Abstract
Increased frequency and intensity of anomalies in climate change ultimately affect soil health and are heightened in biodiverse areas of extreme gradients, thus effecting soil biodiversity in the Himalayas. The current study investigates diversity of soil nematodes, in free living (FLN) and plant parasitic groups (PPN) associated with Himalayan vegetation and shows their relationships with soil physicochemical parameters (pH, moisture content, nitrogen, soil organic matter and soil organic carbon) in this previously unsurveyed region. Samples were taken randomly from four sub sampling sites in 20 km2 average areas of ten districts using the Southy method. Nematode isolation was performed using the Cobb sieving and decantation method, and modified Bearmann’s funnel technique. Community indices of each site’s vegetation were calculated and subjected to statistical analysis—Principal Component analysis (PCA) and Multiblock Partial Least Squares (MBPLS). MBPLS analysis illustrated associations of organic-matter and nitrogen content with mixed-cropping and pH in soil with grassland, alpine-forests and shrubland; bacterivores were positively correlated with organic-matter and nitrogen content. Negative correlations (pH, moisture content, organic carbon) were seen in a minority of fungivore and PPN genera. Correspondance Analysis illustrated nematodal contributions in substrates and impacts of substrate origin on genera distribution. Ditylenchus, Aphelenchoides, Prodorylaimus, Laimydorus, Dorylaimellus, and Aphelenchus were related to grassland, shrub, herbaceous and tree soils. Rhabpanus, Diplogastritus, Leptolaimus, Teratorhabditus, Diploscapteroides were related to mixed-cropping, mono-cropping and garden-soils. Mixed cropping or organic practices of cultivation improve the nematode community structure and functional diversity. Moreover, altitude, soil nutrients, physicochemical factors and vegetation of the Himalayan region affect the diversity and abundance of soil nematode communities. These key areas assist our understanding of future challenges for agroecology, especially in megadiverse locations.