Managing for multiple outcomes on rangeland agroecosystems: Quantifying synergies and tradeoffs

Background/Question/Methods

California’s oak woodlands and savannas, also known as hardwood rangelands, are among the state’s most valuable land resources, providing food, fiber, and other key ecosystem services. Historically, rangeland science and management have focused on agricultural production with little explicit incorporation of conservation goals; during the mid-20th century, hardwood rangelands were cleared of trees and shrubs to create open grasslands to enhance livestock production. Due to an expanding and diverse stakeholder base and increased landowner interest in managing for multiple outcomes, growing importance is being placed on rangeland conservation goals.

In moving forward on merging production and conservation goals, the first critical task will be to assess potential tradeoffs and synergies between managing for multiple goals versus only managing for traditional agricultural production goals. We utilized state-and-transition models as a framework to explicitly incorporate multiple ecosystem service-based goals, allowing for such assessments. We measured soil and vegetation properties indicative of key ecological functions and services across an existing gradient of oak and shrub management, including undisturbed oak woodland, thinned oak savanna, and open annual grassland states. 

Results/Conclusions

Open grasslands had 2-fold greater productivity, but lower herbaceous diversity than undisturbed oak woodlands. Total carbon was 1.7-fold greater in woodlands relative to open grasslands. Infiltration capacity was ~10-fold greater in woodlands than in grasslands; however, even the lowest infiltration rates observed in grasslands exceeded the 100 year rainfall depth-duration frequency by a factor of 4, indicating no real functional differences in terms of water supply. Overall savannas exhibited intermediate values. Explicit incorporation of ecosystem service goals into management models will be valuable to both landowners interested in managing for multiple outcomes, and government agencies responsible for assessing outcomes of conservation practices and allocating funds.