Community structure and habitat specific variations of soil-inhabiting nematodes in the forests of Gangotri National park, Uttarakhand, India

Studies conducted on soil-inhabiting nematode community structure in the forests of Gangotri valley in Gangotri National Park (GNP), Uttarakhand, yielded 57 genera belonging to eight orders. In terms of abundance of nematodes, Dorylaimida (30%) represented the most abundant order followed by Araeolaimida (21%), Rhabditida (17%), Tylenchida (13%), Monhysterida (11%), Aphelenchida (5%), Enoplida (2%), and Mononchida(1%).The trophic diversity exhibited the relative abundance of bacterivores (43%), which was the highest, followed by predators (21%), plant parasites (16%), fungivores (11%), and omnivores (9%). Aporcelaimus and Discolaimus were the most dominant genera among predatory nematodes, followed by bacterivorous nematodes Plectus and Wilsonema. Bacteriovorus nematodes were significantly positively related to Nitrogen (P=0.017), whereas total nematode diversity positively correlated with soil organic carbon, nitrogen and soil moisture content (p<0.5). Multivariate analysis showed that the areas with higher nitrogen, organic carbon and soil moisture had higher faunal diversity of bacterial and fungal feeders. Low channel Index (0.52±0.08) showed the bacterial decomposition pathway in the region. High nematode diversity (2.80± 0.09), Structure Index (74.88±3.02), and Maturity Index (2.6±0.08) indicated that the soil of GNP was less disturbed, structured, and mature. The results provided preliminary data on the ecological aspects of soil-inhabiting nematodes which can be used to assess soil health status in the high-altitude forests of GNP. The baseline data on nematode community structure in the region can also be utilized as a tool to understand and compare the soil health status in long term biomonitoring studies in the Indian Himalayan Region.