水力性状对荒漠植物群落物种多度分布格局的影响

Effects of hydraulic traits on the species abundance distribution pattern of desert plant communities

干旱引起的植物死亡是陆地生态系统物种组成改变的一个重要原因。水力学性状作为连通植物和水分匮缺间的桥梁,揭示其对物种分布的影响对理解植物干旱适应性、荒漠生态系统植被恢复和管理具有重要的理论意义。以新疆艾比湖湿地自然保护区的木本植物为研究对象,比较物种多度、水力学性状在土壤干旱梯度下的变化特征,并分析水力性状与物种多度分布之间的关系。结果表明,在土壤干旱梯度下,所有物种的多度之和未有显著变化,但在物种层面,不同物种的多度对干旱胁迫响应明显不同;比导率、准稳态导水率和胡伯尔值均随土壤干旱增加呈增加趋势,而枝叶水势不断降低,但干材密度没有显著变化;水力性状在种间的差别随土壤干旱程度发生变化;冗余分析和广义加性模型的结果表明,基于所测水力性状可以解释荒漠木本植物多度分布格局变化的92.8%,其值远高于单个或少数几个性状的组合(13.30%~86.40%);植物多度随着准稳态导水率、比导率、胡伯尔值和枝叶水势等水力性状的升高而增加,随着干材密度的增加而降低。可见,水力性状与荒漠植物物种多度分布之间存在明显关系,利用水力性状的变化可以预测木本植物多度分布的变化。

Plant death caused by drought is an important cause of species composition changes in terrestrial ecosystems.Revealing the influence of hydraulic triats on species distribution,which is of great theoretical significance for understanding plant drought adaptation,restoration and management of desert vegetation.In this study,the woody plants in the Ebinur Lake Wetland Nature Reserve were selected as subject to compare the variation characteristics of species abundance and hydraulic traits under soil drought gradient and analyze the relationship between hydraulic traits and species abundance distribution.Results showed that the sum of abundance(community density) of all species did not change significantly.However,the responses of different species abundance to drought stress were significantly different.With the increase in soil drought,the specific conductivity,quasi-steady conductivity,and Huber value increased;the water potential of branches and leaves decreased continuously,and the stem wood density did not change significantly.The difference of hydraulic triats among species changed with the degree of drought.Redundancy analysis and generalized additive model showed that 92.8% of the variation of desert woody plant abundance distribution pattern can be explained by the measured hydraulic triats.In addition,plant abundance increased with the quasi-steady conductivity,specific conductivity,Huber value,and water potential of branches and leaves but decreased with the increase in stem wood density.Therefore,the changes of the woody plant abundance distribution can be predicted using the changes of hydraulic traits.