A Biome in Transition: Co-Produced Science for Grassland Conservation

Confronting biome-scale threats in the 21st century will require new and adaptive approaches for conservation. The overarching theme of this dissertation is co-produced science for the conservation of grasslands threatened by woody encroachment. Each chapter reflects a research question co-developed by scientists and managers to better understand and manage the threat of woody encroachment. First, I examine the dimensions of grassland risk through a series of field studies. Risk is the outcome of a grassland’s sensitivity and exposure to encroaching woody plants. Sensitivity reflects the rate and ease of grassland transition to a woodland, while, exposure is driven by propagule sources and their dispersal. My findings demonstrate the importance of exposure in driving patterns of encroachment and provide a basis for managing the spatial dimensions of exposure. Second, I assess the potential impacts of plant invasions in grasslands using a participatory ecosystem service assessment. Findings illustrate the potential for severe impacts associated with woodland transitions driven by a native invasive tree compared to non-native invasive weeds. Third, I assess the sustainability of grassland conservation approaches, including the lifespan of restoration treatments. Overall, I find unsustainable trends of grassland loss to encroachment across a network of priority conservation areas. Conservation efforts tended to be outpaced by encroachment of intact grasslands and re-encroachment of sites undergoing restoration, which rapidly transition back to a woodland without follow-up management. Large-scale fire management provided the only example of counteracting regional trends of encroachment and serves as a model for improving conservation efforts in other grasslands threatened by encroachment. However, the viability of this approach will likely depend upon broader acceptance of the role of prescribed fire in grasslands. To this end, I developed fire management scenarios to contrast air-quality outcomes of large-scale fire management versus those of fire exclusion. The scenarios illustrate the inevitable nature of fire in flammable ecosystems and provide a basis for communicating the role of prescribed fire in avoiding long-term consequences associated with wildfire