Earthworm community structure and diversity in different land-use systems along an elevation gradient in the Western Himalaya, India

Abstract

The state Himachal Pradesh in Western Himalaya was explored to know the community structure of earthworms in agroecosystems along the elevation gradient ranges from 300 to 2500 m above sea level. The study aimed to determine the influence of climate, soil variables and the cropping pattern on species diversity and abundance. Therefore, a total of six land-use types including three crop land, and three orchards (Apple, Pear and Mango) were studied at low (300-500 m), middle (500–1500 m) and high (1500-2500 m) elevations. The results indicate that the earthworm community varies with the cropping intensity, with a greater species richness observed in the traditional cropping system including organic input vegetable field than in the cereal crop field having a high input of chemical fertilizers and using more up-to-date heavy and deep ploughing machines. The number of species significantly increased with the increasing elevation, reaching a peak at the middle but decreasing with the further elevation. The Metric-multidimensional scaling (MDS) analysis showed the highest similarity of 61% between sites of high elevation, 49% between the sites of low elevation, and 21% similarity between sites of middle and high elevations based on the density of earthworm. The Canonical correspondence analysis showed the significant positive (rainfall, soil moisture, and organic carbon) and negative (pH) relationship with earthworm density. It supports the role of physicochemical parameters in determining the earthworm community along the elevations. Except mango orchard, all sites were predominated by exotic peregrine earthworm species, which is a matter of concern for invasion and impact on the native species. While it is true that anthropogenically influenced ecosystems are more prone to invasion by alien species, further research is required in the adjacent forests to compare the impact of land-use changes on earthworm communities.