Crop tree release increased the density of soil nematodes and improved the food web structure

Abstract

As a special thinning method, crop tree release (CTR) has a beneficial effect on forest environments and structures by changing forest light, heat, and water. However, the impact of CTR on underground biodiversity remains unclear. Therefore, we analyzed the composition, diversity, and metabolic footprints of soil nematode communities under three CTR (100, 150, and 200 trees·ha–1) treatments, as well as a no CTR treatment, in Pinus massoniana Lamb. plantations. The results showed that CTR increased the density of soil nematodes (P < 0.05), the number of omnivore–predator nematodes (P < 0.05), and the diversity (H′) of nematodes (P < 0.05) and enriched the food web structure of soil nematodes. In the medium CTR density treatment (150 trees·ha–1), the nematode density and diversity (H′) were the highest (P < 0.05), the number of omnivore–predator nematodes was also the highest (P < 0.05), and the enrichment index and structure index values of the soil nematodes reached the maximum at the depth of 0–10 cm (P < 0.05). Our results indicated that the community structure of soil nematodes became more stable and mature after CTR, which may be attributed to the changes of soil condition, especially soil organic matter, and plant diversity indirectly.