河西走廊荒漠植物多样性及其对环境因子的响应

Diversity of Desert Plants in Hexi Corridor and Its Response to Environmental Factors

研究河西走廊荒漠植物多样性结构特征及其对环境因子的响应有利于保护干旱区植物多样性、维持荒漠生态系统稳定。沿河西走廊由东南至西北方向自然降水递减梯度设置样带,探讨荒漠植物α、β多样性的变化规律及其对环境因子的响应。研究结果显示,(1)Margalef丰富度指数(R)范围为1.22-8.22,Simpson优势度指数(D)范围为0.25-0.97,Shannon-Wiener多样性指数(H')范围为0.05-1.52,Pielou均匀度指数(E)范围为0.08—0.90。河西走廊荒漠植物物种数少且分布不均,少数物种占据较大优势。(2)表征β多样性的Bray-Curtis距离指数(dBC)普遍较高,河西走廊东、中部样带间dBC平均值为0.91,西部样带间dBC平均值为0.78。东、中部样带(年均降水量大于50 mm)与西部样带(年均降水量约50 mm)之间dBC大都为1.00,说明东中部与西部之间荒漠植物相似性极低。(3)α多样性和环境因子的Spearman分析和冗余分析(Redundancy Analysis,RDA)表明,α多样性的变化由比湿、年均风速、年均降水量、短波辐射总强度、土壤含水量、土壤氮磷等因素解释,其中比湿、年均风速的解释率较高,分别为35.4%、19.8%。(4)β多样性和环境因子的Mantel检验表明,β多样性与土壤、气候和经纬度都显著相关,其中表征水分的比湿、年均降水量相关系数较高,分别为0.40、0.36。综上所述,水分是影响河西走廊荒漠植物多样性的主要因子,年均风速、年均温度、辐射总强度、土壤养分等也会影响植物多样性。

The study of the structural characteristics of desert plant diversity in Hexi Corridor and its response to environmental factors is conducive to protecting plant diversity in fragile arid areas and maintaining the stability of desert ecosystem.This paper explored the changing rules ofαandβdiversity of desert plants in Hexi Corridor and their responses to environmental factors by setting up sample plots along the decreasing natural precipitation gradients from southeast to northwest in Hexi Corridor.The results showed that(1)Margalef richness index(R)ranged from 1.22 to 8.22,Simpson dominance index(D)ranged from 0.25 to 0.97,Shannon-Wiener diversity index(H')ranged from 0.05 to 1.52,and Pielou evenness index(E)ranged from 0.08 to 0.90,indicating that desert plant species in Hexi Corridor are small in number and unevenly distributed,and a few species show a great advantage.(2)In terms of plantβdiversity,Bray-Curtis distance index(dBC)was generally high,the average value of Bray-Curtis distance index in the east and middle of Hexi corridor was 0.91,and that in the west was 0.78.The average value of the Bray-Curtis distance index between the eastern and central sample plots(the average annual precipitation was more than 50 mm)and the western sample plots(the average annual precipitation was about 50 mm)was mostly 1.00,indicating that the similarity of desert plants between the eastern and western regions is extremely low.(3)Spearman analysis and redundancy analysis ofαdiversity and environmental factors showed thatαdiversity was affected by soil water content,soil nitrogen and phosphorus,specific humidity,average annual wind speed,average mean precipitation and short wave radiation,among which specific humidity and average annual wind speed had higher explanation rates,which were 35.4%and 19.8%respectively.(4)Mantel test ofβdiversity and environmental factors showed thatβdiversity is significantly related to soil,climate,latitude and longitude.Compared with other environmental factors,the specific humidity and average mean precipitation had higher correlation coefficients,which were 0.40 and 0.36 respectively.To sum up,the plant diversity in Hexi Corridor desert is under a combined influence of water,average annual wind speed,average mean temperature,total radiation intensity and soil nutrients,with water playing the major role.