次生常绿阔叶林的群落结构与物种组成:基于浙江乌岩岭9 ha森林动态样地

常绿阔叶林是我国亚热带地区的地带性植被, 但由于长期的人为干扰, 目前仅有少量分布且主要以次生常绿阔叶林的形式存在。因此, 了解次生常绿阔叶林的物种共存机制对于保护森林生物多样性非常重要。基于大型动态监测样地对森林的物种组成及群落结构进行研究, 是揭示生物多样性维持机制的重要手段。按照美国史密森研究院热带森林科学研究中心(Center for Tropical Forest Science, CTFS)大型森林动态样地建设标准, 于2011-2012年在浙江省乌岩岭国家级自然保护区内建立了1个9 ha森林动态监测样地。通过对样地内胸径≥ 1 cm木本植物的物种组成(如重要值)、群落结构(如区系组成和径级结构等)以及空间分布的分析发现: (1)样地有木本植物存活个体47科92属200种71,396株, 其中壳斗科、樟科、山茶科、冬青科、杜鹃花科和山矾科等占优势; (2)在区系组成上, 热带成分略多于温带成分; (3)群落径级结构接近倒“J”型, 表明群落更新良好, 其中优势种径级结构呈倒“J”型、偏常态型和波动型等各种形态, 且并未表现出种群衰退的趋势; (4)优势种表现出明显的生境偏好和聚集分布格局, 暗示生境异质性可能是影响亚热带次生常绿阔叶林物种空间分布的重要因素。

Community structure and species composition of the secondary evergreen broad-leaved forest: the analyses for a 9 ha forest dynamics plot in Wuyanling Nature Reserve,Zhejiang Province,East China

The zonal vegetation type of subtropical China is evergreen broad-leaved forest (EBLF). However, due to long term anthropogenic disturbance, primary EBLF is now scarce in this region; most of the EBLFs exist as secondary forests. Therefore, to preserve the regional forest biodiversity, it is important to understand the mechanisms underlying biodiversity maintenance of the regional secondary EBLF. One method for examining the mechanisms of forest biodiversity maintenance is to investigate the species composition and community structure on the basis of a large forest dynamics plot (FDP). According to protocols of Center for Tropical Forest Science (CTFS), we established a 9 ha FDP in the secondary EBLF of Wuyanling National Nature Reserve in Zhejiang Province, China, during 2011-2012. Here, we carried out analysis on species composition (e.g., importance value), community structure (e.g., floristic composition, size-class structure), and spatial distribution of woody plants with diameter at breast height (DBH) ≥1 cm. Results indicated that there were 71,396 woody plant individuals belonging to 200 species, 92 genera and 47 families within the FDP. The dominant families were Fagaceae, Lauraceae, Theaceae, Aquifoliaceae, Ericaceae and Symplocaceae. There were slightly more tropical elements than temperate elements found both at family and genus level. DBH size-classed community structure was reverse ‘J’ shaped, indicating abundant regeneration. Dominant species showed various shapes, such as reverse ‘J’, skewed or waved shapes, but no signs of population decline. Dominant species showed habitat priority and aggregated distribution patterns possibly related to habitat conditions, suggesting that habitat heterogeneity might be responsible to the spatial distribution of the dominant species in this FDP.