Fire-driven dynamic mosaics in the Great Victoria Desert, Australia - II.A spatial and temporal landscape model

摘要

An explicitly spatial, large scale, high resolution model of fire driven landscape dynamics in the Great Victoria Desert is constructed and parameterized to simulate frequency distributions of fire size and shape obtained from previous analyses of satellite chronosequences. We conclude that probabilities of fire spread cannot be constant over time, and that realistic distributions of fire size and plausible rates of fire spread can be obtained by assuming that fire spread is conditional on observed durations of windy conditions. Landscapes subject to this form of disturbance show large scale correlation structure many times greater than the average dimensions of single fires, and exhibit low frequency quasi-periodic stochastically driven oscillations in proportions of the landscape at different successional states over spatial scales exceeding 100,000 km(2). Average fire return intervals are similar to 30 yrs. Analysis of patch structure suggests that this landscape is composed of few large younger patches, embedded in a mature sea of surrounding habitat. Intermediate and late successional habitat must exist in more abundant patches somewhat smaller than young habitat. Numerous small patches of mature habitat are likely to be scattered throughout this younger habitat. The model predicts that fire size frequency distributions are relatively insensitive to changes of as much as +/- 50% of observed fire ignition frequency.