Abstract: In this study, we compared the community structure and species biodiversity in three 28-year-old plantations, i.e., monoculture Pinus massoniana (PPS), monoculture Castanopsis hystrix (PCS), and mixed C. hystrix and P. massoniana (MCP) stands at Fubo Forest Station located in Pingxiang County, Guangxi, to provide a strategy of nature-based forest management in the southern subtropical China. The results showed that the canopy in PPS was able to be classified into two layers (layer I at the height of 13-24 m dominated by P. massoniana, and Layer II at the height of 2-9 m with C. hystrix as the dominant species). The canopy in PCS also could be divided into two layers (Layer I at 12-17 m dominated by C. hystrix, and layer Ⅱ dominated by C. hystrix at the height of 2-8 m). MCP had the three layers of canopy (Layer I at the height of 20-25 m with C. hystrix as dominant trees, layer II dominated by P. massoniana at the height of 13-20 m, and layer III occupied by C. hystrix at the height of 4-7 m). The number of species (DBH ≥1cm) in different plantation stands was ordered as PPS (11 species)>MCP (7 species)>PCS (4 species), stem number (DBH ≥1 cm) was ranked as PPS (1 949 stem ·hm^-2)>PCS (825 stem ·hm^-2)>MCP (383 stem ·hm^-2), basal area was presented as PPS (30.05 m² ·hm^-2)>MCP(17.48 m² ·hm^-2)>PCS(12.35 m² ·hm^-2), and average DBH was MCP (21.7 cm)>PCS (9.9 cm)>PPS (9.7 cm). In terms of shrub layers in three plantation stands, the diversity index of Shannon-Wiener index, Simpson index and Pielou index in MCP was significantly lower than those in PCS and PPS (P<0.05). The diversity index of herbaceous plants in PCS was relative lower without significant difference among the three plantation stands (P>0.05). These findings suggest that based-nature forest management with target diameter stands can be a good silvicultural alternative to large-scale plantations in the southern subtropical China. For monoculture P. massoniana stand, the uneven-aged and mixed coniferous-broadleaved stands with dominant by broadleaved trees would be established after changing community structure, promoting natural regeneration and replanting broadleaved species in the understory vegetation. For monoculture C. hystrix stand, the uneven-aged and mixed broadleaved-broadleaved stands would be developed after optimizing community structure and replanting broadleaved species in the understory vegetation. For mixed C. hystrix and P. massoniana stand, the uneven-aged and mixed coniferous-broadleaved stands would be established after logging some disturbed individuals, promoting natural regeneration of P. massoniana and C. hystrix based on target diameter stands management system.

Key words: Pinus massoniana, Castanopsis hystrix, plantation, community structure, species diversity, nature-based forest management