Plant community survey and resurvey data from the Wisconsin Plant Ecology Laboratory

Legacy data provide valuable baselines for assessing ecological changes. Excellent baseline data for Wisconsin's plant communities exist because of the surveys conducted by J.T. Curtis and colleagues (the Wisconsin Plant Ecology Laboratory or PEL, GIVD ID NA-US-008) in the 1940s and 1950s. They surveyed >2,000 sites to test how plant community composition varies along environmental gradients. These sites include upland and lowland forests, prairies, savannas, meadows, sand barrens, dunes, fens, and bogs. They devised new techniques to sample and compare plant communities. Their data include species lists and often quantitative data on occurrences and tree sizes. At intensively sampled prairies and savannas, data include cover and/or the composition of quadrats. At forested sites, researchers characterized the overstory by recording tree identity and measuring size and spacing using plotless methods. For the understory, they tallied all vascular species present in 20 (occasionally 40) spaced 1 m quadrats. Subsequent PEL researchers have resurveyed >500 of these sites. The original quadrats and sites were not marked, requiring that resurveys approximate the original locations. Sampling uses either the original or more intensive protocols. We have characterized environmental conditions at many sites (soil chemistry, exotic earthworms, deer browse, and landscape conditions). We also now measure functional traits on many species. Our goals are to test theories of community assembly and assess how plant traits interact with patch size and landscape conditions to affect species and community dynamics. We have also redesigned sampling methods. The many sites and species provide great statistical power to characterize ecological changes and evaluate the factors driving these changes. These results serve to inform the public about ecological change and improve our ability to manage these communities wisely.