Developing Success Criteria for Ecosystem Restoration and Habitat Management in Central Wisconsin

Abstract

Before European settlement, one of the dominant ecological communities of Wisconsin was prairie and oak savanna. Overall, savannas encompass a broad group of open, disturbance-mediated cover types. In Central Wisconsin, oak (Quercus spp.) and pine (Pinus spp.) barrens were the prevalent types of savannas. Barrens have relatively poor nutrient availability but support rare plant species adapted to these conditions and provide important site characteristics for many wildlife species like migratory songbirds and the endangered Karner blue butterfly (KBB; Lycaeides melissa samuelis). However, information on how to successfully restore these ecologically important cover types is incomplete, because many barrens that could have functioned as reference ecosystems were converted into production agriculture, pasture, or red pine (Pinus resinosa) plantations during early European settlement. The objectives of this study were to (1) describe the flora and avian communities associated with restored barrens and determine if flora, avian richness/diversity has been altered from historic barren communities and (2) to assess fifteen years of active barren management throughout Central Wisconsin to develop success criteria aimed at wildlife site characteristics elements for KBB and migratory songbirds. Twenty sites with extensive restoration history were surveyed. At each site, we performed the Wisconsin Department of Natural Resources KBB occupancy survey, National Ecological Observatory Network bird point count surveys and vegetation sampling to describe the avian and vegetation communities, we compiled a comprehensive list of all observed species, including their occurrence across sites and per hectare estimates for plant species. Through stepwise regression analysis, we identified key predictor variables that influenced KBB abundance and migratory songbird presence. For KBB, the average lupine percentage positively predicted variation across study sites, while forb diversity negatively influenced it, together explaining 42.5% of the total variation across our study sites for migratory songbirds, both total acres of restoration unit and KBB nectar plant richness positively predicted variation across study sites, together accounting for 33.9%. Among these, total acres stood as the stronger predictor, with KBB nectar plant richness providing a lesser but still positive contribution. Our findings indicate that the flora and avian communities in restored barrens are distinct and diverse, emphasizing the ecological importance of these vegetation cover types for both KBB and migratory songbirds. The identified predictor variables can be used to guide future restoration and management efforts to support these communities. Additionally, this study contributes valuable knowledge to the understanding of the factors that shape barrens and helps inform conservation strategies for maintaining and enhancing the richness and diversity of flora and avian species in central Wisconsin barrens.