Changes in mite richness and diversity along a gradient of land-use intensity from mid-west Ivory Coast

The conversion of natural forest to agricultural land, and different management practices contribute extremely to soil physico-chemical and biological degradation. One of the key factors influencing this alteration is land use intensity. The objective of this study was to evaluate the changes in soil mite abundance, richness and diversity orchestrated by land use intensification. Eight agroecosystem with an increased land use intensity index were selected: Primary forest - Secondary forest - Multi-species planted trees - 10-year old teak plantations 4-year old teak plantations - Cocoa plantations - Recurrent fallows - Mixed crops fields. On each land use type 5 grills point were sampled. The results showed that soil mite density decreased significantly (P < 0.05) from Primary forest to Mixed crops field, showing that mite abundance was hugely influenced by the degree of agroecosystem stability. The average number of species per sampling point varied significantly (P = 0.0013) from Primary forest (9.6 +/- 0.8) to Mixed crops fields (1.4 +/- 0.5). The same pattern was observed with the Shannon index, which was ranked between Primary forest (2.92 +/- 0.21) and Mixed crops fields (0.45 +/- 0.28). Cumulative alpha diversity varied from 5 species in Mixed crops fields to 22 species in Primary forest. The beta diversity (turnover or dissimilarity) were generally high and varied from 42.3% (Primary forest and Secondary forest) to 82.3% (Multi-species planted trees and Mixed crops fields). The results demonstrated that higher was the land use intensity index, the lower were the mite abundance, diversity and species richness. Interactions between mite abundance and diversity and trophic resource characteristics, shade and soil organic carbon is discussed.