• A personal note on IGBP and the social sciences

    Humans are an integral component of the Earth system as conceptualised by IGBP. João Morais recalls key milestones in IGBP’s engagement with the social sciences and offers some words of advice for Future Earth.
  • IGBP and Earth observation:
    a co-evolution

    The iconic images of Earth beamed back by the earliest spacecraft helped to galvanise interest in our planet’s environment. The subsequent evolution and development of satellites for Earth observation has been intricately linked with that of IGBP and other global-change research programmes, write Jack Kaye and Cat Downy .

Measuring pattern outcomes in an agent-based model of edge-effect externalities using spatial metrics

Agriculture, Ecosystems & Environment (2004)
Parker D C and Meretsky V (ed)
ISSN: 01678809
Doi: 10.1016/j.agee.2003.09.007
Vol 101; Issue 2-3; pp. 233-250

This paper presents an agent-based model of land use designed to explore the impacts of edge-effect externalities-distance-dependent spatial externalities-on land-use pattern. While the impacts of externalities on aspatial economics measures such as equilibrium land rents and the distribution of economic activity are well explored, links between externalities and landscape pattern are not well understood. This gap reflects a more general gap between aspatial theoretical land-use models and descriptive, pattern-based empirical analysis. The model presented in this paper, designed to link changes in socioeconomic parameters to changes in macroscale measures of landscape pattern, was developed with the specific goal of formally bridging this gap. The model simulates land-use decisions of parcel managers in an environment where potential conflicts between urban and agricultural land uses affect the payoffs to particular land uses. In the model, spatial and aspatial macroscale outcomes emerge from the independent, but dynamically linked, decisions of individual parcel managers. Land-use composition, land-use pattern, and the location of land uses are jointly determined, and interactions between composition and pattern feedback to microlevel landowner decisions through endogenous land rents. The paper demonstrates a series of results. First, the paper demonstrates the economic inefficiency of landscape fragmentation when edge-effect externalities are present and illustrates a series of landscape metrics appropriate to measure this fragmentation. Second, the agent-based model is used to demonstrate links between externality impacts and landscape pattern: that conflicts between urban and residential land users lead to a more compact urban form, that when the profitability of agricultural production is reduced by proximity to urban land, the urban-rural fringe expands to a socially inefficient degree, and that conflicts between urban land users can lead to fragmented patterns of urban development consistent with existing definitions of urban sprawl. Finally, the paper concludes by proposing a methodology for establishing the robustness of the model's conclusions over a wide range of parameter values.

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