Density, Biomass and Species Richness of Earthworms in Agroecosystems of Garhwal Himalaya, India

Abstract

Earthworm population dynamics were studied at Narayankoti (29o30’3” N and 79o77’02” E) in Garhwal region of western central Himalaya, to evaluate the impact of ecosystem type, quality of organic inputs and land management practices on earthworm population. Earthworm populations were studied in the three agroecosystem types viz: agroforestry, intensive and traditional agroecosystems, under different cropping patterns at monthly intervals over a period of two years. A total of eight species belonging to five families was found in the agroecosystems: Moniligastridae (Drawida nepalensis), Octochaetidae (Lennogaster pusillus), Ocnerodrilidae (Thatonia exilis and Ocnerodrilus occidentalis), Acanthodrilidae (Plutellus sadhupulensis and Plutellus sp.) and Megascolecidae (Metaphire houlleti and Perionyx excavatus). Drawida nepalensis had the widest distribution while O. occidentalis was found exclusively in agroforestry. Plutellus sadhupulensis was absent under agroforestry but was common to intensive and traditional agroecosystems. Perionyx excavatus was confined to Intensive only whereas, Plutellus sp., T. exilis, L. pusillus and M. houlleti were the species found only in traditional agroecosystems. Density of earthworms and number of species was higher under traditional agroecosystems, may be due to higher moisture content, absence of chemical fertilizer and low perturbations. Biomass of earthworms was significantly higher in intensive and lowest in traditional agroecosystems. Density of earthworm species was higher during summer crops compared to winter crops. This difference may be related to higher moisture, temperature and organic matter content during summer. Earthworm density showed positive correlation with moisture, temperature and organic matter. Earthworm densities were found very low during the fallow phase in all agroecosystems which could be due to absence of plant cover and reduced soil moisture.