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Detailed project information for Study Plan Number 02101 |
Branch : | Aquatic Ecology Branch |
Study Plan Number : | 02101 |
Study Title : | Importance of small wetlands to the diversity of amphibian assemblages in the Delaware Water Gap National Recreation Area |
Starting Date : | 10/01/2004 |
Completion Date : | 12/31/2006 |
Principal Investigator(s) : | Snyder, Craig D. |
Primary PI : | Snyder, Craig |
Telephone Number : | csnyder@usgs.gov |
Email Address : | (304) 724-4468 |
SIS Number : | |
Primary Program Element : | |
Second Program Element : | |
Status : | Active |
Abstract : | BACKGROUND
The contribution of small and ephemeral wetlands to the maintenance of landscape-level biodiversity is often overlooked in both scientific studies and in legislative protection. Despite the national commitment to wetland protection legislated in the Clean Water Act, a recent study by the Fish and Wildlife Service suggests that the total amount of wetland habitat has continued to decline nationally (Dahl 2000). The steepest declines have occurred in freshwater wetlands in the eastern United States, and much of these recent declines have been attributed to the loss of smaller wetlands (< 1 ha) that are exempt from federal protections (Snodgrass et al. 2000). Although protection of large wetlands may be adequate for the conservation of migratory birds and maintenance of some important ecosystem functions such as filtration of pollution and flood control, it may not be sufficient to preserve overall biological diversity on the landscape. In particular, these smaller wetlands may be critical components of the landscape for amphibian assemblages. Small wetlands frequently offer unique habitat characteristics such as reduced predator populations (Semlitsch 2000), and their presence on the landscape reduces dispersal distances among breeding ponds thereby increasing gene flow and reducing the probabilities of local extinction of individual wetlands (Dodd and Cade 1998). Consequently, the high rate of loss of these small, isolated wetlands may be contributing to regional and global amphibian declines (Blaustein et al. 1994, Dodd 1997). In addition, five out of seven state threatened and endangered amphibians species in New Jersey breed in small, ephemeral wetlands and two of those species are found in counties in which DEWA is located. Delaware Water Gap National Recreation Area (DEWA) consists of nearly 70,000 acres of mostly forested habitat containing hundreds of bodies of water that include wetlands, natural depression ponds, beaver ponds, and artificially impounded ponds and wetlands. Research from a three year study on ambystomatid salamander breeding habitats performed by the USGS-BRD Leetown Science Center (LSC) suggests that the majority of wetland acreage suitable for amphibian colonization in DEWA consists of wetlands < 1ha in size, and wetlands < 0.5 ha in size comprise nearly 50% of all cumulative wetland area surveyed (Figure 1). Furthermore, natural wetlands of all size classes display a variety of hydroperiods, with some permanent wetlands that are smaller than 0.01ha, and some temporary wetlands that are larger than 1.0 ha in area. Although, small and temporary wetlands make up a significant proportion of potential amphibian breeding habitat in this landscape, little is known about the contribution of these wetlands to overall amphibian diversity in the park. OBJECTIVESOur objective will be is to determine the importance of small wetlands on the diversity patterns of amphibian assemblages in DEWA by conducting amphibian surveys in the park and using the data to relate amphibian species richness patterns with the distribution, abundance, and hydroperiods of wetlands of different sizes. The comparative research study will have short-term and long-term significance to park management. In the short term, the data collected could be used to evaluate the use of ephemeral wetlands as candidate habitats for the NPS Park Vital Signs Monitoring (PVSM) program. Small, ephemeral wetlands (i.e. vernal pools) in DEWA deserve consideration as candidate habitats not only because of significant proportion of wetland acreage they represent park-wide, but also because increased water usage associated with urbanization surrounding the park, global climate changes (global warming), and the conversion of hemlock dominated to hardwood dominated forest stands within DEWA (a result of wooly adelgid, Adelges tsugae, infestation) could potentially shorten the hydroperiods of these habitats, making them unsuitable for plant and animal assemblages that exploit these seasonally available habitats. In the longer term, the models developed from the data could be used to predict the consequences of wetland protection measures or of natural or man-induced changes in the park landscape on wetlands and wetland communities. In addition, the models developed could be tested in other NPS lands to evaluate the exportability of predictive models of amphibian diversity, and to compare the relative abundance of small and ephemeral wetlands in DEWA to other parks. |
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