common pepperweed

LELA2 Lepidium latifolium broadleaved pepperweed X

LEPID Lepidium spp. pepperweed X

LESQU Lesquerella spp. bladderpod

PHLU99 Physaria ludoviciana foothill bladderpod

PHRE8 Physaria reediana alpine bladderpod S2S4

ROSI2 Rorippa sinuata spreading yellowcress

SIAL2 Sisymbrium altissimum tall tumblemustard X

THAR5 Thlaspi arvense field pennycress X

Cactaceae ESMI3 Escobaria missouriensis Missouri foxtail cactus

ESVI2 Escobaria vivipara spinystar

OPFR Opuntia fragilis brittle pricklypear

OPMA2 Opuntia macrorhiza twistspine pricklypear

OPPO Opuntia polyacantha plains pricklypear

OPUNT Opuntia spp. pricklypear

Caprifoliaceae LOTA Lonicera tatarica Tatarian honeysuckle X

SYOC Symphoricarpos occidentalis western snowberry

Caryophyllaceae PADE4 Paronychia depressa spreading nailwort

Chenopodiaceae ATCA2 Atriplex canescens fourwing saltbush S3S5

CHAL7 Chenopodium album lambsquarters X

CHBE4 Chenopodium berlandieri pitseed goosefoot

CHENO Chenopodium spp. goosefoot X

CHFR3 Chenopodium fremontii Fremont's goosefoot

CHPR5 Chenopodium pratericola desert goosefoot

KOSC Kochia scoparia burningbush, kochia X

KRLA2 Krascheninnikovia lanata winterfat S3S5

SAKA Salsola kali Russian thistle X

SALSO Salsola spp. Russian thistle X

SATR12 Salsola tragus prickly Russian thistle X

Commelinaceae TRADE Tradescantia spp. spiderwort

TRBR Tradescantia bracteata longbract spiderwort

TROC Tradescantia occidentalis prairie spiderwort

Convolvulaceae COAR4 Convolvulus arvensis field bindweed X

EVNU Evolvulus nuttallianus shaggy dwarf morning-glory

IPLE Ipomoea leptophylla bush morning-glory

Cupressaceae JUSC2 Juniperus scopulorum Rocky Mountain juniper

Cyperaceae CADU6 Carex duriuscula needleleaf sedge

CAFI Carex filifolia threadleaf sedge

CAIN9 Carex inops sun sedge

CAREX Carex spp. sedge

Elaeagnaceae SHAR Shepherdia argentea silver buffaloberry

SHCA Shepherdia canadensis russet buffaloberry
35

Family Code Scientific Name Common Name Exotic Rare

Euphorbiaceae CRTE4 Croton texensis Texas croton

EUMA8 Euphorbia marginata snow on the mountain

EUGL3 Euphorbia glyptosperma ribseed sandmat

EUSE5 Euphorbia serpyllifolia thymeleaf sandmat X

EUPHO Euphorbia spp. spurge, sandmat X

Fabaceae ASAG2 Astragalus agrestis purple milkvetch S1

ASBI2 Astragalus bisulcatus twogrooved milkvetch S3S5

ASGR3 Astragalus gracilis slender milkvetch

ASLA27 Astragalus laxmannii Laxmann's milkvetch

ASMI10 Astragalus missouriensis Missouri milkvetch

ASMO7 Astragalus mollissimus woolly locoweed

ASTRA Astragalus milkvetch

DACA7 Dalea candida white prairie clover

DAPU5 Dalea purpurea purple prairie clover S3S5

DAVI Dalea villosa silky prairie clover

GLLE3 Glycyrrhiza lepidota American licorice

LAPO2 Lathyrus polymorphus manystem pea

LUPIN Lupinus spp. lupine

MELIL Melilotus spp. sweetclover X

MELU Medicago lupulina black medick X

MEOF Melilotus officinalis yellow sweetclover X

MESA Medicago sativa alfalfa

OXLA3 Oxytropis lambertii purple locoweed

OXSE Oxytropis sericea white locoweed

PEAR6 Pediomelum argophyllum silverleaf Indian breadroot

PEES Pediomelum esculentum large Indian breadroot

PSLA3 Psoralidium lanceolatum lemon scurfpea

PSTE5 Psoralidium tenuiflorum slimflower scurfpea

THRH Thermopsis rhombifolia golden pea

VIAM Vicia americana American vetch S2S4

Grossulariaceae RIAU Ribes aureum golden currant

RIBES Ribes spp. currant

RICE Ribes cereum wax currant

Hydrophyllaceae ELNY Ellisia nyctelea Aunt Lucy

Lamiaceae HEDR Hedeoma drummondii Drummond's false 

pennyroyal

HEHI Hedeoma hispida rough false pennyroyal

MAVU Marrubium vulgare horehound X

MEAR4 Mentha arvensis wild mint

MOFI Monarda fistulosa wild bergamot

MOPE Monarda pectinata pony beebalm

NECA2 Nepeta cataria catnip X

TECA3 Teucrium canadense Canada germander

Liliaceae ALTE Allium textile textile onion

ASOF Asparagus officinalis garden asparagus X

FRAT Fritillaria atropurpurea spotted fritillary S2
36

Family Code Scientific Name Common Name Exotic Rare

LEMO4 Leucocrinum montanum common starlily

MAST4 Maianthemum stellatum starry false lily of the valley

ZIVE Zigadenus venenosus meadow deathcamas

Loasaceae MEDE2 Mentzelia decapetala tenpetal blazingstar

Malvaceae SPCO Sphaeralcea coccinea scarlet globemallow

Melanthiaceae TOVE2 Toxicoscordion venenosum meadow deathcamas

Nyctaginaceae MIAL4 Mirabilis albida white four o'clock

MIHI Mirabilis hirsuta hairy four o'clock

MILI3 Mirabilis linearis narrowleaf four o'clock

Oleaceae FRPE Fraxinus pennsylvanica green ash

Onagraceae OEBI Oenothera biennis common evening primrose

OECE2 Oenothera cespitosa Tufted evening primrose S2S4

OECU99 Oenothera curtiflora velvetweed

OESE3 Oenothera serrulata yellow sundrops

OESU99 Oenothera suffrutescens scarlet beeblossom

Orobanchaceae ORFA Orobanche fasciculata clustered broomrape

Papaveraceae ARPO2 Argemone polyanthemos crested pricklypoppy

Pinaceae PIPO Pinus ponderosa ponderosa pine

Poaceae ACHY Achnatherum hymenoides Indian ricegrass

AGCR Agropyron cristatum crested wheatgrass X

ANGE Andropogon gerardii big bluestem

ARPU9 Aristida purpurea purple threeawn S3S5

BOCU Bouteloua curtipendula sideoats grama

BODA2 Bouteloua dactyloides buffalograss

BOGR2 Bouteloua gracilis blue grama

BOHI2 Bouteloua hirsuta hairy grama

BRHOH Bromus hordeaceus ssp. 

hordeaceus

soft brome

X

BRIN2 Bromus inermis smooth brome X

BRJA Bromus japonicus Japanese brome X

BROMU Bromus spp. brome X

BRTE Bromus tectorum cheatgrass X

CALO Calamovilfa longifolia prairie sandreed

DASP2 Danthonia spicata poverty oatgrass S1

DISP Distichlis spicata saltgrass

ELCA4 Elymus canadensis Canada wildrye

ELEL5 Elymus elymoides squirreltail

ELLA3 Elymus lanceolatus thickspike wheatgrass S1

ELTR7 Elymus trachycaulus slender wheatgrass S1

ELYMU Elymus spp. wildrye

HECO26 Hesperostipa comata needle and thread

HESP11 Hesperostipa spartea porcupinegrass

HOJU Hordeum jubatum foxtail barley

KOMA Koeleria macrantha prairie Junegrass

MUCU3 Muhlenbergia cuspidata plains muhly

MURA Muhlenbergia racemosa marsh muhly
37

Family Code Scientific Name Common Name Exotic Rare

NAVI4 Nassella viridula green needlegrass

PACA6 Panicum capillare witchgrass S3S5

PASM Pascopyrum smithii western wheatgrass

PAVI2 Panicum virgatum switchgrass

PHAR3 Phalaris arundinacea reed canarygrass X

PIMI7 Piptatherum micranthum littleseed ricegrass

POPR Poa pratensis Kentucky bluegrass X

POSE Poa secunda Sandberg bluegrass

PSSP6 Pseudoroegneria spicata bluebunch wheatgrass S1

SCSC Schizachyrium scoparium little bluestem

SEVI4 Setaria viridis green foxtail

SONU2 Sorghastrum nutans Indiangrass

SPCR Sporobolus cryptandrus sand dropseed

BUDA Buchloe dactyloides buffalograss

FEOC3 Festuca octoflora sixweeks fescue X

THIN6 Thinopyrum intermedium intermediate wheatgrass X

VUOC Vulpia octoflora sixweeks fescue

Polemoniaceae IPCO5 Ipomopsis congesta ballhead ipomopsis S2S4

PHAN4 Phlox andicola prairie phlox

PHHO Phlox hoodii spiny phlox

Polygonaceae ERFL4 Eriogonum flavum alpine golden buckwheat

ERPA9 Eriogonum pauciflorum fewflower buckwheat S3S5

POAC3 Polygonum achoreum leathery knotweed

FACO Fallopia convolvulus black bindweed X

RUSA Rumex salicifolius willow dock

Ranunculaceae CLHI Clematis hirsutissima hairy clematis S1

Rosaceae PRVI Prunus virginiana chokecherry

ROAR3 Rosa arkansana prairie rose

ROSA5 Rosa spp. rose

ROWO Rosa woodsii Woods' rose

Rubiaceae GAAP2 Galium aparine stickywilly

Salicaceae PODE3 Populus deltoides eastern cottonwood

SAAM2 Salix amygdaloides peachleaf willow

SAIN3 Salix interior sandbar willow

Santalaceae COUM Comandra umbellata bastard toadflax

Scrophulariaceae BEWY Besseya wyomingensis Wyoming kittentails

PEAL2 Penstemon albidus white penstemon

PEGR5 Penstemon gracilis lilac penstemon

PENST Penstemon spp. beardtongue

VEAM2 Veronica americana American speedwell

VETH Verbascum thapsus common mullein X

Solanaceae PHHE4 Physalis hederifolia ivyleaf groundcherry S3S5

PHHE5 Physalis heterophylla clammy groundcherry

PHHI8 Physalis hispida prairie groundcherry

PHLO4 Physalis longifolia longleaf groundcherry

PHVI5 Physalis virginiana Virginia groundcherry
38

Family Code Scientific Name Common Name Exotic Rare

Ulmaceae CEOC Celtis occidentalis common hackberry

ULAM Ulmus americana American elm

Urticaceae PAPE5 Parietaria pensylvanica Pennsylvania pellitory

Verbenaceae VEBR Verbena bracteata bigbract verbena

VEST Verbena stricta hoary verbena

Violaceae VINU2 Viola nuttallii Nuttall's violet

Vitaceae PAVI5 Parthenocissus vitacea woodbine

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