喀斯特常绿落叶阔叶混交林木本植物组成特征

Species composition of woody plants in evergreen-deciduous broad-leaved karst forests, Southwest China

关键词:  物种组成, 径级结构, 动态监测样地, 常绿落叶阔叶混交林, 喀斯特

Key words:  species composition, size class structure, dynamic plot, evergreen and deciduous broad-leaved mixed forest, karst

摘要:

喀斯特常绿落叶阔叶混交林是我国西南喀斯特地区分布的典型森林植被类型之一,由于富钙偏碱的地球化学背景及多样性的生境类型,该森林具有群落结构多样、树种组成丰富、优势物种突出等特点,基于大型动态监测样地的群落特征分析是揭示其生物多样性维持机制的基础。该研究在木论国家自然保护区建立了25 hm²的样地,依照CTFS全球森林生物多样性监测规范,定位并调查了样地内每一棵胸径≥1 cm的木本植物。结果表明:(1)样地内有监测树种254种,隶属于64科161属; 独立个体总数为110 370株(含分枝为144 679株),平均胸径为4.14 cm。(2)个体数最多的15个树种的个体数之和占到总个体数的78.46%,稀有种有100种,占总树种数的39.37%。(3)群落结构稳定且更新良好,木本植物整体径级结构呈倒“J”形。(4)样地内重要值≥1的树种有26种,占总树种数量10.24%; 重要值排名前三的物种分别是小果厚壳桂、栀子皮和香叶树。(5)样地中共有萌生木本植物204 种34 309 株,分属于127属51科,分别占样地总物种、个体数量、属及科数的80.32%、14.42%、78.88% 和79.69%。此结果表明木论喀斯特常绿落叶阔叶混交林物种组成丰富、群落成熟稳定、更新良好,反映了亚热带非地带性喀斯特顶极群落常绿落叶阔叶混交林的典型特征。

Abstract:

Evergreen and deciduous broad-leaved mixed karst forest(EDBLKF for short), locating in the southwestern region of subtropical limestone karst region, China, is one of the most unique types of karst forests in the world. The limestone karst forests in this region display different characteristics such as various community structures, high species richness, abundant endemic biological species, etc. owing to the special limestone soils of abundant Ca and higher pH value, the various heterogeneous habitats. The permanent plot-based approach to community analysis is fundamentally important for revealing mechanisms of biodiversity maintenance. In this study, community structure and species composition were investigated and analyzed using a 25 hm² permanent plot in Mulun National Nature Reserve, Guangxi Zhuang Autonomous Region. Based on the standard field protocol of the Center for Tropical Forest Sciences(CTFS), all free-standing individuals with DBH(diameter at breast height)≥1 cm were tagged, mapped and identified to species in this plot. The results were as follows:(1)A total of 110 370 individual trees(144 679 individuals with branches), belonging to 254 species,161 genera and 64 families were recorded in the plot.(2)The top 15 species with most individuals accounted for 78.46% of the total individuals in the plot. One hundred species were considered to be rare species representing by no more than one tree per hectare, they accounted for 39.37% of the total species.(3)The DBH size-class structure of all species in the plot exhibited a reverse J-shaped pattern, indicating good regeneration across the community.(4)There were 26 species with important value ≥1, which accounted for 10.24% of the total individuals in the plot. The three most dominant species were Cryptocarya microcarpa, Itoa orientalis and Lindera communis.(5)There were total 34 309 woody plants of 204 sprouting species, belonging to 127 genera and 51 families in the plot, accounting for 80.32%, 14.42%, 78.88% and 79.69% of the total number of individuals, species, genera and families, respectively. In conclusion, with rich species composition and a mature community structure, the EDBLKF in Mulun region is typical characteristic of this vegetation type.