Nematodes are the most diverse and highly significant group of soil-inhabiting microorganisms that play a vital role in organic material decomposition and nutrient recycling. Diverse geographical locations and environmental gradients show a significant impact on the diversity of nematodes. Present study aims to assess the effects of ecological (altitude, temperature, moisture) and edaphic (soil pH, nutrients, soil patches) factors on the soil nematode diversity and structure at five different landscape patches (forests, apple orchards, rice fields, pastures, and alpine zone) from ten different sites of Kashmir valley (India). Differences in the altitudinal gradients results in the shift of generic nematode population. Among the soil patches, highest nematode diversity was observed in forest soil and least in alpine soil; however, bacteriovorous nematodes dominated all the soil patches. The temperature and moisture have a significant effect on nematode diversity, the highest nematode trophic levels were observed above 21°C temperature, and 30% moisture. Nematode abundance decreased from alkaline to acidic pH of the soil. Soil nutrients such as, nitrogen (N) and phosphorus (P) have shown a detrimental effect in nematode richness at each site, where nematode diversity and richness of genera were higher at abundant soil N and P but decreased at low soil nutrients. Ecological indices like diversity index (DI), Shannon-Wiener Index (H'), enrichment index (EI), and maturity Index (MI) values demonstrated forest soil more favourable for nematodes and high soil health status than other soil patches. This study suggested that these indices may be helpful as soil monitoring tools and assessing ecosystem sustainability and biodiversity.

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Soil nematodes contribute to nutrient cycling. This year-long study aimed to investigate the changes in the diversity of soil nematodes during the spring, summer, and winter seasons in rice fields at 24 sites and to determine the indicator nematode genera that inhibit the roots of rice plants. A total of 216 soil samples were collected during three seasons, and the collection of 72 root samples was carried out during rice cropping. Forty-four soil nematode genera were identified. They exhibited significant changers in their abundance, which were dependent on the seasons and on soil characteristics. In particular, the abundance of plant-parasitic nematodes (PPNs) and free-living soil nematodes was 49% and 15% higher during the summer than during the spring and winter seasons, respectively. Soil characteristics, such as soil nitrogen (N) contents, carbon (C) contents, and soil moisture were significantly higher during the summer than in the spring and winter seasons, but soil pH was significantly lower during the summer than in the spring and winter seasons. Moreover, Hirschmanniella, Meloidogyne, and Heterodera emerged as good indicators for rice root inhibition, corroborating the frequency, density, and prominence value of PPNs of the sampled soil and rice roots. This study also indicated that free-living nematode genera, such as Rhabdolaimus, Diplogaster, and Rhabditis, might function as ecological indicators for soil health.

Nematodes are critical for soil processes, and changes in nematode community structure have the potential to have a significant impact on ecosystem functioning. As a result, fluctuations in nematode diversity and community structure can be used to ascertain the functional biodiversity of a soil. The aim of the present study was to evaluate the effect of different vegetation and soil pH and N on nematode structure and diversity from ten different sites (Jammu, Kathua, Samba, Udhampur, Reasi, Ramban, Rajouri, Poonch, Doda, Kishtwar) of the Jammu division. The highest absolute frequency of plant parasitic nematodes (91-100%) was observed in subtropical forests in Ramban, temperate forests in Doda, while the highest absolute frequency of bacterivorous nematodes (84-87%) was observed in crop soil in Reasi and Jammu. Soil pH had a detrimental effect on nematodes; bacteriovores were abundant at low pH, and plant parasitic at higher pH. The total nitrogen content also increased in all nematode trophic groups except omnivores. Ecological indices such as the enrichment index (EI), channel index (CI) and maturity index (MI) values indicated that crop soil with organic management is more nematode-friendly and has a better soil health status than other soil ecosystems. Nematode community structure indices may be helpful as soil monitoring tools and for assessing ecosystem sustainability and biodiversity.