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Figure 2.3.

Figure 2.3. In our working definitions, landscapes (C) included two kinds of structural patterns: patchworks (A) and networks (B). Landscape-level questions concern "How does pattern matter to ecosystem processes?" Patchworks and networks may be of natural origin (e.g. wildfire patches, stream networks) or anthropogenic (e.g. harvest patches, road networks). The driving processes in our central question (land use, natural disturbance, and climate) operate in, modify, and create patchworks and networks. These patchwork and network patterns may influence ecosystem processes and hence landscape function through spatial interactions, such as flows of material and energy or movement of organisms. Spatial interactions may occur within and between patches (1), within networks (2), or between patches and networks (3). We propose that different types of spatial interactions characterize different key properties of the Andrews ecosystem. Some properties, such as coarse woody debris movement, are critically dependent upon forest patches in streamside areas or wood in upstream network segments. Species diversity in one landscape patch may depend upon species diversity in adjacent or distant patches or network segments. However, other properties, such as carbon in a patch of vegetation, may be relatively independent of carbon levels in neighboring patches. These examples represent three fundamentally different classes of ecosystem properties. Hence, we suggest that the degree to which an ecosystem property is spatially dependent upon neighboring or distant patches or network segments is fundamental to its function in the landscape and hence to its response to natural disturbance, landuse, and climate variation.