Spatial and Temporal Variation in Food Webs in Water-Filled Treeholes

Abstract

Food webs have been drawn for the community of animals found in water-filled treeholes in south-east Queensland, Australia. Such webs have been constructed on a quarterly basis for each of 11 habitat units, using a technique which allows incorporation of relative abundance as well as presence or absence of a species. A significant inverse relationship was identified between the degree of similarity shown in the webs from pairs of treeholes and the intersite distances involved. No significant relationships could be identified between any of the foodweb characteristics connectance, number of trophic levels, abundance indices or predators of saprophages and the surface area of the treeholes. There was a significant inverse relationship between the mean relative abundance of the predators and the saprophages, their prey. Explanations for the results are examined, and the interaction of stochastic events and shortand mid-term environmental heterogeneity, it is suggested, best account for the observations. Such 'local' webs, shaped by stochastic events are contrasted with full 'regional' webs for which plausible deterministic explanations are available.