The Intermediate Disturbance Hypothesis [IDH] and the Gradual Climate Change Hypothesis [GCC] offer intuitively appealing, verbal non-equilibrium explanations to species coexistence in competitive communities, but so far they lack a solid theoretical background and a proper experimental methodology. To make them testable and comparable on a solid methodological basis, they should be formulated as well-defined non- equilibrium community dynamical models.
Forest types of the Wapiti, Doon and Glaisnock catchments, ranked in order of proportion of preferred food species for deer, paralleled a gradient of landform stability. Seral forests and low altitude silver beech forests were preferred deer habitat because they contained the largest proportions of highly preferred species. They often occurred on unstable landforms such as debris cones, colluvial sideslopes, and terraces with recent and compound soils, assumed to be of high nutrient status.
Numerical and spatial components of dispersion, and the activity of pukeko (Porphyrio p. melanotus) in swamp and pasture in coastal Manawatu, New Zealand, are described. Pukeko are concentrated in few locations during the autumn population peak, but are widely scattered in spring when the population size is minimum. Flocks are consistently larger in pasture than swamp; those of up to ten birds are more frequent in swamp. And those of 25 or more birds more frequent in pasture. In pasture, pukeko distribution and density declines outwards from the edge nearest to water.