Initial Transplant Size and Microsite Influence Transplant Survivorship and Growth of a Threatened Dune Thistle

Identifying optimal transplant size and microsite requirements are critical challenges facing restoration practitioners, and refining this information may lead to more cost effective decisions. In this study, we evaluate the effects of transplant size and microsite on restoration success of the federal threatened Cirsium pitcheri (Pitcher’s thistle), a monocarpic perennial restricted to shoreline sand dunes of the Great Lakes in the United States, using a ten-year dataset. Using general and generalized mixed linear models, we determined how microsite variables influenced first-year-transplant survival and subsequent growth. Our data show a higher probability of first-year survival associated with larger transplants. We also found greater plant growth at higher elevations while plants on steeper slopes are smaller the year after they are transplanted. These results have implications for restoration success, which may be maximized by regulating transplant size and selecting habitat.