岑王老山中山常绿落叶阔叶混交林群落结构动态

Dynamic of community structure in middle mountain evergreen and deciduous broad-leaved mixed forest in Cenwanglaoshan

关键词:  群落动态, 物种多样性, 物种组成, 树木死亡, 径级结构

Key words:  community dynamics, species diversity, species composition, tree mortality, structure of DBH class

摘要:

了解南亚热带中山常绿落叶阔叶混交林群落结构及物种多样性变化,可以为森林的合理管理与经营提供科学依据。该文利用2015和2022年两轮调查的数据,运用α多样性指数、β多样性指数、主坐标分析和空间点格局分析等方法,对岑王老山南亚热带中山常绿落叶阔叶混交林不同海拔上3个1 hm²群落的木本植物的物种组成、物种多样性、胸径结构特征的变化以及树木死亡原因进行研究。结果表明:(1)随着海拔升高,树木死亡率降低,树木死亡主要发生在小径级中,呈现非随机死亡模式且与活树密度无关。(2)7年间不同海拔群落的α多样性普遍减少,但不显著,α多样性指数变化率在不同海拔群落间相对一致。各群落物种组成出现变化,但差异极小(P>0.99),不同海拔群落间的物种组成有趋同趋势。(3)不同海拔群落树木的平均胸径与总胸高断面积增加,径级结构呈现倒“J”型,群落有着良好的自我更新和维持群落稳定的能力。综上认为,岑王老山南亚热带中山常绿落叶阔叶混交林的群落结构变化在不同海拔上总体一致,这说明群落结构稳定,未发生明显变化,各群落物种组成有趋同趋势,优势种的优势地位变化较小,稀有种消亡导致物种丰富度下降。

Abstract:

Understanding the dynamics of community structure and species diversity in evergreen and deciduous broad-leaved mixed forests can provide a scientific foundation for effective forest management. To analyze data from two surveys conducted in 2015 and 2022, we employed α diversity index, β diversity index, principal coordinate analysis, and spatial point pattern analysis. Our study focused on three 1 hm² communities at different elevations to investigate changes in species composition, species diversity and structure characteristics of diameter at breast height(DBH)class while exploring the causes of tree mortality. The results were as follows:(1)Tree mortality was greater in lower elevation communities than higher altitude ones. Tree death primarily affected small diameter trees and exhibited a non-random dead pattern independent of density dependence.(2)Overall α diversity of communities decreased slightly across all elevations over the course of seven years but not significantly so. The rate of change in α diversity index was relatively consistent among communities at different elevations. Although there were slight changes observed in the species composition within each community, these differences were minimal(P>0.99). A convergence trend was observed regarding species composition among communities at different elevations.(3)Average DBH and total basal area of all trees increased across communities at different elevations, with an inverted “J” shaped structure of DBH class indicating good self-renewal capacity and community stability maintenance ability. In summary, the changes observed in community structure of the evergreen and deciduous broad-leaved mixed forest in Cenwanglaoshan mountain are generally consistent across different elevations, thus demonstrating stable community structure with insignificant changes despite minor fluctuations occurring within dominant species population or rare species extinction impacting overall richness level.