Temporal and spatial variations of soil nematode assemblages across distinct forest ecosystems

The bottom-up effects of vegetation are widely recognized as important factors influencing the structure and functioning of soil food webs in forests. However, the influence of forest type on the composition and stability of soil nematode communities remains underexplored. In this study, we investigated the abundance, composition, diversity, and various aspects of soil nematode communities across three distinct forest types - Sub-tropical Pine Forests (STPF), Himalayan Moist Temperate Forests (HMTF), and Himalayan Dry Temperate Forests (HDTF) - during two seasons (summer and autumn). In both summer and autumn, total nematode abundance and the abundance of bacterivores were significantly higher in STPF compared to the other two forest types. Taxonomic diversity, as indicated by the Simpson index, was also greater in STPF during both seasons. The higher maturity index and sigma maturity index values observed in STPF suggest a more stable nematode community in the summer season. The soil nematode faunal profile indicated an enriched and structured food web in STPF across both seasons. Additionally, the metabolic footprint of the entire nematode community was considerably higher in STPF during the summer. Overall, soil nematode communities were most stable in STPF and least stable in HDTF. Our findings suggest that the Sub-tropical Pine Forests in the Pir-Panjal mountain range, across two contrasting seasons, support a higher level of soil food web structure and more complex soil biological communities than the other forest types. This study provides a foundation for understanding soil food web structure, function, and seasonal stability, which has important implications for sustainable forest management.