南亚热带马尾松红椎人工林群落结构、物种多样性及基于自然的森林经营

Community Structure, Species Diversity of Pinus massoniana and Castanopsis hystrix Plantation and the Nature-Based Forest Management in the Southern Subtropical China

研究广西凭祥伏波林场28年生马尾松纯林、红椎纯林及红椎×马尾松混交林的群落结构与物种多样性,根据培育人工大径材和满足生态服务功能的发展目标,提出基于自然的森林经营方向。结果表明:马尾松纯林可划分为2层(Ⅰ层13～24m优势种为马尾松,Ⅱ层2～9m优势种为红椎),红椎纯林可划分为2层(Ⅰ层:12～17m,优势种为红椎;Ⅱ层:2～8m,优势种也为红椎),红椎×马尾松混交林可划分为3层(Ⅰ层:20～25m,优势种为红椎;Ⅱ层:13～20m,优势种为马尾松;Ⅲ层:4～7m,优势种为红椎);胸径大于1cm的乔木物种数表现为马尾松纯林(11种)>红椎×马尾松混交林(7种)>红椎纯林(4种);胸径大于1cm的林木株数表现为马尾松纯林(1949株·hm-2)>红椎纯林(825株·hm-2)>红椎×马尾松混交林(383株·hm-2);胸高断面积表现为马尾松纯林(30.05m2·hm-2)>红椎×马尾松混交林(17.48m2·hm-2)>红椎纯林(12.35m2·hm-2);平均胸径表现为红椎×马尾松混交林(21.7cm)>红椎纯林(9.9cm)>马尾松纯林(9.7cm);除丰富度指数外,红椎×马尾松混交林灌木层的Shannon-Wiener指数、Simpson指数和Pielou指数均显著低于2种纯林(P<0.05);红椎纯林草本层多样性指数最低,但3种林分之间差异不显著(P>0.05)。对于该地区的马尾松纯林,通过林分结构调整,充分依靠林下天然更新,适当补植阔叶树种,最终形成以阔叶树为主的异龄、复层针阔混交林;对于红椎纯林,根据目标树经营体系,通过林分结构调整,补植部分阔叶树种,最终形成异龄、复层阔阔混交林;对于红椎×马尾松混交林,根据目标树经营要求对妨碍目标树生长的林木进行砍伐,促进林下马尾松和红椎更新,最终形成异龄、复层针阔混交林。

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 （P0.05）. The diversity index of herbaceous plants in PCS was relative lower without significant difference among the three plantation stands （P0.05）. 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.