IMPACT OF URBANIZATION ON ABUNDANCE OF SOIL ARTHROPODS

Arthropods have important role in maintaining the soil fertility. The major contribution of arthropods to soil is through decomposition and humification of all organic matter. Both micro and macro arthropods were collected using standard Tullgren extractions on fortnightly intervals from five different sites selected on the basis of habitat differences, identified up to the level of order and counted during rainy season. Soil temperature was noted on the field sites while analysis for soil pH, texture, and soil moisture contents were done in the laboratory. This study suggested that rapid urbanization of Kolkata has led to a drastic change in land use and destruction of natural ecosystems which was also observed in a site, Digha (adjacent to Ramnagar), Purba Midnapore, West Bengal where unplanned urbanization hampers local biodiversity. Uncontrolled and unplanned tourism of Digha deteriorate the biodiversity and population dynamics of soil arthropods mainly of order Mesostigmata, Collembola and Coleoptera. Egra (Habitat E), adjacent to Digha showed highest diversity (as obtained from the calculated diversity indices) in June-July (monsoon) as it was favorable and resourceful for their breeding, proper growth and survival. The soil’s physical condition was correlated with changes in soil moisture and soil pH which in turn correlated with soil fauna. To understand the comparative biodiversity richness between the study areas, Shannon diversity index was calculated. Increasing soil alkalinity and decreasing moisture levels lowered the Shannon diversity index and accelerated the biological degradation to some extent in case of Egra and Ramnagar area. This study revealed that the metro city, Kolkata, with high pollution threats, can nonetheless harbor a large number of Prostigmata. Increased precipitation in June and July, 2018 and 2019, acted favorable on these mite population. By understanding soil arthropod communities will prove useful in developing management plans for both rural and urban ecosystems.