Conceptual Frameworks: Plan for a Half-Built House

The consideration of spatial heterogeneity in ecosystem science is a challenging problem both empirically and conceptually. Although conceptual frameworks have been developed for some aspects of the problem, there is as yet no overarching framework that links them together. In this paper, we review many of the conceptual frameworks used in the chapters of this book.We discuss how the ecosystem concept can be extended to the “landscape system.” Like the ecosystem, the landscape system must have defined boundaries so that inputs and outputs can be distinguished from internal circulation. Given the delineation of the landscape system and its component ecosystems, a series of questions is posed that allow the investigator to determine what aspects of heterogeneity are likely to be important and what kind of model (homogeneous, mosaic, or interactive) most appropriately captures the behavior of the system.