Vernal pools are small and shallow, isolated, ephemeral ponds that change in volume in response to varying weather patterns. These wetlands are important for maintaining healthy forest ecosystems by providing a critical breeding ground for amphibians, invertebrates, and other species. Inundation periods of vernal pools may be influenced by expected changes in precipitation regimes and temperature trends. Hydroperiods may be prolonged or shortened, impacting the species that rely on them. A total of 31 vernal pools previously identified using remote sensing were located, surveyed, and assessed at Indiana Dunes National Lakeshore (INDU) during the summer of 2017. Data regarding area, depth, percent tree canopy cover, and presence of invasive species were collected to determine which characteristics make the vernal pools more or less resilient to climate change. The vernal pools were classified according to their location into Clusters 1, 2, 3, and 4.
Results/Conclusions
Overall results showed that individual vernal pool percent canopy cover ranged from 25-90%. Vernal pool area ranged from about 9-597m². Vegetation surveys showed that 11 of the 31 vernal pools had invasive species presence (Phragmites australis). In terms of resilience characteristics, Cluster 1 had no invasive species presence and had the highest percent canopy cover range (64-90%), but had the smallest vernal pools (size ranged from 9-122m²). Cluster 2 had the lowest canopy cover percent range (25-84%), and 3 out of the 11 vernal pools had Phragmites presence, but had the largest vernal pools (size ranged from 14-597m²). All 5 vernal pools in Cluster 3, the closest to human disturbance, had Phragmites and their sizes ranged from 116-505m². Three of the 7 vernal pools in Cluster 4 had Phragmites, a percent canopy cover ranged from 46-56%, and the vernal pools size ranged from 33-382m². The characterization data formed the basis of an initial database that can be used to document the unique features of each vernal pool. Long-term monitoring will provide insight into the resiliency of vernal pools to climate change and inform resource management to promote healthy vernal pools throughout INDU and other Midwestern National Parks.