Impact of landscape modification on Earthworm diversity and abundance in the Hariyali sacred landscape, Garhwal Himalaya

Abstract

This study in the Hariyali sacred landscape (Garhwal Himalaya, India) was undertaken to evaluate the impact of ecosystem type, quality of organic inputs and water management on diversity and abundance of earthworms. A total of seven species viz., moniligastrid Drawida nepalensis (Michaelsen), lumbricid Allolobophora parva (Eisen), megascolecid Eutyphoeus sp. (near Eutyphoeus pharpingianus), octochaetid Octochaetona beatrix (Beddard), megascolecid Periyonx sp., octochaetid Lennogaster pusillus (Stephenson) and megascolecid Amynthas corticis (Baird), belonging to four families were found in the landscape. D. nepalensis had the widest distribution. Eutyphoeus sp., A. parva and Periyonx sp. were found only in forest ecosystems and L. pusillus and A. corticis only in agroecosystems. Total density of earthworms was highest under pine forest and species richness was greatest under the broad-leaved forest. Density and biomass of D. nepalensis and L. pusillus varied significantly between different years of cropping under rainfed agriculture receiving oak based or pine based organic inputs. Forest ecosystems had a mixed population of endemic and exotic species, whereas in agroecosystems endemics dominated. Epigeic species were the dominant functional group under broad-leaved forest and pine - broad-leaved mixed forests, whilst endogeic species were dominant under the pine forest. Irrigated agroecosystems receiving oak-based as well as pine-based organic inputs supported only endogeics, whereas both endogeic and epi-anecic species were observed in rainfed agroecosystems. This suggests that distribution of functional groups is determined by land use practices. Eutyphoeus sp. was the only species that showed a significant positive correlation with moisture and a negative correlation with pH and organic carbon. D. nepalensis and A. parva occurred under forest ecosystems and showed a significant positive correlation with lignin and C/N ratio, and a negative correlation with litter polyphenol concentration. Soil parameters and FYM-characteristics did not show any significant correlation with species occurring under agroecosystems. D. nepalensis, which is an endogeic but with a wide ecological amplitude, and the epigeic A. parva, present in large numbers in pine forest, are the two species which could be promoted for inoculation into litter-FYM based organic residue management pits.