United States

Department of

Agriculture

Abstracts

Forest Service

Southern Forest Workshop on

Experiment Station

New Orleans,

Louisiana

General Technical Report

Harvesting Impacts on Bottomland *

Hardwood Forest Ecosystems

so-103

May 1994

ABSTRACTS

Workshop on

Harvesting Impacts on

Bottomland Hardwood

Ecosystems

Forest

Edited .and Compiled by

John A. Stanturf

Principal Forest Soils Scientist

Southern Hardwoods Laboratory

USDA FS, Southern Forest Experiment Station

Stoneville, MS 38776

May 18-19, 1994

Delta Branch Experiment Station

Stoneville, Mississippi

Sponsored by:

Southern Forest Experiment Station

Southeastern Forest Experiment Station

Southern Hardwood Forest Research Group

Consortium on Southern Forested Wetlands

National Council of the Paper Industry for

Air and Stream Improvement

National Biological Survey

American Pulpwood Association

Southern Regional Council on Forest

Engineering

Society of American Foresters

With additional financial assistance frcm:

Department of Forest Science, Texas A&M

University

Delta Research Foundation

Program Connnitteet

J. A.

B. J.

W. R.

B. G.

R. C.

W. M.

S. H.

M. G.

W. H.

J. D.

J. P.

Stanturf, southern Station

Stokes, Southern Station

Harms, Southeastern Station

Lockaby, Auburn University

Kellison, North Carolina State University

Aust, Virginia Tech University

Schoenholtz, Mississippi State University

Messina, Texas A&M University

Conner, Clemson University

Hodges, Mississippi State University

Shepard, National Council of the Paper -. - -. Industry for Air & stream Improvement

V. V. Burkett, National Biological Survey
AGENDA

Wednesday, May 18, 1994

7:30 - 8:15

8:15 - 8:30

8:30 - 9:oo

9:oo - 9:30

9:30 - lo:oo

lo:oo - 10:30

10:30 - 11:oo

11:oo - 11:30

11:30 - 12:oo

12:oo - l:oo

l:oo - 1:30

1:30 - 2:15

2:15 - 2:45

2:45 - 3:30

3:30 - 4:15

Registration

t'hCOME MD IaFllRODUCTIOM. J. A. Stanturf, U. S. Forest Service,

Southern Hardwoods Laboratory.

Moderator, V. V. Burkett, National Biological Survey

tiRvIRW OF THE &ZSODRCR--TODAY AND YESTERDAY.

R. C. Kellison and M. Young, Hardwood Research Cooperative, North

Carolina State University.

DEVIGOPMENT AUD ECOLOGY OF &TTOMLNUD -0OD SITES.

J. D. Hodges, Mississippi State University.

SILVICDLTDR&L SYSTRBZS BOR SO~TRRR~ BOTTOMLARD -COD FORRSTS. J. S.

Meadows and J. A. Stanturf, U. S. Forest Service, Southern

Hardwoods Laboratory.

sPAWNIN AND ~IUQ OF FISRES IN &JTTOMLNUD -0OD WRTIANDS OF THE

SOOTRRRSTBRR UNITED STATES. K. J. Killgore, G. Miller, and J. J.

Hoover, USACOE, Waterways Experiment Station and University of

Mississippi.

MSTIIW IWrACTS OH SOILS AND NDTRIRNT CYCLIrsO.

W. H. McKee, Jr. and W. H. Conner, U. S. Forest Service, Wetlands

Center, and Belle W. Baruch Forest Science Institute.

-STIUO SYSTEMS. B. J. Stokes and A. Schilling. U. S. Forest

Service, Southern Forest Engineering Center and International

Paper Company

Lmucn (Catered)

Moderator, T. C. Fristoe, Scott Paper Company

IMPXTS ON LnwDscllpR DIVERSITY. T. B. Wigley and T. Roberts, NCASI and

Tennessee Tech University.

R~CUVERY STATUS OF A C!Y~RR~~-T~PELC WETLARD EIQRT YEARS APTER HARVESTIBICJ. W.

M. Aust, S. H. Schoenholtz, T. Zaebst and B. Szabo, Virginia Tech

University and Mississippi State University

BREnx

IBIFL~~~B OF I&.RVMTI~O 0~ WATER QUALITY, HYDROLOGY, DRIITRIFICATIOIV,

~COMpOSITIOBI, ~HIBIAH POPULATIOUS, MICROBIAL ECOLOOY, AND ~QEHERATIO~ IR

NARRCW FLOODPIAINS OF BLACKUATERSTREAMS II SOUTETERIQ ZUBAML.

B. G. Lock&y, R. H. Jones, R. G. Clawson, A. Griffin, S.

Lloyd,F. C. Thornton, D. A. Brown and J. A. Stanturf.

Auburn University, Tennessee Valley Authority, and U. S.

Forest Service, Southern Hardwoods Laboratory.

TIMBER HARVESTIWJ IMPACTS IN A SOUTE CAROLIIUA BLACXWATER SWAKP.

D. Perison, R. Lea and R. C. Kellison, International Paper

Company and Hardwood Research Cooperative, North Carolina

State University.

2
Thursday, May 19, 1994

8:00 - 8:15

8:15 - 9:00

9:oo - 9:45

9:45 - 10:15

10:15 - 10:45

10:45 - 11:15

11:15 - 11:45

11:45 - l:oo

l:oo - 1:30

1:30 - 3:30

3:30 - 4:30

4:30 - 5:oo

ANNOUNCENZNTS

INxTIu REsp0~sRs OF VB~RTA!~ION, WATER QumITy, mm Soms TO HMTJESTINQ

INTENSITY IN A TExas BOTTOM #ARDRO~D ECOSYSTXM. M. G. Messina, S. H.

Schoenholtz, M. W. Lowe, Ziyin Wang, D. K. Gunter and A. J. Londo.

Texas A&M University and Mississippi State University.

Ron0 CONSTRUCTION AND HARVESTINQ I~ACTS ON FUNCTIONS OF A REDNATER FLOODPLAIN

FOREST IN CENTRAL ~EORQIAB. G. Lockaby, R. G. Clawson, K. M. Flynn, R. B. Rummer,

,B. J. Stokes, and J. A. Stanturf. Auburn University, U. S. Forest

Service, Southern Forest Engineering Center and U. S. Forest

Service, Southern Hardwoods Laboratory.

COI@~ISON OF PRODUCTIVITY VALURS ACROSS A FIAXDINQ C&ADI~T IN A SOUTH

CAROLINA COASTAL PI&N FORRST. M. K. Burke and

W. H. Conner, U. S. Forest Service, Wetlands Center and Belle W.

Baruch Forest Science Institute.

FORESTED WETLAND PRODUCTIVITYS A STUDY OF R&QIONU PROCRSSES.

W. H. Conner, B. D. Keeland and J. P. Megonigal. Belle W.

Baruch Forest Science Institute, U. S. National Biological

Survey and Duke University.

BOTTOMUND HMDWOOD FORRST M?&ZAQEHEZTE AND INFORHATION NEEDS FOR WATERSHED

PLNuNIN~. J. P. Shepard, NCASI.

LUNCH (Catered)

Wmmz IXD WE GO FROM HERE? PROPOSAL FOR A REQIONWIDE STUDY OF ECOSYSTF~N

RRSILIRNCR ACROSS A PRODUCTIVITY GRADIENT.

J. A. Stanturf and B. G. Lockaby, U. S. Forest Service, Southern

Hardwoods Laboratory and Auburn University.

BRRRR-OUT SESSIONS

Purpose of these sessions is to identify common results, good

techniques, and outstanding research questions. Sessions will be

organized around the following functions and processes:

Regeneration

Hydrology

Nutrient Cycling

Water Quality

Biodiversity

SEssroar REPORTS

WRAP-UP

3
Overview of the Resource--Today and Yesterday

R. C. Kellison, Hardwood Research Cooperative, North Carolina State University,

Raleigh, NC

M. Young, Hardwood Research Cooperative, North Carolina State University,

Raleigh, NC

Between 1962 and 1986 the use of hardwoods in the South increased from 1,715

to 2,940 million cubic feet. The increase, almost all from private lands, was

primarily used for fuel (38%) and for the manufacture of pulp, paper and paperboard.

This resource, much of which has been obtained from wetlands, is available from a

shrinking land base. According to Dahl (1990), the southern wetland forest base

shrunk from 112 million acres in 1780 to 57 million acres in 1980. Of the 1980

total, 42 million acres were in private ownership. That ownership class was

extremely vulnerable to conversion from forest to field in the 1970s and 1980s when

the price of agricultural crops (soybeans and corn) reached an all-time high. The

reduction in acreage of wetlands from 1980 to 1987 on non-federal lands was from 42

to 29 million acres. Despite these startling figures, evidence shows that the

bottomland hardwood resource was at a lower ebb during the half century following

the Civil War than it is today.

4
Development and Ecology of Bottomland Hardwood Sites

J. D. Hodges, Department of Forestry, Mississippi State University, Starkville, MS

A basic knowledge of the origin, development, and ecology of bottomland

hardwood sites is important for assessing harvesting impacts on these sites. This

paper will give an overview.of the geologic origin and development of hardwood

sites, species-site relationships and the natural patterns of ecological succession

on these sites, and the implications of this information for forest management.

Past geologic events led to the formation of broad stream valleys within the

Coastal Plain Province of the Atlantic Plain Physiographic Division. Formation of

these valleys was possible because of the easily erodible sedimentary geologic

material. The valleys contain an active floodplain and at least one terrace system.

Bottomland hardwoods occur primarily on the floodplains of these stream valleys.

Elevational differences within the active floodplain occur due to bank

overflow and meandering of the stream across the floodplain. Small differences in

elevation can result in great differences in site quality primarily because of

differences in hydrology. Species occurrence and natural patterns of ecological

succession within the floodplain are strongly influenced by these differences in

elevation and rates of deposition.
Silvicultural Systems for Southern

Bottomland Xardwood Forests

J. S. Meadows, USDA Forest Service, Southern 'Wardwoods Laboratory, Stoneville, MS

J. A. Stanturf, USDA Forest Service, Southern Hardwoods Laboratory, Stoneville, MS

Silvicultural systems integrate both regeneration and intermediate operations

in an orderly process for managing forest stands. Silvicultural practices are

traditionally divided into two systems: even-aged and uneven-aged. The

regeneration methods employed under even-aged silviculture include clearcutting,

seed tree, and shelter-wood. Single-tree selection and group selection are

regeneration methods used under uneven-aged silviculture. Artificial regeneration

can be used to establish new stands through plantation culture or to supplement

natural regeneration through enrichment planting.

The clearcutting method of regeneration, because it provides ample sunlight to

the forest floor, favors the development of moderately intolerant to intolerant

species. In fact, clearcutting is the most proven and the most widely used method

of successfully.regenerating bottomland oak species in the South. However,

successful regeneration of oak depends upon the presence of adequate oak advance

reproduction in the stand prior to clearcutting. The seed-tree method of

regeneration favors the establishment of light-seeded species, such as sweetgum and

yellow-poplar. Site preparation may be necessary if the desired species requires

bare mineral soil for establishment, as for cottonwood and black willow. The

shelterwood method of regeneration favors the development of heavy-seeded species,

such as oaks and hickories, and has been used to successfully regenerate oak in the

southern Appalachians. However, it has produced highly variable results with

southern bottomland oak species. Several variations and modifications of the

classical shelterwood method have been attempted in these stands, with mixed

success.

The single-tree selection method of regeneration favors the development of

shade-tolerant species. However, there are few commercially valuable shade-tolerant

species in southern bottomland hardwood forests. In fact, when single-tree

selection is applied continually to stands containing coxmnercially valuable shadeintolerant species, such as most bottomland oaks, composition will gradually shift

to more tolerant species, such as sugarberry, elms, maples, hickories, and boxelder.

Consequently, the single-tree selection method of regeneration is not recommended

for bottomland oaks.

Group selection, in the classical sense, creates only small openings (0.04 to

0.2 ha) that usually fail to allow sufficient light to the forest floor for

satisfactory establishment and development of shade-intolerant bottomland species.

In practice, a combination of uneven-aged (group selection) and even-aged

(clearcutting) silviculture has been successfully employed. Known as patch cutting,

larger groups of up to 1.2 ha are removed at a time. The result of patch cutting is

an uneven-aged stand that consists of many small, irregularly shaped, even-aged

groups.

The primary artificial regeneration methods used in southern bottomland

hardwoods are planting and direct-seeding (for heavy-seeded species, such as oaks),

both of which can be accomplished by hand or by machine. General guidelines for

artificial regeneration of bottomland hardwoods include (1) match the species to the

site; (2) prepare the site; (3) use vigorous planting stock or sound seed; (4) plant

or direct-seed properly; and (5) practice weed control sparingly.

Silvicultural systems should include a planned program of intermediate

operations designed to enhance the growth and development of those species favored

during the regeneration process.

cutting, thinning,

Intermediate operations can include improvement

or other partial cuttings. Improvement cuttings are generally

applied to previously unmanaged bottomland hardwood stands to remove low-value,

over-mature, damaged, or cull trees and trees of undesirable species. Commercial

thinning is increasingly common in southern bottomland hardwood forests. General

guidelines for thinning in bottomland hardwood stands include (1) begin thinning

early in the life of the stand; (2) favor the largest trees with well-developed

crowns ; (3) thin from below whenever possible to remove trees with inferior crowns;

6
(4) use frequent, light thinnings instead of infrequent, heavy thinnings; and (51

avoid excessive logging damage to residual trees. Other partial cuttings employed

today in bottomland hardwood forests typically involve some form of crop-tree

release, in which individual crop trees are selected early in the life of the stand

and are periodically released from competition to promote maximum growth and quality

development on those trees.

Specific recommendations for the selection of silvicultural systems will be

presented for the eight most important species groups found in southern bottomland

hardwood forests: cottonwood; black willow; cypress-tupelo;

elm-sycamore-pecan-sugarberry; elm-ash-sugarberry; sweetgum-red oak; red oaks-white

oaks-mixed species; and overcup oak-bitter pecan.
Fish Reproduction in Bottomland Hardwood Wetlands

of the Lower Mi~siusippi River Basin

K. J. Eillgore, U.S. Army Engineer Waterways Experiment Station,

Vicksburg, MS

G. L. Miller, University of Mississippi, University, MS

J. J. Hoover, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS

Bottomland hardwood wetlands are conspicuous features of many river systems in

the lower Mississippi River basin. They occur on alluvial floodplains that are

inundated in winter and spring. These forested wetlands are highly productive and

support diverse aquatic communities. Despite their importance to riverine

ecosystems, extensive tracts of bottomland hardwoods continue to be cleared,

especially from those lands bordering the Mississippi River and its tributaries.

Deforestation has become a major issue in the preservation of biodiversity, but the

interrelationships of forested and non-forested wetlands to biotic processes in

rivers are poorly understood. consequently, strategies to conserve and manage these

environments are not well developed.

Between 75 and 100 species of fish complete one or more of their life stages

(i.e., egg, larvae, juvenile, adult) in bottomland hardwood wetlands. Field surveys

of larval fishes conducted in the Yazoo River System, Mississippi and Cache River

System, Arkansas have shown that major groups of fishes that exploit bottomland

hardwood wetlands include gars, minnows and shiners, suckers, catfishes, sunfishes,

and darters. Some fishes migrate to riverine floodplains in spring to spawn on

inundated vegetation, on leaf litter, or near woody debris. The larvae often remain

on the floodplain for extended periods feeding on plankton. Other species spawn in

the seasonally inundated floodplain and then reside as adults in the more permanent

floodplain habitats throughout the year.

There is a temporal trend in the appearance of larval fish species in the

wetland that is usually associated with onset, duration, and magnitude of flooding.

Early spawners include suckers, crappie, and most darters. Species that spawn in

late spring and early summer include catfishes, gar, minnows and shiners, and

sunfishes. Minnows, shiners, and sunfishes may continue to spawn throughout the

summer if suitable habitat is available in the wetland. Other species, such as

buffalo and flathead catfish, have a more punctuated spawning strategy. Their larvae

appear for only short time and usually in high abundance.

Regularly flooded stream systems in the lower Mississippi River basin

typically include six distinct floodplain habitats, each of which can be delineated

from satellite imagery or low-altitude aerial photography: 1) cultivated

agricultural land, 2) fallow land, 3) floodplain ponds, 4) oxbow lakes, 5) an

aggregate type consisting of scatters, brakes, and mouths of tributaries, and 6)

bottomland hardwood.

(1) Cultivated Agricultural Land - These are converted forested wetlands that

have been planted with crops such as soybeans, cotton, and rice. Agricultural land

is structurally homogenous with little herbaceous or woody vegetation. Many of the

fields occur in low-lying areas due to extensive tilling and subsequent erosion.

Thus, water tends to collect and remain in these areas for extended periods. Whether

adult fish deposit eggs in agricultural fields is unknown, but high numbers of

larval buffalo, shad, and sunfishes are collected in this habitat.

(2) Fallow Land - These lands were previously planted with crops but were

allowed to remain uncultivated to increase their productivity. Early succession

herbaceous vegetation is commonly found in fallow land. Depending on the time the

land remains uncultivated, willow trees and hardwood seedlings also occur.

Herbaceous vegetation is a preferred spawning substrate for buffalo, gar, and some

species of minnows and darters.

(3) Floodplain Ponds - Floodplain ponds are depressions or low points in the

floodplain. The major difference between floodplain ponds and oxbow lakes is size;

ponds are often less than 500 m2 in surface area. They usually retain water

year-around, but some become extremely shallow during the summer and fall.

Consequently, high water temperatures and low dissolved oxygen are characteristic of

floodplain ponds during low-water periods. Floodplain ponds support a distinct fish

community that includes some of the rarest fishes of bottomland hardwood wetlands

such as fliers, taillight shiners, and various species of topminnows and darters.

8
(4) Oxbow Lakes - oxbow lakes are meander loops of former river channels that

have been cutoff. They can be permanently connected, seasonally contiguous, or

permanently isolated from the main river. The shoreline is typically wooded and

brush is abundant in the water near shore. oxbow lakes retain water year-around.

oxbow lakes that are contiguous with the river are inhabited by typical riverine

species such as gar, buffalo, paddlefish, and other large species. Oxbow lakes that

are isolated from the river are less turbid and piscivorous fish, such as gar, are

lower in abundance. Consequently, isolated oxbow lakes are inhabited by more

sunfishes, including largemouth bass.

(5) Scatters, Brakes, sloughs, and Tributary Mouths - These are long, narrow

waterbodies that are usually confluent with the main channel. They are permanent

aquatic habitats that rarely become dewatered. Their distinguishing feature in

remote sensing is that are dominated by cypress-tupelo trees. Unlike oxbow lakes

where cypress-tupelo are usually confined to the periphery of the waterbody,

cypress-tupelo trees are found throughout the surface area of scatters, brakes,

sloughs, or tributary mouths. These habitats often drain interior lands, are

subjected to high flows during floods, and are inhabited by a mixture of fish

species from the other habitats. They also serve as corridors for movement between

the parent stream and other wetland aquatic habitats.

(6) Bottomland Hardwoods - Hardwood forests border alluvial river systems and

are seasonally inundated. Frequently flooded hardwoods consist primarily of

cypress-tupelo trees with little understory. Infrequently flooded forest are

comprised of oak-hickory complexes and often have structurally complex understories.

Most are second-growth forests. Agricultural and fallow land were once hardwoods

forests converted to crop land. Historically, bottomland hardwoods were the main

component of riverine floodplains and provided habitat for those fish that require

shallow, structurally-complex areas for deposition of eggs. These include buffalo,

gar , and different species of minnows, shiners, and darters.

Management of wetlands encompasses three options: protection of existing

habitat; creation of new wetland habitat; or restoration of degraded habitat.

General guidelines for management of wetland aquatic habitats are relatively simple

to formulate theoretically: the abundance and spatial distribution of the habitats

should resemble those of productive, faunally diverse, undisturbed sites to the

maximum extent possible. Practical solutions for managing wetlands include

re-foresting agricultural land that is frequently flooded, converting agricultural

land to fallow fields that are periodically inundated, and ensuring that permanent

waterbodies on the floodplain are contiguous with the river during floods.

Accessibility between river and floodplain and structural heterogeneity of

floodplain habitats are two of the most important considerations for maintaining

suitable reproductive habitat for fishes in the lower Mississippi River basin.
Harvesting Impacts on Soil0 and Nutrient Cycling

W. H. McKee, Jr., USDA Forest Service, Wetlands Center, Charleston, SC

W. H. Conner, Belle W. Baruch Forest Science Institute, Georgetown, SC

Evaluation of reports on the impact of harvesting on nutrient properties of

soils indicate variable responses ranging from no effect at all to pronounced

reductions in growth by successional stands. With this complex range in

observations we will try to ,present a rationale for the nature of these findings and

ideas for predicting impacts on sites for future harvesting. Harvesting impacts on

site nutrient supplies and availability can be addressed from two approaches. The

first represents the losses of nutrients from a site through erosion, overflow, or

harvesting. The second concerns availability of nutrients and chemical alteration

of nutrients in the soil and forest floor.

The removal of biomass, primarily the stem, is not considered to be a

significant drain on nutrient pools for bottomland hardwoods since most of the

nutrients are in foliage and soil. normal stem-only harvest removes nutrients from

the forest ecosystem at rates compatible with nutrient inputs. Where short

rotations or total harvest of the tree is undertaken, changes in nutrient supplies

are small enough to allow for correction of mineral nutrition through fertilization.

Harvesting effects on nutrient availability are more significant where

harvesting changes the physical environment of the site. This alters biological

activity, coupled with changes in nutrient cycling and "intensity" factors such as

pH, redox potential, and gas partial pressures. The two physical properties with

documented changes due to harvesting are temperature and alteration of the soil

water table. These changes take place regardless of the direct impact of harvesting

equipment, road construction or other disturbance of the site by harvesting. In

general, greater site disturbance causes greater change in the physical nature of

the site.

Change in soil temperature occurs regardless of drainage. With the removal of

the overstory vegetation, soil temperature will be measurably higher regardless of

the harvesting equipment employed. An increase in soil temperature will accelerate

biological processes which release nutrients. At the same time, an increase in

temperature decreases the solubility of gasses in the soil solution. This lowers

the amount of carbon dioxide in the soil on drained sites which results in an

increase in soil pH. Depending upon the nature of a specific site, this may

increase or decrease nutrient availability. Higher temperature will accelerate the

soil reduction process through greater biological activity.

The loss of evapotranspiration following tree harvest can significantly raise

the water table sufficiently to saturate the surface soil or at least extend the

period of surface saturation. This condition causes a loss of soil oxygen which in

itself decreases nutrient availability through restricted root respiration. !fhe

flooding and soil reduction further alters nutrient availability through soil

reduction where microorganisms use mineral oxides in the soil as a source of

oxident.

Harvesting can indirectly alter nutrient status of a wet forest site. This

takes place through changes in the physical environment that alters biological

processes. Impacts of harvesting effects on nutrient availability can best be

controlled by limiting disturbance of the site through planning of the harvest

operation and the selection of favorable soil moisture conditions. In some cases,

application of fertilizer can be used as a remedial treatment. knowledge of soil

properties and growth limiting factors of the site are needed to predict harvesting

effects on site nutrient properties.

1 0
Harvesting Systema and Concept8 for Wet Sites

B. Stokes, USDA Forest Service, Engineering Research Unit, Auburn, AL

A. Schilling, International Paper Company, Hattiesburg, MS

Environmentally acceptable and economical forest operations for sustainable

management of forest resources are needed for bottomland hardwood forests. such

operations; i.e., techniques and technologies for roading, site preparing,

harvesting, and transporting, are especially needed to perform forest management

activities on wet sites. As the demand for hardwood resources continues to

increase, improved and alternative forest operations are needed to ensure acceptance

of harvesting on wet sites, typical of bottomland hardwoods.

Some alternative technologies and techniques include wide tires, fell-top-pile

feller-bunchers, clam-bunk skidding, two-stage hauling, towed vehicles,

cut-to-length systems, mats, helicopters, large forwarders, and cable systems.

These concepts have *the potential to improve system performance and reduce impacts

in conventional operations and on difficult sites such as wet areas. Although many

of these new alternatives are operational, some are just concepts or evolving

prototypes. More research is still needed to optimize these alternative

technologies and reduce costs associated with their implementation.

1 1
Impacts on Landrcape Diveruity

T. B. Wigley, National Council of the Paper Industry for Air and Stream Improvement,

Inc., Clemson University, Clemson, SC

T. H. Roberts, Department of Biology, Tennessee Technological University,

Cookeville, TN

Forest management activities potentially influence ecosystems at many Spatial

scales. For most forest systems, influences at the stand level have been most

intensively studied and are best understood. Management impacts at the larger,

landscape scale are poorly understood and many hypotheses regarding landscape

effects remain untested. This lack of knowledge is particularly acute in bottomland

hardwood forest ecosystems. This paper will provide an overview of prominent

theories regarding landscape-scale impacts of forest management and will identify

research opportunities for testing those theories.

Most hypotheses regarding landscape-level impacts were derived from island

biogeography and related disciplines. Landscape theory has primarily focused on the

concept of fragmentation and the consequences of breaking habitats presumed to have

once been uniform into islands or isolated patches. Species presence and

productivity in patches is sometimes viewed as a function of patch characteristics

(e.g., size, shape, amount of edge); degree of isolation from larger, similar

habitats; time since isolation; extinction rates; and immigration rates. Landscape

theorists have largely been concerned about older successional stages. The

effective size of older forest patches are thought by many to be reduced by changes

in solar radiation, wind patterns, and water fluxes along edges where timber

harvesting has occurred. Thus, habitat for species dependent upon conditions common

to interior forests may be reduced. Many conservationbiologists also seek to

minimize high-contrast edge because of potentially high rates of predation and

parasitism of bird nests associated with these habitats.

Corridors sometimes are promoted to encourage movements between otherwise

isolated patches of older forest. Wildlife species are presumed by many theorists

to reside as metapopulations within fragmented landscapes, generally exchanging

individuals and genetic material along connecting corridors. The rate of

interchange, however, is hypothesized to be less frequent than if fragmentation had

not occurred. While many of these theories are intuitively sound, there are few

data to demonstrate their applicability to managed forest systems, particularly

bottomland hardwood forests. And, much theory is directed at designating reserves

rather than improving our ability to manage forests while also maintaining

biological diversity.

Most bottomland forests have been altered since settlement, thus pristine

reserves generally are not feasible. Therefore, we suggest that high priority be

given to Using adaptive management to simultaneously test hypotheses about how

biotic communities function in managed, bottomland hardwood landscapes. Such

information would help managers understand the consequences of their activities,

provide them with more flexibility, and improve their ability to protect biological

diversity while also meeting society's needs for forest resources.

1 2
Recovery status of a Baldcypress-tupelo Wetland

Eight Years After Harvesting

W. M. Aust, Department of Forestry, Virginia Tech University, Blacksburg, VA

S. H. Schoenholtz, Department of Forestry, Mississippi State University,

Starkville, MS

T. Zaebst, Department of Forestry, Virginia Tech University, Blacksburg, VA

B. A. Szabo, Department of Forestry, Mississippi State University, Starkville, MS

Harvesting of timber in a forested wetland has the potential to alter the

wetland functional status through impacts on soil properties, hydrologic dynamics,

and plant communities. Research documenting functional changes in response to

wetland harvesting has often been limited to initial-response time frames of one or

two years following treatment. Because of the dynamic nature of floodplain wetland

systems, initial impacts to soil properties and hydrologic dynamics may be mitigated

by relatively frequent flooding-drying cycles and by rapid natural revegetation.

This research is being conducted to evaluate the recovery status of a

baldcypress-tupelo wetland eight years after harvesting. The effects of three

harvesting treatments are being tested: (1) clearfelling with chainsaws followed by

helicopter extraction of logs; (2) clearfelling with chainsaws followed by

helicopter extraction and glyphosate herbicide application; (3) clearfelling with

chainsaws followed by skidder simulation of log removal. The glyphosate treatment

was implemented to investigate the role of vegetation in the recovery of the

wetland. An undisturbed area of baldcypress-tupelo forest adjacent to the treated

area serves as a reference area of age 78 years. The variables used to assess the

functional status of the wetland include soil temperature, soil pH, soil

oxidation-reduction potential, water table depth, woody regeneration, total

aboveground biomass, and sediment deposition.

The study design is a 3x3 Latin square replicated three times for a total of

27 treatment plots. Each plot is 0.36 hectares. The reference area is a

pseudo-replicated square of 9. plots. Two l-meter deep wells for measuring water

table depth and-a soil sampling station for measuring soil temperature, pH, and

redox potential with a portable meter at 10 cm and 40 cm are located within each

treatment plot. There are two soil sampling stations in the skidder plots, one

within a skidder trail and one adjacent to the skidder trail. Woody regeneration

for trees > 5.0 cm dbh was measured in one 0.12-ha sub-plot and regeneration for

trees < 5.0 cm dbh was measured in one 0.04-ha sub-plot within each treatment plot.

Herbaceous biomass estimates were acquired from four 1 m x 1 m sub-plots within each

treatment plot.

Periodic measurements of soil properties; water table depths, and vegetative

regrowth were initiated in June 1993. Sediment deposition was measured using nine

erosion/deposition stakes systematically located in each plot immediately after

harvesting. Data for the treatments were analyzed by Latin square analysis of

variance according to date and, for soil properties, depth. Each treatment was then

compared to the reference value for that date using a protected LSD. Preliminary

results from four sampling dates during the summer and early fall of 1993 show that

soil temperature at 10 cm was higher in the glyphosate-treated plots than the other

treatments. The glyphosate plots have the least woody overstory and probably receive

the most direct solar radiation when compared with the other treatments. In

contrast, the reference area tended to have lower soil temperature at the 10 cm

depth. Redox potential varied over time, indicating a general drying trend over the

course of the growing season, but it was not significantly different among

treatments. Soil acidity levels followed redox potential trends. As redox potential

levels increased, pH decreased, but was not consistently altered by treatments.

Water table depth was significantly closer to the surface in the reference area than

the treatment areas in July, August, and September 1993, suggesting that

evapotranspiration rates may have been higher in the treatment areas. During

October 1993 through January 1994, the site was flooded and there were no treatment

effects on water depth.

1 3
Sediment removal was dependent on the amount of herbaceous biomass. The

undisturbed reference area had the least herbaceous biomass and the least sediment

deposition (average deposition=0.5 cm yr-l). The helicopter and skidder treatments

had a denser herbaceous component and abundant regeneration of water tupelo (IVyssa

aquatica) and baldcypress (Taxodium distichum). These areas trapped sediment at a

rate of 1.5 cm yr". The glyphosate-treated plots had the most herbaceous biomass,

sparse woody regeneration of predominately black willow (S&ix nigra), and trapped

2.0 cm yr-' of sediment.

Sampling will continue through another growing season in this ongoing study.

These preliminary results indicate some level of recovery in several key wetland

soil properties and in the regeneration of plant communities within the areas

subjected to helicopter logging and skidder -logging.

1 4
Influemco 02 Harvesting on Water Quality, Hydrology,

Denitrification, Decomposition, Amphibian Populations,

Microbial Ecology, and Regeneration in Narrow Ploodplains

of Blackwater Streams in Southern Alabama

B. G. Lockaby, School of Forestry, Auburn University, Auburn University, AL

R. H. Jones, School of Forestry, Auburn University, Auburn University, AL

R. G. Clawson, School of Forestry, Auburn University, Auburn University, AL

A. Griffin, School of Forestry, Auburn University, Auburn University, AL

S. Lloyd, School of Forestry, Auburn University, Auburn University, AL

F. C. Thornton, Tennessee Valley Authority, Muscle Shoals, AL

D. A. Brown, School of Forestry, Auburn University, Auburn University, AL

J. A. Stanturf, USDA Forest Service, Southern Hardwoods Laboratory, Stoneville, MS

The effects of two harvesting systems (handfell/helicopter and

feller-buncherlskidder) on water quality, denitrification, and decomposition were

investigated in southern Alabama. The research site consists of narrow floodplains

of low-order, blackwater streams. These sites are dominated by Histosols and are

very P deficient. On each of the three floodplains, two harvesting treatments and

an undisturbed treatment were installed during March 1991. The three floodplains

served as replicates in a randomized complete block design.

Composite surface water samples were collected one week per month to assess

the influence of harvests on water characteristics. Surface water samples were

analyzed for NO,, PO,, SO,, TSS (total suspended solids), TDS (total dissolved

solids), and BOD. Nitrate and phosphate concentrations were low with no apparent

harvest effects during first and second growing seasons. Although harvested areas

had higher TSS than undisturbed plots, sediment showed no statistical difference.

Monthly BOD (biological oxygen demand) samples showed no statistically significant

harvest effects, although BOD did increase slightly in harvest zones. High

numerical increases in BOD values were observed in one floodplain that exhibited

slow flow rates.

Groundwater wells were installed at 15-m intervals along six lines

perpendicular to the floodplain (one in upstream unharvested, two in harvested zone,

and three in downstream and unharvested). The bimonthly depth-to-water table was

recorded, and water was pumped for No3, PO,, SO,, and Cl analysis. Drier conditions

were observed following the harvest as indicated by an increase in Cl concentrations

in harvested zones, depth of oxidation (averaging 11 cm in undisturbed and 17 cm in

harvested zones),. and water table depths (averaging 0.2 m in undisturbed and 0.4 m

in harvested zones).

The acetylene inhibition technique and intact soil cores were used to measure

denitrification rates. Denitrification showed a seasonal trend and within-site

variation ranging from 7 to 20 kg per hectare per year, with no treatment showing

consistent high or low denitrification rates throughout the study. Harvesting

treatments did not significantly affect mass loss in decomposing litter, but did

stimulate N and P mineralization from litter. Microsite variation affected

decomposition k values and influenced nutrient availability (P availability greater

in concave areas, mineral N greater on convex areas).

Two of the floodplains were surveyed for amphibians using pit traps.

Harvesting, hydrologic regime, individual site variation, and temperature affected

numbers and types of amphibians captured. Significant decreases in populations of

fungi (Trichodera spp.) active in the decomposition processes were observed

following timber harvest, in the order of undisturbed control greater than minimum

and maximum disturbance treatment. Maximum disturbance harvesting led to a

significant increase in algal and cyanobacterial biomass within treatment plots,

potentially influencing soil nutrient status via nitrogen fixation, photosynthetic

activity, or immobilization.

1 5
Aboveground vegetation production was significantly lower with conventional

logging in the first year,

after treatment.

but differences decreased by the second growing season

The primary mode of regeneration for some species shifted from

sprouts in the helicopter treatment to seedlings in the simulated conventional

treatment.

1 6
The Effects of Timber Harvest OII the Functioning

of a South Carolina BlacloRater Swamp

D. Perison, International Paper Company, Bainbridge, GA

R. C. Kellison, Hardwood Research Cooperative, North Carolina State University,

Raleigh, NC

R. Lea, Hardwood Research Cooperative, North Carolina State University, Raleigh, NC

Bottomland hardwood ecosystems are important in both commercial and functional

terms. This study was designed to document the impacts of forest management on the

vegetation, soil and water quality, and herpetofaunal populations in a Blackwater

swamp. Operational harvest treatments commonly used in the Southeast to extract

bottomland hardwood timber were selected to represent a spectrum of site disturbance

intensity. Treatment were installed between January 1991 and November 1991 and

included: 1) simulated skidder forwarding, representing the highest level of

harvesting impact, 2) helicopter forwarding, representing the lowest intensity of

harvesting impact, and 3) a well-documented undisturbed stand serving as a reference

for the harvest treatments.

Biomass and species richness were greater on the helicopter and skidder

treatments than on the control. The herbaceous biomass measured on the skidder

treatment was not significantly different than the biomass on the helicopter

treatment. Despite the greater number of species present on the two harvest

treatments, overall species diversity was greatest on the control. This is believed

to be the result of the evenness of the biomass distribution among the species

present on each treatment. Skidder forwarding does not appear to be more

detrimental than helicopter forwarding on this site.

Cotton strip assay showed that organic matter decomposition increased with

greater site disturbance. This response is mainly attributed to increasing soil

temperatures as disturbance increased, with the overall effect being ameliorated by

saturated conditions. Greater nutrient concentrations were found in shallow ground

water samples from the more disturbed treatments due to accelerated decomposition.

Harvest treatments filtered greater amounts of sediment from the surface water

column due to the enhanced surface roughness in the harvest areas caused by thick

herbaceous regrowth and logging debris. Neither pre- nor post-harvest bulk density

values exhibited significant treatment differences. The deviation from the

traditional changes in bulk density due to harvest impact may be attributed to the

fact that the hydroperiod on the site was much longer than is typical of a

blackwater river system, with over 50% of the site being flooded for approximately

88% of the monitored days after the harvest treatments were fully installed.

Thirty-one species, of herpetofauna were detected on the site (11 amphibians

and 20 reptiles among 5900 individuals). The 10 ha clearcut was compared to an

adjacent control stand. Diversity did not differ among habitats, except that the

edge had a lower diversity than the clearcut and control. Salamanders were 25 times

more abundant in the control than in the clearcut. Reptiles, especially lizards and

large snakes, were more abundant in the clearcut. Ruts formed by logging machinery

provided breeding habitat for frogs. Two treefrog species present on the site,

green and gray treefrogs, showed preference for the clearcut and the control,

respectively.

1 7
Initial Reeponmrr of Vegetation, Water Quality, and soils to Harvesting Intensity in

a Texas Bottomland Hardwood Ecosystem

M. G. Messina, Department of Forest Science, Texas A&M University, College

Station, TX

S. H. Schoenholtz, Department of Forestry, Mississippi State University,

Starkville, MS

M. W. Lowe, Department of Forest Science, Texas A&M University, College Station, TX

Z. Wang, Department of Forestry, Mississippi State University, Starkville, MS

D. K. Gunter, Department of Forestry, Mississippi State University, Starkville, MS

A. J. Londo, Department of Forest Science, Texas A&M University, College Station, TX

A riparian bottomland hardwood ecosystem in Texas was chosen to test the

effects of standard forest harvesting practices on aspects of vegetation, water

quality, and soils. The study was located in the Neches River floodplain (Tyler

County). Soils are varied but are predominantly acid,

(Ozias and Pophers series) and siliceous,

thermic Aeric Fluvaquents

thermic Fluvaquentic Dystrochrepts

(Laneville and Iulus series). The study area was heavily logged in the early

1920's, but was largely undisturbed since then. The overstory was principally

sweetgum (Liquidambar styraciflua) and water oak (Quercus nigra) while the midstory

was heavily predominated by ironwood (Carpinus caroliniana). Clearcutting (CC),

partial cutting (PC, approximate halving of basal area), and a non-cut control (CT)

were tested on 8.1-ha square plots located along minor drainages within the

floodplain. Three replications were established such that the drainages

approximately bisected the plots, and treatments were arranged in downstream order

as CT, PC, CC. Streamside management zones extending about 20 m from each stream

bank were left either undisturbed or were occasionally selectively harvested.

Mechanical harvesting occurred in September 1992, during dry conditions. No

post-harvest site preparation was performed.

The woody vegetation community was sampled immediately before and about one

year after harvesting. The objectives of this research were to monitor regeneration

dynamics after harvesting and to test the hypothesis that early post-harvest

regeneration cannot be readily predicted from prebharvest composition. Nine

permanent subplots were systematically established in each treatment plot, each

subplot consisting of three concentric plots:

vegetation,

a 0.004-ha plot for understory

a 0.02-ha plot for midstory vegetation,

vegetation.

and a 0.08-ha plot for overstory

Calculation of importance values and:diversity indices as well as

ordination by detrended correspondence analysis (DECORANA) indicated no substantial

changes one year after harvesting in

regeneration composition. However, regeneration composition is expected to change

rapidly in the early years of stand development so annual surveys will continue.

Streamwater and subsurface water quality were monitored in the streams and in

water wells, respectively, to determine if harvesting and subsequent accelerated

leaching, decomposition or mineralization resulted in measurable water quality

changes. Nine 2-m wells were systematically installed two months before harvesting

in each treatment plot for monthly monitoring of water table depth and subsurface

water quality. Water temperature, pH, electrical conductivity, and dissolved oxygen

concentration were measured directly in the wells with a portable analyzer after

bailing and recharge. Subsurface water samples were also analyzed for inorganic

nitrogen and phosphorus calorimetrically with an autoanalyzer. Streamwater was

sampled at permanent grab-sampling stations located at plot borders. Streamwater

quality was measured by the same techniques as those for subsurface water, with the

addition of turbidity measured since May 1992, with a portable turbidity meter.

Results for subsurface water indicate that dissolved oxygen, temperature, pH,

electrical conductivity, and concentrations of asqnonium and phosphate were not

altered significantly during the first 16 months after harvest. Ammonium-N and

phosphate-P concentrations were consistently less than 0.7 and 0.1 mg L-l,

respectively. Dissolved oxygen and temperature showed strong seasonal trends with

low temperature and high oxygen in the winter and high temperature and low oxygen in

the summer. Clearcutting significantly (a = 0.05) increased nitrate-N in subsurface

water four and five months after harvesting. Four-month concentrations were 0.14,

0.58, and 1.29 mg L-' for the CT, PC, and CC, respectively; five-month values were

1 8
0.13, 0.14, and 0.48 mg L-l. Average values during 16 months following harvesting

were 0.06, 0.19, and 0.64 mg L- 1 for the CT, PC, and CC, respectively. During 16

months following harvesting, the average monthly water tables in the CT, PC, and CC

were 110, 95, and 94 cm below the surface, respectively. Pre-harvest water table

depths were approximately equal. Pre-harvest streamwater quality was Consistent

among sampling stations within each stream. Streamwater quality has not been

affected by harvesting. Monitoring will continue to determine if trends are shortlived.

Soil physical properties were monitored to test the hypothesis that impacts

reflect the degree of harvest trafficking, and that degree of impact would decrease

in the order CC > PC > CT. Soil sampling was conducted from May through August

1993. One hundred 5-cm x 5-cm intact cores were systematically collected at O-5 and

5-10 cm depths in each treatment plot. Preliminary results indicate that bulk

density across both sampling depths was 4.3% higher in the CC than in the CT. This

difference was related to a 34% relative decrease in macroporosity across both

sampling depths in the CC. Although not significant (a = 0.05), saturated hydraulic

conductivity and total porosity were also lowest in the CC. Soils in the PC had

intermediate levels of bulk density, microporosity and saturated hydraulic

conductivity.

These early results suggest a gradient of increasing impacts with increasing

trafficking on a treatment area basis. Additional analyses on data separated by

soil texture and disturbance class within treatment plots are being evaluated to

determine more specific responses to treatments.

Disturbance and exposure of mineral soil and the increase in litter from

logging slash following harvesting may result in increased soil heterotrophic

microbial activity. The hypothesis that degree of stand removal is directly related

to subsequent soil microbial activity was tested by measuring respiration rates both

in situ and in laboratory incubations. Eight sampling points were located in each

treatment plot on a common soil series (Ozias) at which soil CO, efflux was measured

for 24 hours with the soda lime absorption technique, and soils were sampled for

ten-day laboratory incubations using a modified version of the wet alkali method.

Soil temperatures were measured prior to in situ incubation, and soil moisture was

determined gravimetrically prior to lab incubation. Lab incubation was performed at

field soil temperatures. Sampling was done approximately monthly as site conditions

permitted. Results to date indicate no mean significant (a = 0.05) treatment effect

on either in situ or laboratory soil respiration rates. However, individual

sampling periods showed efflux rates significantly (a = 0.05) higher in the CC than

in the PC and CT, or no difference between the CC and PC when both were higher than

the CT. Efflux rate, soil temperature, and soil moisture content generally

decreased in the order CC > PC > CT. Both soil temperature and soil moisture were

related to rates of field CO, efflux. Rates will continue to be monitored to

determine if vegetation regrowth affects these processes.

Overall, these analyses show a minimal alteration of wetland functions

resulting from the harvest treatments. However, monitoring will continue in order

to determine the temporal nature of all measured processes as vegetation becomes

reestablished.

1 9
Road Construction and Harvesting Impacts on

Functions of a Redwater Floodplain Forest

in Central Georgia

B. G. LOckby, School of Forestry, Auburn University, Auburn University, AL

R. G. Clawson, School of Forestry, Auburn University, Auburn University, AL

K. M. Flynn, School of Forestry, Auburn University, &bLlrn University, AL

R. Rummer, USDA Forest Service, Southern Forest Engineering Center, Auburn, AL

B. Stokes, USDA Forest Service, Southern Forest Engineering Center, Auburn, AL

J. A. Stanturf, USDA Forest Service, Southern Hardwoods Laboratory, Stoneville, MS

The effects of road construction and silvicultural systems are being evaluated

in terms of their effects on biogeochemistry, regeneration,

on the Flint River floodplain.

and sediment deposition

The research site is composed of three replications

(two located in well-drained high-flats and one in a frequently flooded low-flat)

with three 8.1-ha treatment plots (clearcut, deferment cut, and an undisturbed

control) located on each replicate. Treatments were installed in September 1993.

Twelve shallow water wells (1.2 m below ground surface),

below ground surface),

two deep water wells (2.4 m

two automated water samplers (one 30 m north of the northern

plot boundary, and one 30 m north of the southern plot boundary), twelve 2.4-m crest

gages, 12 welding rods, twenty 1.8-m radius regeneration plots, and twenty 0.5-m'

feldspar clay marker horizons were established on each treatment plot.

Depth-to-water table, dissolved oxygen,

recorded in each of the groundwater wells.

and temperature of groundwater is

Surface water samples collected by

automated composite water samples during each flooding event will be analyzed for

organic and inorganic forms of nutrients in order to assess changes in

biogeochemical transformation functions. Crest gages were used to record the

highest level of floodwaters and will be evaluated on a flood event basis. Cores

from feldspar clay marker horizons will be used to measure sediment deposition over

discrete periods of time. Depth of oxidation will be examined on each treatment

plot after flooding seasons.

conducted.

Preharvest and postharvest regeneration surveys were

All seedlings and saplings were inventoried on the twenty 1.8-m radius

plots and two 3.6-m radius plots.

Sediment deposition and generation associated with four road surfacing

treatments are also being investigated.

gravel with geotextile fabric,

The replicated test consists of gravel,

native surface with vegetative stabilization, and

bare native material test sections. Sediment movement is being assessed using

automated composite water samplers, erosion bags, erosion stakes, and surveyed road

cross-sections. The construction and operational performance of the road test

sections during harvesting will be described as well as the experimental design and

installation of measurement sections.

2 0
Compariron of Productivity Value Acros8 a Flooding

OraUient in a South Carolina Coastal Plain Forest

M. K. Burke, USDA Forest Service, Wetlands Center, Charleston,. SC

W. H. Conner, Belle W. Baruch Forest Science Institute, Georgetown, SC

In floodplain forests the timing, duration and frequency of inundation affect

community development and aboveground productivity. Aboveground primary

productivity is greatest where 1) periodic flooding brings in organic matter and

nutrients as dissolved, particulate, and sediment-absorbed forms, 2) periodic

flooding provides an adequate water supply for trees to use during dry periods, and

3) the frequent draining results in an oxygenated root.zone. We know that there is

tremendous spatial variation in the hydroperiods of floodplain systems, however

previous studies have tended to lump together transition forests as floodplain

communities. We address this heterogeneity issue with our ongoing study of

aboveground production -- leaf litter, mast production, and tree growth -- across a

gradient that includes a hardwood and pine forest, a bottomland hardwood forest, and

a tupelo swamp. This study will help determine how the primary productivity

functions of wetlands are affected by differences in hydrology.

2 1
.

Forested Wetland Productivity: A Study of Regional Processe8

W. H. Conner, Belle W. Baruch,Fgrest Science Institute, Georgetown, SC

B. D. Keeland, National Biological Survey,' National Wetlands Research Center,

Lafayette, LA

J.,P. Megonigal, Botany Department, Duke University, Durham, NC

Much attention has been focused in recent years towards developing a better

understanding of ecological processes in forested wetland ecosystems. While several

investigators have compared structure and function of individual wetlands or

wetlands within a local area (Florida, Kentucky, Virginia, or Louisiana),

attempted to study processes on &,regional scale. This study was no '""5~$@ designed t o

compare the effect of hydrolog&*,regime on tree growth in wetland forests in South

Carolina (Atlantic Coastal Plain) and Louisiana (Gulf Coastal Plain). Specific

objectives included 1) determining the relationship between flooding frequency and

site productivity and 2) comparing the amount, duration, and pattern of diameter

growth of three common wetland species (Taxodium distichum, Nyssa aquatica, and

Nyssa sylvatica var. biflora) with respect to region and hydrologic position.

Site productivity was studied in paired 20 m x 25 m plots established to

represent dry, periodically flooded, and flooded environments in three Louisiana and

three South Carolina study areas. All trees greater than 10 cm diameter at breast

height (dbh) in each plot were tagged and measured beginning in the fall of 1986.

For two years, end of year diameter, monthly litterfall, and monthly water levels

were recorded. Since 1989, annual measurements of dbh only have been made at the

end of each growing season. To study species specific growth parameters,

dendrometer bands were installed on trees in all three Louisiana sites in 1986 and

weekly dbh changes and water levels. were recorded from March to September 1987. I n

.South Carolina, dendrometer bands were installed at five locations during the summer

of 1988 and weekly changes in diameter and water levels were recorded from March

through November 1989, and April through November 1990. Since weekly diameter

changes were made in different years, current and previous year weather patterns

were examined to make comparisons of the two regions more valid.

The degree of flooding varied considerably among plots, and a flooding depth

days index was developed to provide a more accurate definition of the flooding

regime of the sites. Data indicate that the Louisiana sites are wetter (flooded 3-7

months of growing season) than the South Carolina sites (flooded O-l month of

growing season). In our measurements of litterfall and woody productivity, leaf

production was fairly consistent for both years within a plot, but wood production

was highly variable. Wood production increased an average of 173 g/m2 from 1987 to

1988 in South Carolina, but dropped 86 g/m2 in Louisiana. Since trees tend to

allocate carbon resources to leaves and roots first, we would expect litterfall

values to be more consistent from year to year. Woody biomass changes seem to be

better indicators of differences among areas.

In the second part of this project, we found few differences in mean annual

growth, growth phase length, and growth curve shape between regional populations of

the three studied species. In general, annual variations in these parameters were

greater than differences among locations. Differences in hydrologic regime,

however, were shown to have significant effects on all parameters for mature trees.

wssa sylvatica var. biflora was restricted to periodically flooded sites in both

regions and showed little response to differences in mean water depth. Significant

differences among hydrologic regimes were detected for N. sylvatica in both regions,

but in Louisiana, no obvious pattern of growth response was detected across the

gradient of hydrologic regimes. In South Carolina, maximum growth of N. aquatica

trees was inversely related to mean growing season water levels. Maximum growth of

T. distichum was observed at sites with shallow, permanent flooding in both regions.

,;
Bottamland Hardwood Forest Manag-t and

Information Needs for Watershed Planning

J. P. Shepard, National Council of the Paper Industry for Air and Stream

Improvement, Gainesville, FL

There is a rich history of cooperative research on bottomland hardwood forests

in the South. Much of the past research has focused on silviculture, and

substantial progress has been made. Silvicultural research will continue to be

important and should not be neglected. Management of these ecologically rich

forests faces new challenges today, however. There are many other questions that

must be addressed to support the goal of managing bottomlands for timber, while

maintaining ecological functions that society values.

Federal and state agencies charged to protect water quality are reorganizing

their programs to identify watersheds as the basic unit of organization. There is

increasing interest in using watershed planning as a way of coordinating regulatory

efforts between point and nonpoint sources. The Clean Water Act includes a process

for this known as Total Maximum Daily Load. This process attempts to estimate the

total capacity of a waterbody to assimilate pollution and then apportions the

maximum amount allowable among all sources of pollution, including point and

nonpoint sources as well as those resulting from natural processes. This concept is

also being considered in market-based approaches for improving water quality. Point

source dischargers would pay to reduce upstream nonpoint source discharges rather

than decrease their own point source discharges.

There are many technical challenges to be addressed before such programs can

be successful. One is a better understanding of the contribution of natural

processes to nonpoint source pollution. A key step to further our understanding of

natural processes is to develop models to quantify the spatially and temporally

complex hydrology that characterizes bottomlands. Once that is accomplished,

hydrology can be coupled with research on sediment and nutrient import/export and

transformations to better predict nonpoint source pollution in undisturbed

conditions, and as a managerial tool to assess consequences of forestry operations.

In general, we need a better understanding of the many ecological functions

that make bottomlands so valuable to society. This presentation intends to catalyze

a discussion of research needs for future management of bottomland hardwood forests.

few examples are:

Models to quantify bottomland hydrology both spatially and temporally.

Models to quantify sediment and nutrient processes in surface and groundwater.

Quantify the relative contribution of plants, microorganisms, and geophysical

processes in improving water quality.

Characterize the invertebrate communities in bottomlands: species composition,

diversity, spatial and temporal variability, and applicability for use as

bioindicators to assess water quality.

Quantify long-term effects of different timber management practices on ecological

functions.

Quantify soils, vegetation, and hydrology to better delineate the wetland portion

of bottomlands.

*U.S.GPO:1994-565-016/00001

2 3

Stanturf, John A., camp., ed. 1994. Abstracts workshop

on harvesting impacts on bottomland hardwood forest

ecosystems. 1994 May 18-19; Stoneville, MS. Gen. Tech.

Rep. so-103. New Orleans, LA: U.S. Department of

Agriculture, Forest Service, Southern Forest

Experiment Station. 23 p.

The effects of timber harvesting in bottomland

hardwood ecosystems was examined at a workshop held

May 18-19, 1994. Overview papers and results from

studies on six river systems were presented.

Directions for future research were examined.

ICqwordst Bottomland hardwoods, ecosystems, forested

wetlands, harvesting, regeneration, water quality.
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