Responses of soil nematode communities to human trampling in Alpine forests

Alpine forests at high elevations are critical for sustaining ecosystem processes and delivering essential ecological services. However, human trampling represents a pervasive disturbance that can profoundly alter soil biodiversity and ecosystem functioning. In this study, we evaluated the effects of varying levels of human trampling on soil nematode communities in the Pir-Panjal mountain range. Soil samples were collected from the 0-15 cm layer across four trampling intensities: non-trampled control (C), low trampling (LT), moderate trampling (MT), and extreme trampling (ET). Total nematode abundance, as well as abundances of bacterivores, fungivores, herbivores, omnivores, and predators, were significantly reduced under extreme trampling compared to control, LT, and MT. Specifically, extreme trampling caused declines of 69.3% in total nematode abundance, 67.7% in bacterivores, 69.6% in fungivores, 78.0% in herbivores, 78.4% in omnivores, and 48.0% in predators relative to control conditions. At the generic level, diversity was significantly lower at LT sites compared to control and other trampled sites. Generic richness increased under MT, decreased under ET, and remained unchanged under LT compared to control. Similarly, the maturity index (MI) was significantly reduced in MT and ET relative to control and LT, reflecting shifts in community composition toward opportunistic taxa under higher trampling pressure. These findings demonstrate that human trampling induces marked alterations in nematode abundance, diversity, and functional indices, which are closely linked to changes in belowground abiotic conditions and trophic structure. These insights are critical for guiding alpine forest management, emphasizing the need for strategic trail planning, access regulation, and targeted restoration efforts in areas experiencing high human disturbance to maintain soil health and ecosystem resilience