On the evaluation of spatial diversity of soil microarthropod communities

The research work was done in a cultivated land, a rice field, and a non-cultivated one, a waste land, near Agartala, Tripura, India. The soil microarthropods sampled were grouped into four categories: oribatid mites, other mites, Collembola and other insects. The temporal evolution of the cenotic (spatial) diversity of these taxonomic groups in the two sites is studied in comparison with their spatial distribution patterns. An overall (ecological) diversity was estimated from five parameters: group abundance, system group richness, group spatial distribution (in number of samples), system group diversity, and system cenotic diversity. The degree of change of their ecological diversity was estimated by a new ecological index. This index seems to be a useful tool to measure the intensity of the disturbing human impact on biological communities and systems.