UC Santa Cruz
Where to restore? Influence of surroundings on stream restoration outcomes
- Author(s): Stanford, Bronwen
- Advisor(s): Zavaleta, Erika
- et al.
Streams and rivers are both highly important for biodiversity and ecosystem function and highly sensitive to human land use change. Efforts to restore and enhance stream condition have created a booming industry; however, many restoration projects fail to achieve recovery. This dissertation explores how surrounding conditions can help explain variation in stream restoration outcomes. I assess the influence of site surroundings and land cover on stream restoration and recovery at local, watershed, and regional scales. In Chapter 1, I present results of an observational field study monitoring stream recovery following riparian restoration in rangelands in Marin County, CA, and show that greater linear lengths of riparian trees can partially buffer stream condition from grazing stresses. In Chapter 2, I present a global meta-analysis combined with land cover analysis to assess stream recovery following a disturbance to water quality. I show that most streams fail to recover to baseline conditions within the study period, and that streams with more upstream natural land cover may experience lower recovery completeness than streams in more human-dominated watersheds. Finally, in Chapter 3, I analyze the spatial distribution of stream restoration and management sites over the past 30 years on the California Central Coast using both sociopolitical and biophysical indicators. I find more restoration near more white, wealthy, and educated human communities, suggesting that current practice could better match restoration effort and need. Together these findings reinforce calls for watershed planning to prioritize overlooked opportunities and to position restoration projects to achieve the greatest regional benefits.