The only thing that is certain about Nature is its patchiness. Patchiness is ubiquitous, occurring across systems, organizational levels, and spatio-temporal scales. Traditional modeling approaches in ecology often fail to recognize spatial patchiness because they usually assume spatial homogeneity. A landscape may be viewed as a hierarchical mosaic system of patches that are different in their age, size, shape, content, and other aspects. The spatial change of the patch mosaic results in the landscape pattern, whereas the phase change of individual patches at the local scale and temporal change in patch mosaics at larger scales gives rise to the landscape dynamics. Following such a patch dynamics conceptualization, a spatially explicit patch dynamic modeling approach has been developed based on a serpentine annual grassland. The model has two basic submodels: a spatially-explicit, age/size- structured patch demographic model and a multi-specific plant population dynamic model of a non-equilibrium island biogeographic type. In this paper, the basic structure and some computational aspects of the model are discussed.