EFFECTS OF FIRE INTENSITY ON SOIL NEMATODE COMMUNITIES OF THE Pinus Densata FOREST IN SOUTHEASTERN TIBET

To understand the effect of fire intensity on soil nematode communities in subalpine forest of southeastern Tibet, we collected soils from 0-10 cm of forest plots with different fire intensities for 3 months after fire in the Pinus densata forest of Biri National Forest Park, Nyingchi, Tibet, and adopted high-throughput sequencing techniques to analyze the characteristics of soil nematode communities in control, low, moderate and severe burned forest plots. The results showed that the soil dissolved organic carbon content decreased and the available phosphorus content increased with increasing fire intensity. Fire reduced the Shannon index and species richness index of soil nematodes and shifted the soil organic matter decomposition pathway from bacterial to fungal. The increased intensity of fire altered the soil nematode community structure, but all were dominated by bacterivorous nematodes. Dissolved organic carbon and available phosphorus content were significantly correlated with soil nematode community diversity and structure. This study revealed that during the 3-month recovery from fire in the Pinus densata forest in southeastern Tibet, the reduction in soil dissolved organic carbon due to increased fire intensity was a key factor in stalling post-fire soil microbial growth and shifting organic matter decomposition pathways, thereby limiting the food resources available to soil nematodes and altering soil nematode community diversity and structure.