广西弄岗自然保护区中国无忧花群落木质藤本的多样性及其空间分布格局

Diversity and spatial distribution pattern of woody lianas in Saraca dives community in Nonggang Nature Reserve,Guangxi

木质藤本植物是热带森林生物多样性的重要组成部分,但在生物多样性丰富的北热带喀斯特森林中,木质藤本的多样性及其空间分布格局鲜为人知。本研究以广西弄岗自然保护区北热带喀斯特季节性雨林的典型群落类型——中国无忧花(Saraca dives)群落为对象,基于100个10 m×10 m样方的调查数据,分析群落中木质藤本的多样性及其空间分布格局,以揭示木质藤本的多样性分布以及不同类群间空间分布格局的差异。结果表明:(1)在1 hm2中国无忧花群落中,共有木质藤本52种,分属25科43属,占木本植物种类数的55.32%;木质藤本的Simpson指数为0.909,Shannon指数为2.842,Pielou均匀度指数为0.723,总体多样性较高;群落中优势种和特有种较为明显,物种丰富度和多度最高的科分别是豆科(Fabaceae)和葡萄科(Vitaceae),扁担藤(Tetrastigma planicaule)为重要值排名第一的优势种,特有性物种占总物种数的34.61%。(2)木质藤本在0~25 m空间尺度呈聚集分布,通过泊松异质性零模型剔除生境异质性后,发现随着空间尺度增大,木质藤本趋于随机分布;就木质藤本种类而言,剔除生境异质性后,70%以上木质藤本种类在一定尺度上表现出不同程度的随机分布,但仍在小尺度上呈现聚集分布,说明生境异质性和扩散限制均可能影响木质藤本的空间分布格局;木质藤本的聚集度与多度、平均胸径和最大胸径呈负相关,攀援效率为2(茎缠绕)的木质藤本聚集度较高。在中国无忧花群落中,木质藤本多样性非常丰富,为群落的重要组成成分;木质藤本的空间分布格局可能与生境异质性有关外,木质藤本自身的属性特征如攀援效率和方式也在一定程度影响木质藤本的分布格局。本研究为区域典型森林群落物种多样性维持机制以及木质藤本对森林碳储量和森林动态过程的影响研究提供重要基础。

Lianas constitute a crucial component of biodiversity in tropical forests,yet the extent of their diversity and spatial distribution patterns in the north tropical karst forest remains poorly understood.In this study,we investigated the diversity and spatial distribution patterns of lianas within a typical Saraca dives community in the northern tropical karst seasonal rainforest of Nonggang,Guangxi.We elucidated the diversity distribution patterns of lianas and explored the disparities in spatial distribution patterns among distinct taxonomic groups based on 100 quadrats,each measuring 10 m×10 m in a 1 hm^(2) plot.We found that:(1)In the 1 hm^(2) Saraca dives community,52 species of woody lianas were identified,belonging to 25 families and 43 genera.They represented 55.32%of the total woody species.Furthermore,the Simpson index for lianas was 0.909,the Shannon index was 2.842,and the Pielou evenness index was 0.723.These indices collectively indicate a relatively high level of diversity within the community.There was clear presence of dominant and endemic species.Fabaceae and Vitaceae families stood out for their remarkable species richness and abundance,respectively.Tetrastigma planicaule was the dominant species,with the highest importance value.Furthermore,endemic species constituted 34.61%of the total species number.(2)Lianas demonstrated an aggregated distribution within the spatial scale ranging from 0 to 25 m.Upon removing habitat heterogeneity via the heterogeneous Poisson null model,lianas tended towards a random distribution pattern as the spatial scale increased.When habitat heterogeneity was eliminated,over 70%of liana species exhibited varying patterns of random distribution across specific spatial scales.However,at finer scales,these species still exhibited aggregated distributions.These findings suggest that both habitat heterogeneity and dispersal limitations may influence the spatial distribution patterns of lianas.The observations suggest that both habitat heterogeneity and dispersal limitations may influence the spatial patterns of lianas.Furthermore,there was a negative correlation between the aggregation of lianas and their abundance,as well as their average and maximum diameters at breast height.Notably,lianas with a climbing efficiency of 2(stem twining)exhibited a higher degree of aggregation.The community of Saraca dives exhibited remarkable diversity in lianas,served as a crucial component of the community.Additionally,the spatial distribution pattern of lianas was not solely related to habitat heterogeneity,but was also influenced,to some extent,by intrinsic attributes such as climbing efficiency and mode.This study lays a crucial foundation for examining the maintenance mechanisms of species diversity in typical forest communities,as well as assessing the impact of lianas on forest carbon storage and dynamic processes.