Water-Resources investigations Report 96-4277 

Hydrology and Tree-Distribution Patterns of 

Karst Wetlands at Arnold Engineering 

Development Center, Tennessee 

Prepared by the 

United States Geological Survey 

in cooperation with the 

United States Air Force, 

Arnold Engineering Development Center 
Cover photograph: Flooded interior of Sinking Pond. Photograph by W.J. Wolfe. 
Hydrology and Tree-Distribution Patterns of 

Karst Wetlands at Arnold Engineering 

Development Center, Tennessee 

BY WILLIAM J. WOLFE 

United States Geological Survey 

Water-Resources Investigations Report 96-4277 

Prepared in cooperation with the 

United States Air Force, 

Arnold Engineering Development Center 

Nashville, Tennessee 

1996 
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director 

Any use of trade, product, or firm name in this report is for identification 

purposes only and does not constitute endorsement by the U.S. 

Geological Survey. 

For additional information write to: 

District Chief 

U.S. Geological Survey 

810 Broadway, Suite 500 

Nashville, Tennessee 37203 

Copies of this report may be purchased from: 

U.S. Geological Survey 

Branch of Information Services 

Box 25286 

Denver, Colorado 80225-0286 
CONTENTS 

Abstract.................................................................................................................................................................................. 1

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

Purposeandscope...................................................................................................................................................... 4 .

Acknowledgments...................................................................................................................................................... 4 .

Studyarea................................................................................................................................................................... 4 .

Karst features..................................................................................................................................................... 4

Soils, vegetation,andclimate...........................................................................................................................5 .

Hydrogeology.................................................................................................................................................... 6

Hydrology.............................................................................................................................................................................. 7

Site selectionanddatacollection................................................................................................................................7 .

Waterlevelsanddischarge......................................................................................................................................... 11 .

Geomorphiccontrolsof wet&mdwaterregimes......................................................................................................... 20 .

Tree-distributionpatterns..................................................................................................................................................... . 23 .

Transectlocationsandsamplingmethods................................................................................................................... 24

Flooding-durationandelevationdistributionsof selectedtreespecies........................................................................ 26

Geomorphicandhydrologiccontrolson wetland-treedistribution............................................................................. 29

Summaryandconclusions..................................................................................................................................................... 31

Referencescited..................................................................................................................................................................... 33 

Appendix 1. Commonandscientific namesof plantsidentifiedalongvegetationtransects.................................................39 

Appendix2. Relativeimportanceandelevationquartilesfor treespeciesalongvegetation 

transectsin the Sinking Pondarea,Arnold EngineeringDevelopmentCenter.......................................................41 

FIGURES 

l-2. Maps showing: 

Physiographic regions of Tennessee and location of The Barrens ................................................................... 

2. Locationof Arnold EngineeringDevelopmentCenterandstudyarea........................................................... 

3-4. Photographsshowing: 

3. A karstpanin the Sinking Pondarea............................................................................................................... 5

4. The internaldrainagesystemof a compoundsink northwestof Sinking Pond............................................... 6 

5. Map showinglocationof monitoredwetlandsitesandwells at Arnold Engineering 

DevelopmentCenter................................................................................................................................................. 8

6-8. Graphsshowing: 

6. Waterlevelsin Sinking Pondandadjacentwells anddaily rainfall at WestallSwamp.................................. 11 

7. Cumulativefrequencydistributionsof daily meanwaterlevel in Sinking Pondfor 

wateryears1993and 1994............................................................................................................................... 12 

8. Graphshowingcomparisonof daily rainfall at RowlandCreek,Arnold Engineering 

DevelopmentCenter,with monthly rainfall at Tullahoma,Tennesseefor , water 

years1993and 1994andwith meanmonthly rainfall at Tullahomafor 1961-1990...................................... . 13 

9. Map showingtopographyof Sinking Pond.............................................................................................................. 15

10-16. Graphsshowing: 

10. Relationof daily meandischargeat Sinking Pondoutflow gageto stagein Sinking Pond 

andrainfall at WestallSwamp.......................................................................................................................... 16

11. Waterlevelsin Willow Oak SwampandSinkingPond...................................................................................17 

12. Waterlevelsin TupeloSwampandadjacentwells anddaily rainfall at WestallSwamp................................ 18 

13. Relationof daily meandischargeat Sinking Pondinflow gageto stagein Tupelo 

Swampandrainfall at WestallSwamp............................................................................................................. 19 

14. Waterlevelsin WestallSwampandadjacentwells anddaily rainfall at WestallSwamp............................... 20 

Contents iii 
15. Waterlevels in GoosePondandnearbywells anddaily rainfall at RowlandCreek...................................... 21 

16. Comparisonof waterlevelsin four wetlandsitesat Arnold EngineeringDevelopment 

Centerduring theperiodOctober1993throughJanuary1995....................................................................... 22 

17. Map showinglocationof vegetationtransectsin the Sinking Pondarea................................................................ 25 

18-20. Graphsshowing: 

18. Relationof basalareato standdensityalong 10vegetationtransects 

in the Sinking Pondarea.................................................................................................................................. 27 

19. Flooding-durationdistributionsfor selectedtreespeciesalongfive transects 

throughmonitored

20. Frequencydistributionsof elevationfor land surfaceandselectedtreespeciesalong 

five transectsthroughuninstrumentedwetlandsitesin the Sinking Pondarea............................................... 30 

TABLES 

1. Gagedatafor surface-waterstationsat Arnold EngineeringDevelopmentCenterwetlands................................. 9 

2. Well-constructiondatafor continuouslymonitoredwells nearwetlandsat Arnold 

EngineeringDevelopmentCenter........................................................................................................................... 10

3. Normal geographicrangesandpreferredsite characteristicsfor six wetlandtreespecies 

at Arnold EngineeringDevelopmentCenter..........................................................~ .............................................. 24 

4. Summaryof lengths,areas,andforestdensityfor vegetationtransectsin the Sinking Pondarea......................... 26 

CONVERSION FACTORS, VERTICAL DATUM, AND WELL-NUMBERING SYSTEM 

Mllltlply BY To obtain 

millimeters(mm) 0.0397 inch 

centimeter(cm) 0.3937 inch 

meter(m) 3.28084 foot 

kilometer(km) 0.621504 mile 

squarekilometer(km*) 0.3861 squaremile 

cubicmeterpersecond(m3/s) 0.0283 cubicfootpersecond 

degreeCelsius(“C) (9 degreeFahrenheit(OF)

‘Temp ‘F=1.8 temp ‘C+32. 

Sealeveland water level: In this report “sealevel” refersto the National GeodeticVertical Datum of 1929-a geodetic 

referencedatumderivedfrom a generaladjustmentof the first-orderlevel netsof the United StatesandCanada,formerly 

calledSeaLevel Datum of 1929. 

Well-numberingsystem:The U.S. GeologicalSurveyassignedeachwell in this reporta local well numberanda station 

identification number.The local well numberis usedasa conciselabel for a well. The stationidentification numberis used 

asanidentifier for site datastoredin the nationalcomputersystemof theU.S. GeologicalSurvey.Thesenumbering 

systemsareusedin addition to the well numbersassignedby Arnold EngineeringDevelopmentCenter. 

The local well numberin Tennesseeconsistsof threeparts:(1) an abbreviationof the nameof the countyin which the well 

is located;(2) a letter designatingthe 7.5-minutequadrangleon which the well is plotted; and(3) a numbergenerally 

indicating the numericalorderin which the well wasinventoried.For example,the local well numberCf:G-067indicates 

that the well is locatedin Coffee County on the “G” quadrangleandis identified aswell 67 in the numericalsequence. 

Quadranglesareletteredfrom left to right, beginningat the southwestcomerof the county. 

The stationidentification numberis a uniquenumberfor eachwell basedon latitudeandlongitude.The numberconsistsof 

15digits. The first 6 digits denotedegrees,minutes,andsecondsof latitude;the next 7 digits denotedegrees,minutes,and 

secondsof longitude;andthe last 2 digits sequentiallyidentify wells within a l-secondgrid. 

iv Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
Hydrology and Tree-Distribution Patterns of Karst 

Wetlands at Arnold Engineering Development Center, 

Tennessee 

By William J. Wolfe 

Abstract 

Flooding regimes, ground-water interactions, and tree distribution patterns were determined in seasonally flooded sinkhole wetlands at 

Arnold Engineering Development Center near 

Manchester, Tennessee.The wetlands are ecologically significant becausethey support coastal-plain 

plants and animals far from their typical ranges. 

Surface-water stage, ground-water levels, 

rainfall, and streamflow were monitored at or near 

five wetland sites. Sinking Pond, Willow Oak 

Swamp, and Westall Swamp are compound sinks 

with depths greater than 2.5 meters, visible internal drains, and complex bottom topography dominated by coalesced sinkholes and connecting 

channels. Tupelo Swamp and Goose Pond are 

karst pans with depths less than 1.5 meters, flat 

bottoms, and without visible internal drains. Stage 

rose and fell abruptly in the compound sinks. 

Maximum water depths ranged from 2.6 meters in 

Westall Swamp to 3.5 meters in Sinking Pond. 

Water levels in wells adjacent to Sinking Pond and 

Westall Swamp rose and fell abruptly, corresponding closely to surface-water stage throughout periods of high water. The two karst pans filled and 

drained more gradually, but remained flooded 

longer than the compound sinks. The maximum 

recorded water depths were 1.1 meters in Tupelo 

Swamp and 0.7 meter in Goose Pond. Water levels 

in nearby wells remained lower than the stage in 

the pans throughout the study period. Tree species 

were identified and the elevations and diameters of 

individual trees were measured along 10 transects. 

Two transects crossed Sinking Pond, two crossed 

Tupelo Swamp, and one crossed Willow Oak 

Swamp. The remaining five transects crossed 

intermittent drainageways that carry flow into or 

out of Sinking Pond. Transects through ponds had 

fewer trees but more basal area per unit area of 

land surface than did transects through channels. 

Water tupelo (Nyssa aquaticu L.) dominated the 

interior of Tupelo Swamp and had minimal overlap in terms of elevation and flooding duration 

with other wetland trees that were confined to the 

ponds periphery. Overcup oak (Quercus Zyrutu 

Walt.) dominated the interior of Sinking Pond. 

Overlap between overcup oak and other wetland 

trees in terms of elevation and flooding frequency 

was minimal across the deeper Sinking Pond 

transect but was substantial across the shallow 

transect. Willow oak (Quercus phellos L.) dominated the interior of Willow Oak Swamp and had a 

relation to other wetland trees similar to that of 

overcup oak in the shallow Sinking Pond transect. 

Transects across broad swales had a relatively 

large degree of vertical zonation among wetland 

and upland tree species. Along transects through 

well defined channels, elevation distributions of 

wetland and some upland tree species were 

grouped near each other and near the distribution 

of land-surface elevations. 

INTRODUCTION 

Wetlands within karst landforms are distributed 

across the unglaciated uplands of the southeasternand 

south-central United States (Barclay, 1957; Greear, 

1967; Ellis and Chester, 1989; Jones, 1989). Southern 

karst wetlands constitute a small fraction of the 

regional wetland areacompared with the coastal plains 

and large alluvial valleys (Mitsch and Gosselink, 

Introduction 1 
1993),but they make up a much larger proportion of 

wetlandswithin extensiveareasunderlain by carbonaterocks. Many karst wetlandssupportnorthern and 

coastal-plainplantsandanimalsthat areotherwiserare 

or absentin southernuplands.The ecological significanceof karst wetlandsis thus disproportionateto 

their limited area(Killebrew and Safford, 1874; Svenson, 1941;Barclay, 1957;Greear, 1967;Ellis and 

Chester,1989;Jones,1989;Bowen and Pyne, 1995). 

One extensiveconcentrationof karst wetlands, 

known locally as “The Barrens,” occurson the Eastern 

Highland Rim (fig. 1). Within the context of southern 

karst wetlands,The Barrenscontainsan exceptionally 

rich and diverseassortmentof disjunct plants and animals. Disjunct plants have beenreportedfrom three 

distinct ecological regions:the northern Appalachians, 

the southernAtlantic and Gulf coastalplains, and the 

northern prairies (Svenson,1941; Shanks,1958; Kral, 

1973;DeSelm, 1981,1986,1989,1990; Bowen and 

Pyne, 1995).Recently,severalcoastal-plainreptiles 

and amphibianshave also beenidentified (Brian 

Miller, Middle TennesseeStateUniversity, written 

commun., 1995;Edward Clebsch,University of TenILO’ 

Physiographicregionsmodifiedfrom Miller, 1974 

nessee,oral cormnun., 1995).Disjunct taxa arenot 

distributed evenly acrossThe Barrens,but arehighly 

localized in discretesites,notably in seasonally 

flooded karst depressions. 

One of the most notable concentrationsof wellpreservedBarrenswetlandsis locatedin and around 

Arnold Engineering DevelopmentCenter (AEDC), an 

aerospacetesting facility operatedby the U.S. Air 

Force nearManchester,Tennessee(fig. 2). The reservation lies within The Barrensand includes about 

0.24 squarekilometer (km2) of wetlands.Thesewetlands include three RegisteredNatural Landmarks 

(Sinking Pond,GoosePond,andthe AEDC Powerline 

Barrens); a fourth (May Prairie) is separatedfrom the 

reservationboundaryby a road (BenhamGroup, 1989; 

Bowen and Pyne, 1995). All of thesesitesand many 

other wetlandsin the areasupportrare or protected 

plants and animalsincluding a wide variety of coastalplain disjuncts (Svenson,1941;BenhamGroup, 1989; 

Patterson,1989;Bowen and Pyne, 1995). At least68 

rare and endangeredplants and animalshavebeen 

identified at AEDC, most of them in or nearkarst 

117’ 

Eastem 

Highland 

0 25 50 KlLoM4xERs 

t ‘1’ I 

0 25 so MILES 

TheBanenshasedmsoildalati0mS0ilConservationService,1991 

figure 1. Physiographii regions of Tennessee and location of The Barrens. 

2 HydrologysndTlw-oMbutlon~sofKlvstw-(It

Amom Enghbserhg Dsve~ centsr, Tsnnessw 
bluIILh,,cu,u 

Plateau .E-‘ 

Escarpment FI 

f I 

Study .; I 

I’ Normandv area 

- I 

I 

Map modified hm Haugb andMahoney, 1994 

0 1 2 3 4 KILOMETERS TENNESSEE 

0’ 1 3 4 MILES 

EXPLANATION 

q INCORPORATED TOWNS SMY 

area 

1\\\1 ARNOLD AIR FORCE BASE 

I I I t 1 LOCATION OF ESCARPMENT 

Figure 2. Location of Arnold Engineering Development Center and study area. 

mroductlofl 3 
wetlands (David Campbell, TennesseeNature Conservancy, written commun., 1995). 

Balancing the goals of protecting natural 

resources with the mission of an active military facility requires a detailed knowledge of environmental 

factors that affect ecologically sensitive sites. In the 

case of karst wetlands, understanding the interactions 

among geomorphic characteristics, flooding patterns, 

and plant distribution is critical for effective natural 

resource management and protection. In order to 

develop such an understanding, the U.S. Geological 

Survey, in cooperation with the U.S. Air Force, conducted a study of the geomorphic features, hydrology, 

and tree-distribution patterns of several karst wetlands 

at AEDC. 

Purpose and Scope 

This report describes the results of the hydrologic study at AEDC. The technical scopeof the report 

includes field observations of geomorphic features, 

hydrologic processesand tree-species distribution and 

continuous or periodic monitoring of precipitation, 

surface- and ground-water levels, and streamflow. 

Specific objectives are: 

1. Describe typical geomorphic features associated 

with karst wetlands at AEDC. 

2. Determine the relation between wetland water 

regimes and ground-water system among karst 

wetland sites with contrasting vegetation and 

sinkhole morphology. 

3. Characterize the distribution of tree-species 

within karst wetlands with different geomorphic 

and hydrologic characteristics and along the 

transitions between such wetlands and welldrained uplands. 

Acknowledgments 

The staff at Arnold Engineering Development 

Center played a central role in this study from its 

inception through its conclusion. The support and 

assistance of Clark Brandon, Dennis Flatt, and Mark 

Moran are gratefully acknowledged. William Patterson of Louisiana State University generously shared 

his intimate knowledge of the soils and vegetation of 

the Sinking Pond area, including a strenuous week in 

the field. David Campbell and Robert Brown of the 

TennesseeNature Conservancy and Milo Pyne, TennesseeDepartment of Environment and Conservation, 

assisted with plant identification. Professor Laurence 

Lewis of Clark University, Dr. Virginia Carter of the 

U.S. Geological Survey Wetlands Research Program, 

and Dr. L. Katherine Kirkman of the J.W. JonesEcological Research Center reviewed early drafts of this 

report and provided numerous helpful comments. 

Bradley Bryan and Timothy Diehl of the U.S. Geological Survey were active in site reconnaissanceand 

planning the investigation. Along with Donald League 

and Ronald Kemp, they also provided invaluable 

assistancein the field. 

Study Area 

AEDC occupies an area of about 160 km2, of 

which about 10 percent is developed for industrial 

activities. The remainder is managedfor multiple uses, 

including wildlife, forestry, and agriculture (Benham 

Group, 1989). The study area straddles the divide 

between the Duck and Elk River drainage basins and 

typifies the low-relief upland topography of The Barrens (Burchett, 1977; Smalley, 1983). Surface drainage networks are weakly to moderately well 

developed, with a high proportion of seasonally flowing streams. Many of these streams flow into or out of 

seasonally flooded sinkholes. Ridges are typically 

broad and relatively flat or gently undulating. The 

ridgetops are generally well drained but commonly 

contain small, shallow depressionswith poor drainage. 

The elevation difference between headwater-valley 

bottoms and the tops of adjacent ridges rarely exceeds 

20 meters (m). Valley side-slope gradients typically 

range from 5 to 15 percent. 

Karst Features 

Sinkholes-losed karst depressions with depth 

less than diameter (White, 1988)-and other karst 

landforms are common features at AEDC and elsewhere in The Barrens. In comparison with the Pennyroyal Plateau (White and others, 1970) in southern 

Kentucky or the base of the Cumberland Plateau in 

Tennessee(White and White, 1983), karst features in 

The Barrens have low relief and subtle surface expression. A few sinkholes are deeper than 3 m, but most 

are less than 2 m deep. 

At AEDC, wetlands occur in two distinct types 

of karst depressions-karst pans and compound sinks 

(Wolfe, 1996). Karst pans are shallow, flat bottomed 

depressions with diameters ranging from 2 m to 

greater than 100 m and depths less than 1.5 m (fig. 3). 

4 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
Figure 3. A karst pan in the Sinking Pond 

The panslack visible internal drains,but commonly 

havewell-developedoverflow channels.A few pans 

drain areasaslarge as0.2 km2, but most havemuch 

smaller drainageareasor are situatedat intermittent 

streamheadsatop flat ridges.Most pansat AEDC support wet forestsof willow oak, sweetgum,black 

tupelo, or red maple,but severalsupportrare or disjunct plants.For example,GoosePond supports 

numerousrare herbaceousplants (BenhamGroup, 

1989),and a karst pan north of Sinking Pond contains 

a locally rare standof water tupelo (Wolfe, 1996).The 

wetland vegetationin many small ridge-top panscontrastssharply with the surroundingupland vegetation. 

Compound sinks arerelatively large, steepsideddepressionsthat include severaldiscreteor coalescedsinkholes.The largestcompoundsink at AEDC 

is the main body of Sinking Pond. Other examples 

include a tributary basin northwest of Sinking Pond 

andthe northern part of Westall Swamp.Diametersof 

thesedepressionsrangefrom about 50 m to greater 

than 500 m. Overall depthsare generally greaterthan 

3 m. Compound sinks are distinguishedby complex 

internal drainagenetworks and intermittent surface 

outlets.Typically, the internal drainagenetworks consist of elongatedor coalescedsinkholesconnectedby 

well-defined channels(fig. 4). Other karst featuresat 

AEDC include small, well-drained sinkholeson slopes 

area. 

and ridges,vertical shaftsas deepas7 m, and slopebreak springs(Wolfe, 1996). 

Soils, Vegetation, and Climate 

Soilsbelongto the Dickson-Mountview-Guthrie 

soil associationandconsistchiefly of Ultisols developedon a thin (cl .5 m), silty mantle overlying cherty 

limestoneresiduum (Love and others, 1959; Springer 

andElder, 1980;Smalley,1983;Patterson,1989).The 

Dickson silt loam andMountview silt loam are the 

most important soils on well-drained slopesand 

ridges.Both of thesesoils are strongly to very strongly 

acid, moderatelypermeablein their surfacehorizons, 

and low in fertility; they differ primarily in that the 

Dickson soil hasa discontinuousfragipan (relatively 

impermeablelayer) at the baseof the silty upper mantle (Love and others, 1959). 

The Guthrie silt loam is the characteristicsoil of 

headwaterwetlandsin The Barrens.This soil is developedon parentmaterialssimilar to thoseof the DicksonandMountview soils andcontainsa discontinuous 

fragipan. It is strongly to very strongly acid and low in 

fertility. The Guthrie silt loam differs from the Dicksonsilt loam primarily in its poor drainageand landscapeposition. The most extensiveoccurrencesof 

Guthrie silt loam occupy the bottoms of intermittent 

headwaterstreamsand sinkholes.Small patchesof 
Figure 4. The internal drainage system of a compound sink northwest of Sinking Pond. 

Dark moss lines at the bases of trees mark normal seasonal high water level. 

this soil occur aswet inclusions within the Dickson silt 

loam and other upland soils on ridgetops.Other soils 

within the associationarethe moderatelywell-drained 

Sang0silt loam and the somewhatpoorly-drained Taft 

(formerly Lawrence) silt loam (Love andothers, 1959; 

Patterson,1989). 

Vegetationis generally correlatedwith topography, drainage,and soil (Patterson,1989).Well-drained 

ridges and slopessupportdeciduoustreessuchas scarlet oak, southernred oak, and mockemut hickory, 

except where clearedor planted in pines.Moister, 

moderatelywell-drained slopesarecharacterizedby 

white oak, hornbeam,sourwood,and yellow poplar. 

The vegetationof poorly drained sitescommonly 

includes sweetgum,black tupelo, red maple, and willow oak. Someof the wettest sitessupport standsof 

coastal-plaintreessuch asovercup oak, and water 

tupelo (BenhamGroup, 1989;Patterson,1989).Other 

poorly drained sitesare occupiedby emergentherbaceousvegetationand shrubs(BenhamGroup, 1989). 

Long-term weatherrecordsfor Tullahoma,Tennessee,nearthe southwestboundaryof AEDC, arerepresentativeof averageconditionsin the studyarea.Mean 

annualprecipitationis 1,438millimeters(mm). Monthly 

meanprecipitationrangesfrom 83 mm in Octoberto 

171mm in March. Monthly meantemperaturesrange 

from 3.50 “C in Januaryto 25.11OCin July (National 

OceanographicandAtmosphericAdministration,1991). 

Hydrogeology 

The bedrock geology of the EasternHighland 

Rim is dominatedby gently dipping Mississippian 

limestonesand inter-beddedchertsand shales.Most of 

the AEDC areais mappedasUpper Mississippian 

Warsawand St. Louis Limestones(Wilson, 1976). 

Both units areheterogeneous,including lensesand 

bedsof sand,silt, and chert. In the studyarea,both formationsare weatheredto clay-rich residuumwith 

inclusions of chert and limestone.The uppermostunit 

of relatively unweatheredbedrock is the Lower MississippianFort PayneFormation. The Fort PayneFormation consistsprimarily of chert, limey chert, and 

cherty limestonewith interbeddedunits of shaleand 

shaleylimestone.The Fort PayneFormation is underlain by the Upper Devonian/Lower Mississippian 

ChattanoogaShale(Wilson, 1976;Burchett, 1977; 

BenhamGroup, 1989). 

The primary aquifers in the study areaare,from 

top to bottom, the shallow aquifer, the Manchester 

aquifer, and the Fort Payneaquifer. The shallow aquifer consistsof 1.5to 23 m of clay-sizedchert and 

includesthe soil cover and root zone.The Manchester 

aquifer, a product of the weathering of the lower 

6 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
WarsawLimestone andthe Fort PayneFormation 

(Burchett and Hollyday, 1974), is the most productive 

aquifer, and the most complex. The upper part of the 

Manchesteraquifer consistsof chert gravel, weathered 

limestone,and rubble. The lower part includesfractures and solution openingsin bedrock. Theseopenings are most common nearthe top of bedrock in the 

Fort PayneFormation, but someare 25 m or more 

below the top of bedrock (Haugh and others, 1992). 

The Fort Payneaquifer consistsof that part of the Fort 

PayneFormation which is relatively dense,with few 

small fractures or solution openings.The thicknessof 

this aquifer is variable, dependingon the depth of the 

weatheringprofile. 

ln general,the northern part of the baseis characterizedby weatheringprofiles lessthan 15 m thick 

(Haugh and others, 1992) and a high concentrationof 

solution openingsin the Fort PayneFormation (Haugh 

andMahoney, 1994).The shallow aquifer andthe 

upper part of the Manchesteraquifer are better developed in the southernpart of AEDC where the regolith 

is relatively thick and rich in coarse-grainedchert. 

The relatively greaterdensity and coherenceof the 

Fort PayneFormation in the southernpart of AEDC 

limit ground-waterflow in the lower part of the 

Manchesteraquifer (C.J. Haugh, U.S. Geological Survey, oral commun., 1995). 

Sinkhole wetlandsat AEDC fall into two major 

geomorphicclasses:karst pansand compoundsinks. 

Both types aregenerally connectedto fluvial systems 

with drainageareasof lessthan 5 km2 but karst pans 

are more numerousand occupy a wider variety of 

landscapepositionsranging from ridgesto thebottoms 

of small headwaterhollows. Compound sinks invariably occupy headwatervalley bottoms.The two wetland typesalso differ in their internal geometry.Karst 

panshaverelatively flat internal topography and 

depthsof lessthan 1.5m. In contrast,compoundsinks 

haverelatively complex internal topographycomprising severalintermittent, funnel-shapedsinkholes, 

someof which havecoalescedto varying degrees,and 

well-developedinternal channels;compoundsinks 

generally havedepthsgreaterthan 2.5 m. 

The geomorphicdifferencessuggestdifferences 

in water regime andhydrologic functions. On thebasis 

of field observations,it was hypothesizedthat: 

1. Karst panshave lower maximum flooding depths 

than compound sinks. 

2. Karst pansarerelatively isolatedfrom the 

ground-water system. 

3. Compoundsinks areclosely connectedto the 

ground-water system. 

Site Selection and Data Collection 

Surface-waterstageand ground-water levels 

were monitored in or near five wetland sites(fig. 5). 

The monitored wetlandsinclude Sinking Pond, 

WestallSwamp,GoosePond,andtwo depressionsthat 

overflow into Sinking Pond. One of the tributary 

depressions,north of Sinking Pond, supportsa locally 

rare standof water tupelo and is referred to as “Tupelo 

Swamp” in this report. The secondtributary depression, designated“Willow Oak Swamp” in this report, 

is northwest of Sinking Pond. 

Sinking Pond,Westall Swamp,andWillow Oak 

Swampare seasonallyflooded compoundsinks that 

supportforestsof water-tolerantoaksand other trees. 

Sinking Pond and Willow Oak Swampcontain welldevelopedinternal drainagesystemswith depthsof 

3 to 4 m. The internal drainagesystemat Westall 

Swampis disruptedby a constructedberm that separatesthe pond’smain body from its natural internal 

drain. The drain receivesflow through a pipe in the 

berm. The bottom of the main body of Westall Swamp 

is about0.8 m higher than the bottom of the internal 

drain. GoosePond and Tupelo Swampare karst pans 

with depthslessthan 1.5 m. 

Pond stageswere monitored with continuousstagerecordersat Sinking Pond,Tupelo Swamp, 

Westall Swamp,and GoosePond and with a creststagegageat Willow Oak Swamp. Streamflow was 

monitored in two channelsflowing into and out of 

Sinking Pond.The channelrunning from Tupelo 

Swampto Sinking Pond,designatedSinking Pond 

inflow (fig. 5), drains an areaof 0.57 km2, about 

17 percentof the 3.34 km2 catchmentof Sinking Pond 

(table 1). Sinking Pond outflow was locatedat a culvert southand downstreamof Sinking Pond (fig. 5). 

The Sinking Pondcatchmentrepresents84 percentof 

the 3.99 km2 drainedby the Sinking Pond outflow 

gage(table 1). 

Daily rainfall was monitored with two tippingbucketrain gages,oneat Westall Swampandthe other 

at Rowland Creek, about 5 km from Westall Swamp 

(fig. 5). Data from the Rowland Creek rain gagewere 

usedasestimatesfor rainfall in the Sinking Pond/ 

Hydrology7 

HYDROLOGY
Map based on U.S. Geological Survey Manchester topographic quadmgle, scale 1:24,000 

EXPLANATION 

* 354 WE!LLLOCATIONANDNUMBER - ROADS 

A CONTINUOUS STAGE RECORDER - HYDROGIM’HY 

a coNTINuous s- W STATION 1 KILOMETERS 

Oo;5 * RECORDING RAIN GAGE 0 0.6 1 MILES 

0 CRESTSTAGE GAGE 

Figure 5. Location of monitored wetland sites and wells, Arnold Engineering Development Center. 

8 Hydrobogy and Tres-Obtrlbutlon Patterns of Karst Wetlands at 

Arnold Englneerlng Development Center, Tennessee 
Table 1. Gage data for surface-water stations at Arnold Engineering Development Center wetlands 

[d-m-s, degrees-minutes-seconds; masl, meters above sea level; km*, square kilometer] 

Station name 

Tupelo Swamp 

Willow Oak 

Swamp 

Sinking Pond 

inflow 

Sinking Pond 

Sinking Pond 

outflow 

Westall Swamp 

GoosePond 

USGS site Latitude and Station type Gage Drainage 

identification longitude datum area 

number (d-m-s) (masl) (km*) 

03596073 3.5”25’ 07” N Continuous 325.215 0.135 

86O03’ 45” w stage 

3525090860410 35” 25’ 09” N Creststage 312.80 .785 

86” 04’ lo” w 

03596074 35” 25’ 04” N Continuous 313.24 .570 

86’ 03’ 32” W streamflow 

03596075 35” 24’ 36” N Continuous 321.03 3.351 

86” 04’ 11” w stage 

035960755 35“ 24’ 00” N Continuous 308.575 3.996 

86” 03’41” w streamflow 

035960815 35’ 24’ 41” N Continuous 322.125 1.512 

86” 04’ 46” W stage 

035785012 35’ 23’ 11” N Continuous 322.03 .318 

86” 01’ 33” w stage 

Westall Swamp areaduring the period October 1,1992 

through November 5,1992. 

Ground-water levels were continuously monitored at eight wells (fig. 5) to assessthe relation of 

wetland water regimes to the local ground-water system. Seven new wells were constructed near the wetland sites, and one pre-existing well in the study area 

was monitored. 

Two wells were constructed at Sinking Pond. 

One well (355) was located on the southwest side of 

the pond, adjacent to the stage recorder. The second 

(356) was located on the north side of the pond. Both 

were drilled to the top of bedrock and screenedin the 

upper part of the Manchester aquifer (table 2). At 

Westall Swamp, two wells were drilled in close proximity to the stage recorder. One well (353) was drilled 

in bedrock and screenedin the lower part of the 

Manchester aquifer. The second well (354) was drilled 

to the top of bedrock and screenedin the upper.part of 

the Manchester aquifer. Similarly, wells 358 and 359 

were installed and monitored next to the Tupelo 

Swamp stage recorder; they were screenedin the 

upper and lower parts of the Manchester aquifer, 

respectively. Well 357 was drilled next to Goose Pond 

and screened in the shallow aquifer. A pre-existing 

well (198), located about 0.8 km southeast of Goose 

Pond (fig. 5) and screenedin the Fort Payne aquifer 

(table 2), was also monitored. Elevations above sea 

level were established for all wells and surface-water 

gages. 

Hydrologic measurementswere made at Sinking 

Pond, Sinking Pond outflow, Westall Swamp, and 

GoosePond from October 1992 through January 1995. 

Hydrologic monitoring at Tupelo Swamp, Sinking 

Pond inflow, and Willow Oak Swamp began in 

October 1993 and continued through January 1995. 

Continuous-stage recorders recorded surface-water 

stageevery 15 minutes. Monthly discharge measurements were made to relate discharge to the stage 

records of streamflow stations. Continuous recorders 

on wells recorded ground-water level every hour. Data 

from the continuous stage, streamflow, and groundwater level stations were reduced to daily averagesfor 

use in this report. The stage of Willow Oak Swamp 

was observed every month and crest-stage marks were 

measured.Probable dates of flood crests were estimated based on daily stage and rainfall records from 

the Sinking Pond/Westall Swamp area.Tipping-bucket 

rain gagesrecorded depth of rainfall every 5 minutes. 

The rainfall data were reduced to daily totals for use in 

this report. 

Hydrology 9 
Hydrology and Tree-Distribution Patterns of Ksrst Wetlands at 

Amold Engineering Development Center, Tennessee 
r : 

-- 

The topographyof Sinking Pond was surveyed 

to illustrate the geomorphiccomplexity of a compound sink and the relation betweensinkhole morphology and hydrologic response.A circuit of 

temporarycontrol points was establishedusing a total 

station.Vertical control was the Sinking Pond gage, 

andhorizontal control was mappedtrail intersections. 

Horizontal and vertical closure of the temporarycontrol points was lessthan 3 cm. Topographicpoints’ 

were surveyedwith a total station centeredabovethe 

temporarycontrol points. The internal topographic 

points were incorporatedin a digital elevation model 

previously establishedby AEDC and the USGS. New 

contourswere generatedusing the Lattice-Contour 

utility of the ArcInfo geographicinformation system 

328 

326 

(Environmental SystemsResearchInstitute, 1992).A 

contour interval of 1 foot (0.3048 m) was selectedto 

facilitate comparisonwith pre-existing topographic 

mapsof the areaand becausethis interval is appropriateto the sizeand relief of the surveyedarea. 

Water Levels and Discharge 

Abrupt seasonalrisesandfalls area striking feature of the Sinking Pondhydrograph.For example,on 

November 3, 1992,Sinking Pond stagerose2 m in 

lessthan 24 hours. Subsequentseasonalrisesandfalls’ 

were similar in magnitudeand abruptness(fig. 6). 

Recordedstagesin Sinking Pond,in metersabovesea 

level (masl),rangedbetweena fully drainedminimum 

-I2 SPILLWAY ELEVATION 

---_- _T 

i$ 324 I--

9 

4 322 

UY 

g

!3 320 

E POND BOTTOM 

ti 318 

3 

I 

i! 316 

WE&LB&TOM 

- SlNKlNGPoND 

\ 

MISSINO DATA \

WELL355 

s 

314 - WELL356 I 

IIIIl~~~l~‘l~~lI~~~l~~lI~l~~~ 1 

0 J A J 0 J A J 0 J 

1992 1993 1994 1995 

Figure 6. (A) Water levels in Sinking Pond and adjacent wells and (B) daily rainfall 

at Westall Swamp. 
of 321.31to a maximum of 324.81(fig. 6) with correspondingmaximum water depthsof 0 to 3.5 m. 

The frequencydistribution for Sinking Pond 

stageis distinctly bimodal. Pond stagewasbelow 

321.6 masl for 27 percentand above324 masl for 

65 percentof daysin water year 1993(October 1992 

through September1993).The intervening 2.4 m 

accountsfor 71 percentof the annualrangebut only 

8 percent of the distribution (fig. 7). Flooding came 

later in water year 1994 (fig. 6) but the shapeof the 

cumulative frequencydistribution for daily stagein 

Sinking Pond is similar to that for water year 1993 

(fig. 7). Forty-six percentof daysin water year 1994 

had stagesbelow 321.7 masl, and 41 percenthad 

stageshigher than 324 masl (fig. 7). The intervening 

2.3 m, 66 percentof the annualrange,represents 

13 percentof the distribution. 

325 I I I I 

- 1993 

- 1994 

321 

0 10 20 30 40 

The differencesin the Sinking Pondhydrographsand stage-frequencycurves betweenwater 

years1993and 1994(figs. 6 and7) suggestthat 1994 

was the drier of the 2 years.However, rainfall records 

from the Rowland Creek gageandTullahoma,Tennessee,indicate that the annualtotal rainfall for water 

year 1994was about 500 mm greaterthan that for 

1993(fig. 8). The fall and early winter monthsof 

water year 1993were wetter than the corresponding 

monthsin 1993,but the difference is relatively modest 

comparedto the annualtotal (fig. 8). Nonetheless, 

rainfall during thesemonthsandlate summerseemsto 

be a critical determinantof the hydrologic behavior of 

Sinking Pond and similar systems.At Tullahoma, 

monthly rainfall for water year 1993wascloser to the 

30-yearaveragethan were monthly totals for water 

year 1994(fig. 8). Theseobservationssuggestthat the 

I I I I I 

50 60 70 80 90 100 

PERCENT DAYS AT OR BELOW GIVEN MEAN WATER LEVEL 

Figure 7. Cumulative frequency distributions of daily mean water level in Sinking

Pond for water years 1993 and 1994. Water year begins 3 months earlier than 

corresponding calendar year. 

12 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
act Jan APr Jul Ott 

Figure 8. Comparison of daily rainfall at Rowland Creek, Arnold Engineering Development Center, with monthly rainfall at Tullahoma, Tennessee, for water years 1993 and 1994 and 

with mean monthly rainfall at Tullahoma for 1961-l 990. Tullahoma data from National 

Oceanographic and Atmospheric Administration, 1991-l 995. 

1,~ 

1,899 

1,769 

1,600 

1,500 

L400 

1,366 

Ii 

ROWLAND CREBK, 1993 X 

ROWLAND CREEK, 1994 X 

TULLAHOMA, 1993 

TULLAHOMA, 1994 X 

TULLAHOMA MONTHLY MEAN, 1961-1990 r : 

act Jan APr Jul Ott 

Figure 8. Comparison of daily rainfall at Rowland Creek, Arnold Engineering Development Center, with monthly rainfall at Tullahoma, Tennessee, for water years 1993 and 1994 and 

with mean monthly rainfall at Tullahoma for 1961-l 990. Tullahoma data from National 

Oceanographic and Atmospheric Administration, 1991-l 995. 

1993hydrographfor Sinking Pond is more representative of averageconditions than the 1994hydrograph. 

Sinking Pond stagedisplayeda closerelation to 

ground-waterlevels in nearbywells. Beginning at the 

seasonalrise, and continuing through much of the 

periods of inundation, the water level in the well on 

the southwestside of Sinking Pond (355) was essentially identical to the pond stage(fig. 6). Waterlevel in 

the well at the north end of Sinking Pond (356) rose 

0.3 to 1.5m aboveSinking Pond stageduring storms, 

then fell toward equilibrium with the pond. The head 

difference betweenthe two wells coincideswith a general north-to-south flow gradient that affects surfaceandground-water flow throughout the Sinking Pond 

area.During seasonalrecessionsin 1993and 1994, 

water levels in wells 355 and 356 fell 0.3 to 0.6 m 

below Sinking Pond stagefrom mid-May through late 

July. Ground-water levels fell rapidly asthe pond 

drained and continuedto decline after the pond was 

dry, reachingdepthsabout4 m below the pond bottom 

in October and November. 

The hydrologic responseof Sinking Pondto 

rainfall reflectsthe interaction of antecedentbasin 

conditions, ground-water levels, and sinkhole morphology. A given depth of rainfall is more likely to 

producerunoff during winter, whenevapotranspiration 

is lowest, than during other seasons.Mechanismsthat 

producerunoff in the Sinking Pondcatchmentinclude: 

1. Seepagenearslopebreaksand the up-gradient 

endsof sinkholes. 

2. Diffuse overlandflow. 

3. Intermittent channelizedflow. 

Oncerunoff is initiated, its routing within the 

pond is controlled by ground-waterconditions. When 

the local water table is below a thresholdof about 

320 masl, runoff drainsquickly into the sinkholesthat 

dominatethe interior of Sinking Pond.When the water 

tablerisesabovethe 320-maslthreshold,runoff cannot 

Hydrology 13 
infiltrate and instead remains in surface storage in the 

pond. The threshold water-table elevation for rapid 

drainage of Sinking Pond appearsto be about 

321.6 masl-about 1.6 m higher than the threshold for 

filling. 

When the water table is high enough to promote 

ponding, the surface-water responseof Sinking Pond 

to a given volume of runoff dependson antecedent 

stage. At stagesbetween 321.31 and 323.6 masl 

(below the 1,061-foot contour on fig. 9), ponded water 

is confined to the sinkholes within the pond. These 

sinkholes represent about 15 percent of the maximum 

ponded area (fig. 9) but 65 percent of the range of 

recorded stages.Within this range, a relatively small 

volume of runoff can abruptly increase surface-water 

stage by 2 m or more. At stagesabove 323.6 masl, 

ponded water overflows the interior sinkholes and 

floods the rest of the pond. 

At stagesabove 324.45 masl (the spillway elevation), Sinking Pond discharges to the Sinking Pond 

outflow channel. The maximum recorded stage in 

Sinking Pond, 324.8 masl, represents a water depth of 

0.35 m across the spillway. Overflow of Sinking Pond 

increases the effective drainage area of the Sinking 

Pond outflow gage from 0.65 km2 to 3.99 km2. The 

sixfold increase or reduction of effective drainage area 

results in relatively rapid fluctuations in streamflow. 

Daily mean discharges at the Sinking Pond outflow 

gage south of Sinking Pond ranged from 0 to 

1.23 cubic meters per second (m3/s) (fig. 10). 

The hydrographs of two headwater sub-basins, 

Willow Oak Swamp and Tupelo Swamp, illustrate 

some of the geomorphic controls on runoff in the 

Sinking Pond catchment. The importance of these tributary depressions in routing surface runoff to Sinking 

Pond became evident from field observations during 

1993. Water levels were monitored beginning October 

1993 to determine interaction between these basins 

and Sinking Pond. 

Willow Oak Swamp contains a prominent sinkhole about 3 m deep. Observed stagesin Willow Oak 

Swamp ranged from 322.82 masl under fully drained 

conditions to 325.88 masl (fig. 11). Filling and draining of this depression follows a pattern similar to that 

of Sinking Pond. However, this sub-basin begins to fill 

later than Sinking Pond and drains earlier (fig. 11). 

The difference in timing of seasonalrises and recession probably reflects the difference in the bottom elevations of the two ponds but also may indicate 

connection to a different point in the subsurface conduit flow system. Willow Oak Swamp, like Sinking 

Pond, acts as a closed basin for most of the time, but 

overflows into Sinking Pond when its surface storage 

is exceeded. 

Tupelo Swamp differs from Sinking Pond and 

Willow Oak Swamp in its relatively shallow depth 

(about 1 m), flat internal topography, and the absence 

of a visible internal drain. Tupelo Swamp rarely 

behaves as a closed basin, but overflows throughout 

the winter and early spring. Seasonalflooding generally occurred earlier and persisted longer than in Sinking Pond or Willow Oak Swamp. During water year 

1994, stage in Tupelo Swamp ranged from 326.11 

(fully drained) to 327.20 masl (fig. 12). The range of 

stage in Tupelo Swamp was roughly one third as large 

as the ranges observed at Sinking Pond and Willow 

Oak Swamp. 

Both wells at Tupelo Swamp were subject to 

rapid rises and falls, essentially simultaneous to the 

responsesof other wells and surface-water stagesin 

the Sinking Pond area (figs. 6 and 12). Ground-water 

levels at Tupelo Swamp remained lower than pond 

stage throughout the study (fig. 12). The constant 

downward gradient between surface water in Tupelo 

Swamp and the water table contrasts with the close 

connection between Sinking Pond stage and the local 

ground-water system. Soil borings revealed a clay-rich 

layer about 1 m below the bottom of Tupelo Swamp. 

Periodic probing showed that the soil above this layer 

remains at or near saturation even when the pond is 

dry but that the underlying material is unsaturated 

throughout the year. The low permeability of the pond 

bottom and the absenceof a discrete internal drain 

contribute to the relatively long hydroperiod of Tupelo 

Swamp. 

Overflow from Tupelo Swamp discharges to the 

Sinking Pond inflow channel. Discharge at this site 

remained less than 0.15 m3/s throughout the period of 

record. The intermittent channel generally remained 

dry throughout the summer and fall. The earliest winter flows generally followed ground-water emergence 

in the interior sinkholes of Sinking Pond but preceded 

the filling of Sinking Pond. Daily mean flow at this 

station reached or exceeded 0.1 m3/s during four 

storms between January and April 1994 (fig. 13). 

The water regime of Westall Swamp closely 

resembles that of Sinking Pond in the abruptness of 

14 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
-- 

SPILLWAY 

\ h 

pogmphic survey by W.J. Wolfe, 1993. 

0 76 160 226 METER6 I I I I 

0 300 600 BOO FEET 

EXPLANATION 

- ------+ -m FLOW PATH 

,1m (323.‘)- TOPOGRAPHICDEPRESSIONCO~OUR-SHOWS 

___- “---- .--- ELEVATION OF LAND SURFACE.CONTOURINTERVAL 

1 FOOT (0.3048 METER). DATUM IS SEA LEVEL. 

Figure 9. Topography of Sinking Pond. 

Hydrology 15 
d 

-- 

325 

iI 324 

9 

I? 321 

s 

320 

100 

--I - SINKING POND STAGE 1.2 - SINKING POND OUTFLOW 

. I 

MISSINCI 

DATA d 

- B DAILYRAINFXLLATWESTAILSWAMl 

1.1 g 

1.0 # 

.09 i 

0.8 2 

0.4 % . 

0.3 g 

%

0.2 8 

0.1 g 

I I I I I I l I II I 11 1 I 11 I f I 11 ’ I l I I l I II 

0 J A J 0 J A J 0 J 

1992 1993 1994 1995 

Fi ure 10. Relation of daily mean discharge at Sinking Pond outflow gage to 

(A! stage in Sinking Pond and (6) rainfall at Westall Swamp. 

16 Hydrology and Tree-Dlatrbution Patterns of Karst Wetlands at 

Amold Engineering Development Center, Tennessee 
326 I I I I I I I I I I I I I 

a- -c 

I ‘0 

I \ 

325 

2 

m 324 

9 

s

UY 

ii 323 

54 

& . 

!2Y 322 POND BOll’OM 

I! 

s 

321 

MISSING DATA 

- l - WILLOWOAKSWAMP 

- sINKlNciPoND 

l320 I I I I I I I I I I I I I 

Ott Jan Apr Jul act 

1993 1994 

Figure 11. Water levels in Willow Oak Swamp and Sinking Pond. 

HYdtolosy 17 
-- 

328 

326 

4 

3 324 

9 

s 322 

m 

E! B 320 

5 

$ 318 

!Y 

El 316 

iz 314 

- TUPELOSWAMP 

WELL358 

- WELL359 

100 ALL’AT WESTALL SWAMP 

0 J A J 0 J A J 0 J 

1992 1993 1994 1995 

Figure 12. (A) Water levels in Tupelo Swamp and adjacent wells and (8) daily 

rainfall at Westall Swamp. 

18 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
A - TUPELO SWAMP STAOE 

- slNKlNGPoNDINFLow 

ISSINff DATA -j 

MIssn 

DATA

IJf 

B I DAILY RAINF’ALL AT WESTALL SWAMP -I 

I II III II III II III II 

act Jan APT Jul OCi Jan 

1993 1994 1995 

Fl ure 13. Relation of daily mean dischar e at Sinking Pond inflow gage to 

(Aystage in Tupelo Swamp and (B) rainfalBat Westall Swamp. 

seasonalrises and recessions, the bimodal frequency 

distribution of surface-water stage, and the close connection between surface-water stageand ground-water 

levels. Surface-water stage in the main body of 

Westall Swamp (west of the constructed berm) ranged 

from 322.5 masl (fully drained) to 325.2 masl with 

corresponding water depths of 0 and 2.7 m. Stages 

between 322.6 and 324.5 masl, about 70 percent of the 

observed range of stage, accounted for only 7 percent 

of the stage distribution for water year 1993 and 

12 percent of the distribution for water year 1994. 

Ground-water levels in two adjacent wells stayed 

within 0.06 m of each other and of Westall Swamp 

stage during much of the flooding season(fig. 14). 

Water levels in both wells dropped below the pond 

bottom during the seasonalrecessions. Head differences between the two wells greater than 0.3 m 

occurred only when the pond was dry, notably in 

November and December of 1993 (fig. 14). 

Westall Swamp fills and drains in responseto 

the same controls that determine the filling and draining of Sinking Pond. Surface runoff flows through 

Westall Swamp and drains into a prominent sinkhole 

east of the constructed berm. As with Sinking Pond, 

surface water ponds after the local water table reaches 

a certain threshold elevation and persists until the 

water table recedesto a second threshold. The watertable threshold for filling Westall Swamp is about 

320 masl, and the threshold for draining is about 

323.5 masl. 

The surface-water regime of Goose Pond and its 

relation to the ground-water system are much more 

similar to those of Tupelo Swamp than to the other 

sites examined in this study. Surface-water stage 

Hydrology 19 
a 

-- 

328 1 

326 

3 

ii 324 

25 

3 322 

v1 

E! 5! 320 

El 

t 318 

3 

B 316 

$ 

314 

100 

EN 2 80 

$1: 

20

24 

0 

I” I” I ’ ’ I ” I’ ’ I ” I ” I ’ ’ I ” I’ 

A 

MISSINC3DATA 

- WESTALL SWAMP 

WELL354 

- WELL353 

B DAILY RAINFALL AT WESTALL SWAMP 

0 J A J 0 J A J 0 J 

1992 1993 1994 1995 

Figure 14. (A) Water levels in Westall Swamp and adjacent wells and (B) daily rainfall 

at Westall Swamp. 

in Goose Pond ranged from 325.2 to 325.9 masl 

(fig. 15), the narrowest range of the five monitored 

wetland sites. The frequency of water depth in Goose 

Pond was relatively evenly distributed within that narrow range. The pond bottom remained saturated 

within 0.15 m of the surface throughout the study 

period. Ground-water levels in nearby wells remained 

consistently below Goose Pond stage throughout the 

study period. The hydrograph for the shallow-aquifer 

well (357) next to the Goose Pond gage displays relatively steady rises and falls and a lag in its responseto 

rainfall events compared to that of the pond (fig. 15). 

Water levels in well 198, about 1.2 km southeast of 

Goose Pond and screenedin the Fort Payne aquifer, 

were consistently 6 to 10 m below Goose Pond stage 

and lower than water levels in the shallow aquifer at 

Goose Pond (fig. 15). 

Geomorphic Controls of Wetland Water 

Regimes 

Hydrologic monitoring revealed two contrasting 

styles of wetland water regime corresponding to the 

two major geomorphic classes of sinkhole wetlands at 

AEDC. Three compound sinks, Sinking Pond, Westall 

Swamp, and Willow Oak Swamp, share the geomorphic characteristics of about 3 m of internal relief and 

plainly visible sinkhole drains. Surface-water stagesin 

Sinking Pond and Westall Swamp rise and fall 

abruptly (2 m or more during 1 to 3 days) and reach 

20 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
-- 

328 

326 

3 

a 324 

9 

s 322 

v) 

B

54 320 

& 

i 318 

3 

n 316 

s 

314 

1’ 1 II 1 II 1 II 1 II I I I I I II 1 II 1 II I r 

A POND BOTTOM 

I 

- GOOSEPOND 

WELL357 

- WELL 198 

t I I I I II I I I I I I I I I I I I I I I I I II,, I I 

II I II I II I II 1 II, I ,,,,,,I, ,- IB I 

_ DAILY RAINFALL AT ROWLAND CREEK I 

I I I I II I I I I I, I I, I , , 1, , 1, , I,, I, 

0 J A J 0 J A J 0 J 

1992 1993 1994 1995 

Figure 15. (A) Water levels in Goose Pond and nearby wells and (B) daily rainfall at 

Rowland Creek. 

Hydrology 21 
E -- 

maximum depths of about 3 m (fig. 16). Surface water 

in these compound sinks interacts closely with ground 

water. The interactions include water-table control of 

sinkhole drainage and rapid fluctuations of the water 

table in responseto recharge. 

In contrast to the compound sinks, two karst 

pans, Tupelo Swamp and Goose Pond, have depths of 

less than 1.5 m and lack visible internal drains. Surface water in both karst pans is isolated from ground 

water by relatively impermeable bottom material that 

acts as a confining layer. The two karst pans fill and 

drain less abruptly than the compound sinks and have 

longer hydroperiods. For example, Tupelo Swamp and 

Goose Pond filled in December 1993 and retained 

water through September 1994. Sinking Pond and 

Westall Swamp filled in January 1994 and drained in 

July 1994 (fig. 16). 

The general patterns of the water regimes in 

compound sinks and karst pans observed at AEDC 

reflect geomorphic and hydrologic controls that determine the water regimes of sinkhole wetlands in other 

settings. These controls include: 

1. Sinkhole geometry. 

2. Connection to the ground-water system. 

3. Bottom elevation relative to normal range of 

water table. 

4. Periodicity of water-table fluctuation. 

5. Drainage-basin characteristics (basin area,relief, 

ground cover, and other factors affecting runoff 

generation). 

The relative importance of these factors varies 

from site to site. Karst pans such as Tupelo Swamp 

and Goose Pond are poorly connected to the groundwater system and therefore relatively insensitive to 

either the elevation range or periodicity of water-table 

fluctuations. Analogous sites have been described in 

the Coastal Plain of southwestern Georgia (Hendricks 

and Goodwin, 1952) and the Valley and Ridge of 

northwestern Georgia (Greear, 1967). In all these 

cases,pan depth approximated maximum flooding 

327 

326 

d 

9 325 

2 

B 324 2-

!4

3 323 

I! 

5 

322 

321 

I I , I I I I I I 1 I I 1 

/ hd!WNCi DATA ’ 

- QCXXBFGNDSTAGB 

- WJJSTALLSWAMPSTAGE 

SJNKINGPGNDSTAGE 

Ott Jan 

1993 

Figure 16. Comparison of water levels in four wetland sites at Arnold Engineering 

Development Center during the period October 1993 through January 1995. 

22 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Englneering Development Center, Tennessee 
depthwhether the water table remainedbelow the 

pond bottom or roseaboveit in wet seasons.At AEDC 

and in the Georgia studies(Hendricks and Goodwin, 

1952;Greear,1967),basin runoff was sufficient to 

completely fill karst pans,and shallow pan depthslimited maximum stageto an elevation typically 5 to 

40 cm abovethe spillway. 

Sinkhole depth limits maximum potential flooding depth in compoundsinks and other deep(>2 m) 

depressions.However, basin characteristics,connection to the ground-water system,and the rangeand 

periodicity of water-tablefluctuations play a role in 

determining whether maximum potential flooding 

depth is realized.At AEDC, deepcompoundsinks 

suchas Sinking Pond,Westall Swamp,and Willow 

Oak Swampgenerally haveefficient internal drains. 

Thesedepressionsoverflow when (1) ground-water 

levels rise sufficiently to block internal drains to the 

underlying aquifer, and (2) subsequentrainfall generatesrunoff sufficient to fill the pond. Theseconditions 

tend to occur more frequently and persistlonger in 

lower-elevation sinks with larger drainageareassuch 

asSinking Pondthan in higher sinks with smaller 

drainageareassuchasWillow Oak Swamp. 

Greear(1967) documenteda generalcorrelation 

betweengreatersinkhole depth and better internal 

drainagesimilar to that describedat AEDC. One 

important difference wasthat ground-water levels 

remainedbelow the bottom elevationsof both deep 

andshallow ponds(Greear,1967).The combinationof 

unimpededinternal drainageand greatersinkhole 

depthpreventeddeeperpondsfrom overtlowing during Greear’s(1967) study.In contrast,the sinkhole 

wetlandsstudiedby Hendricks and Goodwin (1952) 

displayedno relation betweendepth and internal 

drainageefficiency. All of thesesinkholesreceived 

sufficient runoff to causeoverflowing (Hendricks and 

Goodwin, 1952).Deepersinkholesgenerally had 

longer hydroperiodsthan shallow sinks because 

greaterevapotranspiration’was necessaryto dry them 

out in the absenceof internal drainage.This relation 

betweenhydroperiod and sinkhole depth is opposite 

that observedat AEDC and in Greear’s(1967) study 

where deepersinkholeswith efficient internal drains 

dried out faster than shallow sinkholeswith poor internal drainage. 

At AEDC, sinkhole depth and the presenceor 

absenceof visible evidenceof internal drainageare 

good indicators of relative hydroperiods,flooding 

depths,and ground-water influence.Theseindicators 

arepotentially useful managementtools because 

assessingthem is rapid, simple, and inexpensivecomparedwith hydrologic monitoring. However, evidence 

from karst wetlandsin other settingsshowsthat the 

relation betweengeomorphic featuresand water 

regimesvariesamong and within regions, depending 

on hydrogeologic conditions. Extrapolating the patterns observedat ABDC to other areaswithout local 

hydrologic datacould producehighly erroneous 

results.Nonetheless,the samegeomorphicand hydrologic processesthat control water regimesin the sinkhole wetlandsat AEDC-sinkhole development, 

runoff generationandrouting, ground-waterperching, 

andconcentratedrecharge-exert analogouscontrols 

in other karst wetlands. 

TREE-DISTRIBUTION PAlTERNS 

The geomorphicallycontrolled water regimesof 

the sinkhole wetlandsat AEDC haveecological significance.Seasonalpatternsof flooding and soil saturation are important controls of wetland plant 

distribution (Cowardin and others, 1979;Carter, 1986; 

Gill, 1970).At AEDC and similar settings,karst wetlandssupporta wide variety of disjunct plants (Benham Group, 1989;Ellis and Chester,1989;Patterson, 

1989).The water regimesof karst wetlandsenabledisjunct wetland plants to survive in isolatedpocketsfar 

from their normal ranges(Barclay, 1957;Greear, 

1967).This investigation examinesthe relation of 

water regime to the distribution of disjunct and local 

wetland tree speciesin karst depressionsand intermittent drainagewaysat AEDC. 

Wetlandtreesat AEDC can be groupedaccording to their normal geographicrange(local or disjunct 

in The Barrens) and their inherent affinity to wetland 

settings.Table 3 lists the normal geographicranges 

and site preferencesof six prominent wetland tree species found at AEDC. Two of thesespecies,water 

tupelo and overcup oak, are coastal-plaindisjuncts 

that occur nearly exclusively in wetland sitesunder 

natural conditions. The third species,willow oak, is 

common in The Barrenswhere it usually occupieswet 

depressionsand streambottoms. The three remaining 

species,sweetgum,black tupelo, andred maple, are 

amongthe most widely distributed andadaptabletrees 

in North America. All are common in The Barrens 

wherethey occupy a wide rangeof wetland and 

upland sites.Other local tree speciesthat are ableto 

exploit somewetland sites,but are not restrictedto 

Tree-Distribution Patterns 23 
Table 3. Normal geographic ranges and preferred site characteristics for six wetland tree species at Arnold 

Engineering Development Center 

Tree Normal geographic range Preferred site characteristics 

species 

Water 

tupelo 

Overcup 

Oak 

Willow 

Oak 

Atlantic and Gulf CoastalPlainsnorth to 

southeasternVirginia and southern 

Illinois; rare disjunct in Interior Low 

Plateaus(Johnson,1990). 

Atlantic andGulf CoastalPlainsfrom 

northwesternFlorida north to Delaware 

andsouthernIllinois and Indiana;rare 

disjunct in Interior Low Plateaus 

(Solomon, 1990). 

Atlantic CoastalPlain from New Jersey 

to SouthCarolina; southernUnited States 

from southeasternTexasto southern 

Illinois to northwesternFlorida; endemic 

to Interior Low Plateaus(Schlaegel,1990). 

Sweetgum SoutheasternUnited Statesexcept 

Black 

tupelo 

Red 

maple 

southernFlorida andhigh elevationsin 

the Appalachians;Atlantic CoastalPlain 

north to southwesternConnecticut; 

endemicto Interior Low Plateaus 

(Kormanik, 1990). 

EasternUnited Statesexceptfor lower 

Mississippi River Alluvial Plain; 

southernMaine to centralFlorida, west 

to easternOklahoma,north to southern 

Ontario; endemicto Interior Low 

Plateaus(McGee, 1990). 

EasternNorth America from 

Newfoundlandsouthto southernFlorida, 

westto southeasternTexas,north to 

Wisconsin,northwestto southeastern 

Manitoba; endemicto Interior Low 

Plateaus(Walters andYawney, 1990). 

wetlands, include American hornbeam, eastern 

Deepswampsand wet depressionsand sloughs;preferssiteswith soil at 

or nearsaturationthroughoutgrowing season;toleratesprolonged 

flooding to 4 m andoccasionalflooding to 6 m; seedsdevelopbestin 

saturatedsoil with shallow periodic flooding by flowing water 

(Johnson,1990). 

Poorly drained,clay-rich alluvial soils of southernriver flood plains, 

shallowswampsandsloughs,first bottomsandterracesof large 

streams;toleratescontinuousflooding through two growing seasons 

or longer; growsbest in well-drained, loamy soil, but natural 

occurrencein upland sitesis rare (Solomon, 1990). 

Higher siteson first andsecondbottoms of major streams;minor stream 

bottoms,wet uplandflats anddepressions;rare in upland sites; 

toleratesepisodicgrowing-seasonflooding; requiresamplesoil 

moisturebut intolerantof prolongedsoil saturation;grows bestin 

deep,loamy, uncompactedsoils with water-tabledepthof 0.6-1.8 m 

androot-zonepH between4.5 and 5.5 (Schlaegel,1990). 

Adaptedto a wide rangeof soil characteristicsandmoistureconditions; 

commonalong streambottoms,wet depressions,andon well-drained 

slopesandridges;grows bestin medium texturedsoils without 

hardpanand with moderateto good internal drainage;seedlings 

moderatelytolerant of completeinundationfor aslong as 10days 

(Hosner, 1960;Kormanik, 1990). 

Grows on a wide variety of sitesfrom seasonallyflooded river bottoms 

to well-drainedslopesandridges;growsbeston well-drainedfloodplain sites;maturetreestolerant of flooding during growing season 

for 21 daysor longer (Broadfoot and Williston, 1973;McGee, 1990). 

Thrives over an extraordinaryrangeof soil characteristics,moisture 

availability, temperaturerange;suitablesitesrangefrom sandridges 

to peatbogsandswamps;grows best in moist, well-drained soil, but 

commonly found in siteswith extremesoil-moistureconditionseither poorly or excessivelydrained;commonin southernswamps, 

flood plains, andwet depressions;seedlingsmoderatelytolerant of 

completeinundationfor aslong as 10days(Hosner, 1960;Walters 

andYawney, 1990). 

table 4). The transects were located and oriented to 

hophornbeam, and pawpaw. The spatial distribution of cross areasof forested wetlands along soil-moisture 

these and other tree species were evaluated across a and flood-duration gradients. Six transects crossed 

range of hydrologic conditions to relate tree distribu seasonally flooded ponds. Two transects were estab

tion to elevation and water levels. lished across Sinking Pond (Al -A2 and B 1-B2) and 

two across Tupelo Swamp (Cl-C2 and Dl-D2). 

Transect Locations and Sampling Methods Transect Al -A2 and Dl -D2 crossed shallower parts of 

Sinking Pond and Tupelo Swamp, respectively, near 

Ten transects, 150 to 800 m in length, were the transitions between the disjunct trees and more 

established in the Sinking Pond area (fig. 17 and typical local wetland trees. Transects B 1-B2 and 

24 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
-

Pondmarginsmodifiedfrom Patterson,1989 

EXPLANATION - DRAINAGE DIVIDE 

- PONDMARGIN 

- - + INTERMITTENT FLOW PATH 

_- ^ ROAD 

_____ _ 

A CONTINUOUS STAGE RECORDER 

A CONTINUOUSSTREAMFLOW STATION 

a’ CREST STAGE GAGE 

LOCATION AND DESIGNATION OF 

VEGETATION TItANSEm 

Figure 17. Location of vegetation transects in the Sinking Pond area. 

Tree-Dktributlon Patterns 25 
Table 4. Summary of lengths, areas, and forest density for vegetation transects in the Sinking Pond area 

[m.meters;m*,squaremeters;Ire&l00 m*,treesper100 squaremeters; cm*/m*, squre. centimeters per squaremeter] 

Transect 

Al-A2 

Bl-B2 

Cl-C2 

Dl-D2 

El-E2 

Fl-F2 

Gl-G2 

Hl-H2 

H-12 

Jl-J2 

Stem 

‘Number density 

Geomorphic Length Area Of 2Number (treed Basal area 

setting ON (m2) species of trees 100 m2) (cm2/m2) 

Compoundsink 793 2,898 30 427 15 38.0 

Compoundsink 730 2,671 24 332 12 41.2 

Karst pan 209 766 18 171 22 58.1 

Karst pan 189 692 13 115 17 43.5 

Channel 168 614 17 265 43 36.1 

Compoundsi@ 373 1,363 15 178 13 30.5 

Swale 426 1,557 20 543 35 25.9 

Swale 181 663 18 169 25 36.1 

Compoundsink 244 892 16 148 16 35.6 

Channel 176 643 21 276 43 30.3 

‘Includes plant varieties identified to genusonly; details given in text andAppendix 2. 

2Vucciniumspp.andAzalea spp. were not enumerated. 

Cl-C2 crossedthe deeperparts of Sinking Pond and 

Tupelo Swamp,through the coresof the disjunct 

stands..TransectFl-F2 bisectedWillow Oak Swamp 

near the crest-stagegage,and transectI1-12crosseda 

small sinkhole pond along the Sinking Pond outflow 

’ channel. 

Two transectscrossedintermittent drainageways that carry flow into the north end of Sinking 

Pond: transectEl -E2, on the channelfrom Tupelo 

Swampto Sinking Pond, and transectGl-G2, on the 

broad drainagewaybetweenWillow Oak Swamp and 

Sinking Pond.The two remaining transectscrossed 

the Sinking Pond outflow channel:transectHl-H2, 

about 100 m downstreamof the Sinking Pond spillway, and transectJl-52 acrossa relatively welldevelopedchannelabout 300 m north of the Sinking 

Pond outflow gage. 

Land-surfaceelevationsin metersabovesea 

level were surveyedto the nearest0.01 m along the 

10 vegetationtransectsusing vertical control from the 

nearestsurveyedgage.Horizontal distancealong the 

transectswas measuredto the nearest0.3 m with a 

fiberglasstape. Breast-heightdiameter (DBH) of trees 

and saplingswas measuredto the nearest0.5 cm and 

usedto calculatebasalarea.All treesand saplings 

within a 4-m wide swath along eachtransectwere 

identified, measured,and counted.Land-surfaceelevation at the baseof eachtree was assumedto equal that 

along the centerline of the transectat the samehorizontal distance.Horizontal distance,elevation, species, andDBH were noted for eachindividual tree and 

sapling. 

Daily recordsfrom the continuous-stagerecorders were usedto relate tree elevationsto flooding duration along the transectsthrough Sinking Pond and 

Tupelo Swamp.A similar relation was developedfor 

the Willow Oak Swamptransect,basedon linear interpolation betweenthe periodic stageobservationsand 

crest-stagemarks.Water year 1994(October 1993 

through September1994)was selectedasthe period of 

comparisonbecausestagewas monitored in the three 

pondsduring that time. Elevation was usedasa surrogatefor moisture availability alongthe other transects. 

Lower siteswere assumed to be generally wetter than 

higher sites. 

Flooding-Duration and Elevation Distributions 

of Selected Tree Species 

Forty speciesof treeswere identified, and members of six generawere noted but not identified to species (Appendix 1). Watertupelo andovercupoak were 

restrictedto Tupelo Swamp (transectsCl-C2 and 

Dl-D2) and the main body of Sinking Pond (transects 

Al -A2 and B 1-B2), respectively.In both cases,the 

disjunct wetland treesdominatedthe deeperparts of 

the pondsin which they occurred,in terms of both relative frequency and relative basalarea.Willow oak 

dominatedthe interior of Willow Oak Swamp 

(transectFl-F2) and was prominent in Sinking Pond 

and along Sinking Pond inflow channel(transect 

El-E2). Red maple and sweetgumwere amongthe 

five most numerousspeciesin all 10 transects.Black 

26 Hydrology and Tree-Dlstribution Patterns of Karst Wetlands at 

Arnold Engineerlng Development Center, Tennessee 
tupelo was presentin all transectsand amongthe five 

most numerousspeciesalong seventransects.Other 

wetland treessuchaspawpaw,American hornbeam, 

and easternhophornbeamwere prominent along one 

or two transects.Appendix 2 containsthe number of 

individuals, relative frequency,relative basalarea,and 

summariesof the elevation distributions for all tree 

speciesnoted along the 10 transects. 

The 10 transectsshoweddifferencesbetween 

seasonallyflooded pondsand intermittent drainageways with respectto stemdensity (number of treesper 

unit area)and basalarea.In general,the pondshad 

higher basalareas(normalized by the land-surface 

areaof the transect)but lower stemdensitiesthan the 

drainageways(table 4 and fig. 18). Wilcoxon rank 

60 

tests(Wannacottand Wannacott,1985) indicate these 

differencesarestatistically discernibleat the0.057 and 

0.005 error levels for stemdensity and basalarea, 

respectively.In addition to the consistentdifferences 

betweenpondsandchannels,speciescomposition and 

distribution also varied considerablyamongtransects. 

The transectsacrossWillow Oak Swamp 

(Fl-P2), and the shallow part of Sinking Pond 

(Al-A2) show similar patternsof wetland tree-species 

distribution with respectto flooding duration (fig. 19). 

The flooding-duration distributions for red maple and 

sweetgumlie closeto the flooding-duration distributions for the land surfacealong thesetransects.The 

similarity of the flooding-duration distributions of red 

maple and sweetgumto that of the land surface 

io 20 30 40 

STAND DWSlTY, IN TREES PEU 100 SQUARE METERS 

EXPLANATION 

l ‘IRANSBCTS ACROSS PONDS 

q +lRANsEcrs ACROSS CHANNELS

Figure 18. Relation of basal area to stand density along 10 vegetation transects 

in the Sinking Pond area. 

Tme-DWbutlonPattems 27 
I ” ” I ” ” I ’ “‘I”“1 

EXF’LANATION 

- LANDSURFACE 

0 WATERTUPELO 

0 ovERcuPoAK 

l SWEETOUM 

•I REDMAPLE 

x BLACKTUPELO 

o WILLOWOAK 

180 

200 

E 220 

4 240 

B

(3 260 

El 0 

fl 20 

TBANSECTBl-B2 TRANSECT Al-A2 TRANSBCF Pl -F2 

SJNKlNOPoND sINKlNoPoND WILLOW OAK SWAbIF 

0 25 50 75 100 0 25 50 75 100 0 25 50 75 100 

CUMULATIVE PREQuENcY.IN PERCENT 

Figure 19. Flooding-duration distributions for selected tree species along five transacts through monitored 

wetland sites in the Sinking Pond area. 

28 Hydrobgy and lree-Dlstrlbutlon patterns oi Karst Wetlands at 

Arnold Englnwrlng Development Center, Tannessw 
indicates that thesetrees are exploiting the entire range 

of sites along the two transects with little preference in 

regard to flooding duration. More specialized wetland 

trees, overcup oak and willow oak, are concentrated in 

the wettest sites but share some of these sites with red 

maple, sweetgum, and black tupelo. Overcup oak and 

willow oak have similar flood-duration distributions 

along transect Al-A2; both species were flooded at 

least 110 days in 1994 (fig. 19). About 60 percent of 

sweetgum and 70 percent of red maple along transect 

Al-A2 had 1994 flood durations of 110 days or 

greater, overlapping the flood-duration ranges of overcup oak and willow oak. Similarly, 45 percent of red 

maple, 50 percent of black tupelo, and 60 percent of 

sweetgum along transect Fl-F2 had 1994 flooding 

durations greater than 117 days, overlapping the floodduration range of willow oak in Willow Oak Swamp 

(fig. 19). 

The deep transect through Sinking Pond 

(B 1-B2) showed pronounced vertical zonation of wetland tree species. Flooding durations for overcup oak 

along transect B 1-B2 rangedfrom 120 days to 190days 

in 1994. Only one willow oak along this transect was 

flooded fewer than 120 days in 1994, indicating a 

90 percent overlap with the flood duration of overcup 

oak. However, the entire flood-duration distribution of 

willow oak along transect B 1-B2 lies above the corresponding percentiles for overcup oak along this 

transect (fig. 19). The vertical segregation of overcup 

oak and willow oak along transect B 1-B2 differs from 

the similar flood-duration distribution of these two 

species in the shallow part of Sinking Pond (transect 

Al-A2) (fig. 19). The flood-duration distribution for 

sweetgum along transect B 1-B2 is skewed toward 

drier sites in comparison to transect Al-A2. The 

median 1994 flood duration for sweetgum along the 

deep Sinking Pond transect (Bl-B2) is 33 days, compared to 114 days along the shallow transect (Al-A2) 

(fig. 19). Red maple shows a similar difference 

between the two Sinking Pond transects. Along the 

deepertransect (B 1-B2), 73 percent of red maple were 

never flooded in 1994 compared with 19 percent along 

transect Al-A2 (fig. 19). 

Along both Tupelo Swamp transects (Cl-C2 

and Dl-D2), water tupelo occupied sites that were 

flooded 160 days or longer in 1994. The water tupelo 

form a single-species stand that occupies the wet interior of the pond. The wettest sites along transect 

Cl-C2 were flooded longer than 260 days in 1994. 

Sweetgum, red maple, and willow oak were restricted 

to’sites flooded fewer than 180 days in 1994, and 

fewer than 30 percent of these species had 1994 flooding durations greater than 160 days along either 

Tupelo Swamp transect (fig. 19). 

The two transects across well defined channels 

showed relatively little vertical zonation of most wetland tree species. The elevation distributions for red 

maple, sweetgum, and black tupelo are close to each 

other and to the elevation distribution of the land surface along most of transects El-E2 and 51-52(fig. 20). 

Willow oak is concentrated in the lower parts of 

transect El-E2. Along transect Jl-J2, the upper percentile elevations of wetland tree species fall below 

the corresponding percentile elevations for land surface (fig. 20). 

Two transects across broad swales shared a similar pattern of vertical zonation among wetland tree 

species. Along transect Gl-G2, northwest of Sinking 

Pond, elevation distributions for red maple and sweetgum were skewed downward relative to the elevation 

distribution for land surface. The lowest part of this 

transect was dominated by a thick stand of small 

papaw. Along transect Hl-H2, the elevation distribution for red maple lies close to that of the land surface, 

but the distributions for sweetgum and black tupelo 

are skewed downward. 

The pattern of vertical zonation among wetland 

trees across a small compound sink south of Sinking 

Pond (11-12)shared some characteristics of the patterns across the larger compound sinks but resembles 

the patterns across broad swales in other respects. 

Along this transect, the elevation distribution for one 

locally common wetland tree, red maple, was skewed 

upward relative to the distribution of land-surface elevations. Elevation distributions for two other locally 

common wetland trees, sweetgum and black tupelo 

were skewed downward relative to land surface 

(fig. 20). 

Geomorphic and Hydrologic Controls on 

Wetland-Tree Distribution 

Tree-species composition and distribution in 

Tupelo Swamp and Sinking Pond reflect the distinct 

geomorphic and hydrologic characteristics of the two 

ponds and the physiological adaptations and competitive strategies of the trees they support. Domination of 

the wet interior of Tupelo Swamp by water tupelo is 

nearly exclusive, with minimal overlap in elevation or 

flooding duration between the water tupelo and other 

Tree-Dlstrlbution Patterns 29 
327 

326 

325 

327 

326 

325 -

324 -

323 ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ 

0 25 50 75 

EXl’L4NATION 

- LANDSURFJACB 

0 WILLOWOAK 

l SWEETGUM 

0 REDMAPLE 

x BLACK TUPELO 

T PAWPAW 

r 

’ ’ ’ 

100 0 25 50 75 1000 25 50 75 100 

CUMULATIVE FREQUENCY, IN PERCENT 

Figure 20. Frequency distributions of elevation for land surface and selected tree species along five transects through uninstrumented wetland sites in the Sinking Pond area. 

30 Hydrology and Tme-Dls!rbuUon Pattems of Karst Wetlands at 

Arnold Englneering Development Center, Tennessee 
wetland trees.Water tupelo grows bestin saturated 

soil and thrives in sitesthat are too wet for most trees 

(Johnson,1990).This strongaffinity for very wet sites 

reflectsphysiological and anatomicaladaptationsthat 

include controlled anaerobicrespiration and root systemsthat createoxidized zonesin the rhizosphere 

(Johnson,1990).The single-speciesstandof water 

tupelo in Tupelo Swamp,and the rather abrupt transition betweenthe water tupelo and other wetland trees 

nearthe pond’speriphery,appearto reflect physical 

site conditions and physiological limitations on the 

abilities of different tree speciesto exploit or eventoleratethoseconditions. 

Tree-distribution patternsin Sinking Pond vary 

from one part of the pond to another.In the shallow 

part of the pond, overcup oak and willow oak have 

similar flooding-duration distributions, and both species overlap substantiallywith red maple and sweetgum in terms of elevation and flooding duration. Near 

the deeperpart of the pond, vertical zonation of wetland treesis much more pronounced.In part this stronger zonation reflectsthe concentrationof overcupoak 

in the deeperand wetter sitesavailable in the interior 

of Sinking Pond.‘However,the merepresenceof 

deepersitesdoesnot explain why red mapleand 

sweetgumareconcentratedin drier sitesalong the 

deepSinking Pondtransect(B 1-B2) thanthesespecies 

occupy along the shallow transect(Al-A2). 

One possibleexplanationis that competition 

from overcup oak and willow oak actively excludes 

red mapleand sweetgumfrom otherwise suitablesites 

in the interior of Sinking Pond. In contrastto water 

tupelo, overcup oak grows bestin well-drained loamy 

soil (Solomon, 1990).The natural occurrenceof overcup oak in wet sitesreflectsthe ability of matureplants 

to tolerate flooding and developmentaladaptations 

that give its acornsand seedlingsa significant competitive advantagein seasonallyflooded sites.Unlike 

most white oaks,overcup oak acornsremain dormant 

during the winter monthsuntil the recessionof surface 

water triggers germination (Solomon, 1990). Someof 

the wettestsitesin Sinking Pond may be too wet for 

red maple, sweetgum,and other local wetland plants. 

Suchsites,oncecolonized by overcup oak, would provide a seedsourcefor expansioninto adjacent,somewhat drier sites.Sitesthat would normally be marginal 

to red maple and sweetgummight becomesubmarginal in the presenceof a better adaptedtree, while 

normally suitablesitesmight becomemarginal. 

Transectsacrossseasonallyflowing drainageways revealedtwo distinct patternsof vertical zonation. Transectsacrossbroad, poorly definedchannels 

(swales)had a large degreeof vertical zonation, with 

elevation distributions for locally common wetland 

treesskeweddownwardsrelative to the land surfacethe oppositeof vertically zonedtransectsthrough pond 

interiors. In contrast,transectsacrossnarrow, welldefinedchannelswere characterizedby the near 

absenceof vertical zonation amongwetland trees.The 

difference in vegetationpatternsacrossthe two types 

of channelsuggeststhat even limited incision (or 

excavation)may have a pronounceddrying effect in 

thesesmall headwatervalleys. Conversely,filling 

small ditchesmay be a highly effective wetland restoration techniquein The Barrens. 

SUMMARY AND CONCLUSIONS 

Surface-waterstageand flow, rainfall, and 

ground-waterlevels were measuredat or nearfive 

sinkhole-wetlandsitesat Arnold Engineering DevelopmentCenter,nearManchester,Tennessee.Treedistribution patternswere determinedat three of the 

sinkhole-wetlandsitesand acrossnearbyintermittent 

drainageways.The datawere collected to assessthe 

relationsbetweensinkhole morphology, flooding 

regime, ground-waterinteraction, and tree-species 

distribution. 

The wetland sitesoccupiedtwo geomorphically 

distinct typesof karst depression:compoundsinks and 

karst pans.Three sites,Sinking Pond,Westall Swamp, 

andWillow Oak Swamp,occupy compoundsinksrelatively deep,steepsideddepressionswith depths 

greaterthan 2.5 m and readily discernible internal 

drains.The interior topography of the compoundsinks 

is typically dominatedby an internal drainagesystem 

that includescoalescedsinkholesand connecting 

channels.lXvo sites,Tupelo swampandGoosePond, 

occupy karst pans-flat-bottomed, shallow (cl.5 m) 

depressionsthat lack visible internal drains. 

The water regimesof compound sinks were 

characterizedby rapid risesand recessions-about 

2 m in 24 hoursin Sinking Pond and 1.7m in 24 hours 

at Westall Swamp.Ground-water and surface-water 

levels closely trackedeachother at Sinking Pond and 

Westall Swampduring periods of high surface-water 

stage.During seasonalrecessions,ground-waterlevels 

fell 3 to 4 m below the bottom elevationsof thesewetlands.Periodic observationsat Willow Oak Swamp 

Summary and CopAusions 31 
indicate a water regime analogous to Sinking Pond 

and Westall Swamp. Willow Oak Swamp began filling 

later and drained earlier than the two other compound 

sinks. Maximum water depths were 3.5 m in Sinking 

Pond, 2.6 m in Westall Swamp, and 3.1 m in Willow 

oak swamp. 

The two karst pans, Tupelo Swamp and Goose 

Pond, had narrower ranges of water levels and longer 

hydroperiods than the compound sinks. Water depths 

ranged from 0 to 1.1 m in Tupelo Swamp and 0 to 

0.7 m in Goose Pond. Periodic sampling indicated the 

bottoms of both pans remained at or near saturation 

throughout the year, including periods when standing 

water was absent. Ground-water levels at Tupelo 

Swamp and Goose Pond remained below surfacewater levels throughout the monitoring period. 

Surface-water flow into and out of Sinking Pond 

occurred primarily during winter and early spring. 

Plow from Tupelo Swamp to Sinking Pond never 

exceeded 0.15 m3/s. Plow at a gage downstream of 

Sinking Pond was generally less than 0.2 m3/s but 

exceeded 0.5 m3/s during winter storms. Maximum 

recorded discharge at this gage was 1.23 m3/s. 

The water regimes of sinkhole wetlands reflect 

geomorphic and hydrologic controls including: 

1. Sinkhole geometry. 

2. Connection to the ground-water system. 

3. Bottom elevation relative to normal range of 

water table. 

4. Periodicity of water-table fluctuation. 

5. Drainage-basin characteristics (basin area, relief, 

ground cover, and other factors affecting runoff 

generation). 

At AEDC these controls produce a consistent relation 

between sinkhole morphology, ground-water interaction, and flooding regime. Analogous relations have 

been documented in other karst settings, but the details 

of such relations vary with hydrologic conditions. 

Tree species were identified and the elevations 

and diameters of individual trees were measuredalong 

10 transects. Two transects crossed Sinking Pond, two 

crossed Tupelo Swamp, and one crossed Willow Oak 

Swamp. Two transects crossed intermittent drainageways that carry flow into Sinking Pond. One of the 

tributary drainageways is a well-developed channel 

that carries flow from Tupelo Swamp, and the second 

is a broad swale that carries overflow from Willow 

Oak Swamp. Three transects crossed different sections 

of the Sinking Pond outflow channel including (1) a 

broad swale near the Sinking Pond spillway, (2) a 

small compound sinkhole downstream of the spillway, 

and (3) a well-defined channel upstream of the Sinking 

Pond outflow gage. 

Transects through ponds had fewer trees but 

more basal area per unit area of land surface than did 

transects through channels. Water tupelo, a coastalplain tree that is rare in the study area, dominated the 

interior of Tupelo Swamp but was absent from the 

other sampled sites. The elevation and flood-duration 

distributions for water tupelo had minimal overlap 

with the distributions for local wetland trees such as 

red maple and sweetgum. The local wetland trees were 

largely confined to the ponds periphery. 

Another coastal-plain tree, overcup oak, was 

found only in the flooded interior of Sinking Pond 

where it was the dominant tree species. Overlap 

between the elevation and flood-duration distributions 

for overcup oak was minimal across the deeper Sinking Pond transect but was substantial across the shallow transect. Along the deeper Sinking Pond transect, 

red maple and sweetgum were excluded from elevations at which these trees are common along the shallow transect. Willow oak dominated the interior of 

Willow Oak Swamp and had a relation to other wetland trees similar to that of overcup oak in the shallow 

Sinking Pond transect. 

Transects across broad swales had relatively 

large degreesof vertical zonation among wetland and 

upland tree species. Wetland trees such as red maple, 

sweetgum, black tupelo, and pawpaw tend to be concentrated in the moist lower parts of the swale 

transects. Vertical zonation of tree species was much 

less pronounced along transects through well-defined 

channels. Red maple, sweetgum, and black tupelo 

were distributed fairly evenly along the channel 

transects, showing little preference between sites in or 

near the channel and sites on adjacent slopes. 

The hydrologic and tree-distribution results of 

this investigation have implications for environmental 

management in The Barrens. The consistent relation 

between sinkhole morphology, ground-water interactions, and flooding regime indicate that geomorphic 

characteristics provide a rapid, inexpensive means for 

estimating a given wetland’s connection to the local 

ground-water system. Depending on the relation 

between a wetlands flooding regime and the groundwater system, natural processessuch as sedimentation 

and sinkhole collapse, localized human activities such 

as ground-water extraction, or global climate change 

32 Hydrology and Tree-Distribution Patterns of Karst Wetlands at 

Arnold Engineering Development Center, Tennessee 
could have pronounced drying or wetting effects with 

subsequentecological consequences. 

Compound sinks, with visible internal drains, 

are closely connected to the ground-water system. 

Flooding of compound sinks depends upon seasonal 

rises of the water table to levels that prevent water 

from entering the sinks’ internal drains. Any human 

activity or natural occurrence that results in a general 

lowering of the local water table would have a drying 

effect on compound sinks in the immediate vicinity. 

Under such circumstances, specialized wetland plants 

that are successful under the present flooding regime, 

such as the overcup oak stand in Sinking Pond, would 

be at risk. Conversely, accelerated sedimentation from 

logging or other land-use changes has the potential to 

fill the internal drains of compound sinks. If their 

internal drains stopped functioning, sites such as Sinking Pond and Willow Oak Swamp would become wetter, possibly exceeding the flooding tolerance of their 

present vegetation. 

Karst pans are relatively isolated from the 

ground-water system and therefore less sensitive to 

water-table fluctuations than compound sinks are. The 

wettest pans, such as Tupelo Swamp and Goose Pond, 

are too wet for many plants but provide scarce habitat 

for plants with specialized physiplogical adaptations. 

Sinkhole collapse has the potential to turn these sites 

into compound sinks with drastically altered flooding 

regimes. Specialized wetland plants such as water 

tupelo might not survive such a transition, Becausethe 

pans are shallow, they are potentially vulnerable to 

sedimentary filling. Excessive sedimentation would 

raise the land surface, creating a drying effect with 

potential ecological consequencessimilar to sinkhole 

collapse. 

This investigation raises several questions for 

future study. Karst development is an active process in 

The Barrens, but its nature, distribution, and rate are 

not yet understood. In particular, the geomorphic stability of karst pans-and the ecosystems they support-is difficult to assesswithout a better 

understanding of the processesby which they formed. 

Another question is the degreeto which soil-moisture, 

soil-chemistry, and understory-plant gradients interact 

with flooding patterns and tree-species distribution. 

This study has documented relatively strong associations between tree distribution and flooding patterns. 

However, many of the rare or threatened speciesat 

AEDC are understory plants which may respond 

strongly to environmental factors other than surfaces 

flooding. Finally, the direction and environmental controls on ecological succession associated with disjunct 

trees is unclear. The peripheral (shallow) transects 

through Sinking Pond and Tupelo Swamp indicate that 

the disjunct trees are interspersed with local species 

near the edges of relatively pure stands. This intermingling may represent a stable transition zone, an expansion of the disjuncts into drier sites from a stable, 

wetter core, or invasion of the disjunct stands by local 

species. Periodic resurvey of the vegetation transects 

established for this study would provide a framework 

for monitoring the stability of the disjunct stands at 

AEDC. 

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References Cited 35 
APPENDIXES 
APPENDIX 1. COMMON AND SCIENTIFIC NAMES OF PLANTS IDENTIFIED 

ALONG VEGETATION TRANSECTS 

[Nomenclature follows Duncan and Duncan, 1988, unless otherwise noted] 

ash 

azalea,wild 

birch, river 

buckthorn, Carolina 

buttonbush 

cherry, black 

dogwood, flowering 

silky 

swamp 

elm 

hackberry, sugarberry 

herculesclub 

hickory, mockemut 

holly, American 

hophornbeam,eastern 

hornbeam,American 

maple, red 

sugar 

oak, black 

northern red 

overcup 

pin 

post 

scarlet 

southernred 

water 

white 

willow 

oleaster 

pawpaw 

persimmon, common 

pine, loblolly 

privet 

sassafras 

serviceberry 

sourwood 

storax (American snowbell) 

sumac,winged 

sweetgum 

sweetshrub 

sycamore,American 

tuliptree (yellow poplar) 

tupelo, black (blackgum) 

water 

Vaccinium 

Virgina willow 

Fraxinus spp. 

‘Azalea spp. 

Betula nigra L. 

Rhamnus caroliniana Walt. 

Cephalanthus occidentalis L. 

Prunus serotina Ehrh. 

Cornusflorida L. 

‘Cornus amomum Mill. 

Cornus stricta Lam. 

Ulmus spp. 

Celtis spp. 

Aralia spinosa L. 

Carya tomentosa (Poir.) Nutt. 

Ilex opaca Ait. 

Ostrya virginiana (Mill.) K. Koch 

Carpinus caroliniana Walt. 

Acer rubrum L. 

Acer saccharum Marsh. 

Quercus velutina Lam. 

Quercus rubra L. 

Quercus lyrata Walt. 

Quercus palustris Muenchh. 

Quercus stellata Wang. 

Quercus coccinea Muenchh. 

Quercus falcata Michx. 

Quercus nigra L. 

Quercus alba L. 

Quercus phellos L. 

Eleagnus spp. 

Asimina triloba (L.) Dunal 

Diospyros virginiana L. 

Pinus taeda L. 

Lingustrum vulgare L. 

Sassafras albidum (Nut-t.) Nees 

Amelanchier arborea (Michx. f.) Fem. 

Oxydendrum arboreum (L.) DC. 

Styrax americanus Lam. 

Rhus copallina L. 

Liquidambar styraciflua L. 

‘Calycanthusf7oridus L. 

Platanus occidentalis L. 

Liriodendron tulipifera L. 

Nyssa sylvatica Marsh. 

Nyssa aquatica L. 

Vaccinium spp. 

‘Itea virginica L. 

‘According to B&ton and Brown, 1970 

Appendix 1 39 
APPENDIX 2. RELATIVE IMPORTANCE AND ELEVATION QUARTILES FOR TREE 

SPECIES ALONG VEGETATION TRANSECTS IN THE SINKING POND AREA, 

ARNOLD ENGINEERING DEVELOPMENT CENTER 

[N, number of stems; Min. minimum; F25,25th percentile; Med. median; W5,75th percentile; Max, maximum; ~1, less than 0.1 percent] 

Transect Al -A2 

Relative Relative 

frequency basal area Percentile elevations (meters above sea level) 

Species N (percent) (percent) Min P25 Med P75 Max 

sweetgum 88 20.6 

red maple 49 11.5 

silky dogwood 46 10.8 

American hornbeam 38 8.9 

overcup oak 35 8.2 

flowering dogwood 32 7.5 

black tupelo 27 6.3 

sourwood 22 5.2 

willow oak 20 4.7 

pawpaw 10 2.3 

pin oak 10 2.3 

hackberry, sugarberry 9 2.1 

white oak 8 1.9 

ash 7 1.6 

water oak 5 1.2 

sassafras 3 .7 

elm 3 .7 

storax 3 .7 

southern red oak 2 .5 

river birch 2 .5 

swamp dogwood 1 .2 

Carolina buckthom 1 .2 

black cherry 1 .2 

tuliptree 1 .2 

American sycamore 1 .2 

northern red oak 1 .2 

mockemut hickory 1 .2 

eastern hoohombeam 1 .2 

17.7 323.62 324.02 324.34 324.64 329.86 

13.4 323.92 324.08 324.19 324.60 329.83 

c.1 323.99 324.12 324.21 324.29 324.48 

.8 324.35 324.39 324.42 324.47 324.93 

23.1 323.49 323.67 323.94 324.15 324.34 

.4 324.77 324.93 326.06 326.98 329.81 

1.8 323.94 324.10 324.49 324.67 325.67 

4.9 324.51 325.86 327.60 329.37 329.87 

8.6 323.60 323.98 324.04 324.13 324.25 

c.1 324.37 324.42 324.48 324.68 329.68 

6.8 323.95 324.09 324.12 324.19 324.39 

2.4 324.35 324.38 324.41 324.42 325.80 

12.2 324.43 324.62 324.97 326.01 328.13 

1.7 324.41 324.71 324.93 325.00 325.12 

.8 324.13 324.24 324.36 324.37 324.38 

c.1 325.04 325.30 325.56 327.60 329.64 

.l 324.54 324.61 324.68 324.68 324.68 

c.1 323.99 323.99 323.99 324.03 324.08 

3.6 325.56 326.63 327.70 328.77 329.84 

.7 323.60 323.67 323.73 323.79 323.86 

c.1 323.89 323.89 323.89 323.89 323.89 

c.1 324.68 324.68 324.68 324.68 324.68 

c.1 324.79 324.79 324.79 324.19 324.79 

.5 326.53 326.53 326.53 326.53 326.53 

.3 324.17 324.7 324.17 324.17 324.17 

.l 324.39 324.39 324.39 324.39 324.39 

c.1 329.83 329.83 329.83 329.83 329.83 

.2 324.41 324.41 324.41 324.41 324.41 

Appendix 2 41 
Transect Bl -82 

Relative Relative 

frequency basal area Percentile elevations (meters above sea level) 

Species N (percent) (percent) Min P25 bled P75 Max 

sweetgum 60 18.1 

overcup oak 60 18.1 

sourwood 53 16.0 

red maple 51 15.4 

black tupelo 25 7.5 

flowering dogwood 20 6.0 

willow oak 15 4.5 

tuliptree 9 2.7 

white oak 8 2.4 

scarlet oak 6 1.8 

water oak 5 1.5 

sassafras 5 1.5 

serviceberry 2 .6 

post oak 2 .6 

mockemut hickory 2 .6 

black cherry 2 .6 

Virginia willow 2 .6 

southern red oak 1 .3 

river birch 1 .3 

pawpaw 1 .3 

storax 1 .3 

elm 1 .3 

Transect Cl 42 

Relative 

11.1 323.21 324.10 324.57 324.79 328.47 

43.1 322.51 323.50 323.58 323.71 324.27 

6.9 324.5 324.77 325.18 327.94 328.3 

7.6 323.89 324.83 324.91 325.05 328.23 

4.2 323.65 324.10 324.21 324.75 325.21 

.2 325.38 327.31 328.19 328.27 328.47 

9.2 323.65 323.81 323.95 324.08 324.41 

<.l 324.90 324.92 324.94 324.98 328.14 

5.4 324.54 324.67 324.74 325.58 327.91 

3.1 325.36 325.89 326.09 326.44 327.82 

1.3 324.14 324.20 324.23 324.58 324.58 

.l 325.89 326.78 328.05 328.47 328.47 

<.l 325.64 325.80 325.96 326.13 326.29 

.8 325.39 326.12 326.86 327.59 328.32 

4.5 326.91 327.25 327.58 327.92 328.26 

c.1 327.93 327.98 328.04 328.10 328.16 

<.l 324.07 324.11 324.15 324.19 324.23 

1.6 328.11 328.11 328.11 328.11 328.11 

.7 324.07 324.07 324.07 324.07 324.07 

<.l 325.36 325.36 325.36 325.36 325.36 

<.l 323.99 323.99 323.99 323.99 323.99 

.l 324.28 324.28 324.28 324.28 324.28 

Relative 

frequency basal area Percentile elevations (meters above sea level) 

Species N (percent) (percent) Mln P25 Med P75 Max 

water tupelo 58 33.9 47.9 326.37 326.47 326.59 326.64 326.73 

black tupelo 24 14.0 .7 326.92 327.08 327.36 327.45 328.02 

sweetgum 19 11.1 10.3 326.72 326.83 327.08 327.44 328.13 

red maple 18 10.5 2.2 326.72 326.78 327.09 327.43 329.42 

flowering dogwood 12 7.0 .5 327.45 328.07 330.10 330.52 331.00 

sourwood 10 5.8 .7 327.07 327.42 327.60 327.76 328.65 

pawpaw 10 5.8 <.l 327.09 327.15 327.17 327.25 327.34 

white oak 

mockemut hickory 

tuliptree 

willow oak 

water oak 

sassafras 

scarlet oak 

northern red oak 

loblolly pine 

eastern hophombeam 

5 2.9 13.5 327.37 327.65 327.93 328.05 331.10 

5 2.9 .2 328.48 329.35 330.07 330.22 330.47 

3 1.8 11.3 327.58 327.78 327.99 328.86 329.74 

1 .6 8.0 326.92 326.92 326.92 326.92 326.92 

1 .6 <.l 327.10 327.10 327.10 327.10 327.10 

1 .6 <l 328.07 328.07 328.07 328.07 328.07 

1 .6 1.3 328.02 328.02 328.02 328.02 328.02 

1 .6 3.4 327.86 327.86 327.86 327.86 327.86 

1 .6 <.l 327.00 327.00 327.00 327.00 327.00 

1 .6 <.l 330.22 330.22 330.22 330.22 330.22 

42 Hydrology and Tree-Distribution Patterns of Karet Wetlands at 

Arnold Engineering Development Center, Tennessee 
Transect Dl -D2 

Species 

sweetgum 

sourwood 

water tupelo 

red maple 

flowering dogwood 

willow oak 

loblolly pine 

mockemut hickory 

black tupelo 

white oak 

southern red oak 

tuliptree 

river birch 

Transect El -E2 

Species 

sweetgum 

red maple 

black tupelo 

water oak 

white oak 

sourwood 

willow oak 

flowering dogwood 

pawpaw 

southern red oak 

button bush 

black oak 

Relative Relative 

frequency basal area Percentile elevations (meters above sea level) 

N (percent) (percent) Min P25 Med P75 Max 

63 54.8 27.3 326.66 326.74 327.04 327.22 331.66 

12 10.4 4.8 327.21 327.3 1 327.38 327.56 327.96 

9 7.8 6.1 326.66 326.67 326.67 326.67 326.77 

8 7.0 1.8 326.67 326.71 327.09 327.15 327.46 

4 3.5 .5 327.65 327.65 329.44 331.50 332.29 

4 3.5 17.4 326.74 326.81 326.88 326.96 327.04 

3 2.6 7.3 331.10 331.31 331.52 331.66 331.80 

3 2.6 3.8 327.89 328.38 328.87 329.92 330.96 

2 1.7 3.9 327.03 327.21 327.40 327.58 327.76 

2 1.7 11.4 327.12 327.15 327.19 327.22 327.26 

2 1.7 .5 327.74 327.8 327.85 327.91 327.96 

2 1.7 13.5 328.01 328.15 328.30 328.44 328.58 

1 .9 1.8 326.66 326.66 326.66 326.66 326.66 

Relative Relative 

frequency basal area Percentile elevations 

N (percent) (percent) Min P25 

108 40.8 

57 21.5 

30 11.3 

22 8.3 

18 6.8 

7 2.6 

7 2.6 

4 1.5 

4 1.5 

3 1.1 

1 .4 

1 .4 

9.4 324.79 324.90 

17.8 324.79 324.91 

3.4 324.69 324.90 

.8 324.83 324.91 

39.8 324.91 324.91 

.6 324.84 324.84 

27.7 324.85 324.87 

.5 324.78 325.08 

<.l 324.83 324.84 

c.1 324.91 324.9 1 

C.1 324.91 324.91 

<.l 324.91 324.91 

c.1 325.34 325.34 

c.1 324.79 324.79 

c.1 324.79 324.79 

(meters above sea level) 

Yed P75 Max 

325.00 325.20 326.03 

325.01 325.09 326.08 

324.93 325.36 325.57 

324.91 325.19 326.13 

324.91 325.16 325.44 

324.84 324.88 325.19 

324.88 324.90 324.91 

325.53 325.88 325.88 

324.84 324.85 324.85 

324.91 325.12 325.33 

324.91 324.91 324.91 

324.9 1 324.91 324.91 

325.34 325.34 325.34 

324.79 324.79 324.79 

324.79 324.79 324.79 

Appendix 2 43 

eastern hophornbeam 1 .4 

sassafras 1 .4 

tuliotree 1 .4 
Transect Fl-F2 

FklatlW Relative 

frequency basal area Percentile elevations (meters above sea level) 

species N (w-W (w-W Mln P25 lued Fvb Max 

red maple 42 23.6 11.6 324.26 324.91 325.29 325.69 327.09 

black tupelo 39 21.9 2.3 324.14 324.9 325.18 325.64 327.15 

willow oak 34 19.1 48.6 323.16 324.53 324.81 324.91 325.2 

sweetgum 27 15.2 14.2 324.28 324.8 325.21 326.04 327.12 

water oak 9 5.1 5.6 325.04 325.16 325.32 325.42 325.87 

white oak 7 3.9 6.2 325.46 325.59 325.85 326.04 326.34 

privet 4 2.2 <.l 324.95 324.98 325 325.05 325.14 

mockemut hickory 4 2.2 .2 325.83 326.04 326.44 326.87 327.15 

flowering dogwood 4 2.2 .4 325.79 325.83 325.87 325.94 326.07 

sourwood 2 1.1 .6 326.4 326.43 326.47 326.5 326.54 

northernred oak 2 1.1 1.4 325.94 326.11 326.27 326.44 326.6 

southernred oak 2 1.1 5.9 325.95 325.99 326.02 325.06 326.1 

American sycamore 1 .6 2.7 323.76 323.76 323.76 323.76 323.76 

elm 1 .6 <.l 325.36 325.36 325.36 325.36 325.36 

Transect 01-62 

Relative Relative 

frequency basal area Percentile elevations (meters above sea level) 

Species N (percent) (percent) Min P25 Med P75 Max 

pawpaw 158 29.1 2.7 325.2 325.33 325.34 325.35 325.49 

sweetgum 78 14.4 13.1 325.17 325.50 325.60 326.01 328.77 

easternhophornbeam 68 12.5 2.7 325.25 325.57 326.01 326.47 326.54 

red maple 58 10.7 14.9 325.2 325.62 325.77 326.10 328.73 

American hornbeam 49 9.0 1.8 325.19 325.23 325.39 325.83 326.50 

flowering dogwood 38 7.0 1.7 325.20 326.38 326.67 326.95 328.97 

sourwood 

black tupelo 

white oak 

mockemut hickory 

elm 

ash 

tuliptree 

sugarmaple 

serviceberry 

black oak 

sweetshrub 

southernred oak 

black chenv 

23 4.2 5.4 326.01 326.47 326.64 327.24 328.89 

23 4.2 1.7 325.22 325.58 325.67 326.28 326.75 

18 3.3 47.3 325.34 325.52 325.91 326.49 326.97 

9 1.7 5.4 325.23 325.42 326.29 326.44 328.79 

4 .7 .5 325.23 325.51 325.63 326.38 328.56 

4 .7 .l 325.50 325.53 325.61 325.77 326.03 

3 .6 <.l 325.70 325.73 325.75 325.92 326.09 

3 .6 .3 326.47 326.47 326.47 326.47 326.47 

2 .4 .l 326.51 326.52 326.53 326.54 326.54 

2 .4 .3 325.50 325.75 326.01 326.27 326.53 

1 .2 -Cl 328.35 328.35 328.35 328.35 328.35 

1 .2 2 326.76 326.76 326.76 326.76 326.76 

1 .2 c.1 325.79 325.79 325.79 325.79 325.79 

44 Hydrology and Tree-Dlstrlbutlon Patterns of Karst Wetlands at 

Amold Engineerlng Development Center, Tenneesee 
Transect Hl-H2 

Species 

red maple 

sweetgum 

flowering dogwood 

black tupelo . mockemuthickory 

sassafras 

white oak 

northernred oak 

silky dogwood 

oleaster 

pawpaw 

scarletoak 

southernred oak 

sourwood 

serviceberry 

wateroak 

Transect I1 -12 

Species 

sweetgum 

red maple 

sassafras 

flowering dogwood 

black tupelo 

postoak 

scarletoak 

sourwood 

willow oak 

black cherry 

mockemuthickory 

southernred oak 

white oak 

winged sumac 

Relative Relative 

frequency basal area 

N (percent) (percent) Min 

54 32.0 13.9 324.21 

47 27.8 8.3 324.25 

17 10.1 2.0 324.64 

13 7.7 4.5 324.24 

12 7.1 4.2 324.70 

9 5.3 .6 324.56 

5 3.0 44.6 324.47 

4 2.4 c.1 324.72 

1 .6 c.1 324.36 

1 .6 <.l 325.45 

1 .6 <.l 324.58 

1 .6 10.1 326.36 

1 .6 11.2 326.45 

1 .6 c.1 324.54 

1 .6 c.1 324.90 

1 .6 .6 324.32 

Relative Relative 

frequency basal area 

N (percent) (percent) Min 

56 37.8 12.4 322.88 

23 15.5 10.2 324.25 

20 13.5 .8 324.65 

19 12.8 3.7 324.81 

9 6.1 9.6 322.67 

3 2.0 7.9 325.26 

3 2.0 14.1 324.72 

3 2.0 <.l 324.82 

3 2.0 20 323.34 

2 1.4 .l 325.15 

2 1.4 .3 324.60 

2 1.4 8.7 325.19 

2 1.4 12.1 324.60 

1 .7 <.l 325.29 

Percentile elevations (meters above sea level) 

P25 Med P75 Max 

324.45 324.68 324.93 326.15 

324.46 324.58 324.77 325.07 

324.86 325.17 325.30 326.37 

324.43 324.47 324.48 326.12 

324.98 325.06 325.61 326.24 

324.68 325.90 326.14 326.21 

324.64 324.68 324.88 325.11 

325.82 326.18 326.20 326.27 

324.36 324.36 324.36 324.36 

325.45 325.45 325.45 325.45 

324.58 324.58 324.58 324.58 

326.36 326.36 326.36 326.36 

326.45 326.45 326.45 326.45 

324.54 324.54 324.54 324.54 

324.90 324.90 324.90 324.90 

324.32 324.32 324.32 324.32 

Percentile elevations 

P25 

323.52 

324.61 

324.97 

325.13 

323.94 

325.32 

325.96 

324.82 

323.36 

325.26 

324.74 

325.23 

325.32 

325.29 

(meters above sea level) 

Med P75 Max 

324.36 324.58 325.58 

325.03 325.37 325.65 

325.92 327.10 327.62 

325.61 326.48 327.64 

324.48 324.52 324.79 

325.37 325.48 325.58 

327.21 327.40 327.60 

324.82 324.82 324.83 

323.39 323.48 323.58 

325.37 325.49 325.60 

324.89 325.03 325.17 

325.26 325.30 325.33 

326.04 326.76 327.48 

325.29 325.29 325.29 

Appendix 2 45 
Transect 51112 

Relative Relative 

frequency basal area Percentile elevations (meters above sea level) 

Species N (percent) (percent) Min P25 ruled Fv5 Max 

red maple 94 34.1 

sweetgum 78 28.3 

black tupelo 41 14.9 

flowering dogwood 23 8.3 

white oak 10 3.6 

sassafras 7 2.5 

loblolly pine 4 1.4 

water oak 3 1.1 

oleaster 2 .7 

post oak 2 .7 

scarlet oak 2 .7 

southern red oak 2 .7 

sourwood 2 .7 

black cherry 1 .4 

hercules club 1 .4 

American holly 1 .4 

northern red oak 1 .4 

common persimmon 1 .4 

servicebe-& 1 .4 

46 Hydrology and Tree-Distribution 

Arnold Engineering Development 

9.0 324.09 324.54 324.59 324.66 325.26 

24.9 324.07 324.39 324.51 324.58 326.01 

4.6 324.09 324.35 324.47 324.60 324.83 

2.8 324.78 324.87 325.10 325.48 326.14 

27.4 324.38 324.49 324.72 324.80 325.48 

2.5 324.54 324.59 324.66 325.01 325.33 

c.1 324.67 324.79 324.92 325.02 325.05 

c.1 324.51 324.60 324.70 324.71 324.72 

c.1 325.47 325.50 325.54 325.58 325.61 

12.4 324.54 324.96 325.38 325.80 326.22 

2.8 324.65 324.66 324.66 324.67 324.67 

11.7 324.81 324.83 324.85 324.87 324.89 

1.7 324.54 324.54 324.54 324.54 324.54 

.l 325.48 325.48 325.48 325.48 325.48 

<.l 325.09 325.09 325.09 325.09 325.09 

C.1 324.91 324.9 1 324.91 324.91 324.91 

<.l 324.65 324.65 324.65 324.65 324.65 

<.l 326.01 326.01 326.01 326.01 326.01 

c.1 324.61 324.61 324.61 324.61 324.61 

Patterns of Karst Wetlands at 

Center, Tennessee