不同水盐梯度下功能多样性和功能冗余对荒漠植物群落稳定性的影响

功能多样性和功能冗余是物种多样性的两个组成部分,也是影响群落稳定性的两个重要因素。基于不同水盐梯度下植物功能多样性、功能冗余、物种多样性和群落稳定性及其相关关系的计算结果,分析功能多样性和功能冗余对群落稳定性的影响,结果表明:(1)功能多样性、物种多样性和群落稳定性均表现为高水高盐和中水中盐群落显著高于低水低盐群落(P0.05);(2)高水高盐群落,功能多样性与物种多样性的相关系数小于功能冗余与物种多样性的相关系数,且功能多样性与稳定性的相关系数也小于功能冗余与稳定性的相关系数,而中水中盐和低水低盐群落的相关系数则呈现相反的规律;(3)中水中盐和低水低盐群落的功能多样性的标准化偏回归系数均大于功能冗余的标准化偏回归系数;(4)典范对应分析中,土壤含水量可以解释总特征根的22.7%,而土壤含盐量仅可以解释总特征根的1.3%;(5)高水高盐群落的稳定比最接近20/80,稳定性最高;低水低盐群落远离20/80,稳定性最低。改进后的Godron稳定性测定方法与物种种群密度变异系数方法得出的结果相同。综上可知,功能多样性和功能冗余两者中与物种多样性关系更为密切者对群落稳定性的影响也越大,且两者均可提高群落稳定性,也就证明冗余假说在温带干旱荒漠区域的隐域性植物群落中是成立的;群落稳定性、功能多样性、功能冗余及物种多样性主要是受土壤含水量的影响,土壤含盐量对其影响较小。

Effects of functional diversity and functional redundancy on the stability of desert plant communities under different water and salt gradients

Functional diversity and functional redundancy are two components of species diversity, and are also two important factors that affect the stability of a community. The effects of functional diversity and functional redundancy on the community stability were analyzed based on the estimation of functional diversity, functional redundancy, species diversity, community stability, and their correlations of plant populations under different water and salt gradients The results revealed that:(1) The functional diversity, species diversity, and community stability of plant populations in high and moderate water and salt gradients were significantly higher than those of in low water and salt gradients (P < 0.05). (2) For populations in high water and salinity gradient, the correlation coefficient between functional diversity and species diversity was lower than that of between functional redundancy and species diversity, moreover, the correlation coefficient between functional diversity and stability was lower than that of between functional redundancy and stability. However, the correlation coefficients of populations in moderate and low water and salinity gradients were contrary to those of in high water and salinity gradient. (3) The standardized partial regression coefficients of functional diversity were greater than that of functional redundancy of communities in moderate and low water and salt gradients. (4) In the canonical correspondence analysis, the water and salt content of soil could explain 22.7% and 1.3% of the total characteristic root, respectively. (5) The stability was highest in plant communities in high water and salt gradient, with the stability rate near 20/80, whereas populations in low water and salt gradient had the lowest stability, with the stability rate far from 20/80. These results were consistent with those of estimated by the improved Godron Stability Test Method and Population Density Variance Coefficient Method. In summary, both of the functional diversity and functional redundancy could enhance the stability of plant community, and their effects were dependent on their relationships with species diversity which provided evidence for the redundancy hypothesis of plant communities in the temperate arid desert region. The stability, functional diversity, functional redundancy, and species diversity of plant communities were much more affected by soil moisture, but less by soil salinity.