The ecology of Atlantic white cedar wetlands - USGS National ...

of the existence of the forests and their contents havediscouraged extensive investigation of this wealth ofintriguing life strategies.European colonization and subsequent centuriesof development have progressively so alteredthe landscape that much of the tree's original habitatwas destroyed. Those stands that remain were inmany cases protected only by the difficulty and highcost of penetrating the swamps. Cedar wetlands areincreasingly encroached upon. They have beenlogged for their valuable lumber since the first explorersset foot in the New World (Emerson 1981;Frost, unpubl.; Kalm 1753-1761) and have beendrained for agriculture for more than two centuries(Frost 1987; Sipple 1971 -1 972). As areas becomemore heavily populated, industrial, commercial, andresidential uses displace cedar wetlands where theyare not protected by law (Laderman et al. 1987;Roman et al. 1987). Cedar peat is being experimentallymined as an energy source.Despite these multiple incursions, it is clearfrom the vigor of many stands that, with appropriateprotection and, in some cases, aggressive management,cedars can successfully regenerate, and canrepopulate many former cedar sites as well.1.2 CLASSIFICATIONAtlantic white cedar occurs almost exclusivelywith other hydrophytes on hydric soils inwetlarlds commonly known as swamps and bogs. Itis also found, though rarely, near established cedarstands as a colonizer where there are hydrophytesbut nonhydric soils. This may occur, for instance, atthe margins of new impoundments or excavationswhere hydric soils have not yet developed. Atlanticwhite cedar forests may be composed exclusively ofan even-aged monospecific stand of close-rankedtrees, which is often referred to in the literature as"typical" for C. thyoides. In forests successfullymanaged for harvest and regeneration, as well as inmany natural stands that originated after fire or flood,this is often the picture. However, in many natural orselectively harvested situations, cedars grow in uneven-agedmixed stands which provide a greaterdiversity of habitats that support a more species-richfauna and flora. Animal and plant life, and thevarietyof cedar landscapes they inhabit, are described inChapters 2, 5, and 7; the known flora and fauna arerecorded in Appendixes A and B respectively.Under the U.S. Fish and Wildlife Service(USFWS) classification system (Cowardin et al.1979) (Figures 2,3), most cedar wetlands key out as:SYSTEM PalustrineCLASS Forested WetlandSUBCLASS Needle-leaved EvergreenDOMINANCE TYPE Chamaecyparis thyoides; inmixed forests, common associates in the canopy arered maple (Acer rubrum), black gum (Nyssa sylvatica),sweet bay (Magnolia virginiana), and one ormore pine species: loblolly (Pinus taeda), white (P.strobus), or pitch pine (P. rigida)WATER REGIME Nontidal; Semipermanently orSeasonally Flooded, or SaturatedWATER CHEMISTRY Fresh-Acid; rarely, CircumneutralSOIL Organic; rarely, MineralA detailed classification of various cedarwetlands is presented elsewhere (Laderman, unpubl.).Cedar swamps are situated shoreward oflakes, river or stream channels, or estuaries; on riverfloodplains; in isolated catchments; or on slopes.They may also occur (rarely) on bars or islands inlakes or rivers. Slightly elevated hummocks dominatedby cedar are often interspersed with waterfilledhollows in a repeating pattern that forms areadily identified functionally interrelated landscape.1.3 RELATIONSHIP WITH ADJACENT HABITATSThe USFWS (Cowardin et al. 1979) designatesthe upland limits of wetlands as (1) the boundarybetween land with predominantly hydrophytecover and land with predominantly mesophytic orxerophytic cover or (2) the boundary betweenpredominantly hydric and nonhydric soil. The lowerbounds of wetlands, both riverine and palustrine, lieat 2 m below low water or, if rooted plants growbeyond this depth, the border is at the deepwateredge of tree, shrub, or herbaceous emergent growth.In practice, however, consideration of theecosystem for management must go beyond technicallydefined borders. Indeed, the adjacent area maybe a critical determinant in the structure and functionof the entire wetland. The hydrological regime of acedar wetland is a major determinant of the biota inboth lotic (flowing) and lentic (nonflowing) systems.Mature Atlantic white cedars are adapted to a widerange of water depths, but rapid, prolonged changein water depth kills seedlings outright and stresses orkills mature specimens (see Figure 4)(Little 1950;Laderman 1980). In streamside, lakeside, and estuarine-bordercedar swamps, the depth of water adjacentto and contiguous with a wetland is a majorcontrolling influence on the wetland's water regime(Laderman, unpubl.). The impact of cedar wetlandson adjacent biota, hydrology, climate, etc., is at thistime a matter of interest, but there are insufficientdata for a clear vnderstanding of such effects.