Ecosystem Services on Shrub-Encroached Rangelands; Balancing Supply and Demand

View the project final report

Commodities

Practices

• Education and Training: decision support system
• Natural Resources/Environment: biodiversity, carbon sequestration, wildlife
• Production Systems: agroecosystems

Many rangelands have experienced shrub encroachment in concert with the loss of native grasses. Efforts to combat this phenomenon include a variety of ‘brush management’ practices (BM) traditionally aimed at restoring losses in forage production that occur when shrubs proliferate: but such practices are seldom economically viable from that standpoint. However, shrub encroachment also affects numerous other ecosystem services (ESs). A broader evaluation of the impacts of shrub encroachment and BM on ES would enable: (i) more accurate assessments of the utility of BM and (ii) development of guidelines for determining when, where and under what circumstances to use BM to promote a broader suite of desired ESs. Shrub encroachment/BM influences on ES are locally constrained by soils, topography, natural disturbance, and livestock grazing, but no conceptual framework integrating these factors with ES presently exists. This project aims to take a holistic approach to the shrub encroachment phenomenon, how it has altered ESs and the ability of BM to recover and restore valued lost services.

Outcomes will include:

(1) Improved understanding of producer demands for ESs on shrub-encroached landscapes

(2) Enhanced knowledge of shrub encroachment/BM patterns and processes

(3) Improved targeting of range management planning and practices by characterizing spatiotemporal changes in ES, and

(4) Assessments of ES trade-offs/synergies associated with shrub encroachment/BM in rangeland environments.

To achieve these outcomes, I have been (i) quantifying rates/patterns of shrub cover across the Las Cienegas National Conservation Area (LCNCA), a working rangeland, with contrasting soils, topography, and management histories in order to (ii) set baseline levels of ESs and (iii) identify maximum potential shrub cover based on topo-edaphic variables. This information is being used to (iv) model how future shrub encroachment/BM actions will impact capacities of stakeholder-desired ES. Recent and ongoing outreach activities have included presentations at local workshops, annual meetings of the Society for Range Management, and county-level Cooperative Extension programs. Written documents (e.g. fact sheets, articles for popular outlet and peer-reviewed scientific journals) are in draft stages at this writing.

The overarching goal of this project is to take a holistic approach to the shrub encroachment phenomenon, how it has altered ESs and the ability of brush management to restore services valued by stakeholders.

Specific objectives are to:

(1) Identify and rank producer demands for rangeland ESs through semi-structured interviews and surveys.

(2) Characterize spatial and temporal dynamics of shrub cover on sites with

             a) contrasting soils and topography, and

             b) known histories of brush management

(3) Model spatiotemporal ecosystem service capacity using

             a) Land cover classifications from (2), and assign ES values based upon field data and peer-reviewed literature, and

             b) Statistical analysis to evaluate relationships between multiple ESs and identify possible trade-offs and synergies.