西藏天然草地植物功能群分布的初步研究

天然草地是西藏最主要的植被类型,其植物种类组成复杂多样、结构特殊,但目前对该地区的物种分布研究还比较薄弱。本文根据野外调查资料以及通过文献收集的物种分布点数据,选取了包括气候、地形、植被和土壤等19种环境因子,利用物种分布模型Maxent模拟了西藏天然草地4种植物功能群的分布。结果表明:植物功能群的分布范围与模型模拟时所采用的分布点具有一定关联,如在没有物种分布点的西藏西北部(羌塘高原的无人区),几乎没有预测到物种的分布;气候因子对4种植物功能群的分布都具有重要作用,尤其是降水量的季节性变化、最干旱月的降水量、年平均温度、最冷月温度和最暖月温度,这些气候因子反映了该研究地区的降水和温度变化范围,是调控生态系统过程的关键因子;海拔也是重要影响因子之一,不仅直接影响着温度的变化,还局限了一些温度敏感性物种的分布。本研究结果为增强对该地区资源分布的了解提供了方法参考,也为草地保护和畜牧业的发展提供了依据。

Distribution of Plant Functional Groups in the Natural Grasslands of Xizang,China

Grassland is a predominant vegetation type in Xizang and is characterized by complex composition and structure. Studies on species distribution in this region are limited. Integrating species presence data from field surveys and literature, with 19 environmental factors, including categories of climate, topography, vegetation and soil, we modeled the distribution of four plant functional groups (PFGs) using Maxent. Results showed that the simulated distribution ranges of the PFGs highly corresponded with the in-situ investigation results. Precipitation seasonality, precipitation of the driest month, annual mean temperature, and temperature of the coldest and warmest months played important roles in determining the distribution of the four PFGs. These climatic factors, which reflect the precipitation and temperature ranges of the study area and are key factors regulating ecosystem processes, significantly influenced the distribution ranges of the four PFGs. Furthermore, elevation, which directly affects temperature and limits the distribution of some temperature-sensitive species, was also important to the distribution of PFGs. This study will assist in clarifying resource distribution, and can provide a valuable theoretical basis for the ecological protection of grassland and sustainable development of the local economy in Xizang.