Chapter 20 (AQUA-2): Forested Wetlandsforested wetlands were derived pri-marily from NWI reports...

Chapter 20: Forested Wetlands 479 AQUATI C

■ As of 1997, Georgia, Florida, andLouisiana have the greatest amountof forested wetland in the South,followed, in descending order, byMississippi, South Carolina, NorthCarolina, Arkansas, Texas, Alabama,Virginia, Tennessee, and Kentucky.

■ Restoration has been attemptedprimarily in riverine wetlands in theLower Mississippi Valley, but successin restoring wetland acreage andfunction has been limited. Restorationof other forested wetlands, likemineral-soil pine flats, would haveto include the reintroduction of fire.

■ Offsetting losses of wetlandfunctions through the Clean WaterAct, section 404 permitting processhas not been well documented butappears to have had limited success.

Introduction

This chapter describes the history,status, and likely future of forestedwetlands in the South. Key issuesinclude: (1) the quantity of forestedwetlands in the South, (2) the qualityof forested wetlands in the South,(3) how function is affected byimpacts associated with developmentand agricultural and silviculturalconversions, (4) restoration of thesewetland systems to replace lostfunctions; and (5) public policiesdesigned to protect and restore forestedwetlands. All these issues are discussed.Due to public concerns about theeffects of silvicultural operations onforested wetlands and their surroundinglandscapes, special attention is givento changes in condition of forestedwetlands caused by silviculture.

HistorySouthern forested wetlands have

undergone natural and human-induceddisturbances for thousands of years.These disturbances have led to thespecies-rich flora and fauna found inthese ecosystems today. Even beforeprehistoric humans arrived in theSouth, geologic changes due to platetectonics, Appalachian Mountain upliftand subsequent erosion, rising sealevels, and the advance and retreat ofglaciers resulted in ecological changes,species migrations, and shifts incommunity composition. Warmerclimates, beginning about 16,000 yearsago, caused southern forests to shiftfrom predominantly northern softwoodforests to forests dominated by oaksand hickories (Delcourt and others1993). These climate changes andconcomitant sea level rise causedmany wetlands to form due to risesin water tables, which often inundatedriver valleys. Pre-European settlementforests were diverse, with varyingtree ages interspersed with openingsproviding habitat for a diverse rangeof wildlife (Dickson 1991). Fire, icestorms, tornadoes, hurricanes, insects,and diseases disturbed these ecosystemsand influenced forest composition(Askins 2001).

In addition to the long-term geologicand climatic changes and the frequentnatural disturbances (primarily stormsand fire), Native Americans impactedsouthern forested wetlands by settlingand farming the fertile and tillablefloodplains from the Little TennesseeRiver to the Mississippi River (Delcourtand others 1993). Forests were clearednot only for agriculture but also forfirewood and stockades. Cleared areaswere also burned regularly to prepare

Key Findings

■ Approximately half of U.S. wetlandspresent in colonial times have beenlost, primarily due to agriculture.The South had approximately 35million acres of forested wetlandremaining by 1996, 91 percentof which were riverine wetland.

■ Rates of loss—change from wetlandto nonwetland—were greatest fromthe 1950s to the 1970s. Since thenthe rates have slowed, but losses arestill occurring due to agriculture,urban and rural development,and silviculture.

■ According to the National WetlandInventory (NWI), 3.5 million acresof southern forested wetland under-went changes between 1986 and1997. Ninety percent of the changeswere conversions to another wetlandor aquatic habitat type. Of theseconversions 95 percent were toscrub-shrub or emergent wetlands.During this same time periodapproximately 119,000 acres offorested wetland went into urbanand rural development, 112,000acres were converted to agriculture,and 102,000 acres underwentintensive silviculture. While NWIattributes causes of losses, they donot attribute causes of conversion.

■ Effects of harvesting are shortlived, and harvested riverine standswill return to pretreatment speciescomposition; however, additionallong-term research is needed tocompare composition and ecologicalfunction of harvested and non-harvested stands.

Chapter 20:ForestedWetlands

William B. AinslieRegion 4, U.S. Environmental Protection Agency

What are the history,status, and likelyfuture of forested

wetlands in the South?

Southern Forest Resource Assessment480

AQUATIC

them for planting (Wigley and Roberts1997). In the 16th and 17th centuries,80 percent of Native Americans in theSouth died due to diseases brought byearly European explorers. One resultwas a decline of the Native Americanagricultural system. Agricultural fieldswere abandoned, and tree growthbecame established on many acres offorested wetland and upland (chapter24). Consequently, the forest vegetationencountered by southern colonistsin the mid-1700s was the result ofthousands of years of geologic, climatic,and human influence. Growth of foreststands that regenerated after climaticand biologic disturbances and NativeAmerican abandonment affected forestcomposition and age at the time ofEuropean settlement. For instance,in the Coastal Plain, abandonedagricultural fields probably supportedextensive tracts of pure pine (Allenand others 1996). The forests encoun-tered in the 1700s were not the vast,unbroken expanses of giant treesromantically portrayed early in the19th century (Delcourt and others1993, Wigley and Roberts 1997).Many were young stands resultingfrom natural and human-induceddisturbances. The flora and faunaof these ecosystems were and areadapted to disturbance. In the caseof mineral-soil pine flats, they requirefire to maintain them. Therefore,disturbance is a natural and oftenforgotten component of forestedwetland systems that is necessaryin considering their restoration.

DefinitionsWhat is a wetland? Current defini-

tions include three main components:(1) the presence of water at the surfaceor within the root zone, (2) unique soilconditions that differ from adjacentuplands, and (3) vegetation adaptedto the wet conditions (Mitsch andGosselink 2000). Precise wetlanddefinitions are needed by wetlandmanagers and regulators as wellas wetland scientists (Mitsch andGosselink 2000). The wetland reg-ulatory definition used to establishFederal jurisdiction for the wetlandpermitting program under section404 of the Clean Water Act is:

. . . those areas that are inun-dated or saturated by surfaceor ground water at a fre-quency and duration

sufficient to support, and thatunder normal circumstancesdo support, a prevalence ofvegetation typically adaptedfor life in saturated soilconditions. Wetlandsgenerally include swamps,marshes, bogs, and similarareas [33 CFR 328.3(b);1984].

This definition of wetlands out-lines the three parameters necessaryfor wetland development, namelyhydrology, vegetation, and soils. Thesite-specific criteria for determining theextent to which these three parametersexist in the field is contained in the1987 Federal Manual for DeterminingWetland Boundaries (U.S. Army Corpsof Engineers 1987) which is used todetermine the geographic boundariesof wetlands in the United States.

The wetland definition adoptedby scientists in the U.S. Fish andWildlife Service for the purposes ofinventorying wetland resources inthe United States is:

Wetlands are lands transi-tional between terrestrial andaquatic systems where thewater table is usually at ornear the surface or the land iscovered by shallow water. . . .Wetlands must have one ormore of the following threeattributes: (1) at least peri-odically, the land supportspredominantly hydrophytes,(2) the substrate is predomi-nantly undrained hydric soil,and (3) the substrate is non-soil and is saturated withwater or covered by shallowwater at some time duringthe growing season of eachyear (Cowardin and others1979).

This definition is the standard forthe NWI and is the national standardfor wetland mapping, monitoring, anddata reporting as determined by theFederal Geographic Data Committee(Dahl 2000).

Once a wetland-upland boundaryis defined and delineated, the qualityor capability of the wetland to functionbecomes a concern. There is greatdiversity in the types of wetlands in theSouth, the functions they perform, andthe goods and services they providesociety. To deal with this diversity,

wetlands are grouped according tofactors that substantially contribute towetland functioning. Hydrogeomorphic(HGM) classification (Brinson 1993)groups wetlands based upon theirlandscape position, water source,and hydrodynamics. By groupingor classifying wetlands using theHGM classification, the presumptionis that wetlands with similar landscapeposition, water source, and hydrod-ynamics will function similarly. In theSouthern United States, most forestedwetlands are classed as riverine, flat,and depression wetland. Much ofthe following discussion deals withthese three classes.

Methods

The status of and trends in southernforested wetlands were derived pri-marily from NWI reports (Dahl 1990,2000; Hefner and Brown 1985; Hefnerand others 1994). Information fromthese reports was used to develop acomposite picture of the acreage andloss of forested wetlands in the Southfrom the 1780s to the present. Acreageswere taken directly from the U.S. Fishand Wildlife Service Wetland Status andTrend reports for the 10 SoutheasternStates of Kentucky, Tennessee, NorthCarolina, South Carolina, Georgia,Florida, Alabama, Mississippi,Louisiana, and Arkansas. Data for the1986 to 1997 time period, generatedfor this report by the U.S. Fish andWildlife Service, were also used directly.The NWI Status and Trends reportsrepresent the most comprehensiveand consistent source of informationon forested wetland conversions andlosses over the last 200 years.

Information from the NationalResources Inventory (NRI) preparedby the Natural Resources ConservationService (NRCS) and the Forest Inven-tory and Analysis (FIA) units of theUSDA Forest Service were used to fillgaps in information about impact andrestoration acreages and changes inforest type and ownership. NWI andNRI data have similar geographiccoverage but are not directly compar-able because NRI does not classifywetlands in the same manner as NWIand does not include Federal land orcoastal areas in its estimates. Otherdifferences between NWI and NRIare discussed in Dahl (2000). The FIAforested wetland data cover only five


States—Virginia, North Carolina, SouthCarolina, Georgia, and Florida. Todate FIA has collected wetland dataat only one point in time for each State.Thus, data do not represent changesin forested wetland acres over time.Since NRI and FIA data are limitedgeographically and temporally, NWIdata are the primary basis for the statusand trend numbers reported herein.

Literature, including HGM approachmodels for low-gradient riverinewetlands, pine flatwood wetlands,hardwood flat wetlands, and foresteddepressions were reviewed to develophypotheses about the effects ofalteration on the structure and functionof forested wetlands. Hypothesizedimpacts were then checked againstscientific studies done in similarwetlands where available. Predominantforested wetland types in the South(Messina and Conner 1998) wereplaced in HGM classes. Functionalassessment models for those classesand/or subclasses were then reviewedto hypothesize, based upon structuralalterations to the wetland, the impactsof alterations by silviculture, agri-culture, or development. Due to thelarge geographic area encompassedby the Southern Forest ResourceAssessment (13 States) and the largevariability in onsite wetland and sur-rounding landscape conditions, theestimated impacts are generic. Anyspecific projects must be individuallyassessed. The generic assessments ofimpacts described here do provideuseful insights into the ecologicalramifications of these activities, the fateof wetlands which have been modified,and potential hypotheses for additionalresearch. Wetland restoration literaturewas reviewed, as were ongoing studieson the extent and success of wetlandrestoration. NRI and data from theWetland Reserve Program (WRP)administered by NRCS was also usedto estimate the number of acres wherewetland restoration has been attempted.The assumption with WRP data is thatacres enrolled in this program result ina gain in forested wetland.

Data Sources

Status and trends of southern forestedwetlands were derived from NWIreports for the United States and theSoutheast (Dahl 1990, 2000; Hefnerand Brown 1985; Hefner and others

1994). These reports also providedinformation on the causes of forestedwetland loss. The NWI was undertakenby the U.S. Fish and Wildlife Serviceto provide a comprehensive inventoryof the Nation’s wetlands. The NWI isconducted at 10-year intervals. Gainsand losses of wetlands are estimatedusing aerial photographs, soil surveys,topographic maps, and field work ona permanent set of randomly selectedpoints (Dahl 2000, Shepard and others1998). These photos are analyzed fora selected 10-year interval to detectchanges in wetlands. Quality control isincluded throughout the data collectionand analysis stages, and 21 percent ofthe plots are field verified (Dahl 2000).Studies have been completed forthe 1950s to 1970s, 1970s to 1980s,and 1980s to 1990s.

Since NWI is used as the primarysource of status and trends data forthis chapter, terminology used byNWI in reporting changes in forestedwetlands (Dahl 2000) is important tounderstand. Terms regarding wetlandtypes and land use definitions canbe found in Dahl (2000). However,two pivotal terms are defined here.“Conversion” is a change in vegetativecover on an area that is still a wetland.In other words, when a forestedwetland is converted, it remains awetland, i.e., soils and hydrologyremain intact, but the dominantvegetation is changed. Wetland “loss”is a change in which an area no longerhas the hydrologic characteristics of awetland. Losses involve the detectionon high-resolution aerial photographsof: (1) significant hydrologic alterationssuch as large ditches and levees, (2) soilalterations such as filling or leveling,and (3) upland vegetation indicatingthe wetland character of a site hasbeen removed.

The NRI, prepared by the NRCS,is an inventory of multiple naturalresource conditions on non-Federalland in the United States (Shepardand others 1998). The purpose ofthe NRI is to provide informationfor policymaking in natural resourceconservation programs at State andFederal levels. The NRI is based uponstratified random samples distributedthroughout the country. Data arecollected using aerial photographsand ancillary data and by makingselect field visits.

FIA data gathered by the USDAForest Service also were used in thisreport. The purpose of FIA is to provideinformation on forest resources at thelocal, State, and national levels. Theevaluations are State-by-State multipleresource inventories of land use, timber,wildlife, range, recreation, water, andsoils completed on a 7- to 10-yearcycle. Data in this report were collectedbetween 1989 and 1998 during theforest surveys in Virginia, North andSouth Carolina, Georgia, and Floridafrom field plots that met Federalwetland criteria (areas having wetlandsoils, plants, and hydrology) (Brownand others 2001).

Scientific literature including HGMmodels for low-gradient riverinewetlands (Ainslie and others 1999;Smith and Klimas 2002), pine flatwoodwetlands (Rheinhardt and others 2002),hardwood flat wetlands (Smith andKlimas 2002) and forested depressions(Smith and Klimas 2002), werereviewed as a means to hypothesizethe effects of conversion on the struc-ture and function of forested wetlands.Information on land ownership andtimber harvests came from FIA dataand Brown and others (2001). Wetlandrestoration literature and universitystudies on the extent and success ofwetland restoration also were reviewed.

Results and Discussion

Status of Forested WetlandsIn colonial times (circa 1780) the

conterminous United States hadapproximately 221 million acres ofwetlands (Dahl 1990). These wetlandshad been, and would continue to be,affected by natural and anthropogenicdisturbances. Over the next 200 years(circa 1980) the total wetland areain the country was reduced by over50 percent to 104 million acres (table20.1). Losses are primarily attributableto clearing and draining for agriculture.Frayer and others (1983) suggest thatthe greatest losses between the 1950sand the 1980s were in freshwaterforested wetlands. Abernethy andTurner (1987) estimated losses offorested wetlands were up to fivetimes greater than those of nonforestedwetlands between 1940 and 1980.Almost 7 million forested wetlandacres were lost in the Lower MississippiValley alone.


AQUATIC

Table 20.1—Composite of National Wetland Inventory wetland status and trend information for the conterminousand Southeastern United States

Time Geographic extent Total Forestedperiod of estimate wetland wetland Source

- - - - - - - - - - Acres - - - - - - - - - -

1780 Conterminous U.S. 221,000,000 No estimate Dahl (1990)1980 Conterminous U.S. 104,000,000 No estimate

% change 47%

1950 Southeast (10 States) 54,257,000 38,000,000 Hefner and Brown (1985)1970 Southeast (10 States) 46,500,000 32,000,000

% change 15% 16%

1970 Southeast (10 States) 51,200,000 35,300,000 Hefner and others (1994)1980 Southeast (10 States) 48,900,000 33,004,000

% change 5% 7%

1986 Conterminous U.S. 106,135,700 51,929,600 Dahl (2000)1997 Conterminous U.S. 105,500,000 50,728,500

% change 1% 3%

1986 Southeast (10 States)a 49,883,779 33,735,0001997 Southeast (10 States)a 49,585,000 32,643,000

% change 1% 3%

a Estimated from percentages, specific to the South, from Hefner and others (1994) applied to national data from Dahl (2000). Wetland acreagesderived from National Wetland Inventory reports and/or calculated from reported percentages.

Hefner and Brown (1985) reportedthat 47 percent (48.9 million acres)of the wetlands in the conterminousUnited States occurs in 10 SoutheasternStates (Kentucky, Tennessee, NorthCarolina, South Carolina, Georgia,Florida, Alabama, Mississippi,Louisiana, and Arkansas). In addition,65 percent of all the forested wetlandsin the conterminous United Statesoccurred in these 10 Southern States.Table 20.2 provides an estimate of totalwetland acres, forested wetland acres,and forested wetland change inSouthern States. Hefner and Brown(1985) reported that for the periodbetween the 1950s and 1970s theSouth sustained the greatest wetlandlosses in the country. Forested wetlandlosses were attributed to massiveclearing and drainage projects designedto bring wetlands into agriculturalproduction. As of the 1970s Hefner andBrown (1985) reported that 80 percentof the 25 million acres of forestedwetlands in the Lower Mississippi RiverValley had been lost to agriculture.Major losses of pocosins and CarolinaBays in North Carolina were attributedto agriculture and peat mining. Overall,forested wetland acres in the South

declined by 16 percent between the1950s and 1970s (table 20.1).

Hefner and others (1994) reportedthat approximately 3.1 million acres(9 percent) of forested wetlands in theSouth were lost or converted in the1970s and 1980s (table 20.1). Forestedwetlands in these 10 SoutheasternStates were lost or converted at anaverage rate of 276,000 acres per yearfrom the 1950s to 1970s but lost at anaverage rate of 345,000 acres per yearfrom the 1970s to 1980s (Hefner andothers 1994). More than 719,000 acresof forested wetlands were converted toscrub-shrub wetlands from the 1970sto 1980s. Almost 69 percent of theSouth’s forested wetland losses wererecorded in the Gulf-Atlantic CoastalFlats and Lower Mississippi AlluvialPlain (fig. 20.1). The Gulf-AtlanticCoastal Flats of North Carolina andthe Lower Mississippi Alluvial Plainof Louisiana suffered the greatestlosses during this time period. Nearly1.2 million acres were lost in NorthCarolina, presumably to silvicultureand agriculture, and nearly 1 millionacres of forested riverine wetlands(bottomland hardwood wetlands)were severely affected primarily by

agriculture in the Lower MississippiAlluvial Plain. Although the net rateof wetland loss declined from 386,000acres per year from the 1950s to 1970sto 259,000 acres per year from the1970s to 1980s, the rate at whichforested wetlands declined accelerated(Hefner and others 1994). The dropin overall wetland loss rate resumedbetween 1986 and 1993, declining80 percent to 58,500 acres per year forthe conterminous United States (Dahl2000). The change in forested wetlandacres during this time period wasapproximately 3 percent (table 20.1).Dahl (2000) estimated that nationally4 million acres of forested wetlandunderwent some change in conditionbetween 1986 and 1997. Most wereconverted to freshwater shrub wetlandsby timber harvesting or other processesthat removed the tree canopy butretained the wetland character. Table20.1 indicates forested wetland lossesexceed total wetland losses for the1986–97 time period. This is due to theinclusion of restored wetland acreage inthe “total wetland loss” category whichreduces the actual losses. Table 20.3shows a breakdown of the number ofpalustrine (freshwater) forested wetlandacres lost or converted by activity and


Table 20.2—Comparison of total wetland and forested wetland acres and the predominant cause of change

State land ForestedTotal surface in Forested wetland Predominant cause

State wetland wetland wetland change of change

Acres Percent - - - - - - - Acres - - - - - - -

Alabama 2,700,000 8 2,200,000 97,000 AgricultureArkansas 3,600,000 10 2,800,000 210,000 AgricultureFlorida 11,000,000 30 5,500,000 184,100 Other wetland types and

urbanizationGeorgia 7,700,000 20 6,100,000 500,000 Other wetland typesKentucky 388,000 1 274,000 9,884 Agriculture and miningLouisiana 8,800,000 28 4,900,000 628,000 AgricultureMississippi 4,400,000 14 3,700,000 365,000 AgricultureNorth Carolina 5,000,000 15 3,400,000 1,200,000 OtherSouth Carolina 4,700,000 24 3,600,000 125,000 Agriculture, urban, forestryTennessee 632,000 2 630,000 25,000 AgricultureTexas 6,400,000 2,500,000 60,540 Agriculture, reservoirsVirginia 683,000 20,000

Source: Data abstracted from Hefner and others 1994, Frayer and Hefner 1991, and Shepard and others 1998.

33 Lower New England

34 Gulf–Atlantic Rolling Plain

35 Gulf–Atlantic Coastal Flats

36 Coastal Zone

29 East Central Drift and Lake-bed Flats

30 Eastern Interior Uplands and Basins

31 Appalachian Highlands

32 Adirondack-New England Highlands

21 Dakota–Minnesota Drift and Lake-bed Flats

22 Nebraska Sand Hills

23 West Central Rolling Hills

24 Mid-continent Plains and Escarpments

25 Southwest Wisconsin Hills

26 Middle Western Upland Plain

27 Ozark–Ouachita Highlands

28 Lower Mississippi Alluvial Plain

by State for the period of 1986–97,recorded by NWI, for the 13 SouthernStates included in the Southern ForestResource Assessment. Georgia, NorthCarolina, Mississippi, South Carolina,and Alabama showed the greatestchange in forested wetland area—over 300,000 acres per State. In eachof the above cases, over 80 percent of

the change in wetland type resultedfrom a conversion from forestedwetland to shrub-scrub or emergentwetland. Overall, 90 percent of thechange in forested wetland acres inthe 13 Southern States resulted fromthese types of conversions. Ninety-fivepercent of the conversions of forested

wetland were to shrub-scrub oremergent wetland types.

According to NWI, losses (changesfrom wetland to nonwetland) accoun-ted for 10 percent of the change inforested wetlands in the South or356,000 acres between 1986 and 1997.Thirty-three percent of the losses weredue to urban/rural development, 31percent to agriculture, and 29 percentto silviculture. The remaining 7 percentof losses of forested wetlands wereattributed to other land uses. TheNWI attributes losses to silviculture,if drainage occurs on any forested site(including those in agricultural orurban landscapes) such that a shift fromwetland vegetation to upland vegetationis apparent (Personal communication.2001. Charles Storrs, National WetlandCoordinator, Southeast Region, U.S.Fish and Wildlife Service, Atlanta,GA) The three States with the greatestreported losses due to silviculture wereLouisiana, Georgia, and Arkansas. Thethree States with the greatest loss dueto agriculture are Mississippi, Georgia,and Tennessee. The three States withthe greatest losses to developmentwere Florida, Mississippi, and Georgia.

Direct comparisons of variouswetland inventories is difficult dueto the dynamic nature of wetlands,differences in the time period in whichthe inventories are made, differencesin geographic cover, and differencesFigure 20.1—Physiographic regions of the Southern United States

(Hammond 1970).


AQUATIC

Tabl

e 20

.3—

Est

imat

ed a

cres

of p

alus

trine

fore

sted

wet

land

con

vers

ion

and

loss

by

Sta

te a

nd b

y ac

tivity

in th

e S

outh

a

Est

imat

ed a

cres

of

pal

ust

rin

eE

stim

ated

acr

es o

f p

alu

stri

ne

fore

sted

con

vert

ed t

o:fo

rest

ed l

ost

to:

Tota

l es

tim

ated

acr

es

Pal

ust

rin

eP

alu

stri

ne

Pal

ust

rin

eD

eep

-A

gric

ul-

Urb

anR

ura

lSi

lvi-

Stat

eem

erge

nt

shru

bot

her

wat

ertu

red

evel

opd

evel

opcu

ltu

reO

ther

Con

vers

ion

Los

sC

han

ge

AL

53,7

1728

9,10

33,

317

2,68

618

6,30

151

234

6,13

7(2

7)9,

517

(43)

355,

654

(26)

AR

25,4

1110

0,81

313

,262

5,25

91,

404

149

3,61

928

,958

3,21

314

4,74

5(2

2)37

,343

(37)

182,

088

(23)

FL

41,6

5418

7,28

43,

366

492

6,78

911

,487

26,4

2458

23,

892

232,

796

(21)

49,1

74(2

3)28

1,97

0(1

8)G

A10

8,77

867

7,99

418

,593

2,55

424

,049

12,4

227,

330

30,7

456,

075

807,

919

(11)

80,6

21(2

8)88

8,54

0(1

1)K

Y17

49,

629

868

174

(*)

10,4

97(6

0)10

,671

(59)

LA

21,8

3483

,700

25,4

4713

,357

9,01

51,

311

4,92

140

,319

4,74

214

4,38

8(2

1)60

,308

(31)

204,

646

(18)

MS

32,9

6338

6,42

911

,250

6,58

734

,841

4,95

115

,508

1,10

243

7,22

9(2

9)56

,402

(45)

493,

631

(26)

NC

56,3

9347

2,11

66,

235

862,

888

1,24

52,

677

246

534,

830

(16)

7,05

6(2

2)54

1,88

6(1

6)O

K18

,352

5,34

015

,536

922,

628

3,67

939

,320

(42)

6,30

7(6

9)45

,627

(38)

SC60

,368

294,

246

5,29

833

1,18

49,

293

3,44

563

02,

185

359,

945

(19)

16,7

37(3

5)37

6,68

2(1

8)T

N21

4216

,882

174

9463

(*)

17,1

50(6

4)17

,213

(64)

TX

30,3

5770

,262

755

118

3,04

01,

005

5910

1,49

2(5

4)4,

104

(50)

105,

596

(53)

VA

9,69

71,

279

1,17

71,

177

12,1

53(6

4)1,

177

(*)

13,3

30(5

9)

Tota

l45

9,52

42,

568,

587

104,

278

28,7

5211

1,99

545

,906

73,3

5910

2,23

922

,894

3,16

1,14

135

6,39

33,

517,

534

(10)

(8)

(25)

(19)

(21)

(29)

(18)

(7)

(13)

(7)

Val

ues

in

par

enth

eses

are

per

cen

t co

effi

cien

t of

var

iati

on w

ith

an

ast

eris

k (*

) in

dica

tin

g it

is

stat

isti

call

y u

nr e

liab

le.

a E

stim

ate

base

d on

U.S

. Fis

h a

nd

Wil

dlif

e Se

rvic

e, N

atio

nal

Wet

lan

d In

ven

tory

dat

a fr

om 1

986-

97 (

Dah

l 20

00).

in sampling and delineation protocols(Shepard and others 1998). However,indirect comparison of the NWI andNRI results are interesting. From 1982through 1987 the NRI data indicatedthat urban, industrial, and residentialland uses caused 48 percent of thewetland losses in the conterminousUnited States. Agriculture wasresponsible for 37 percent of wetlandlosses, while the remaining 15 percentwere converted to barren land, openwater, or forest (Brady and Flather1994). For this time period the NRIdata suggest a shift from agriculture tourban development as the major causeof wetland conversion. From 1982 to1992 NRI data indicate that 55 percentof the total wetland loss in the Nationoccurred in the 12 Southern States.During this period, wooded wetlandsshowed the lowest loss rate in recentdecades. According to NRI, 75 percentof the losses from 1982 to 1992 weredue to development (Shepard andothers 1998). The updated 1997 NRIreport shows that 12.5 percent ofthe losses of wetlands in the Southare attributable to silviculture, 18.4percent to agriculture, 58 percentto development, and 10.1 percent tomiscellaneous climatic and hydrologicchanges (fig. 20.2). Differences indefinitions for attributing loss are aprimary reason for discrepancies inwetland loss and conversion estimatesbetween NWI and NRI (Personalcommunication. 2001. Charles Storrs,National Wetland Coordinator,Southeast Region, U.S. Fish andWildlife Service, Atlanta, GA).

Land ownership patterns of forestedwetlands have been summarized for5 of the 13 Southern States by Brownand others (2001). About 60 percentof the wetland timberland in Virginia,North and South Carolina, Georgia,and Florida is privately owned. Forestindustry owns 28 percent of the land,and the public owns 12 percent (Brownand others 2001). Data from the othereight Southern States is unavailable.Of the wetland timberland in the fiveSouthern States for which data areavailable, 62 percent is covered withbottomland hardwoods, 25 percentwith pine plantations and naturalpine stands, and 10 percent oak-pinestands. Most of these forest types arein private nonindustrial ownershipexcept for pine plantations, whichare largely owned by forest industry


Change in percent£ -10.00

-9.99 – -0 .010.00

.01 – 9.99≥ 10.00

(68 percent) (Brown and others2001). The percentage of timberlandin wetlands and the expected increasein timber harvest in the South (chapter13) indicate the likelihood of additionalwetland modifications due tosilvicultural activities.

Likely future of forested wetlandsin the South—Projecting changesin forested wetlands in the South isdifficult, if not impossible, because ofthe wide variety of scientific, societal,and economic factors that affect theforested wetland resource. Sciencehas provided a great deal of informationon how wetlands function and howhuman activities affect those functions.However, much information is notknown and is difficult to discern.The values that people associate withforested wetlands vary greatly. Theyrange from valuing old-growth forestto the exclusion of timber harvestingto valuing forested wetlands asmerchantable timber or nothingmore than potential developmentsites. Economic factors are importantbecause, ultimately, wetlands arelost to development or agricultureor converted to intensive silviculturebased upon economics.

This section of the chapter addresseschanges in wetland condition, withparticular emphasis on silviculture,current policies, and the efficacy ofcurrent forested wetland restorationefforts in the South. Additionalinformation about forces of changein southern forests can be gained fromother chapters in this Assessment.

Forested wetland types in the Southare highly variable, ranging frombaldcypress swamps to scrub-shrubbogs that undergo cycles of wildfire.Due to these differences in vegetation,hydrology, landscape position, anddegree of alteration, wetlands differ inthe functions they perform and theirability to perform those functions(Brinson and Rheinhardt 1998).Wetland functions can be simplydescribed as the things that wetlandsdo. Many of these functions, such assurface and ground-water conveyanceand storage, nutrient cycling, andorganic carbon export provide societalbenefits, goods, and services, (suchas floodwater storage, water-qualityenhancement, and wildlife habitat).Because of the large geographic areaencompassed in this study (13 States),generalizations about forested wetlandsmust be made. The HGM (Brinson

1993) and functional assessmentapproach (Smith and others 1995)provide a means to make these broadgeneralizations about similar forestedwetland types, the functions theyperform, and the effects of certainactivities on those functions.

The predominant forested wetlandsin the South can be classified into fourHGM classes: (1) riverine, (2) organicsoil flats, (3) mineral-soil flats, and (4)depressions (Brinson 1993). Wetlandsin each class occupy similar landscapepositions and have similar hydrology.The presumption in HGM classificationis that if wetlands occupy similarlandscape positions so that the water,which drives wetland functions, comesfrom similar sources and flows intoand out of wetlands in similar ways,the ecological processes (functions)that make wetlands important will besimilar. This is a logical simplificationthat facilitates the discussion of wetlandecological characteristics and processesand human impacts.

In general, southern deepwaterswamps, major alluvial floodplains,and minor alluvial floodplains (Messinaand Connor 1998) can be combinedinto the riverine class. Carolina Bays,

Figure 20.2—Change in forested wetlands in the South based on Natural Resources Inventory 1982 to 1987.


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Table 20.4—Comparison of forested wetland community types and extents with hydrogeomorphic class

Forested Predominant Extent incommunity type HGM class the South Source

Acres

Southern deepwater swamp Riverine a Conner and Buford (1998)Major alluvial floodplain Riverine 11,800,000 Kellison and others (1998)Minor alluvial floodplain Riverine 20,000,000 Hodges (1998)Carolina bays Depressions Sharitz and Gresham (1998)Southern mountain fens Depression/slope 6,200 Moorhead and Russell (1998)Pondcypress swamps Depression Ewel (1998)Pocosins Organic flats 695,000 Sharitz and Gresham (1998)Wet flatwoods (pine) Mineral flats 2,500,000 Harms and others (1998)

HGM = hydrogeomorphic.a Included in major and minor alluvial floodplain estimates.

pondcypress swamps, and mountainfens can all be classified as depressionswith similar depressional geomorph-ology and low-energy surface runoff orground-water hydrodynamics. Wet pineflatwoods are classified as mineral-soilpine flats due to their soil composition,flat topography, and the predominanceof rainfall for their hydrology. Pocosinsare classified as organic soil flats. Theirtopography and hydrology are similarto those of mineral-soil flats, but soilcomposition is dominated by peat.The flats class encompasses areasdominated by pines and by hardwoods.However, mineral-soil pine flats willbe the predominant flats class discussedin this chapter due to their extent, fireecology, and vulnerability to alteration.Based upon the acreage estimates intable 20.4, riverine is the predominantHGM class in the South, followed byflatwoods and depressions.

In general, the hydrologic regimeis one of the main factors controllingecosystem functions in all wetlandsand differentiating wetland types.The timing, duration, depth, andfluctuations in water level affectbiogeochemical processes and plantdistribution patterns. The rate, magni-tude, and timing of biogeochemicalprocesses are determined by hydrologyand the living components of anecosystem. For instance, primaryproducers (plants) assimilate nutrientsand elements in soil and use energyfrom sunlight to fix carbon. Whenthey die, they depend upon microbialorganisms in soil to transform carbonand nutrients such as nitrogen andphosphorous to forms that are available

to other plants. Therefore, wetlandconditions that maintain plants andsoil microbial populations are thosethat drive characteristic biogeochemicalprocesses. These processes help tosustain the wetland plant community,which provides much of the structurerequired by wildlife. The integratedcombination of water, soils, andplants sustains the ecosystemand provides many of the valuesattributed to wetlands.

Riverine wetlands—Riverinewetlands occur in floodplains andriparian corridors in associationwith stream channels (Brinson 1993).The dominant water source for thesewetlands is from the stream channelvia overbank flooding or throughsubsurface connections betweenthe stream channel and the wetland.Riverine wetlands lose surface waterin four ways: (1) surface flow offloodwater to the channel, (2) sub-surface water flow to the channel,(3) percolation to deeper groundwater, and (4) evapotranspiration.Evapotranspiration includes evapora-tion from soil and water surfaces andmovement of water through plants tothe atmosphere. Unimpacted southernforested riverine wetlands typicallyextend perpendicularly from a streamchannel to the edge of the stream’sfloodplain. They have unaltered soilsand a mature tree canopy, and theyrange from narrow riparian strips inlow-order streams to broad alluvialvalleys several miles wide (Sharitz andMitsch 1993). This wetland ecosystemoccurs in the Lower Mississippi RiverValley as far north as southern Illinois

and along many streams that drainthe South Atlantic Coastal Plain intothe Atlantic Ocean.

The functions of riverine wetlandsare closely tied to flooding of adjacentstreams and the soil and vegetationwhich result. Flooding is importantboth ecologically and societally becausefloodwaters move sediments andnutrients into and out of the wetlands.Wetlands detain floodwaters andprevent or minimize flood damagesdownstream (Kellison and others 1998,Mitsch and Gosselink 2000, Sharitzand Mitsch 1993). Riverine wetlandsenhance water quality by interceptingsediments, elements, and compoundsfrom upland or aquatic nonpointsources of pollution. They permanentlyremove or temporarily immobilizenutrients, metals, and other toxiccompounds (Ainslie and others 1999).Hydrologic, soil, and biological factorsdetermine the ability of a riverinewetland to sustain a characteristicplant community. The vegetation oflow-gradient alluvial riverine wetlandsis extremely diverse (Sharitz andMitsch 1993). The ability to maintaina characteristic plant communityis important because of the intrinsicvalue of the plants themselves, andthe many attributes and processes ofriverine wetlands influenced by theplant community. For example, plantsinfluence primary productivity, nutrientcycling, and the ability to provide avariety of habitats necessary to maintainlocal and regional diversity of animals(Brinson 1990, Gosselink and others1990, Harris and Gosselink 1990).Riverine wetlands provide habitats for


a diversity of terrestrial, semiaquatic,and aquatic organisms. They provideaccess to and from uplands for com-pletion of aquatic species’ life cycles,provide refuges and habitat for birds,and act as conduits for dispersal ofspecies to other areas. Most wildlife andfish species in riverine wetlands dependon the amount and timing of flooding,the variable topography which allowsdifferent plants and animals to becomeestablished, forest tree compositionand structure, and proximity to otherhabitats. Riverine wetlands also must beviewed in their landscape context or inrelation to the other land uses aroundthem. Generally, the continuity ofvegetation, the connection betweenspecific vegetation types, the presenceand size of corridors between uplandand wetland habitats, and corridorsamong wetlands all have direct bearingon the movement and behavior ofanimals that use wetlands.

Depression wetlands—These wet-lands occur in topographic depressionsthat allow the accumulation of surfacewater (Brinson 1993). Depressionwetlands may have a combinationof inlets and outlets or lack themcompletely. Potential water sources areprecipitation, overland flow, streams, orground water/interflow from adjacentuplands. Water typically flows from theoutside of the depression to the center.Upward and downward movementof the water table may vary daily toseasonally. Cypress domes and CarolinaBays are typical regional forestedwetland types (Messina and Conner1998) that occur in depressions.Pondcypress domes are poorly drainedto permanently wet depressionalwetlands that occur in the southeasternCoastal Plain and are abundant inFlorida (Ewel 1990). Cypress domesare shallow, circular, nutrient-poorswamps located in depressions on low-relief landscapes. They often have anunderlying impervious layer of soil thatinhibits downward movement of water.These wetlands are called “domes”because the tallest trees are in thecenter and the smaller trees near theedge give the appearance of a dome.Domes have long-standing, nutrient-poor water which is often dominated byprecipitation and surface inflow (Mitschand Goselink 2000). Limited plantgrowth rates are related to both lowflow and lack of nutrient availability.

Carolina bays occur on the AtlanticCoastal Plain from New Jersey toFlorida. The water source for Carolinabays ranges from predominantlyprecipitation to predominantly groundwater. These bays occur in clusters,are commonly elliptical in shape, andare often oriented in a northwesterlyto southeasterly direction. Larger,deeper Carolina bays contain lakes,but the majority of them are wetlandswith diverse plant communities rangingfrom shrub-bog pocosins to marshesto hardwood- or cypress-dominatedswamp forests. Many bays may becomeblanketed by an overgrowth of bogvegetation, which compresses lowerlayers of peat, making them relativelyimpervious to water movement. Theresult is a ponding of water, making thedepression saturated for long periodsof time. Bays are critical breeding sitesfor amphibians and habitat for birdsand other wildlife. They often hostrare or endangered plants.

Detention of runoff water is an impor-tant depressional wetland functionbecause runoff, or occasional overbankflooding in riparian depressions, altersflood timing, duration, and magnitude.The result is reduced flood flow down-stream. Water storage or detention hassignificant effects on biogeochemicalcycling; plant distribution, compositionand abundance; and wildlife popula-tions. Just as in riverine wetlands,nutrient cycling is mediated primarilyby two processes: (1) nutrient uptakeby plants (primary production), and(2) nutrient release from dead plantsfor renewed uptake by plants (detritalturnover). Because of their location onthe landscape, depressional wetlands,particularly those in lower portionsof watersheds, are strategically locatedto remove and sequester sediments,imported nutrients, contaminants,and other elements and compoundsbefore they can contribute to groundwater and surface-water pollutiondownstream. These contaminants areremoved from incoming water by theinteraction of water, wetland vegetation,wetland microbes, detrital material,and soil. The primary benefit of thisfunction is that the removal, conver-sion, and sequestration of compoundsby depressional wetlands reducesthe load of nutrients and pollutantsin ground water and in any surfacewater leaving the depressional wetland.Not all depressions are positioned or

capable of removing these sediments,compounds, and contaminants. Forinstance, depressions at the top ofdrainage basins, or those in flat topo-graphy, may not receive pollutantsfrom upstream.

Depressional wetlands support manyanimal populations. They providehabitats within the actual wetland andin conjunction with the surroundinglandscape. They maintain regionalbiodiversity by providing open water,nesting cavities, cover and food chainsupport for a variety of animals (Ewel1998). In some regions, Carolina baysare major and critical focal pointsfor breeding and feeding of a largevariety of nonaquatic vertebrate andinvertebrate animal species. Thebiomass of animals in these Carolinabays is extremely high comparedto adjacent terrestrial habitats ormore permanent aquatic habitats(Richardson and Gibbons 1993).

Forested wet flats—In the SouthernUnited States, wet flats occur on poorlydrained mineral or organic soils inlowland areas (Harms and others 1998,Rheinhardt and others 2002). Wet flatson organic, or peaty, soils are calledpocosins. Pocosins differ from mineral-soil flats in both geomorphology andvegetation. Pocosins are located ontopographic highs and are dominatedby evergreen shrubs, and most burnevery 15 to 30 years (Rheinhardtand others 2002, Richardson 1981).The hydrologic regime of pocosins isdriven by precipitation, but water flowsoutward from the center and eventuallyforms headwater streams near thewetland’s outer boundaries (Brinson1993). The organic soils of pocosinstend to hold water longer than mineral-soil flats. As a result, frequency of fireis less than in mineral-soil flats.

Mineral-soil flats are most commonon areas between rivers, extensive lakebottoms, or large floodplain terraceswhere the main source of water isabundant precipitation and slow drain-age associated with a landscape of lowrelief (Brinson 1993, Rheinhardt andothers 2002). This class predominantlyoccurs on the Atlantic Coastal Plainfrom Virginia to Texas (fig. 20.1). Thereare two subclasses of mineral-soil flats:those dominated by a closed canopyof hardwoods, and those characterizedby open savanna with widely scatteredpines (Rheinhardt and others 2002).Mineral-soil hardwood flats in the


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Yazoo Basin of Mississippi occur onformer and current floodplains createdby the Mississippi River and itstributaries (Smith and Klimas 2002).Mineral-soil flats receive virtuallyno ground-water discharge. Thischaracteristic distinguishes them fromdepressions. The dominant direction ofwater movement is downward throughinfiltration. These wetlands lose waterby evapotranspiration, surface runoff,and seepage to underlying groundwater. They are distinguished fromflat upland areas by their poor drainagedue to impermeable layers (hardpans),and slow lateral drainage. Mineral-soilpine flats will be the focus of thefollowing discussion due to the millionsof acres that still exist and theirsusceptibility to alteration due to fireexclusion, development, and silvi-cultural conversion to pine plantation.

The pre-European landscape waslargely maintained by fires resultingfrom lightning strikes and NativeAmerican burning. However, with thecolonization and subsequent manage-ment by Europeans, less than 2 percentof the fire-maintained character ofmineral-soil pine flats remained by the1990s. In their least altered condition,wet pine flats have very few trees.When trees are present, longleaf, pond,and occasionally slash and loblollypines are naturally associated with thiswetland type. All four pines can tolerateground fires by the time they reach6 to 9 feet in height, but longleaf is theonly pine whose seedlings are adaptedto tolerate fire. The combined stressesof fire and wetness led to the evolutionof an unusually rich flora on manywet pine flats (Rheinhardt andothers 2002).

Wet pine flats differ from other wet-lands due to a combination of factorsthat do not occur together in any otherwetland type. These factors combine tocontrol the biogeochemical processescharacteristic of wet pine flats:

1. The source of water, dominated byprecipitation and vertical fluctuationsin water level driven by evapotrans-piration, is generally low in nutrients.

2. When flooding occurs, it is shallow(10 to 20 cm) and flows slowly.

3. The number of pits and mounds onthe ground surface is high and providesa diverse array of aerated and anoxicconditions for soil microbial organisms.

4. Nutrient recycling occurs in pulsesfollowing fires, which recur on afrequent basis, thus enabling a rapidturnover of nutrients. These fourattributes enable wet pine flats totightly and rapidly cycle nutrients.As a result, wet pine flats rapidlyrecover their characteristic biomassand structure after fires (Rheinhardtand others 2002).

Plant communities characteristic ofunaltered wet pine flats are maintainedby an appropriate hydrologic regime,fire regime, and biogeochemicalprocesses that require intact soilconditions. Under relatively unalteredconditions, these three parameterscombine to maintain a grassy savannawith few or no trees. On some sites,the herbaceous plant community isextremely rich. In fact, the herbaceousspecies richness is the highest recordedin the Western Hemisphere (Walkerand Peet 1983). This herbaceousassemblage is extremely sensitive toalteration and, as a consequence, manyspecies associated with this ecosystemare rare or threatened with extinction.Because the herbaceous communityof wet pine flats is so sensitive toalteration (fire exclusion, hydrologicalteration, and soil disturbance), itscondition provides information onhabitat quality. Plant populations inwet pine flats have evolved to bothwithstand and require frequent fire.Fire stimulates flowering and seed setin many wet savanna species, such astoothache grass and wiregrass. As aresult, species composition and spatialhabitat structure reflect fire frequency.In the absence of fire, wet pine flatvegetative composition becomesdominated by shrubs or hardwoodtrees. This is a degraded conditionwhen compared to a fire-maintainedwet pine flat.

Animals that use unaltered wetpine flats for all or part of their livesare adapted to habitats maintained byfrequent fire. Frequent fire maintainsopen savanna, which is important tosome animal species using wet pineflats. For animal species that utilizeboth unaltered wet pine flats and othersimilar fire-maintained landscapes, thetotal area of fire-maintained landscape(both wetland and upland) is critical.Because fire frequency has been dras-tically reduced in most areas of theSoutheast, many animal species thatrequire habitat maintained by frequent

fire are threatened or endangeredover most of their historic range.Maintenance of a characteristic animalassemblage depends upon: (1) habitatquality within the site (onsite quality),and (2) the quality of the surroundinglandscape that provides supplementalresources (landscape quality). Onsitehabitat quality can be inferred fromthe structure and composition of theplant community.

A number of species rely on fire-maintained pine ecosystems of whichwet flats are a part. For example,birds and other wide-ranging animalsthat rely on fire-maintained systemsdo not appear to differentiate wetpine flats from uplands, as long asboth are fire-maintained. Thus, fire-maintained uplands supplementresources available in fire-maintainedwet flats and vice versa.

Alterations to ForestedWetlands Due toDevelopment, Agriculture,and Silviculture

Functions of forested wetlandsand the concomitant goods andservices they provide can be degradedor destroyed by human activities.Activities that affect forested wetlandsfit into four broad categories: (1) urbandevelopment, (2) rural development,(3) agriculture, and (4) silviculture.Since each wetland impact carriesa unique set of circumstances andresponses, these categories are rathergross. Their use, however, helpsto describe wetland status, trends,and impacts in the South.

NWI defines urban developmentas intensive use in which much of theland is covered by structures, includingbuildings, roads, commercial develop-ments, power and communicationfacilities, city parks, ball fields, andgolf courses. In rural development,land use is less intensive, and thedensity of structures is more sparse.Agriculture is defined as land useprimarily for the production of foodand fiber, including horticultural, row,and close-grown crops as well as animalforage. Silviculture is defined here asmanagement of land for production ofwood (Dahl 2000).

The replacement of forested wetlandswith urban and/or rural developmentconstitutes an irreversible loss, sincethe wetland is replaced by upland.


Developed areas lack wetland hydro-logy, soils, and vegetation, either singlyor in any combination. Changing aforested wetland to an agriculturalfield typically changes its hydrologyand vegetation and disturbs its soil.However, some of these agriculturalactivities, such as drainage and removalof native vegetation, can be reversedand wetlands restored. Silviculturalactivities typically do not lead to a lossof wetland status but may temporarilyaffect wetland functions. In forestedriverine wetlands, for example, theoverstory vegetation is removed buthydrology is left largely intact. Likesome agricultural effects, silviculturaleffects can be reversed and the wetlandfunctions restored. More specificaspects of these activities will bediscussed next.

Urban and rural development—Theeffects of urban and rural developmenton riverine, flat, and depressionalwetlands in the South are similar. Forestvegetation is cleared, areas are drainedor filled to escape flooding, structuresare built, and wetland vegetation isreplaced. These activities eliminatethe ability of forested wetlands to storeand convey surface water and groundwater. Water runs off these developedsurfaces faster, reaching streams quickerand contributing to larger floods down-stream. Development also eliminatesthe water-quality enhancement of for-ested wetlands. Development alters thehydrology and replaces the soils andvegetation with manmade structureswhich are not able to take up excessnutrients and other pollutants. Thestructures may actually contributepollutants to adjacent aquatic eco-systems. Basnyat and others (1999)reported that urban land is thestrongest contributor of nitrate toadjacent streams in Alabama. Alterationof hydrology and replacement ofvegetation and soils with manmadestructures also eliminate the forestedwetland plant community and thewildlife associated with these areas. Inother words, urban and rural develop-ment typically replace the wetland withupland and developed land with noneof the functions of wetlands and littlechance of restoration.

Agriculture—Generally, agricul-tural activities in forested wetlandsmanipulate hydrology, remove nativevegetation, and disturb the soils for thepurpose of crop production. Drainage,

channelization, and levee constructionimpact the flow of water to and from awetland site in an effort to dry out thearea. When wetlands are drained foragricultural use, they no longerfunction as wetlands (Mitsch andGosselink 2000).

In riverine wetlands, hydrology isthe principal force for maintainingecological processes and vegetationstructure (Gosselink and others 1990).Drainage and channelization allowedwater to reach the wetland but removedit from the site and/or watershed morequickly. Levees prevent floodwatersfrom reaching the wetland at naturalintervals (once to several times peryear). Thus, drainage, channelization,and levee construction result inchanges in the timing of delivery ofwater (frequency), the amount of waterdelivered (magnitude), and the lengthof time the water remains in the wet-land (duration). Duration of inundationis important in nutrient cycling,removal of pollutants and sediments,and export of organic carbon. Changesin hydroperiod also change the plantcommunity, which alters the livingand dead plant biomass componentsof nutrient cycling and organic carbonexport. Construction of drainageditches and channelization can affectthe flow of subsurface water in ariverine wetland by changing thegradient of subsurface flow. Typicallythe result is a lower water table inthe vicinity of the ditch or deepenedchannel. A shallower water table affectsthe ability of the riverine wetland togradually contribute to stream flowsduring dry periods. Lowering thewater table also affects biogeochemicalprocesses and plant and animalcommunities that depend on themaintenance of a stable ground-watertable (Ainslie and others 1999).

By impairing the ability of overbankflows to reach riverine wetland sites,levees prevent elements and com-pounds and sediments from reachingthe wetland where they are depositedor removed. Levees prevent flood flowsfrom transporting organic carbon todownstream aquatic ecosystems. Theyalso act as barriers to aquatic speciesthat use the floodplains for spawningand rearing (Baker and Kilgore 1994,Lambou 1990).

Clearing the native vegetation of aforested riverine wetland and replacingit with a crop dramatically reduces the

site’s structural diversity, wildlife-food-producing capacity, and nesting andescape cover (Gosselink and others1990). Clearing also affects forest patchdynamics by decreasing forest patchsize, interrupting forest continuity,decreasing the percentage of regionalforested wetland, and increasing edgebetween community types. Soil tillingis likely to decrease the amount oforganic matter in the soil due tooxidation. It also reduces waterinfiltration by creating a plow pan(Drees and others 1994). Therefore,clearing of native vegetation and foreststructure and repeated plowing andtilling have the aggregate effect ofcausing more water to run off farmfields, contributing greater flows andnonpoint-source pollutants (Basnyatand others 1999).

Many Carolina bays have beensignificantly altered by agriculturalpractices, and some are being usedfor wastewater treatment (Richardsonand Gibbons 1993). Managing foresteddepressions for agriculture involvesclearing existing vegetation, installingdrainage ditches through the rim ofthe Carolina Bay, tilling the soil, andplanting the site in the desired cropspecies. Draining the depression altersthe duration of ponding and theamount of water in the wetland. Plants,animals, and the biogeochemistryof the wetland are affected. Disruptingthe surface of the soil by tilling affectsthe amount of organic material in thesoil. As water is drained from thedepression, soil organic material isexposed to the air, speeding its removalthrough oxidation. As soils are dis-turbed and more organic carbon isexposed from deeper in the soil andmore is oxidized as a result, thebalances among water, carbon,and other elements like nitrogenand phosphorous are disrupted.Accumulation of too much sedimentin depressional wetlands, from erosionin nearby uplands, decreases wetlandwater storage volume, decreases theduration of water retention in wetlands,and changes plant community structureby burial of seed banks. As withriverine wetlands, clearing the existingvegetation in Carolina bays alters thecomposition and structure of the nativeplant community and affects wildlifespecies that utilize the depression.

Sharitz and Gresham (1998) reportthat 97 percent of the Carolina bays


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in South Carolina have been disturbedby agriculture (71 percent), logging(34 percent), or both. Agriculture isthe oldest and predominant use of bays,having started in the 1940s.Soils in Carolina bays are highly organicand have a high nutrient-holdingcapacity. They are attractiveto farmers if drainage is accomplished;soil pH is raised by liming; minornutrients tied up by the highly organicsoils are supplied to the crops withspray; and weeds are controlled,primarily with herbicides. If theseactivities are completed, Carolina baysare 10 to 15 percent more productivethan upland soils, but these activitiesalter the structure and function of theCarolina bay.

Organic soil flats were cleared anddrained for agriculture as early as the1780s. Several large pocosins have beenimpacted by corporate agriculturaloperations, which have drained, limed,and fertilized these wetlands for cornand soybean production. Offsite effectsof draining pocosins for agricultureincluded decreased salinity in adjacentestuaries; increased turbidity inadjacent streams immediately afterdevelopment; and increased phosphate,nitrate, and ammonia inputs intoadjacent streams and estuaries,particularly when runoff volumes arehigh (Sharitz and Gresham 1998).These problems can be minimizedby managing the water levels in thedrainage ditches with risers, whichmaintain water tables and slow thedelivery of water to adjacent streamsand estuaries. In 1989 14 percentof pocosins in North Carolina wereowned by corporate agriculture and36 percent by major timber companies(Richardson and Gibbons 1993).Originally pocosins covered 2,244,000acres in North Carolina, but by 1980this had been reduced by 739,000acres due to agriculture, silviculture,and development (Richardson andGibbons 1993). Clearing pocosinsfor agriculture is no longer practiceddue to restrictions placed on land-owners by the Food Security Act andsection 404 of the Clean Water Act.

Silviculture—Silvicultural activitiesin forested riverine wetlands typicallyconsist of clearcutting overstory vege-tation and allowing natural regenerationfrom sprouts (Kellison and Young 1997,Lockaby and others 1997b, Walbridgeand Lockaby 1994). The stand then

progresses from a thicket dominatedby briars, vines, and tree seedlings andsprouts to a sapling stage after 10 to20 years, to a pole timber stage after20 to 30 years, to a small saw-log stageat 30 to 50 years, and finally to amature forest stage beyond age 50(Kellison and Young 1997). Hydrologicresponses to this silvicultural regimetypically are short-term elevationsin the water table due to a reductionin evapotranspiration (Lockaby andothers 1997b, Sun and others 2001).Removing the trees reduces the amountof the soil water transpired by plants,and the water then fills more soil pores,resulting in a water-table rise. However,this reduction in evapotranspirationis typically negated by the sproutingvegetation on the clearcut site within2 years (Lockaby and others 1997a).Another hydrologic effect of harvestingriverine wetlands is soil compactionwhich interferes with the movementof water through the soil. Lockabyand others (1997) determined that thehydraulic conductivity of the saturatedsoil was reduced 50 to 90 percent in theruts caused by skidding of logs. Thiseffect can be temporary, depending onthe soil type and hydrology of thewetland (Perison and others 1997,Rapp and others 2001).

There is concern that harvesting andsite preparation in wetlands cause orcontribute to the generation of non-point-source pollutants, particularlysediment. Ensign and Mallin (2001)found that when compared to anupstream reference site, a stream inthe Coastal Plain of North Carolinaexperienced higher levels of nutrients(nitrogen and phosphorous), higherfecal coliform levels, and recurrentalgal blooms for up to 15 months afterclearcut harvesting of adjacent forestedwetlands. The authors speculated thatthese effects were due to the inabilityof the clearcut wetland site to retainand transform upstream agriculturalpollutants. However, other studiesindicate the magnitude of these effectsis small and the longevity is brief(Lockaby and others 1997b, Messinaand others 1997, Shepard 1994,Walbridge and Lockaby 1994).Studies indicate that after revegetation,sediment deposition in wetlands isactually greater on harvested sitesbecause the amount of vegetationis greater, thus slowing floodwatersto a greater degree and allowing moresediment to drop from the water

column (Aust and others 1997,Perison and others 1997).

The capacity of forested riverinewetlands to act as sinks, sources ortransformers of nutrients and carbon,depends upon landscape position,the amounts of nutrients entering thewetland, and the time since distur-bance. The degree to which silvicultureaffects a riverine wetland’s capacityto transform nutrients and sequesterother pollutants is uncertain (Lockabyand others 1997b). Conceptually,riverine wetlands serve as sinks whenthey receive high inputs of nutrients.They may serve as sources whendisturbed to the point where activeoxidation of soil organic matteror export of mineral sediment isoccurring, and they may serve astransformers in relatively undisturbedsituations. However, Lockaby andothers (1999) point out that fewgeneralizations can be made aboutbiogeochemical cycling and nutrientretention functions because of thevariable nature of responses of riverinewetlands to harvests, and the inabilityof current scientific methods to detectsubtle biogeochemical changes dueto silvicultural activities. Thus, theyconclude that the ability to predictwhether long-term shifts in biogeo-chemical transformations occur dueto silviculture is minimal and that thereis a critical need to understand howsilviculture affects the enhancementof water quality in riverine wetlands.

Perhaps the most apparent effectof silvicultural operations on forestedriverine wetlands is the removal of thetree canopy. The ability of the forestedwetland to recover from harvesting isof interest to both forest industry andconservation interests. Generalizationsabout the productivity of forestedriverine wetlands and their abilityto recover from harvests are difficultdue to the diversity of forestedwetlands. Different moisture regimes,hydrologic conditions, and soil typeshave resulted in the diversity of wetlandtypes (Conner 1994). Comparisonsbetween harvested sites and referencesites require long-term study. A studyconducted 1 year after harvesting ina Texas riverine wetland showed littledifference in the composition of treespecies regenerating on the harvestedsite and the presence of those specieson an unharvested site (Messina andothers 1997). Another study conducted


7 years after harvest in a tupelo-cypressriverine wetland indicated that har-vested stands were stocked with treespecies similar to the reference. Thestand harvested by helicopter had aneven distribution of overstory species,while the stand harvested with ground-based methods was dominated bytupelo gum (Aust and others 1997).In a study conducted 8 years afterharvesting a riverine wetland in SouthCarolina, no difference between thespecies composition of the overstoryof harvested and unharvested standswas detected. However, midstory andunderstory vegetation differed betweenthe two treatments (Rapp and others2001). These authors concluded thatthe effects of harvesting are short-livedand that these stands will return topretreatment species composition.Additional long-term research is neededto continue to track the developmentof the plant community and ecologicalfunctions in harvested stands comparedwith unharvested stands.

Wildlife species have a variety ofecological roles that contribute to themaintenance of the forested riverinewetland. Wildlife contributes to thedispersal of plants by caching andtransporting seeds, and they alter foreststructure and composition by eatingvegetation and creating impoundments.They alter soil and forest productivityby burrowing and preying on macroin-vertebrates. They support food webs,transport energy to surroundingecosystems, and recolonize adjacenthabitats (Wigley and Lancia 1998).Biotic and abiotic factors determine theinherent capacity of a forested wetlandto support a community of wildlifespecies. Soils, topography, hydrology,disturbance, climate, stand vegetation,landscape pattern of habitats and landuses, wildlife community interactions,and human-related alteration of foreststructure and composition affect theabundance of wildlife (Wigley andLancia 1998). The contribution ofwildlife to ecological processes andthe factors influencing wildlife presenceare complex. As a result, evaluatingthe effects of clearcutting with naturalregeneration on riverine wetlandsis difficult.

At the stand scale, the verticaland horizontal dimensions of foreststructure are important, because themore layers present from the forestfloor to the canopy and the taller

they are, the more opportunities forforaging, nesting, and escaping frompredators (Wigley and Lancia 1998).As plant succession proceeds in forestedwetlands, structural diversity tendsto increase, but the frequency andduration of flooding may reducethe mid- and understory vegetation.Thus, some animals needing lowerlayers of the forest, such as the woodthrush, hooded warbler, and Swainson’swarbler, may not be present in naturalforest stands (Howard and Allen 1989).However, flooding may contributeto vertical diversity by creating snags,which are important to some specieslike the prothonatary warbler, woodducks, woodpeckers, and bats (Wigleyand Lancia 1998). Horizontal diversityrefers to the distribution of vegetationor other structural features in patchesthroughout the stand. This horizontaldiversity can provide habitat for earlysuccessional species in a mature standor mature stand species in an earlysuccessional stand. Diversity of mast-producing species can also ensure aconsistent food supply. When prod-uction of one tree species is low, thatof another species may be high.

Edges occur between wetland foresttypes, wetland and upland forest types,or between land uses. The effects ofthese edges vary. Edges can increasespecies diversity by providing habitatfor the species in the abutting habitatsplus those species that prefer edges.On the other hand, edges can increasepredation and brood parasitism bybrown-headed cowbirds and add exoticspecies (Wigley and Lancia 1998).Riverine wetlands can serve as regionalmigration corridors for black bear,neotropical songbirds, and waterfowl(Gosselink and others 1990). However,these corridors can aid in the convey-ance of species from one habitat toanother or, as with edges, can conveypredators, diseases, and parasites.Forested wetlands also fit into alandscape mosaic of habitat typesthat may be important to speciesneeding several habitats to fulfill liferequirements. Species presence andproductivity are sometimes viewedas functions of the size and shape ofa wetland habitat patch, amount ofedge, distance from patches of similarhabitat (isolation), amount of timesince isolation, and immigration anddispersal of animals from habitats(Wigley and Roberts 1997). However,much of the landscape-scale

information on the effect of thesewildlife habitat functions on thepresence and productivity of wildlifepopulations is based on theory. Fewdata exist for managed forest landcapesto validate these theories (Wigley andLancia 1998; Wigley and Roberts 1994,1997).

Riverine forested wetlands have anabundance of detritus, hard and softmast, snags, cavity trees, and largewoody debris on the ground as wellas multilayered vegetation, and thesetypically support conditions rich anddiverse wildlife communities (Ainslieand others 1999, Gosselink and others1990, Wigley and Lancia 1998). Forestmanagement activities potentiallyinfluence wildlife habitat at site-specificand landscape scales. Clearcuts withnatural regeneration temporarily reduceavailability of hard mast and canopyand cavity trees (Wigley and Roberts1994, 1997). However, regenerationof woody vegetation and groundvegetation growth typically increaseafter harvest, downed woody debrisoften increases due to harvesting(assuming it is not windrowed andburned), and early successional wildlifespecies may increase. Clawson andothers (1997) found that amphibianpopulation diversity and abundancewere only temporarily affected byharvesting. Thus, many habitatalterations due to forest managementare temporary.

From a landscape perspective thereis a growing recognition that the lackof early successional forest, includingbut not exclusive to forested wetland,is limiting biodiversity in the EasternUnited States (Hunter and others 2001,Litvaitis 2001, Thompson and Degraaf2001, Trani and others 2001, Wigleyand Roberts 1997). Thompson andDegraaf (2001) suggest that silviculturaloperations can contribute to landscapediversity by creating early successionalhabitats in forested landscapes. Severalstudies have suggested that in largelyforested landscapes, early successionalpatches increase wildlife diversity(Thompson and others 1992, Welshand Healy 1993). However, aspreviously pointed out, little is knownof the effects of forest managementin landscapes permanently fragmentedby conversion to agriculture orurban development.

Silviculture: depressions—Sharitz and Gresham (1998) note


AQUATIC

that managing Carolina bays fortimber requires clearing the existingvegetation, installing drainage ditcheswithin the bay and through the rim,bedding the bay soil, and planting trees.Any of these activities greatly altersthe structure and function of thebay ecosystem.

Pondcypress swamps are harvestedfor sawtimber and increasingly forlandscape mulch. Typically, they areharvested by clearcutting. Clearcutsregenerate well (Ewel and others1989), but leaving some mature treesto produce seed is advocated dueto uncertainty of resprouting andseed production (Ewel 1998). Afterharvesting, water levels in pondcypressswamps typically rise, and amphibianand wading bird usage of the post-harvest swamp increases. Mammalusage also changes, with fewer nestand den sites but more prey available(Ewel 1998).

Silviculture: mineral-soil pineflats—On mineral-soil flats, threeparameters stand out as being essentialfor determining the degree to whichecosystem processes are altered by agiven impact: (1) the alterations in thehydrologic regime, (2) alterations in fireregime, and (3) alterations in the soil.These changes in ecosystem processeson mineral-soil flats alter plant andanimal habitats. Hydrologic fluctuationsdetermine the composition of fire-tolerant vegetation, and soil conditionscontrol the dynamics of biogeochemicaltransformations by soil microbes. Firesmaintain open, sometimes treelesssavannas by precluding species thatwould otherwise shade outcharacteristic savanna plants andprovide nutrients in discrete pulsesutilized by savanna plants (Rheinhardtand others 2002).

Silvicultural impacts on flat wetlandstypically include surface and subsurfacedrainage, ditching, harvest and mech-anical reduction of native vegetation,bedding, which alters microtopographicrelief, and the construction of roads(Harms and others 1998). The objectiveof intensive management on thesemineral-soil flat wetlands is to producepine plantations. Most biogeochemicalprocesses in wetlands depend on thedistribution and timing of floodedand dry conditions. Draining a mineral-soil flat eliminates flooding and soilsaturation, which in turn altersprocesses that depend on flooded

conditions, including fermentation,and denitrification.

With the exception of artificialdrainage, most alterations to hydrologicregime are localized in their effect onbiogeochemical processes and habitatquality. For example, a dam (even a lowone such as a road fill) can impedesurface flow and back water up over alarge area. One result is a longer periodof inundation. Input of excess waterfrom offsite can likewise increase theduration and depth of water levels.Alterations to water balance changethe duration and timing of floodingand the saturation of soil in the upperhorizons. In contrast, artificial drainagereduces inundation periods. Artificialdrains transport water, nutrients, anddissolved organic matter into streamsdownstream, altering the water flowand chemistry for a period of 2 to 3years. (Amatya and others 1997,Beasley and Granillo 1988, Lebo andHerrmann 1998). However, thesestudies also indicate that the hydrologiceffects of ditches can be amelioratedwith water-control structures suchas flashboard risers (Sun andothers 2001).

Soil condition on mineral-soil flatsalso can be affected by intensivesilvicultural activities (Miwa andothers 1997, 1999). Microbialorganisms and plants are adaptedto characteristic microtopographicstructure, soil texture, and nutrientregime. Alterations to soils affect theseconditions upon which soil microbesand plants depend. The result maybe a change in biogeochemical cyclingprocesses. For example, harvestingunder wet conditions can affect water-holding capacity and available waterfor plant growth and slow internalsoil drainage, causing higher watertables and slower site drainage inthe immediate area of the harvest(Miwa and others 1997). Bedding iscurrently the best available techniqueto ameliorate these effects. However,bedding also may affect soil-bulkdensity both on the beds and inthe trenches between, thus alteringinterstitial pore space and substrateconditions on which soil microbesand plants depend. In addition, micro-topographic variation is changed by aregular distribution of small, low (10to 20 cm high), regularly distributedhummocks to a parallel array oftrenches and high ridges (15 to 30+ cm

high). On bedded sites, duration andfrequency of flooding are increased intrenches and decreased on beds relativeto unaltered conditions, which result inaltered rates, timing, and magnitudes ofbiogeochemical processes (Rheinhardtand others 2002).

Mechanical treatment of native vege-tation and bedding a mineral-soil flatto produce pine plantations affectsfire-maintained wildlife habitat ofwet pine flats. For example, severalamphibian species are associated withfire-maintained landscapes and travelacross wet flats to breeding pondsin cypress depressions. There isevidence that intensive silviculturemay detrimentally affect amphibianand reptile populations (Rheinhardtand others 2002), because intensivesilviculture relies on a series of raisedparallel-aligned beds on which pineseedlings are planted. Standing waterin the troughs between beds maycue amphibians to lay their eggs inthese troughs, where water sits fortoo short a time to support larvaldevelopment, rather than in deeper,more permanent cypress depressionswhich are commonly scatteredthroughout wet pine flats.

PolicyDevelopment, agriculture, and

silviculture are regulated primarily bytwo Federal laws: the Food Security Act(Public Law 104-127) (FSA), and theClean Water Act (CWA). The objectiveof the “Swampbuster” provision ofthe FSA is to discourage alteration ofwetland hydrology, vegetation, and soilsto facilitate production of commoditycrops (Strand 1997). FSA penalizeslandowners who alter wetlands for thispurpose by removing their eligibility forFederal subsidies. However, agriculturallandowners may retain their eligibilityfor benefits by restoring, enhancing,or creating wetlands to compensatefor lost wetland functions and values.

Development, agriculture, andsilviculture are also regulated undersection 404 of the CWA. Section 404requires that anyone proposing to placefill material into waters of the UnitedStates, including wetlands, must obtaina permit from the U.S Army Corps ofEngineers (COE). In order to obtain apermit the applicant must show: (1)why the project cannot be locatedsomewhere besides a wetland, (2) whythe project will not adversely harm the


South-Central Southeast

14.4%21.8%

4.5%

59.3%

10.1%19.4%

58.0%

12.5%

Total (United States)

Miscellaneous

Agriculture

Silviculture

Development

12.8%

26.4%

11.9%

48.9%

wetland, and (3) what the applicant willdo (if granted the permit) to offset theloss of wetland functions and values.Replacement of lost wetland functionsand values is typically accomplishedthrough mitigation—the restoration,enhancement, or creation of wetlandsin another location. For a more indepthdiscussion of these laws see chapter 8.

Under section 404 (f) of the CWA,normal silvicultural and agriculturalactivities, such as plowing, seeding,cultivating, minor drainage, andharvesting for the production of food,fiber, and forest products, are exemptfrom the permitting requirements.However, these activities must be partof an ongoing agricultural or silvi-cultural operation and may not changea wetland to an upland. In addition,construction of forest roads is exemptunder section 404(f) as long as 15federally prescribed best managementpractices (BMPs) are implemented.The issues surrounding forest roadconstruction and the BMPs used toameliorate water-quality impacts ofroads are discussed further in chapter22. In 1995, the U.S. EnvironmentalProtection Agency (EPA) and theCOE issued guidance on BMPs formechanical site-preparation activitiesfor the establishment of pine planta-tions. This guidance established thecircumstances where mechanicalsilvicultural site-preparation activitiesrequired a section 404 permit as wellas those where no permit is required(U.S. Environmental Protection Agency1995). In general, sites which are wetfor a large portion of an average year

[i.e., permanently flooded, inter-mittently exposed, semipermanentlyflooded, or seasonally flooded(bottomland hardwoods)] require apermit for mechanical site-preparationactivities. Sites which are wet for onlya portion of the year [i.e., seasonallyflooded (higher elevation in thefloodplain) intermittently flooded,temporarily flooded, or saturatedhydrology] do not require a permitas long as BMPs, discussed in theguidance, follows.

RestorationApproximately half of the South’s

forested wetlands have been lost in thelast 200 years. Along with this loss inacreage has been the loss of wetlandfunctions and societal benefits, goods,and services described in the lastsection. In an attempt to ameliorate theenvironmental damage of wetland loss,restoration of former forested wetlandsis being attempted throughout theSouth. Wetland restoration is definedby the Society of Wetland Scientistsas “actions taken in a converted ordegraded natural wetland that resultin the establishment of ecologicalprocesses, functions, and biotic/abioticlinkages and lead to a persistent,resilient system integrated within itslandscape.” The goal of restoration ofwetland ecosystems was expressed bythe National Research Council (1992)as “returning the system to a closeapproximation of the predisturbanceecosystem that is persistent and self-

sustaining (although dynamic in itscomposition and functioning).”Therefore, since much of the forestedwetland loss in the past has been dueto agriculture, any national or regionalprogram designed to restore millionsof acres of former wetlands will have tofocus primarily on wetlands convertedto agricultural use (National ResearchCouncil 1992). Presumably theseagricultural lands would still occupythe same landscape position and havethe same or similar hydrology as theoriginal wetlands prior to conversion.An exception to this is in areas whereextensive levee systems like those inthe Lower Mississippi Valley haverestricted flooding on a broad scale.

Although forested wetlands havebeen lost throughout the South,perhaps the most acute losses havebeen in the Lower Mississippi AlluvialValley (LMAV). There, approximately18 million acres of wetland were lostto agricultural conversions (King andKeeland 1999). Such conversions haveinvolved clearing the natural forestedwetland vegetation, drainage, and floodcontrol. In the LMAV, the estimatedoriginal 25 million acres were reducedto approximately 5 million acres by 1978(Hefner and Brown 1985). Ninety-sixpercent of the forested wetland losses inthe LMAV were due to agriculture; theremaining losses were due toconstruction of flood control structures,surface mining, and urbanization(Schoenholtz and others, in press).

Figure 20.3—Causes of palustrine andestuarine wetland losses based on 1992to 1997 National Resources Inventory data.


AQUATIC

Table 20.5—Wetland Reserve Program acres by State in the South as percentof national and regional totals

Total National total Southern totalState WRP acres WRP acres WRP acres

- - - - - - - - - - - Percent - - - - - - - - - -

Virginia 1,063 0.12 0.219North Carolina 18,216 1.99 3.751South Carolina 13,507 1.48 2.781Georgia 7,374 .81 1.518Florida 45,225 4.94 9.312Kentucky 7,613 .83 1.568Tennessee 13,976 1.53 2.878Alabama 1,410 .15 .290Mississippi 92,107 10.06 18.965Arkansas 87,664 9.58 18.050Louisiana 132,319 14.46 27.245Oklahoma 30,304 3.31 6.240Texas 34,892 3.81 7.184

Total 485,670 53.07 100.000

WRP = Wetland Reserve Program.

30304

34892

67664

132319

92107

45225

7613 1063

1410 7374

13507

13976 18216

1,001– 10,00010,001– 20,00020,001– 40,000

> 40,000

WRP Acres

In the 1970s and 1980s the U.S.Fish and Wildlife Service recognizedthe trend in forested wetland loss andassociated habitat impacts in the LMAVand began a campaign to reestablishforested wetlands in the LMAV (Kingand Keeland 1999). The developmentof the WRP by NRCS as well as smallerprojects undertaken by the COE andState Fish and Game agencies hasintensified reforestation/restorationin the LMAV, making this area thelargest reforestation/restoration effort

in the South. Figure 20.3, derived fromNRI data from 1982 to 1992, indicatesthat 17.5 percent of the watersheds inthe South experienced a gain of forestedwetland, 31.2 percent experienced aloss, and 51.3 percent experienced nochange. However, it is uncertain if theacres reported in the NRI representactual acres restored versus acresenrolled in WRP.

The WRP of the 1990 Farm Billis directed at wetland systems andprovides for conservation easements

for 10 to 30 years. The 1990 FarmBill, which was reauthorized in 1996,established that up to 1 million of the6 million acres of cropland eligiblefor the Conservation Reserve Programmay be wetlands. This program, unlikemost others, has the potential to restorelarge acreages of forested wetlands inthe South.

King and Keeland (1999) reportedthat approximately 195,000 acres havebeen reforested in the LMAV. Restora-tion of forested wetland systems inthe LMAV involves restoration ofthe geomorphic, hydrological, andecological processes that drivethese wetland systems. Massive forestclearing, construction of thousands ofmiles of drainage ditches, broad-scalechannelization of streams and rivers,flood prevention, and farming practiceshave changed hydrology, topography,and soils. Restoration of wetlandfunctions is extremely difficult there.Table 20.5 shows that 64 percentof the WRP acres are in the States ofMississippi, Louisiana, and Arkansas.Presumably, all or a major portion arein the LMAV. Figure 20.4 shows thenumber of WRP acres by State inthe South. Once again, Mississippi,Louisiana, and Arkansas have thegreatest number of farmers enrolled.In addition to WRP acres, the U.S.Fish and Wildlife Service has plantedapproximately 59,000 acres and StateWildlife Management Areas haveplanted 28,000 acres (Schoenholtzand others, in press). Information couldnot be found to document restorationefforts in other parts of the South.Programmatic suc

Chapter 20 (AQUA-2): Forested Wetlandsforested wetlands were derived pri-marily from NWI reports...

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Transcript of Chapter 20 (AQUA-2): Forested Wetlandsforested wetlands were derived pri-marily from NWI reports...