The U.S. Environmental Protection Agency recently established the Ecosystem Services Research Program to help formulate methods and models for conducting comprehensive risk assessments that quantify how multiple ecosystem services interact and respond in concert to environmental changes.  A major goal is to assess how alternative land use and climate scenarios will simultaneously affect food and fiber production, water quality and quantity, regulation of greenhouse gases, and other ecosystem services.  Essential to this goal are highly integrated models that can be used to define policy and management strategies for entire ecosystems, not simply individual components of the ecosystem.  In this context, an ideal model is one that (1) can unambiguously link effects to causes by identifying key processes that control ecosystem service tradeoffs, (2) can be applied to a wide variety of ecosystems and regions, (3) can be implemented using readily available data, (4) can efficiently map “bundles” of ecosystem services across wide spatial and temporal scales, and (5) can provide a decision support framework for assessing outcomes of alternative policies and management decisions.  We developed an eco-hydrologic modeling framework that aims to meet these emerging risk assessment objectives more closely than other currently available models. 

Results/Conclusions

VELMA (Visualizing Ecosystems for Land Management Assessments) is a spatially-distributed eco-hydrologic model that links a land surface hydrologic model with a terrestrial biogeochemistry model for simulating the integrated responses of vegetation, soil, and water resources to interacting stressors.  Here we describe a proof-of-concept application of VELMA to the H.J. Andrews Experimental Forest, a forested 64 km² headwater basin and LTER site in the Cascade Range of Oregon.  We used VELMA to simulate the effects of three different land use scenarios (100% old-growth, 100% clearcut harvest, and present-day land cover consisting of 45% old-growth and 55% harvested) on changes in five ecosystem services:  timber production, carbon sequestration, greenhouse gas regulation, water quantity, and water quality.  Compared to the old-growth simulation, over a 60-year period the clearcut simulation reduced total ecosystem carbon stocks by 40%, increased total stream discharge by 15%, increased stream nitrogen export by almost 300%, and increased total CO₂ and N₂O radiative forcing by over 200%.  The simulation for present-day land cover resulted in intermediate values in most cases.  Ongoing work is focused on model validation tests for several other LTER sites (Konza Prairie, Hubbard Brook, arctic tundra), and regional applications for Oregon’s Willamette River Basin and Central Plains rangelands.