Earthworm community structure and population dynamics at Minkong forest of Mokokchung, Nagaland, India

Abstract

Aim: The present study was undertaken to assess the seasonal variations of density, biomass and community characteristics of earthworms in two different types of forest at Minkong area, Mokokchung. Methodology: The survey was conducted during the period from January 2019-February 2020 in two areas viz., mixed forest and plantation. Standard methods were followed to determine the ecological categories of earthworms, density and biomass, relative abundance and species richness as well as for determination of different soil parameters viz., pH, moisture, bulk density, organic carbon, total and available nitrogen, available phosphorus and potassium. Results: 12 number earthworm species viz., Amynthas corticis (Kinberg), Amynthus gracilis (Kinberg), Drawida assamensis (Gates), Drawida hodgarti (Stephenson), Drawida nepalensis (Michaelsen), Drawida sp., Eutyphoeus assamensis (Stephenson), Eutyphoeus festivus (Gates) Metaphire houlleti (Perrier), Perionyx excavatus (Perrier), Perionyx simlaensis (Michaelsen) and Pontoscolex corethurus (Müller) were recorded. Dominant earthworm species in both the areas were D. nepalensis, P. excavatus, Drawida sp. and E. festivus. The Shannon diversity, Simpson diversity and Pielou’s species evenness were 2.17, 0.87 and 0.87 in mixed forest and 2.05, 0.86, 0.86 in plantation. The earthworm density and biomass were greater in plantation (276.74 ind m-2 and 338.47g m-2) compared to mixed forest (230.52 ind m-2 and 254.55 g m-2). Interpretation: As earthworm community characteristics differ depending on the type of forest, therefore, earthworm’ sdiversity and its indices can be used as an ecological indicator of anthropogenic disturbances and can help designing conservation programs for reclaiming the depleted areas. Key words: Biomass, Earthworm diversity, Minkong, Relative abundance, Subtropical ecosystem