Spatial methods for low-cost restoration of rangeland ecosystem services

Background/Question/Methods

Rangelands constitute 50% of California, producing 70% of forage for a >$3 billion livestock industry while conveying much of the water used by humans and providing critical habitat for thousands of species. These and other valuable rangeland ecosystem services (ES) have been heavily degraded by invasive exotic species. Rangeland restoration is necessary, but hindered by high costs and low private returns. Our objective is to promote restoration by (a) quantifying restoration effects on rangeland ES, and (b) using spatial selection and seeding methods to reduce cost and improve success. First, in an observational large-scale study, we are surveying rangeland restoration projects in conjunction with unrestored sites to determine the relationship between restoration and selected ES (forage production, plant and arthropod biodiversity, weed abundance, N and C dynamics and water infiltration). Second, at an intermediate scale, we are testing the efficacy of novel strip-seeding treatments for cost-effective restoration. Strip-seeding refers to the planting of seeds in strips to some fraction of total field area, versus seeding uniformly across the entire field. Third, we are testing fine-scale strip-seeding treatments in bounded runoff plots and measuring hydrologic function and water quality as further inputs for the comparison of costs and ES. 

Results/Conclusions

To date, results of the large-scale study suggest that restoration significantly increases the provision of valuable ES relative to native plant diversity, forage production, and weed control. The relationship between restoration and ES is being further explored through analyses of above- and below-ground arthropod, soil, and seed bank samples in addition to economic data. In the intermediate-scale study of strip-seeding as a restoration method, good native grass establishment was observed in 2012 after seeding in fall 2011. Ongoing analysis of baseline data suggests strip-seeding increases beneficial insect diversity. Spread of seeded species into unseeded areas will be monitored in subsequent years, coupled with economic analysis of treatment costs relative to increased ES. Finally, in the fine-scale test of strip-seeding on runoff dynamics, results to date strongly suggest that strip-seeding can be used to manipulate the quality and quantity of runoff, soil temperature and moisture, and plant production. In the future, results from these three research activities will be integrated into a multi-scale assessment of rangeland restoration effects on ES. Ongoing outreach activities, designed to engage diverse stakeholders such as land-owners and managers, farm advisors, and conservation organizations, have drawn significant interest in the region and will expand in the future.