广西大石围天坑群天坑森林主要木本植物种间关联性研究

Interspecific association of main woody plants in tiankeng forests of Dashiwei Tiankeng Group, Guangxi

关键词:  天坑森林, 种间关联性, 主要木本植物, 生态种组, 圈层分布, 大石围天坑群

Key words:  tiankeng forest, interspecific association, main woody plants, ecological species group, circle distribution, Dashiwei Tiankeng Group

摘要:

为了解大石围天坑群天坑森林植物群落的种间联结特征,该文以大石围天坑群中7个典型天坑森林为研究区建立18个样地,取其中重要值大于1的木本植物为研究对象,采用方差比例、 χ2检验、Pearson相关系数检验、Spearman秩相关系数检验及PCA排序方法,对天坑森林内的主要木本植物种间关联性和生态种组进行定量分析。结果表明:(1)乔木层总体联结性呈现显著正联结,灌木层总体联结性呈现不显著正联结,群落总体关联性呈现显著正联结,表明天坑森林植物群落处于稳定的阶段。(2)χ2检验、Pearson相关系数检验和Spearman秩相关系数检验发现,乔木层正联结种对多于负联结种对且显著联结种对占多数,灌木层负联结种对多于正联结种对,且显著联结种对占多数,表明乔木层群落稳定性高于灌木层,乔木层种间竞争合作强,灌木层种间竞争排斥性强,群落主要木本植物之间联结性强,种间保持紧密联结的联结特征。(3)PCA排序将天坑森林植物分为四大生态种组,物种分布由天坑底部至顶部呈现圈层分布方式,且物种分布方式总体受生境差异和物种自身特性影响。可见,植物紧密的联结关系是天坑森林多样性维持机制之一,而群落内部种间关联性的自我调控及物种对生境异质性的趋同适应是群落维持稳定的基础。

Abstract:

For understanding the interspecific associations of main woody plant in tiankeng forests, we chose seven typical tiankeng forests as researched area and established a total of 18 sample plots in Dashiwei Tiankeng Group. We selected woody plants with importance values >1 as the study object, and quantitatively analyzed interspecific associations and correlations by a set of methods, namely, variance ratio, χ2 test, Pearson correlation coefficient test, Spearman rank correlation coefficient test and principal component analysis( PCA ). The results were as follows:(1)Overall interspecific association were significant positive correlations in tree layer, non-significant positive associations in shrub layer and significant positive associations in community, indicating that the plant community in tiankeng forests was at a stable stage.(2)The χ2 test, Pearson correlation coefficient test and Spearman rank correlation coefficient test found that there was a difference between positive and negative correlation in tree layer and shrub layer. Many positive correlation species pairs existed in tree layer and many negative correlation species pairs existed in shrub layer, but both of them were more significant correlation species pairs than non-significantanes, which indicates that the stability of community composition in tree layer was higher than shrub layer, and there was a strong competition and cooperation between species pairs in tree layer, a strong competition and repulsion between species pairs in shrub layer, and a close interspecific association in community.(3)According to the results of PCA, the 24 main woody species were divided into four ecological species groups. The tiankeng forests community distribution was in a circle distribution pattern from the bottom to the top of the tiankeng topography, which was affected by environmental differences and species characteristics. In conclusion, these results suggest that the close interspecific association may be one of the maintenance mechanisms of tiankeng forest species diversity, while the self-regulation of interspecific association within the community and convergence adaptation of species to habitat heterogeneity are the basis for maintaining the stability of the community.