Ecological and social consequences of collaborative bison reintroduction in the western U.S.
Date
2018
Authors
Wilkins, Katherine DeWitt, author
Pejchar, Liba, advisor
Knapp, Alan, committee member
Garvoille, Rebecca, committee member
Knight, Rick, committee member
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Abstract
Collaborative conservation has been underway for centuries in diverse communities across the globe. More recently, collaborative groups of private and public land managers have coalesced around common natural resource objectives in the United States. This dissertation advances the science and practice of collaborative conservation through a literature review and two highly collaborative projects on bison reintroduction in the western United States. My specific objectives are: 1) To evaluate the status and impact of collaborative conservation groups in the United States; 2) To assess the ecological consequences of bison reintroduction for birds, mammals, and plants in Colorado's shortgrass prairie; 3) To understand how bison reintroduction affects human connections to grassland landscapes; and 4) To compare the effects of bison and cattle grazing on birds and plants in Colorado and New Mexico. To evaluate the status of U.S.-based collaborative conservation groups, I conducted a literature review to identify what factors motivate group formation, and to quantify biophysical, social, and economic goals, actions to achieve those goals and outcomes, and how outcomes were assessed. I also characterized the geographic distribution, participants and funding sources of U.S.-based collaborative conservation groups. To accomplish these objectives, I searched for peer-reviewed journal articles, book chapters, and reports in online databases, resulting in 174 papers that described 257 collaborative conservation groups in all 50 states. Overall, information on outcomes and how groups assessed outcomes was sparse. For those groups with published outcomes, most outcomes had positive results for biophysical, social, and economic goals. To assess the ecological consequences of species reintroduction and how reintroductions may catalyze public engagement in grassland conservation, I assessed both the ecological and social effects of bison reintroduction to northern Colorado. Specifically, I explored the effect of bison reintroduction on: 1) bird density and habitat use, 2) mammal habitat use, 3) vegetation composition and structure, and 4) human connections (place attachment) to a shortgrass prairie. To measure ecological responses, I surveyed birds, mammals, and plants before and after bison reintroduction. To understand how bison shape visitor connections to grasslands, I gave structured surveys to people who visited the site before and after bison reintroduction. I found few short-term effects of bison on grassland birds, mammals, and plants. However, I measured a significant increase in place attachment to the grassland site post reintroduction. These results suggest that bison reintroduction does not have strong, short-term ecological effects, but does have immediate, positive benefits for connecting people to ecosystems. I recommend that future projects prioritize monitoring ecological and social outcomes to advance the science and practice of bison reintroduction. To understand whether non-native species can serve as proxies for extinct or rare native species, I evaluated the role of bison and cattle grazing in shaping habitat for grassland birds and plants. To compare ecological responses, I surveyed birds and plants between bison, cattle, and reference sites in Colorado and New Mexico. While I found few differences in plant height and cover among bison, cattle, and reference sites, I did find significant differences in bird densities among the sites. In both Colorado and New Mexico, some grassland obligate birds preferred bison sites, while others preferred cattle sites. Bison and cattle may serve as reciprocal ecological surrogates in cases where they have similar densities on the landscape, where cattle graze on a rotational system. Overall, my dissertation demonstrates that collaborative conservation often achieves success, but these outcomes are not always assessed or reported. I also show that a highly collaborative bison reintroduction effort in Colorado had few ecological effects in the short-term, but did help connect people to a grassland landscape. In addition, my study found that collaboratively managed bison and cattle herds in Colorado and New Mexico create viable habitat for obligate grassland birds.
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Subject
conservation partnerships
grassland conservation
systematic review
ecological proxies
refaunation
Bison bison