Integrated ecological economic modeling of watersheds

The regional scale of large watersheds (several thousands square kilometers) can be considered as the intermediate missing link to connect global biosphere models to the local human induced perturbations. The Patuxent Landscape Model (PLM) is designed to simulate fundamental ecological processes in interaction with an economic component that drives the land use patterns. Central to the PLM is a General Ecosystem Model (GEM) that is replicated in each of the cells that compose the landscape. Various habitats and land use types provide different parameter sets to be fed into GEM. The cells are linked by horizontal fluxes of material and information, driven mostly by the hydrologic flaws. This approach provides additional flexibility in scaling up and down over a range of spatial resolutions. The rescaling experiments are performed to define the spatial sensitivity to various processes and land use changes. These results are especially important to identify the key factors and processes to be included into higher level global models. Similar analysis is performed on the model structure to identify the key processes and parameters and simplify the model by aggregating less important variables and processes. We intend to build a hierarchy of models of varying structural and spatial resolution that could match the available data sets and capitalize on the information obtained in the data-rich geographic locations to apply in the data-poor areas.