Spatial methods for low-cost restoration of rangeland ecosystem services
California’s iconic rangelands are complex socioecological systems in which conservation goals must be balanced against economic realities associated with commodity production. Management involves a diverse range of stakeholders, including producers and other landowners, NGOs, universities, state and federal agencies, and private sector firms. The ecosystem service framework provides a means to align stakeholder objectives, prioritize needs, and assess conservation activities from a cost-benefit perspective. The provision of valuable ecosystem services by California rangelands, such as biodiversity, habitat for wildlife and pollinators, and forage for the >$3 billion livestock industry, has been severely degraded due to exotic species invasion, overgrazing, and habitat conversion. Rangeland restoration is increasingly desired, but is limited by low success, high costs, low private returns, and uncertainty in terms of ecosystem service benefits. We are conducting two stakeholder-driven projects to better understand rangeland restoration in a socioecological context; (a) a survey of existing restoration projects to determine how restoration costs relate to restoration success and ecosystem service benefits at different spatial scales, and (b) tests of a novel strip-seeding method for targeted, cost-effective rangeland restoration. Strip-seeding refers to the concentrated seeding of some fraction of total field area, versus seeding the entire field uniformly.
Results of the observational survey suggest that restoration significantly increases the provision of ecosystem services relative to native plant diversity, forage production, weed control, beneficial arthropods, and infiltration. The relationship between restoration and ES is being further explored through analyses of soil, seed banks, and data on restoration costs. In the manipulative study of strip-seeding as a restoration method, high native grass establishment was observed in 2012 after concentrated seeding in 2011. Preliminary analysis of abiotic data suggests that seeded grasses have rapid and significant effects on soil moisture after seeding. These data will be related to results of infiltration sampling in spring 2013. Analysis of seedbank and vegetation samples strongly suggests that, with proper management, seeded species will spread into adjacent unseeded areas without further direct seeding, leading to a significant reduction in restoration cost. Analysis of arthropod samples is ongoing, but is expected to show that strip-seeding increases the diversity of beneficial arthropods. These projects are generating critical insight into strategies for optimizing restoration efforts in terms of ecosystem services. This approach will be essential for balancing the multiple management goals that are required to enhance the long-term sustainability of California rangelands.