Characterization of Vernal Pools Across National Parks in the Great Lakes Region

Vernal pools are small, ephemeral wetlands that become inundated each spring and provide many ecosystem services, including providing critical habitat to amphibians and invertebrates as their temporary nature keeps them free of fish. We collected data on vernal pool characteristics throughout five Great Lakes National Parks: Pictured Rocks National Lakeshore, Sleeping Bear Dunes National Lakeshore, Apostle Islands National Lakeshore, Isle Royale National Park, and Voyagers National Parks. Our goals were to characterize and assess how vernal pools vary within and across the five national parks, and determine which characteristics are most correlated with the presence of vernal pool indicator species. We sampled 139 pools during spring of 2021 and 2022 where we collected data on pool characteristics related to hydrology, soils, vegetation, geomorphology, and indicator species. We found that vernal pool substrate and forest type does vary between the different parks. Many vernal pool qualities are driven by the type of substrate they occur on and overstory canopy species and amount of tree cover. We also created a classification system that most highly correlated to indicator species presence and can be used in remote sensing products, resulting in a three-class system based on overstory species composition: Deciduous, Coniferous, and Open. Indicator species were more likely to occur in pools with either a deciduous or open canopy than pools with a coniferous canopy. This information can be used to inform land managers within the Great Lakes of vernal pool characteristics they can expect, and which pools are hotspots for indicator species.