Linking Land-use Change with Ecosystem Processes: A Hierarchical Patch Dynamic Model

Urbanization continues to accelerate and profoundly transform the surface of the earth, resulting in devastating effects on the structure and functioning of ecosystems throughout the world. In the Phoenix metropolitan region, urbanization has dramatically changed the Sonoran Desert landscape in the past several decades. To understand how urban ecosystems work and to achieve ecological sustainability in urban areas, we must be able to quantify and project land use and land cover change and its ecological consequences. In this paper, we present the theoretical basis and general structure of a hierarchical patch dynamics model (HPDM-PHX) that integrates land use change with ecosystem processes in metropolitan Phoenix. The spatial hierarchical model explicitly considers three spatial scales: the local ecosystem, landscape, and region. Urban systems are studied as dynamic patch mosaics in which a variety of ecological and socioeconomic processes take place, and in which nonlinear interactions between pattern and process at different scales lead to emergent properties. Our major research goals are twofold: to develop and test a hierarchical patch dynamics modeling and scaling approach to regional analysis and assessment, and to develop an understanding of how land use change (mainly urbanization) affects ecosystem production and biogeochemical cycling at the local, landscape, and regional scales in the Phoenix metropolitan area. Although HPDM-PHX is developed for a particular urban landscape, the modeling approach should be applicable to other landscapes of different types.