茂兰喀斯特森林植物物种丰富度的垂直分布特征及环境解释

茂兰喀斯特峰丛地貌森林是目前罕见的一类原生性强、人为干扰少的非地带性森林生态系统，与常态地貌地带性森林生态系统相比差异大。该研究采用典型样地调查方法对茂兰喀斯特森林海拔在620～910 m之间的垂直样带11个样方进行调查，分析研究区顶级群落物种丰富度的垂直梯度变化特征，并用冗余分析(RDA)法分析环境因子对物种丰富度的影响，以明确垂直梯度上物种丰富度与环境因子的关系，为喀斯特自然森林生态系统的维持与恢复、保护与管理提供理论基础。结果表明：(1)该调查茂兰喀斯特峰丛共记录有维管植物511种，隶属于124科272属。(2)单因素方差分析表明，该群落不同生活型的丰富度之间存在极显著差异(P<0.01);LSD多重比较分析表明，群落丰富度水平表现为总体>灌木层>草本层>乔木层。(3)随海拔梯度的升高，群落总物种丰富度和草本层物种丰富度与海拔呈显著负相关关系(P<0.05),乔木层丰富度和灌木层丰富度与海拔无明显规律。(4)冗余分析表明，土壤C/N/P的解释率达到58%,是影响物种丰富度的主要因素。

Vertical Distribution Characteristics and Environmental Interpretation of Plant Species Richness in Maolan Karst Forest

The Karst peak-cluster landform forest in Maolan is a rare non-zonal forest ecosystem with strong originality and less human disturbance, which is quite different from the normal landform zonal forest ecosystem. In this study, the typical sample plot survey method was used to 11 vertical transect plots in the Maolan Karst forest with an altitude of 620-910 m. We analyzed the vertical gradient variation characteristics of the species richness of the top community in the study area, and used redundancy analysis (RDA) method to analyze the effects of environmental factors on species richness, so as to clarify the relationship between species richness and environmental factors on the vertical gradient, and provide a theoretical basis for the maintenance and restoration, protection and management of Karst natural forest ecosystem. The results showed that: (1) a total of 511 species of vascular plants belonging to 124 families and 272 genera were recorded in the Maolan karst peak cluster. (2) One-way ANOVA analysis showed that the richness of different life forms in the community was very significantly different (P<0.01); Multiple comparison analysis of LSD showed that the richness level of community was overall > shrub layer > herb layer > tree layer. (3) With the increase of altitude gradient, the total species richness of community and the species richness of herb layer were significantly negatively correlated with altitude (P<0.05), while the tree layer richness and shrub layer richness were no obvious regularity with altitude. (4) Redundancy analysis showed that the contribution rate of soil C/N/P reached 58%, which was the main factor affecting species richness.