A Hierarchical Analysis of Species' Abundance Patterns in Grassland Vegetation

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Abstract
The core-satellite hypothesis was proposed to explain regional patterns of species distribution. At the regional level, grassland data from sites in Oklahoma [USA] and Kansas conform to the general predictions of the core-satellite hypothesis. The patterns found on the scale of a local assemblage of species (m2), however, were similar to those of the regional-level distributions (km2). Factors affecting these distribution are competition and dispersal, which operate most commonly on small spatial scales, as well as disturbance, which is often a large-scale phenomenon in grasslands. Thus, grassland community structure exhibits self-similarity, in that the large-scale pattern is composed of numerous small-scale units of similar structure. We therefore concluded that grassland communities essentially exhibit small-scale patterns that are transposable to larger-scale patterns and vice versa. However, the patterns of distribution and abundance are dramatically affected by disturbance, and changes in these patterns are most obvious on an intermediate (community-level) scale of analysis.