Vernal Pool Inventory and Classification at Pictured Rocks National Lakeshore, Michigan, USA

摘要

Vernal pools occur in the glaciated forests of northeastern North America and provide critical breeding and foraging habitat for amphibian and mammal species. Protection for these ephemeral wetlands is not federally mandated, placing them at risk for habitat fragmentation and making them more vulnerable to impacts of climate change. Unlike the northeastern United States, limited information about vernal pools exists for the Great Lakes region, and there is a lack of information about techniques to identify and classify vernal pools using remote sensing and field surveys. At Pictured Rocks National Lakeshore, Michigan, USA, our objectives were to locate vernal pools using true-color, spring leaf-off aerial photography at the 1:12,000 scale, classify vernal pools using modified geomorphological classification systems, and determine landscape associations with soil series and cover type GIS datasets. From the 214 water features identified and categorized via aerial photography, two (water with canopy, water without canopy) of the 12 categories accounted for 91.5% of the pools. The park's 51 vernal pools had a density of 0.19 km(-2) and an average surface pool area of 1078.2 m(2) (+/- 387.6). Using basin morphology and geomorphology, vernal pools were divided into the following five classes: classic, complex, kettle-kame, dune-swale, and minor ponds. Vernal pools were associated with three soil series that were characterized by slopes less than 5%, poorly to very poorly drained soils, and a clay content less than 10%. Nearly three-quarters of the vernal pools occurred in the hemlock-hardwood cover type. The conservation and protection of these discrete and small ephemeral wetlands should be considered within a landscape context, as subsets of vernal pools have specific geomorphology, soil series, and cover type associations.