Exploring social and institutional variation across oak wilt risk management programs in Minnesota, USA

The Minnesota Department of Natural Resources, in cooperation with United States Forest Service, has implemented a risk management program to fund local government action aimed at containing the exotic invasive oak tree pathogen, Ceratocystis fagacearum - the causal agent of oak wilt. In administering the oak wilt ReLeaf program, the Minnesota Department of Natural Resources and United States Forest Service sought to facilitate efficient and effective management through enabling and mobilizing local land managers. Because the program is decentralized and because cities and counties are heterogeneous, local land managers take advantage of the program in different ways. Our goal in this study was to document the social and institutional variation in oak wilt management programs at the local (city and county) level, and provide preliminary insights into the causes of the variation. Specifically we asked: what factors constrain and facilitate oak wilt management at the local level; and how do ReLeaf program funds influence local management? To address these questions, we completed 12 in-depth qualitative interviews with foresters and private contractors, yielding information on 16 oak wilt management programs in the Minneapolis/St. Paul metropolitan area, Minnesota, USA. Through our analysis we identified five emergent themes that produce and reflect the overall variation in oak wilt management programs: (1) existence and enforcement of Potential Spore Producing Tree removal ordinances; (2) amount of local resources and potential effect of decrease in state funding; (3) differences across urban and rural areas; (4) differences in program goals and landowner cost sharing structures; and (5) ability to attain the Minnesota Department of Natural Resources' suppression goal. These findings describe factors contributing to variation across oak wilt management programs, illustrate challenges facing local invasive species management efforts, and provide insights for designing improved invasive species management programs at the federal, state and local level.