Despland, E. 2003. Fractal index captures role of vegetation clumping in locust swarming. Functional Ecology 17:315-322
1.This paper evaluates box-counting dimension as a quantitative clumping index for discontinuous plant cover, and applies it to studies of both small- and large-scale ecological processes in desert locust ( Schistocerca gregaria) swarming.
2.The quadrat under study is tiled with squares of increasing size, and the relationship between the number of occupied squares and square size gives the box-counting dimension. This index is high for random distributions and decreases when the vegetation is clumped; it is also positively linked to the abundance of vegetation.
3. At the scale of individual locusts, this index captures the space-filling properties of vegetation that promote change to the gregarious phase and the onset of swarming. At the very large scale, box-counting dimension measured from satellite imagery reflects topography, which influences the concentration and migration of locust swarms.
4.Fractal geometry considers scale of measurement in quantifying pattern and provides a framework to interpret ecological phenomena across spatial scales. Demonstration of a statistically significant relationship between the box-counting exponent and locust behaviour shows how this approach can be applied to ecological studies.
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