AUTHORS: Joseph B. Deas, U.S. Geological Survey, Lake Michigan Ecological Research Station; Desi Robertson-Thompson, U.S. Geological Survey, Midwest Climate Adaptation Science Center; Ralph Grundel, U.S. Geological Survey, Lake Michigan Ecological Research Station
ABSTRACT: Oak savannas are among the most imperiled habitats worldwide, characterized by their unique structure and biodiversity. These ecosystems have experienced significant decline due to habitat conversion and altered disturbance regimes. To understand the impact of these changes on butterfly diversity, we conducted extensive surveys in 1998/1999 and 2023 across 17-25 sites in Midwestern oak savannas, representing a gradient of canopy cover. Our study aimed to assess butterfly abundance and species composition, alongside additional environmental variables that might influence the relationship between butterfly diversity and canopy cover. We collected data on various environmental factors, including flower abundance, composition, and fire frequency, to determine their predictive value for butterfly presence/absence and to identify key environmental predictors. By comparing data from different time periods, we evaluated how the relationship between butterfly diversity and canopy cover has changed and whether these patterns were influenced by temporal or spatial changes in environmental conditions. Preliminary analyses suggest that the relationship between canopy cover and species richness is influenced by the frequency of historic fires, plant diversity, and local climate. Our findings emphasize the importance of considering multiple environmental factors when assessing biodiversity in oak savannas and highlight the need for ongoing conservation efforts to preserve these critical habitats.
