Objective This study aims to investigate the long-term effects of different intensities (low, medium, and high) of thinning on the species richness, diversity, and community structure of understory vegetation in artificial forests of Pinus taiwanensis plantations in the Dabieshan Mountain of central China through long-term fixed-point observations.
Method This study selected long-term thinning experimental plots of Pinus taiwanensis plantations in the Dabieshan Mountain. Understory plant diversity index and different main soil physicochemical properties were measured after 17 years of thinning intensities of 0 (control), 10%, 20% and 30%, and the indexes of different soil physicochemical properties were determined. The long-term effects of varied thinning intensities on understory plant diversity were analyzed.
Result (1) As thinning intensity increased, soil available phosphorus content gradually decreased, with the rate of decline accelerating progressively. (2) The Margalef richness index, Pielou evenness index, Simpson diversity index and Shannon-Wiener diversity index increased first and then decreased with the increase of thinning intensity. (3) Correlation analysis revealed that surface soil (0–10 cm) organic carbon content was significantly positively correlated with the Pielou evenness index of understory plants.
Conclusion Understory plants play a key role in soil and water conservation, microclimate regulation, and the maintenance of biodiversity. This study finds that the diversity of understory plants in Pinus taiwanensis plantations first increases and then decreases with increasing thinning intensity. Among them, 10%–20% thinning intensity can sustainably enhance understory plant diversity. This finding provides data support and scientific evidence for a better understanding of long-term ecological benefits of thinning in plantations.
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