环境因子对海南岛野生兰科植物物种组成与分布格局的影响

Effects of environmental variables on the species composition and distribution patterns of wild orchids in Hainan Island

海南岛是中国兰科植物物种丰富度较高的地区,了解环境因子对海南岛野生兰科植物物种组成和分布格局的影响,对于该地区野生兰科植物的保护管理和相关研究具有重要指导意义。基于海南岛野生兰科植物调查分布样方的植被类型、海拔、坡向、坡度、年平均气温、年降水量的数据,采用典范相关分析探索了环境因子对物种组成的影响,并计算各个环境因子对物种组成的总效应与净效应,同时分析了6个环境因子对野生兰科植物分布格局的影响。结果表明,所选的6个环境因子共解释了海南岛野生兰科植物组成变异的3.7%;植被类型、海拔、年平均气温、年降水量、坡向、坡度这6个环境因子的总效应与净效应均达显著水平,但其解释率依次减小。所选的6个环境因子对海南岛野生兰科植物的分布均有影响,野生兰科植物在海南岛主要分布在中海拔段、5°–35°的坡度范围、阴坡与半阴坡、年平均气温较低且年降水量较高的环境,并且于原生植被中分布最多。

Aims Hainan Island is an area with high species richness of orchids in China.Understanding the impact of environmental variables on the composition and distribution patterns of wild orchids in Hainan Island is critical for the protection and management of wild orchid species and relevant research in the region.Methods Based on the data of vegetation type,altitude,aspect,slope,mean annual air temperature and precipitation of wild orchids in Hainan Island,this study detected the relationship between species composition and environmental variables by canonical correspondence analysis(CCA),calculated the gross and net effects on species composition for each environmental variable by partial CCA.The effects of different gradients of six environmental variables on the distribution pattern of wild orchids were analyzed.Important findings The six selected environmental variables explained 3.7% of the variation in the composition of wild orchid plants in Hainan Island.The total and net effects of the six environmental factors including vegetation type,altitude,mean annual air temperature,precipitation,slope aspect,and slope gradient reached a significant level,but their effect intensities decreased successively.The selected six environmental variables all have an impact on the distribution of wild orchids in Hainan Island.Wild orchids in Hainan Island are mainly distributed in areas with the middle altitude,the shady and semi-shady slopes with the slope gradient of 5°-35°,and the environment with low mean annual air temperature and high mean annual precipitation.They are most distributed in native vegetation.