Effect of Ecological Thinning on Niche and Interspecific Association Characteristics of Dominant Species in Degraded Broad-leaved Forest Plant Communities

Ecological thinning, as a nature-based forest management measure, plays an important role in the restoration of degraded forests. In this study, a typical degraded broad-leaved forest in Qingyuan County, Zhejiang Province, was selected as the research object, and both a thinning plot and a control plot were established to systematically compare the differences in species composition, niche characteristics and interspecific associations. The results showed that species composition changed significantly after thinning with niche breadth narrowing for some species （e.g., Manglietia yuyuanensis, Ilex chinensis）, while both the niche breadth and importance value of species such as Castanopsis fordii increased significantly. Thinning reduced niche overlap among most species pairs, alleviated interspecific competition, and promoted niche differentiation. Meanwhile, the intensity of interspecific associations weakened considerably, and the community structure shifted from closely connected state to loosely associated one. This study reveals the mechanism that the ecological thinning affects community assembly through altering resource allocation and interspecific relationships. It is recommended that a low-intensity and multi-stage thinning approaches be adopted to facilitate the ecological restoration and biodiversity conservation in degraded broad-leaved forests.