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 encroachment of shrubs in concert with the loss of native grasses. Efforts to combat this phenomenon include a variety of ‘brush management’ practices(BM) usually aimed at restoring forage production –but are seldom economically viable from that standpoint. However, encroachment also affect numerous other ecosystem services (ES). 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 desired ES. Shrub encroachment/BM influences on ES are locally constrained by soils, topography, disturbance, and management, but no conceptual framework integrating these factors with ES exists. This project aims to take a holistic approach to the shrub encroachment phenomenon, how it has altered ES capacities and the ability of BM to promote desired services. Outcomes will include:(1) Understanding of producer demands for ES on shrub-encroached landscapes(2) Enhanced knowledge of shrub encroachment/BMpatterns-processes3)Improved range management planning by characterizing spatio temporal changes in ES on rangelands.(4) Identification of ES trade-offs/synergies associated with shrub encroachment/BM in rangeland environments, and(5) A decision-support framework giving stakeholders a workflow for evaluating ES and associated tradeoffs/synergies. To achieve these outcomes, I will quantify rates/patterns of shrub cover change across the Las Cienegas National Conservation Area, a working rangeland, with contrasting soils, topography, and management histories in order to set baseline levels of ES and identify their change over time. I will then model how future shrub encroachment/BM actions will impact capacities of stakeholder-desired ES across a working rangeland. Outreach will include disseminating results through local annual workshops, Cooperative Extension programs, K-12 educational materials for local communities, and through peer-reviewed journals.

I will evaluate the validity of brush management-a widely used, but controversial conservation tool (Archer et al. 2011) -within a broad ESs portfolio context. Guidelines will be developed for determining when, where, how often and under what circumstances brush management might be used for the provision of a diverse portfolio of ESs. Impacts and outcomes of this project are:

(1) Understanding producer demands for ES on shrub-encroached landscapes: Our current understanding of ES supply is far more developed than that of demand (Yahdjian et al. 2015) yet the fate of a landscape depends on both the sum of ES it can supply and stakeholders’ demands for those services. Understanding which services producers’ value highest when weighing the option to undertake brush management actions would provide a clearer vision on how best to manage rangelands undergoing encroachment.

(2) Enhanced knowledge of the patterns and processes of shrub encroachment and brush management: Long-term rates/patterns of shrub cover change on sites with contrasting soils, topography, and management histories will be quantified and used to set management priorities that make best use of financial resources for contrasting and potentially competing land use scenarios.

(3) Improved land management planning by characterizing spatiotemporal changes in ES. Quantification of temporal changes are a missing component of most ES studies (Renard et al. 2015). Instead, ES are typically estimated, mapped, and valued at a single point in time. This ignores the fact that spatial distributions of ES across the landscape change over time. Viewing ES as static is overly-simplistic and may result in a misunderstanding of their interrelationships, missed opportunities to foster synergies, and the occurrence of undesirable trade-offs (Tomscha & Gergel 2016). Incorporating spatio-temporal changes in ES into land management planning is the first step for evaluating impacts of changes in environmental climate, subsidies or policy.

(4) Identification of ES trade-offs and synergies associated with shrub encroachment/brush management in rangeland environments: Shrub proliferation in grassland threatens the sustainability of livestock enterprises and has led to substantial investments in brush management. Economic analysis indicates these actions are often not justified when returns are based solely on increases in livestock forage. Currently, we are ill-equipped to quantify trade-offs among various ES (Fig 3). While scenario planning and spatial assessment assist in natural resource management planning (Nelson et al. 2009; Ma et al. 2016) they are often not framed within a restoration context. Accounting for the influence of brush management on multiple ESs and understanding trade-offs/synergies will enable a more accurate and objective assessment of the true costs/benefits of brush management. This will reveal value-added synergies or unintended consequences that might occur when manipulating interacting services. This research will focus on creating scenarios around brush management restoration actions and assess subsequent changes in services in a spatially-explicit fashion. This information will be useful to both producers and land managers seeking to more effectively prioritize their allocation of scarce resources.

(5) A decision-support frame work giving stakeholder a workflow for evaluating ES and associated tradeoffs/synergies and recommend best management practices: Public agencies, including those that advise producers (e.g. NRCS)are adopting an ES framework to manage multiple-use landscapes (Ma et al. 2016). Yet, challenges regarding accounting and allocating for ES trade-offs arising from differing management actions remain (de Groot et al. 2010). By contributing new knowledge to the inter-related dynamics of shrub encroachment/brush management and impacts on ESs and trade-offs/synergies, I anticipate outcomes that will improve sustainable range management. This study will provide a robust framework that can be widely adapted to determine how spatio-temporal valuations of ES can be used in restoration planning to help better achieve conservation goals on both public and private lands.