Body size structure of oribatid mite communities in different microhabitats

Abstract

ABSTRACTSize scaling phenomena occur on different levels, from organisms to ecosystems. In predictive ecology, empirical data on body size relation have been used for decades to explain large-scale temporal and spatial patterns. More recently, community ecologists have started to use abundance-weighted mean body sizes as a tool to predict changes in species assemblages along gradients in above-ground systems. In soil and litter systems, however, body size of individuals or the body size structure of communities have rarely been addressed in this way. Here we use community data of oribatid mites from different forest ground microhabitats (dead wood, moss, and litter) in combination with body size measurements to describe some basic body-size relationships for decomposer mites. Generally, we found that the community body size (measured as an abundance-weighted mean of all species) as well as size distribution of sexual and parthenogenetic oribatids differed across microhabitats. Furthermore, our results showed that the abundance of oribatid mites in fragmented (moss), but not in continuous (dead wood, litter) microhabitats, can be predicted by the community body size. All these differences might be explained by specific microhabitat conditions like pore size and food resource quality, but also by the dominance and competitive or facultative interactions among certain species in a particular sample or habitat. Additionally, our results bring renewed attention to body size as an important predictor for patterns, structure, and energy translocation in terrestrial forest soil food webs.