Rangeland managers are charged with managing complex social-ecological systems. While they must be concerned with economic sustainability, they are often under pressure to provide public benefits as well. As the public becomes aware of the additional services these diverse ecosystems provide, land managers are becoming pressured to provide ecosystem services in addition to livestock production. However, there are few tools that provide the type of information rangeland managers need to understand the trade-offs of managing for different ecosystem services in order to make these complex decisions.
In 2010, the USDA Natural Resources Conservation Service (NRCS), US Forest Service (FS), and Bureau of Land Management (BLM) signed an MOU agreeing to adopt state and transition models (STMs) as a standard basis for rangeland inventory and monitoring. STMs are used to assess current conditions in relation to known ecosystem dynamics, identify management objectives and appropriate monitoring indicators, and assess whether objectives are being met (Bestelmeyer et al. 2003, Bestelmeyer et al. 2004). STMs represent a key tool in the process of adaptive management because they provide a clear representation of the best current knowledge about how a given ecosystem responds to different management and environmental factors. Currently, most STMs are diagrams accompanied by narrative descriptions (see figure 1), and may not be useful in determining ‘optimal’ management strategies. Therefore, our team created a linked ecological-economic simulation model with the goal of using a STM to determine optimal rangeland management given a range of management objectives.
We use the STM approach to model decision-making on a typical ranch in the Elkhead Watershed in northern Colorado. The ranch is a collection of ecological sites, or types of land with similar climate, soils and potential vegetation, that can transition between several states based on management and climatic events. We use field data and local knowledge to build the STM of ecological dynamics for each ecological site and determine how likely transitions are given past management and weather. Using an economic model based on the ecological STM and economic data from typical ranches in the region, we examine the decisions that contribute to, and economic outcomes that result from, changes in ecological states. In our framework, past ranch decisions affect existing ecological states, and current decisions play an important role in determining transition potentials. We also examine how current ecological conditions and management decisions influence the provision of ecosystem services other than livestock production
