The Great Plains grasslands of North America provide a multitude of ecosystem services including clean water, forage, habitat, recreation, and pollination of native and agricultural plants. Increasingly variable climate and burgeoning societal demands for goods and services pose unique challenges to managers of these lands. A general lack of quantitative information regarding the effects of varied management strategies on these spatially heterogeneous landscapes complicates our understanding of the processes within them. Given the paucity of studies it is difficult to quantify the interaction of environmental (e.g. drought) influences and managerial strategies, such as grazing intensity and seasonality or fire frequency and behavior. This presents unique challenges to managers seeking to understand, explain, and justify proposed management strategies. We therefore developed a decision support system for helping to understand the risks and impacts of climate and management on production of forage and, ultimately, maintenance of goods and services. This novel decision support system merges two distinct tools which act in concert to produce state-of-the-art ecosystem modelling capabilities. First, the Rangeland Vegetation Simulator (RVS), deterministically estimates growth, succession, and fuels and second, the State-and-Transition Simulation Model (ST-SIM) enables stochastic modelling of ecological processes such as plant community development and response to climate.