The Three Phases of Land-Use Change: Implications for Biodiversity
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Traditional economic models of land-use change have focused on factors such as distance to population centers, available labor supply, population density, and patterns of existing infrastructure, such as roads. While such models can reproduce urban sprawl, they do not address such fundamental issues as the causes of initial human settlement locations, variation in the growth rates of different urban centers, and the ecological consequences of different economic drivers. A complementary approach, based on properties of the environment related to net primary productivity, predicts the temporal and spatial patterns of development and land-use change associated with three distinct phases of economic development: agricultural, industrial, and information/communication. Initial land use patterns, established in response to environmental constraints on agriculture, are selectively amplified based on the subsequent requirements for industrialization. These environmental constraints are later relaxed during the information/communication phase of development, which affects portions of the landscape that were little affected by the first two phases. This sequence of events produces a predictable change in the distribution of human population density and land-use intensity that impacts different components of biodiversity over time. The agricultural phase tends to eliminate those components of biodiversity that depend on high-productivity environments, while preserving those components that can survive on marginal lands. However, the transition from an industrial to an information-driven economy breaks the linkage between productivity and land-use intensity, and allows intensification of human impacts in areas that had been protected by the constraints imposed by agricultural and industrial economies. As a consequence, the remaining reservoirs of biodiversity on marginal lands are now being threatened as formerly remote rural areas are being developed for recreational and residential use, particularly in the western United States.