Many land-use regulations are designed to protect water quality, human lives, and property. These same regulations have the potential to protect both plants and animals by preventing the conversion of relatively natural areas to human dominated ones. For example, regulations affecting forest practices often limit harvest within a certain distance of streams and growth-management regulations often limit building within a given distance of steep slopes. When taken together, these regulations have the potential to protect a substantial amount of land. Here, we ask how the protection of terrestrial plants and animals afforded by land-use regulations compares to the protection provided by recent public land acquisitions in the state of Washington, USA. We looked across six counties that span a range of socio-economic, ecological, and environmental conditions to compare the amount of habitat for state species of concern that has been protected by regulations and by state acquisitions that occurred between 1990 and 2015. We used three different alternative, 50-year, land-use change scenarios to assess the range of possible benefits provided by acquisitions including two different estimated rates of land conversion as projected by an econometric model.
Our preliminary results indicate that although regulations protect a substantial amount of land from conversion, those lands are limited in their ability to provide habitat for a number of larger and wider ranging species given the configuration of habitat protected. We also find that the benefits of both land-use regulations and acquisitions vary by county. Although both regulations and acquisitions may play an important role in protecting habitat, given the spatial arrangement of the land protected through these two processes, their contributions to habitat conservation are not likely to be equal.