Characterization and classification of vernal pool vegetation, soil, and amphibians of Pictured Rocks National Lakeshore

© 2015 American Midland Naturalist. Vernal pools are isolated ephemeral bodies of water that are often overlooked on the landscape. Despite their temporary nature, these pools are important to forest communities, providing critical breeding habitat for amphibians and an important food and water source for other taxonomic groups including birds, bats, and other terrestrial vertebrates. Sparse information about vernal pools in the upper Midwest, including Pictured Rocks National Lakeshore (PIRO), inhibits conservation. We sampled soil, vegetation, and amphibians in 21 vernal pools in PIRO during spring 2010 to provide quantitative and qualitative evaluation of vernal pool abiotic and biotic characteristics within PIRO to help managers determine which pools to prioritize for conservation. Average vernal pool size sampled was 0.124 ha. Soils had an average of 13.5% carbon and 0.7% nitrogen. Vegetation was diverse within the vernal pools, with 115 vascular plants identified. Five species of amphibians were encountered during our surveys. We created a vernal pool classification system based on: (1) pool depression characteristics (one depression versus many interconnected depressions and whether canopy was open or closed) and (2) vegetation community type. This resulted in five vernal pool types: three herbaceous communities with open canopies and defined circular/elliptical boundaries (classic pools) and two forested closed canopy communities with irregular perimeters and interconnected mini-basins (complex pools). The two forested communities had the highest vegetation species richness, due mostly to greater number of microsites (downed logs, hummocks, etc.) for vegetation. Hydroperiod index and soil carbon were found to correspond to the vegetation classes. Amphibian species richness was highest in the classic pools and the majority of the amphibians encountered were in the sedge community type. This classification system, potentially effective for vernal pools throughout glaciated northeastern North America, will help managers prioritize vernal pools for conservation