Litter complexity and composition are determinants of the diversity and species composition of oribatid mites (Acari: Oribatida) in litterbags

To investigate the relationship between litter complexity and composition and the diversity and composition of the oribatid mite fauna inhabiting it, an experiment was carried out at a single forested site in the mountains of North Carolina, USA. Natural litterfall was excluded from a series of 1 m(2) plots and replaced with treatment litters that varied in composition and complexity. Plots of pure birch, maple and oak Litter comprised the simple litter treatments. Two complex litters were made of a mixture of these three litter species and a mixture of seven litter species. Treatment litters were applied to the plots in the autumn of 1993 and again in 1994, The oribatid mites extracted from litterbags of the treatment litters from both years are reported on here. Mixed litters had a significantly greater variety of microhabitats, as defined by substrate type and fungal growth form, than did the simple Litters. Likewise, the oribatid mite species richness in litterbags of mixed litter was significantly higher than that in the simple litters. The fauna within replicates of each litter-type were more similar to each other than to those of other treatments. A third of the mite species tested showed a differential response among the simple Litter-types. These results indicate a link between heterogeneity and diversity of mites active in a particular horizon of Litter and some influence of litter-type upon species composition. Such patterns in habitat use by adult mites are strong, though not conclusive evidence of the ultimate role of heterogeneity in maintaining the diversity of oribatid mites. (C) 1998 Elsevier Science B.V.