Managing Wetland Vegetation - USDAWho has the knowledge and skills? The timing of the treatments and the frequency of repeated or subsequent treatments must be considered. Does the

Managing Wetland Vegetation

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Round-leafed sundew (Drosera rotundifolia).

The purpose of this manual is to assist landmanagers in becoming successful wetlandmanagers. A land manager can be any personor agency aware of the special needs and bene-fits of wetlands who has the power to make the needed changes. The intent is to stop thedecline of wetland plants and animals byproducing more and better wetland habitats.Habitats are environments used by species togrow, live, hibernate, bask, forage, and repro-duce. The management options for specificwetlands vary, based on site character and theobjectives and motivations of the managementplan. Discussed below are some techniquesused to manage wetland vegetation. While theprimary consideration should be to improvethe function of a target wetland, the adage“first, do no harm” is also worth remembering.

Over time, freshwater wetlands in theSoutheast succeed toward a closed forestcanopy; the sunny microhabitats graduallydisappear as the interior surface becomesshady. The time this takes can be relativelyshort. For example, the Southeast experiencedvery dry conditions in the mid-1980s andduring this time extensive woody growthemerged in many wetland sites. Although it isdifficult to predict how global climate changewill impact the wetland hydrology and biotaof the Southeast, clearly the succession toshaded conditions is an important considera-tion in the conservation and management ofsmall wetlands.

Many plants and animals require opensunny habitats and are not found in heavilyshaded areas. Appropriate treatments may beneeded to manipulate the wetland communitiesto the desired mix of woody and non-woodyplants. For example, the ecology of the bogturtle seems to indicate a preference for patchyhabitat of wet shrubby and woody areasinterspersed with open, sunlit, boggy, wet

meadows with various herbaceous vegetationtypes (Box 5.1). This habitat type might havedeveloped and been maintained by naturaldisturbances (high winds, storms, floods) andthe actions of animal herbivores such as beaver(Castor canadensis), elk (Cervus elaphus), or bison(Bison bison). Of the types of animals thatmight have played an important role, thebeaver is the most likely since it not only feedson woody plants, but is also an accomplishedwetland builder. In many cases, our manage-ment strategy might be guided by comparisonwith the actions of beavers on the nativelandscape (see Wetland Management byBeavers, Chapter 6).

Several options for managing woodywetland vegetation include cutting, grazing,chemical methods (herbicides), and the use offire. Each site will present prospects andchallenges for the use of any or all of thesetechniques. Also, new technology and greaterexperience will likely produce new techniquesapplicable to specific problems. This basicdiscussion of vegetation management considersthe dynamics of wetlands, the ecology ofwetland species, and the larger picture of thewatershed. With so many wetland functionsand values at risk, it is helpful to know thatoptions exist for their restoration andmanagement.

Mechanical Woody VegetationRemoval Techniques

As used here the term mechanical meanscutting, sawing, clipping, mowing, uprooting,and related physical techniques that can beused directly on plants. A variety of tools and mechanical equipment may be used to cut back or pull out wetland woody plants,depending on the job required. The size of the wetland and the amount of management


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Box 5.1 Removal of Hardwood Canopy is Beneficial to the Bog Turtle

By Dennis W. Herman

The bog turtle’s ultimate enemy may be a closedcanopy. The turtle’s basking sites and nesting areasare located in open, sunny sedge meadows withemergent vegetation and a subcanopy of shrubs.Later stages of succession produce a closed canopythat blocks sunlight and eliminates surface warmingand herbs. Bog turtles are long-lived, reaching agesin excess of 40 years. Mating and egg-laying canoccur over the life of a bog turtle. Reproductivesuccess declines as adequate nesting sitesdisappear and individual turtles can live to a ripe oldage persisting in sub-optimum sites. If areas open up

in the wetland by man-made or natural reasons, thenreproduction can once again occur in the population.This case study illustrates how an aged population ofbog turtles benefited from the removal of canopyspecies and actually began reproducing again afternearly two decades.

The bog turtle was discovered along a secondorder stream in a north Georgia county in 1979. Thehabitat where the first turtles were found was atypical,comprised of a rocky meandering stream with smallseepages irregularly located along the stream.Some typical wetland species were observed in theseepages including sedges (Carex sp.), bog rushes(Scirpus sp. and Juncus sp.), and small amounts ofpeat moss (Sphagnum sp.). A hardwood canopy ofoaks (Quercus sp.), maples (Acer sp.), and tuliptree(Liriodendron tulipifera) dominated the area preventingsunlight from reaching the forest floor.

A bog turtle survey began in 1979 by a US ForestService biologist ended in 1982. Only one old adultfemale was found during this initial survey. Dr. KenFahey found additional adult bog turtles from 1983 to 1986, all of them very old. No evidence ofreproduction was ever found at this site, and it wasassumed that it was an old population, expected topersist only until the last turtle died out.

The upper slope above the site was logged in1986, but provided no direct benefits to the population.The survey was discontinued from 1987 through 1990.In 1990, Dr. Fahey and the US Forest Service joinedforces, renewed searches, and began a trappingcampaign to locate new turtles. The survey wasmoderately successful, with the capture of additionalspecimens, yet reproduction and recruitment were notobserved. The Forest Service, at the urging of Dr.Fahey, began to selectively remove some vegetationand girdled some large trees in 1993. Girdling of treeshas continued from 1994 to the present. A bog turtlenest containing three eggs was found in the top of arotting hardwood stump in July 1997 in one of theopen areas created by tree and vegetation removal.This was the first reported case of bog turtlesreproducing at the site and in Georgia.

This view of a meadow bog shows how livestock grazing maintains the open, shrubless wetlands preferred by bog turtles.

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A view of the same meadow bog showing the rapidshrub succession two years after livestock wereremoved. Habitat becomes less suitable for bog turtles as shade increases.

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required to implement the plan oftendetermine the most effective and efficientmethod to use. Small wetlands, like the mostcommon ephemeral pools, seeps, and bogs are amenable to skillful management bypeople using hand tools without the aid oflarge, heavy machines. On the other hand,large areas like floodplain forests may requirelarge equipment like trucks, tractors, andearthmoving equipment to achieve themanagement goals. If heavy equipment wasused to drain or otherwise alter the wetland,then it is likely that similar equipment will be required for restoration.

The amount of time required for differenttechniques also needs consideration. Canorganized work crews of volunteers be used at the site? Is there sufficient skilled laboravailable from the landowner or other localgroups to do the job? Can someone subcontractthis work? Who has the knowledge and skills?The timing of the treatments and the frequencyof repeated or subsequent treatments must beconsidered. Does the management plan outlineany alternative treatment options as conditionschange? How will the treatments and subse-quent responses be evaluated for effectiveness?A wetland management project where the goalis to keep conditions sunny will require moreintensive management practices. Considerationmust be given to the fact that managementmight also continue far into the future andplans should be made now to ensure that thebest possible arrangements have been made forthis commitment.

Choice of technique may depend on theseason in which the work will take place. If awetland has deep, soft mud, as required by bogturtles, this condition will limit the machineryused and may make it difficult to walk aroundthe site even in high boots. The impact ofentering a wetland, with either machinery orpeople intent on drastically modifying thevegetation, should not be considered a trivialpart of the management project. In some casesthe trampling, crushing, and breaking of thesurface and the hummock forming vegetationcan cause direct destruction of plants, eggs,nests, or animals who hide in these niches.

This damage can affect reptiles, amphibians,mammals, and invertebrates that live and nestin the low vegetation at the open margins ofwetlands. Excessive trampling may also harmthe hydrology of the wetland by penetratingimpervious soil layers.

Careful cutting of wetland woody treesand shrubs can be effective in opening a closedcanopy to the point of producing a response inthe plant community. Often it might be helpfulto experiment on a small part of the wetland todetermine both the logistics of the site and togauge the response of the treatment before it iswidely applied. Cutting with hand tools orhand-held power equipment is the mostaccurate method of trimming or removingwoody plants. Removing individual plants toopen the canopy and allow more light to reachthe surface can benefit surface basking reptiles,amphibians, and insects. These openings in the canopy may also benefit wetland herbsrequiring sunlight at the surface to germinateand grow.

There can also be drawbacks to suddennew openings in the canopy. In experiments to study the effects of canopy openings onpopulations of mountain sweet pitcher plant(Sarracenia rubra ssp. jonesii), it has beenobserved that grasses and even red mapleseedlings aggres-sively colonize some newopenings. In some cases the new plants

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Managing Wetland Sites

Turk's-cap lily (Lilium superbum) is found in moist conditions in the Mountains.

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Mitigation is a term used to describe actions tocompensate for environmental damage. This essaydescribes the case of a small wetland restoration andpreservation that resulted as part of a mitigationagreement. This site was chosen because it isconsidered to be a freshwater biodiversity site of localsignificance. The wetland is located in a larger floodplainand was purchased by the North Carolina Department ofTransportation (NCDOT) as mitigation for wetlanddamage during the construction of a highway bypass.The construction project and this wetland are in the sameUSGS hydrologic unit.

This wetland, called a “marsh” by locals, consists of arich and diverse biological community in the midst of anhistoric farming and grazing bottomland. Horses andcows have grazed the site as recently as 6-7 years ago.Historic photographs confirm that this wetland has beenexposed to row crops and other agricultural activity sinceat least 1940.

Box 5.2 A DOT Wetland Mitigation Site

Possibly the most significant natural area in thecounty, this wetland has been noted by local naturalists,birders, and herpetologists for over 30 years. An informalgroup of biologists has been studying the site withoccasional visits since about 1971. An array of wildlifestudies have been conducted and information about birds,reptiles, and plants all indicate the special biologicalnature of this wetland. Vegetational analysis and soilsurveys were used to delineate the wetland, and sitehydrology was monitored for a year prior to construction.

The marsh is composed of at least four separatewetland zones including different assemblages of plantspecies. There is some uncertainty about classification ofthese communities, given their long history of human andagricultural disturbance and natural dynamics. Among thenames applied to the existing plant assemblages by thosewho have been there, are Piedmont Fen or Meadow Bog,Wet Meadow, Marsh Hibiscus Pool and a Boggy AlderThicket. There is also a willow and birch lined ditch and alarge, tree-covered clay pan which functions like anextended ephemeral pool. Each aspect of these areasoffers a variety of wildlife habitat based on the diversity ofplant species and water quality.

Present are zones of shrubs such as buttonbush(Cephalanthus occidentalis), swamp rose mallow(Hibiscus moscheutos) and tag alder (Alnus serrulata).Woody plants scattered throughout include silky dogwood(Cornus amomum), swamp rose (Rosa palustris), and thenon-native multiflora rose (Rosa multiflora). Herb-dominated zones include sedges (Carex spp.) andgrasses, American bur-reed (Sparganium americanum),and cattail (Typha latifolia). Other herbs scatteredthroughout include monkeyflower (Mimulus ringens), lamprush (Juncus effusus), arrowleaf tearthumb (Polygonumsaggitatum), swamp milkweed (Asclepias incarnata),orange touch-me-not (Impatiens capensis), white vervain(Verbena urticifolia), and a hedge hyssop (Gratiola sp.).Drier areas support ironweed (Veronia noveboracensis),

Marsh prior to restoration. Note woody growth in backgroundresulting from elimination of cattle and horses that once grazed the area.

By Kenneth A. Bridle, Ph.D. and Ann Berry Somers

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colonize so thickly that other plants areexcluded, including the rare pitcher plant.

Plants can be topped, limbed, or cut backto the ground in order to make openings.However, this treatment often may cause abushy regrowth. Felling of large trees can alsohave a literal impact, depending on what theyhit when they fall. Another method, barkgirdling, removes the bark cutting off nutrientsupplies to the roots, resulting in the death ofthe tree while leaving it standing as a snag.Standing dead snags can provide additionalhabitat for many species for many years.Eventually the tree will fall and provideimportant habitat and cover for animals andother species. Girdling is an easy, effective,and selective technique that can cheaply killwoody species using simple tools.

Managing Woody Debris Cutting techniques generate lots of debris,

which may also need to be managed. In somecases this accumulation must be removed fromthe wet region, and may be used to createnearby brush piles for animal habitat. Anotheruse for this material may be within the wet

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tick trefoil (Desmodium sp.), and grasses such as redtop (Agrostis stolonifera), fescue (Festuca sp.), and timothy(Phleum pratense).

The mitigation plan included a 40 acre buffer of old fields around the wetland site. Key to the projectsuccess may be these enhancements, which restoredadditional parts of this floodplain to a wetland condition,increasing its value as a functional and biodiversewetland. Ditches were filled, two more pools wereexcavated, and raised berms and a freeboard dam wereconstructed to control water levels in the area.Continued monitoring of the plant communitydevelopment and hydrology are taking place in restoredareas now that the construction phase is completed.

On-going threats to the site are primarily a result ofthe nearby human population. The major threat to waterquality is fertilizer runoff from nearby develop-ments,and buffers have been constructed to help absorb someof the excess. The primary animal threats to wildlife arefrom free-ranging domestic cats and an apparent over-abundance of raccoons. Cats hunt wildlife even if theyare well fed at home. Raccoons proliferate as a result offree food offered by humans in the form of garbage,compost piles, and pet food left on porches. Thesepredators endanger the eggs, young, and adults of mostreptiles found in the site; the eggs and chicks of groundnesting birds; and almost all other small animals.Biologists’ recommendations for the site include management for these pest species. Theymenace many conservation initiatives throughouteastern North America.

SITE SIGNIFICANCE: Regionally significant due to the size of the wetland, the complexity of its naturalcommunities, and the presence of at least one specieslisted as threatened and several uncommon species.

PROTECTION STATUS: Easements, managementplan, and transfer of the land to a qualified conservationorganization after the NCDOT mitigation requirementsare fulfilled, will accomplish long-term protection.

Beavers kill large trees by girdling them, eliminatingpatches of canopy. This technique also works well whenused by humans to limit shading.

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core area —by placing it as a beaver might tomake low dams perpendicular to the slope ofthe valley. These structures slow down theflow of water and spread the flows into sheetsacross the ground surface. They also increasethe ability of the wetland to filter and trapsediments, capturing material to increase theorganic material retention. They can be used in conjunction with other methods to increaseretention of water in the site (see Chapter 6). If these structures are effective in altering thesurface hydrology, this modification mayincrease the wetness of the site and might alsohelp modify surrounding vegetation for thebenefit of wetland species like pitcher plants.Excessive flooding may occur during spring-time or other wet periods and should beavoided, as it may drown eggs or otherwiseharm some wetland species.

Mowing and Using Heavy Equipment

On those sites where it is deemed appro-priate to use heavy equipment to fell andremove trees or mow down herbs and brush,care must be taken to minimize the adverseimpacts of this type of work. Not only thephysical impact of the equipment, intentionaland incidental, but also the probability of fueland oil spills, and other contamination must beexpected and planned for. It is important thatthe equipment operator be aware of manage-ment goals or work under close supervision.

In many cases a skilled equipment operatorcan use experience and finesse to augment

the plan and make necessary corrections oncework has started. Do not leave an operatorunsupervised as most equipment can make adramatic impact quickly, and some mistakesare uncorrectable.

Many agricultural techniques like mowingand haying can also be used to manage vege-tation in and around wetland sites. The timingof any vegetation management operationshould be such that no harm is done to nativespecies of plants and animals encouraged bythe wetland management plan. Care should betaken to avoid cutting pastures too low, whichcan damage nests, kill small animals, and scalptufting, clumping, and climbing vegetation.Consultations with local biologists and wildlifemanagers can be used to plan the best time and frequency of cutting, mowing, or hayingoperations. Slight alterations in typical farmactivities can profoundly impact a wetland andits native communities. Delaying mowing justa few weeks or leaving an unmowed area as abuffer and refuge, may only slightly affectfarm operations, but may be critical to aflowering or nesting species’ reproductivesuccess for the year.

Horse logging, a technology of a past era,is regaining favor for use in conditions whereenvironmental impact from standard equip-ment is a concern. Horses can get into tighterareas with less surface stability than wheeledequipment. Horses can also disturb the surfaceless during log skidding. Horse hoof prints alsodo not channel water flow in the same way astire ruts which can dramatically change the waysurface water flows.

Grazing and Browsing Animals as a Means ofVegetation Control

Many types of animals make their homesin native wetland communities, living off theproductivity of the plant communities in aparticular area. Commonly, large animals likedeer and beaver can crop woody vegetationenough to have a dramatic impact. Other

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Box 5.3 Woody Vegetation Cutting Suggestions

• With the help of a professional, assess what to cut based on the desired outcome.

• Use the least impact method possible.• Limit canopy removal to 25-50 percent

per year.• Plan to use or manage the cuttings.• Avoid stepping on hummocks and other

areas where hatchlings or eggs could be disturbed.

• Disturb only one patch of the site at a time. Assess the impact before continuing.

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animals like small mammals, insects, and birdscan have an equally impressive impact onnative plant communities by eating vegetation,pollination, seed dispersal, and other activities.As the biodiversity of the wetland restorationincreases, many more levels of structure andinteraction become evident.

Animals can be one of the most effectiveand important means of controlling unwantedvegetation by their grazing, browsing, barkstripping, root eating, and other woodyvegetation manipulations. While someanimals graze fresh succulent new growth,others gnaw at bark and, in the case ofbeavers, even fell sizable trees. Common large animals, like cows, horses, goats, andsheep, can keep vegetation well trimmed inany paddock. These and other agriculturallyimportant farm animals have been used asvegetation management tools for centuries.

Livestock Grazing

Benefits derived from limited grazinginclude retardation of woody vegetation andshrubs, and prevention of channel formation.

Hooves break up the rootstocks of shrubs andallow sheet flow to be restored. When live-stock are removed from wetlands, water nolonger pools in hoof prints, channels appear,and water flowing out of the site is increased.This enhanced flow in channels can cut deepgrooves into the soil, increasing the detrimentaleffects of water lost to the system. Besidesinhibiting channel formation, hoof prints alsoprovide hiding areas for bog turtles and otherwetland animals and exposes mineral soil for seed germination. However, excessivenumbers of livestock can create problems bydenuding vegetation and increasing nutrientinput from fecal droppings.

At one time many conservationists thoughtthat removing grazers was important for manyrare wetland species populations to persist. In light of recent studies however, cattle andother livestock are now considered vital inmaintaining site suitability for bog turtles andother rare species. The benefits derived fromgrazing can far outweigh negative impactssuch as accidental trampling of plants andanimals, compaction of soil, and additionalnutrient enrichment.

A flexible system with the capacity tomove animals into and out of the wetland, or provide grazer access only at specifiedtimes of the year will be the most useful andpotentially the most agriculturally productive.Paddock management, fencing, alternativewatering sources, heavy use areas, andcontrolled wallows have proved to be positiveinvestments in many streamside and wetlandsites—benefiting both the farmer’s businessand the environment of the watershed. Theseare practices where the strength of conser-vation agencies can help landowners withnew technical information and financialassistance (see Chapter 7).

The best grazers for promotion of bogturtle habitat appear to be beef cattle; goats orsheep may have similar or perhaps greaterbenefits, but these have not been studied.Limiting grazing density to no more than oneanimal unit (= one mature beef cow, also seeGlossary) per acre will optimize the situationfor both pasture health and turtle success.

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Box 5.4 Mowing and Heavy Equipment Use Suggestions

• Use the least impact method possible.• When mowing, don’t cut close.• Don’t mow more than once a year, less

often if possible. Unmowed grassy and weedy areas provide important refuges andforaging areas for many forms of wildlife, including various game species, songbirds, and butterflies.

• Minimize ruts and compaction of soils and vegetation.

• Plan to minimize and mitigate fuel, oil, and grease contamination in the site.

• Avoid working during known breeding timesand in suspected breeding places.

• Limit canopy removal to 25-50 percent per year.

• If using heavy equipment, disturb only one patch of the site at a time. Assess the impact before continuing.

Adjustments can be made when other types ofgrazers, such as dairy cattle, horses, or sheep,are involved. Once a grazing regime is in place it can be fine-tuned by removing oradding livestock to the site.

The use of excluder fencing and seasonalgrazing (winter grazing) are important conser-vation tools for the management and protectionof bog turtle and other wetland species habitats.Seasonal exclusion of cattle has been proven tobe an effective management tool in regulating

soil and vegetation impact: denuded areasbecome reestablished with vegetation, sen-sitive plants can grow, and safer conditionsexist for wetland nesting animals. Cattle canbe permitted free access to the wetland duringlate fall and winter, permitting the benefitsdescribed above. Researchers studying adangerously small population of bog turtles inNorth Carolina recorded a population increaseof 85% within a 5-year period after seasonallyrestricting cattle. Other strategies includeallowing grazers access to the sites year-round, but drastically limiting their numbers.Protection of nesting areas is paramount to the success of turtle populations.

Although bog turtles and some other rarespecies do indeed coexist with wild anddomestic grazers, some plants cannot tolerateinteraction with livestock. The size and typeof wetland community have to be correctlymatched with the amount and type of grazingin order to limit negative impacts on thewetland natural communities.

Chemical Controls ofVegetation

The modern tools of vegetation controlinclude herbicide chemicals. In any vegetationmanagement project, questions will alwaysarise regarding the advisability of chemicalherbicides for the control or elimination ofundesirable plants. Chemical herbicides arecomplex formulations mixed to meet specificgoals in specific situations. Because of thecomplexity of testing, labeling, and use, mostherbicides are targeted for major markets, likeagriculture, lawn care, or terrestrial weed control.

Using Chemicals with Caution

Each year chemicals are released into theenvironment in many forms ranging from rawpetroleum products to refined pharmaceuticals. These chemicals amount to billions of poundseach year. The fates of these chemicals and thelife cycle of their products in the environmentare largely unknown. The release into theenvironment of chemicals commonly known

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Box 5.5 Wetland Grazing Suggestions

• Allow only light to moderate grazing.• Beef cattle are the preferred grazer; but horses are also highly effective. Goats and

sheep may also have important beneficial effects.

• A ratio of 1 animal unit per acre is preferred.• Grazing on a seasonal (winter only) rotation

basis is acceptable. Construct a fence around the site allowing a buffer of native vegetation to filter polluted runoff.

• Use fertilizer and lime sparingly when applying to lawns and fields surrounding any wetland.

• Use excluder fencing around known or suspected turtle nesting areas, sensitive plants or plant colonies.

Managing wetlands may include seasonal exclusion of livestock.

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as pesticides can be especially risky as they aredesigned to be toxic. When deciding to usepesticides, one must consider the balancebetween benefit and risk. Herbicides are atype of pesticide used to kill plants.

Registration of herbicides follows acomplex set of rules that seek to allow the saleand use of chemicals judged to produce morebenefit than harm. However, out of alltheoretical possibilities, it is only possible to research the likely and obvious uses ofchemicals. Therefore the labels of herbicidesare specific about how they can and should beused. Use of any herbicide in a manner notintended on the label is illegal and bothpersonally and environmentally risky. Becauseof the relatively small amount of applications of herbicides in and around water and thecomplexity of adding chemicals to aquaticsolutions, few herbicides are labeled for use inaquatic or wetland conditions.

Testing for labeling includes herbicidetoxicity in several types of models: breakdownproducts, persistence in the environment,potential to accumulate in the food chain, andhazards to non-target species. This complexassessment allows chemical manufacturers toclaim benefits as weighed against potential and documented risks. Few chemicals havebeen tested with rigor for their impact on theenvironment, including unintentional conse-quences to non-target organisms and humans.Many chemicals can and do react to formcomplexes of products, most of which have not been well-studied. The interactions andaccumulation of these products and theirunintended consequences have, however, beendocumented with a few now famous casestudies of DDT and 2,4 D effects on wildlife.Caution in the use of herbicides is alwaysrecommended. It is therefore crucial to applyherbicides according to label recommendations.

There may be conditions in wetlandswhere concerns for the effectiveness andefficiency of plant growth control offsetunintended impacts of chemical herbicides. In these situations the selection of the properchemical, application, timing, and techniquecan reduce negative impacts as well asenhance effectiveness.

At the time of development of yourmanagement plan, a review of the availablelabeled herbicides should be undertaken.Labels and chemical formulations change asolder compounds are replaced with newerformulations for new uses. It is often best tocheck with the local cooperative extensionagent to get an update on what might beavailable to achieve the intended goals forchemical vegetation control. Names andproduct descriptions given in Appendix G arefor discussion and are not intended asendorsements.

Application TechniquesHerbicides are typically applied as sprays,

liquid paints, injections, granular formulations,or fumigants. There are no granular formu-lated products or fumigants appropriate orlabeled for wetland conditions. Some of thesemight be used in adjacent crops and thesemeasures should be researched relative to themanagement plan.

The use of spray equipment allows formany combinations of nozzle type, orientation,and pressure to achieve correct delivery andcontact of the herbicide with the target plantwhile minimizing drift. Label recommen-dations are given regarding equipment andacceptable weather conditions approved foruse. It is worth emphasizing that the use ofspray equipment, while perhaps the easieststrategy, produces the most non-target damageand drift. See Appendix G for more details ofherbicide use in wetland restoration.

Simple tools can be used to stem injectusing the cut and frill technique. A sharp knifeor hatchet is used to make cuts down into thecambium, leaving the bark attached. The barkstays attached and forms a cup for applicationof the herbicide. These cuts, called frills,should be arranged to encircle the stem ortrunk. The number of cuts is proportional tothe diameter of the stem. Each of these cuts isthen filled with herbicide using a squirt bottleor brush.

A treatment called stem injection uses ahatchet equipped with herbicide to injectherbicide with each cut. Cut and frill and

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stem injection techniques are good methods to deliver the active ingredient only to thetarget plant, thus minimizing unintendedimpacts on other vegetation. The number ofcuts or injections made in the stem controlsdelivery of the active ingredient. Larger stemsrequire a larger number of cuts or injections,usually one per inch of stem diameter. Steminjection and cut and frill may not be useful onstems less than a few inches in diameter.

When using the cut and frill, or stem andstump painting techniques, the likelihood of anherbicide spill is high and must be consideredlikely. The results of dripping or splashingherbicide onto the ground, water, or non-targetplants might be risky in habitat containing richbiodiversity or rare species. Extreme careshould be taken when using these techniques.

In the specific case of the bog turtle andsome wetland herbaceous species, woodyvegetation forms a closed canopy over thewetland target of the vegetation management.With the removal or opening of the canopyvegetation, an equally important colonizationof the surface by herbs will most likely bepromoted. These herbs are not only import-ant cover and root mass to hold the deep mud in place, but also the basis for the foodchain. As plants are the foundation of thefood chain, animals that depend on them will ultimately be affected by their loss. Ifherbicides can be confined to the canopy orinside the body of woody stems, the chance ofnegative impact on the herbaceous feeders onthe ground is diminished.

Care must be taken whenever mani-pulations of wetland vegetation might have impacts broader than the target goals.There should always be concern for thesensitivity of non-target species to herbicidechemicals or their by-products in the wetlandecosystem.

Timing and Application VariablesGiven a choice of a particular herbicide

and its labeled uses, a wide range of treatmentvariables will affect the outcome. The amountof active ingredient needed for the desiredeffect will vary, depending on the seasonal and

daily timing of the herbicide treatment, thespecies of plant and its stage of growth, theweather, temperature, and the thoroughnessand consistency of the application technique.An effective result may be hard to duplicate ifthese parameters are not well documented.This difficulty is the reason why most manu-facturers recommend a small test area beforelarge-scale use of herbicides. This recommen-dation is especially useful if there is concernabout effectiveness and other impacts in asituation where there is little experience.

Many herbicides achieve maximumeffectiveness during the period of maximalgrowth of the target plant, a situation which inthis case may also coincide with the maximumactivity of the bog turtle and other wetlandspecies. If convergence is deemed a problem,adjustments in treatment time might still proveeffective. For example, avoiding herbicideapplication during the turtle breeding andnesting period may lower herbicide effective-ness. However, there are obvious benefits ofnot bothering the turtles during this importantpart of their life which may justify this action.Perhaps just avoiding the known nestinghabitat during the active season might beanother solution.

Target Species

Target plant species that need to bemanaged in freshwater wetlands include the native woody species that dominate laterstages of succession into a wetland forestcommunity. The climax woody species ofcanopy size include Canada hemlock (Tsugacanadensis), red maple (Acer rubrum), black gum(Nyssa sylvatica), tuliptree (Liriodendrontulipifera), sweet gum (Liquidambar styraciflua),black willow (Salix nigra), green ash (Fraxinuspennsylvanica), and sycamore (Platanusoccidentalis). Shrubs may include great laurel(Rhododendron maximum), mountain laurel(Kalmia latifolia), silky willow (Salix sericea), tagalder (Alnus serrulata), silky dogwood (Cornusamomum), southern wild raisin (Viburnumnudum), poison sumac (Toxicodendron vernix),and spicebush (Lindera benzoin).

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Many freshwater wetlands in the Piedmontand Mountain regions have been invaded byintroduced alien species like multiflora rose(Rosa multiflora) and Chinese privet (Ligustrumsinense), often specifically mentioned as labeledspecies controllable by herbicides. Poison ivy(Toxicodendron radicans) may pose a problem insome wetlands as it can become dominant indisturbed wet areas along the edges of farmpastures. Any opening of the canopy maybecome an area colonized by poison ivy. Thisdanger may actually be more of a deterrent forhuman visitors than resident species. Poisonivy is, however, a target species for many herbi-cides, which in fact have proved successful inmanagement of this potentially aggressive vine.

When a chemical treatment is consideredfor wetland vegetation control, it should beintegrated into a management plan that out-lines ultimate goals and timelines of steps usedto achieve these goals. These chemical tech-niques can and should be used in conjunctionwith other methods of woody vegetationmanagement. It would be unlikely that asingle herbicide treatment would achieve allthe management goals in the typical wetland.

When used with care, a single herbicidetreatment, correctly and environmentallyapplied, can be an effective tool. However, theuse of herbicides brings with it many docu-mented problems and unknown effects thatmay endanger long-term success of wetlandmanagement. In areas where rare species arefound, all recommendations from the EPA andchemical manufacturers suggest that chemicalsbe considered only as an option of last resort.

Fire as a Management ToolThe influence of fire on the natural

communities of the Mountains and Piedmonthas not been fully appreciated. Studies suggestthat naturally ignited fires burned regularly inthe native plant communities of NorthAmerica. More frequent and larger fires on theCoastal Plain grade to less frequent and smallerfires in the Mountains and Piedmont. Thetopography and variability of habitats make forbarriers, limiting the spread of fire through themajor communities. The impact of fires on


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formation of wetland communities is notdefinitively known. Indeed, no publicationsabout fire ecology in these small, freshwater,Mountain and Piedmont wetlands were found.Likewise, the use of fire as a management toolin these sites is only vaguely covered in theliterature. However, it would be reasonable toassume that wetlands are not immune fromfire when conditions are right. Some parts of awetland, like the fringe communities and thecanopy, could burn without the most sensitivecore of the wetland surface experiencing a hotfire situation. As more is learned about thedynamics and development of naturalcommunities, we will understand the essentialrole that fire can, (and in some cases must)have on natural systems.

Fire is a useful tool, common in the toolkit of many landowners and land managers.Many people and agencies have experiencewith using prescribed fires for maintenance offire dependent natural communities. Forestmanagement went through a period of firesuppression and prevention which has provedboth damaging to natural communities anddangerous when excess combustible fuelaccum- ulates. Foresters have begun to re-introduce fire as a part of the natural andhealthy ecology of many managed areas.

Box 5.6 Chemical Use Suggestions

• Use chemicals only as a last resort.• Use chemicals with the least impact.• Minimize non-target vegetation impact.• Plan to minimize and mitigate chemical

contamination of the site.• Leave refuges for wildlife.• Avoid treating during known breeding times

and in suspected breeding places.• Limit vegetation removal to 25-50 percent

per year.• Use chemicals only on one patch of the

site at a time. Evaluate the impact before continuing.

• Use an application technique that is targeted and appropriate.

There is now significant evidence that fireis an efficient and selective tool, worth usingin the right situations. There are also specifictechniques that use fire to control invasiveweedy plant species, prepare seedbeds,promote seed germination, reduce combus-tible litter, and enhance soil fertility from theash. Most of these forestry techniques rely onprescribed and controlled ground fires setwith drip torches and wicks. These firespropagate along the surface and in the herb,shrub, and sub-canopy species, are generallycontrolled in such a way as to limit the impacton canopy trees. Fire roads, fire breaks,backfires, teamwork, preplanning, permitting,and a careful watch of the weather are allnecessary parts of a successful burn. This type of burn is an integral part of mostterrestrial landscapes; however, the use ofthese techniques might be inappropriate orimpossible to use in wetlands. In some cases a limited ground fire might be the right toolfor a wetland management job and thereforeshould be considered.

Other techniques that use fire as a man-agement tool rely on torches to burn only thetarget species and are much more selective.Several versions of commercially availabletorches have been developed for use in specialapplications. These propane-based torches areusually small, light weight, and easy to use.Torches have been used on specific targets like

weeds growing in cracks in sidewalks or atthe base of metal fences. Some have beenused for weed control in greenhouse, nursery,and tree farming situations. Smaller unitshave even been advertised for homeowner usein weeding flower and garden beds. Theadvantage of control and selectivity makesthese torches promising in the control ofwetland vegetation where burning the surfacecan be avoided. It is often on the surface thatthe most significant and least fire adaptedwetland plants and animals are found.

The benefits of this technique on the target vegetation depends on the type of firetreatment and the sensitivity of the speciesinvolved. The frequency and seasonal timingof fire can dramatically influence effects on thetarget plants. In most cases hot and intensefire can kill plant tissues directly with theeffects of the heat, desiccation, and directcombustion of leaves, stems, and seed. Plantswith significant underground stems or tubersor fire protected stems and buds can surviveand recover from fire. Plants without theseadaptations may not be directly killed by thefire, but may be stressed to the point that theybecome susceptible to attack by insects orother pathogens, which can then kill the plant. A good source of information about the effects of fire as a management tool can befound in the Fire Effects Information System(FEIS). FEIS provides up-to-date informationon fire effects on plants and animals. It wasdeveloped at the USDA Forest ServiceIntermountain Research Station’s Fire SciencesLaboratory (IFSL) in Missoula, Montana. TheNational Wildfire Coordinating Group and theUSDA Forest Service sponsor this nationalinter-agency information source. The FEISInformation Center is maintained by theIntermountain Region computer staff. Thedatabase is available on the Internet at:www.fs.fed.us/database/feis/welcome.htm.

Prescribed controlled burns have beenused to try to eliminate reed canary grass(Phalaris arundinacea) in a bog turtle wetland inPennsylvania. This strategy is based on areport from Illinois that burning five years in arow effectively controls this species. Three

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A hand-held torch can be used to spot burn individualwoody plants.

Kenn

eth

A. B

ridle

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years of early December burns have not proveneffective at the Pennsylvania site. This samegroup is also using experimental light grazing(1 animal unit/acre) on a rotational basis toreduce cover, create water pockets, and controlinvasive species. They also girdle trees tocontrol succession to forest and are consideringsome burning in the tussock sedge habitats ofthe bog. The results of this management studyhave not been published.

One technique of using a torch to elimi-nate woody vegetation depends on thepromotion of systemic pathogen infectionsthat subsequently causes plant death. In thismethod the target vegetation is cut 6-12 inchesoff the surface at some time early in thegrowing season. Several weeks later theplants resprout new succulent growth, whenair and water temperatures have warmed. Atthis point a flame from a torch is used to singeor sere these new shoots, breaking the surfacecuticle and damaging the outer cell walldefenses of the plant. This procedure leavesthe plant susceptible to invasion by naturallyoccurring pathogens that can find their way

into these open wounds. Experiments showthat this treatment results in a higherprobability of plant death than cutting alone.Several field tests of this technique in bogturtle habitat have documented some itseffectiveness in the short term. The long-termeffect of this treatment over several seasons isalso being observed. There is need for bothexperiment and long-term follow-up on theeffects of fires in freshwater wetlands. Also,the results of different variations andaugmentations of the torch technique, alongwith more traditional ground fire, willundoubtedly improve our understanding of the critical aspects of the technique andimprove its application to wetland vegetationmanagement.

A related technique, using super-heatedsteam, has also proved effective in weedcontrol. With water as the active ingredientand only by-product, this technique should beattractive for use in wetlands. Currently, theequipment is produced in New Zealand and is only recently becoming available in theUnited States.

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Bibliography

Ashworth, W. 1995. The Economy of Nature, Rethinking the Connections between Ecology andEconomics. Houghton Mifflin Company, Boston. The fundamentals of enviro-economics andways to change the way we do business to protect and restore the environment.

Corps of Engineers Wetlands Delineation Manual. 1987. United States Department of the Army,Vicksburg, MS. The basis for wetland regulation as practiced in the United States.

Department of Agriculture. 1998. Southern Wetland Flora: SCS Field Office Guide To PlantSpecies. USDA, SCS, South National Technical Center, Fort Worth, TX. A helpful manual ofcommon wetland plants of the Southeast. Line drawings, color photographs, range maps,identification, and diagnostic information included for each species.

Falk, D., C.I. Miller and M. Olwell. 1996. Restoring Diversity, Strategies for Reintroduction ofEndangered Plants. Island Press, Washington, D.C. An edited collection of papers about rareplants that discuss biology, public policy, reintroduction methodologies, and case studies.

Flora, C.B. 1990. Pesticide Risk: Making Decisions. Plant Disease 74(2):108-108. A review article that discusses the issues of societal benefit versus environmental risk. Risk assessment is atthe heart of pesticide regulation and determines what can be used and how.

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Frost, C.C. 1995. Presettlement Fire Regimes in Southeastern Marshes, Peatlands, and Swamps.In: Susan I. Cerulean and R. Todd Engstom (Eds.), Fire in Wetlands: A ManagementPerspective, Proceedings of the Tall Timbers Fire Ecology Conference, No. 19, Tall TimbersResearch Station, Tallahassee, FL., pp. 39-60. A detailed study of the effects of natural firereccurrence intervals on native vegetation in Southeast.

Gover, R. and A.J. Cessna. 1990. Environmental Chemistry of Herbicides. Volume 2. CRC Press,Boca Raton, FL. A review of what is known about the fate of synthetic chemicals that are intended tokill plants once released into the environment. Topics include soil chemistry, microbiology, hydrology,food chains, and weather.

Hammerson, G.A. 1994. Beaver (Castor canadensis): Ecosystem Alterations, Management, andMonitoring. Natural Areas Journal 14:44-57. A review of the biology of beaver, their impact onthe environment, and conflicts with human land use. Important considerations as these animalsbecome more common in a more human developed landscape.

Harris, L.D. 1984. The Fragmented Forest, Island Biogeography Theory and the Preservation ofBiotic Diversity. The University of Chicago Press. A review of relevant ecological theory dealingwith species conservation and habitat fragmentation. A must read for anyone wanting to understandthe impact of current land use on nature.

Hefner, J.M., B.O. Wilson, T.E. Dahl, and W.E. Frayer. 1994. Southeast Wetlands, Status andTrends, Mid-1970s to Mid-1980s. United States Department of the Interior, US Fish andWildlife Service, US Environmental Protection Agency. Inter-agency publication discussing thedefinition, types, and current status of major wetlands in the Southeast. Documents the loss ofwetland acres resulting from alterations and indicates serious and significant declines.

Lyon, J.G. 1993. Practical Handbook for Wetland Identification and Delineation. LewisPublishers, Boca Raton, FL. A discussion of wetland identification and mapping in practical terms with real-world examples.

Shafale, M.P. and A.S. Weakley. 1990. Classification of the Natural Communities in NorthCarolina, Third Approximation. North Carolina Natural Heritage Program Report. Classifiesknown natural plant communities in North Carolina and gives ecological discussion of each, withcomparisons and examples of sites to visit.

Thompson, G.F. and F.R. Steiner (Eds.). 1997. Ecological Design and Planning. John Wiley andSons, New York. Part of the Wiley Series in sustainable design, this book focuses on landscapeecology of created and managed environments.

Tilman, D. 1988. Plant Strategies and the Dynamics and Structure of Plant Communities.Princeton University Press, Princeton, NJ. Includes examples of the dynamics of plantcommunities through space and time. Shows succession, evolution, and the quick responses todramatic change integrated over time.

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Additional Resource

Fire Effects Information System database is available on the Internet at:www.fs.fed.us/database/feis/welcome.htm. An online resource with specific information on abroad list of plant species and their responses to fire. Examples, management case studies, andliterature review for many species.