Catálogo de publicaciones - libros

Relationships between spatial patterns and ecosystem function are briefly reviewed with regard to the current state of the science and its application and some important challenges. Ecosystem functions that are affected by heterogeneity include maintenance of species diversity (habitat) as well as material and energy cycles. Structural diversity and spatial heterogeneity play an important role in all of these functions and require increased attention. Spatial pattern or heterogeneity is important to ecosystem function at all spatial scales from centimeters to kilometers, not just the larger scales. The relevance of spatial patterns to ecosystem function, including the statistical patterns and significance of the relationships, depend on the function or parameters chosen and the spatial and temporal scales of interest. As a consequence, few, if any, general principles exist for interpreting the effects of landscape heterogeneity on ecosystem function. For example, heterogeneity does tend to increase the number of niches available and, hence, the diversity of environmental conditions that are present.Whether the effects of this increased diversity are positive or negative depends on the processes or organisms of interest. One important conceptual challenge in studying landscape heterogeneity is to move beyond the classic patch-corridor-matrix model to approaches that incorporate networks and gradients.

Explanation and interpretation of spatial heterogeneity in nature have been central concerns in ecology since long before the word was first defined.As ecological knowledge has developed during the past century, it has become clear that the problems of heterogeneity are diverse and can be studied as a number of component issues; together, the chapters of this book represent a state-of-the-art summary of current understanding. Simplifying assumptions of spatial homogeneity and temporal stability are still used widely in ecological research and will continue to be used for the foreseeable future, but long-term, global understanding requires a multiscale approach in which homogeneity and heterogeneity are parts of one continuum and change never stops. Future priorities for research include dynamic approaches to heterogeneity in complex spatial networks, the search for broad patterns in heterogeneity across spatial scales, and reconciling the goal of environmental sustainability with the fact that we live in a patchy, constantly changing world.

Four themes emerging from papers presented at the Tenth Cary Conference are discussed in this synthesis. First, conditions are considered in which both landscape composition and configuration influence ecosystem function. Where there is some vector of flow (e.g., water, wind, animal) between landscape components that differ in type or rate of ecosystem processes, configuration will influence ecosystem function. The second theme is that a network perspective offers opportunities to advance both theoretical and applied analyses of landscape heterogeneity. Analyses of the interaction of human and natural networks and of networks and patches are fruitful areas for future research. A third theme is the need to reflect more fully the diversity of human activities and their history and institutions when assessing landscape heterogeneity and ecosystem function. Finally, an enhanced understanding of landscape heterogeneity and ecosystem function will improve four aspects of human interactions with nature: the framework of environmental regulations, management of land and water resources, environmental design, and ecosystem restoration. Realizing these improvements requires that we find a vocabulary to express to the public the influence of landscape heterogeneity on ecosystem function and hence the ecosystem services that society values.

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.