高寒草地植物物种多样性与功能多样性的关系

物种多样性与功能多样性的关系是生态学当前研究的热点问题之一,不同区域典型生态系统物种多样性和功能多样性的关系研究有利于生物多样性保护理论的全面发展。以青藏高原地区的主要草地生态系统—高寒草甸和高寒草原为研究对象,采用4个物种多样性指数(Patrick丰富度指数、Shannon-Weiner多样性指数、Pielou均匀度指数和Simpson优势度指数)和9个功能多样性指数(FAD功能性状距离指数、MFAD功能性状平均距离指数、基于样地的FDp和基于群落的FDc功能树状图指数、FRic功能体积指数、FEve功能均匀度指数、Rao功能离散度常二次熵指数、FDiv功能离散指数、FDis功能分散指数),分析了高寒草地植物物种多样性、功能多样性关系及其与初级生产力的关系,以期阐明3个科学问题:不同草地类型的高寒草地生态系统植物物种多样性和功能多样性有何差异?高寒草地生态系统的植物物种多样性和功能多样性有何关系?高寒草地生态系统物种多样性、功能多样性对生态系统功能的影响有何异同?研究结果表明:(1)与高寒草原相比,高寒草甸具有更高的物种多样性、功能丰富度和功能离散度;(2)高寒草甸中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc)和功能离散度指数(FDiv)的具有较强的相关性,最优拟合方程分别为幂函数和二次多项式函数;(3)高寒草原中,Patrick丰富度与功能丰富度指数(FAD、MFAD、FDp、FDc、FRic)、Shannon指数和Simpson指数与FEve指数的相关性较强,最优拟合方程为二次多项式函数,Pielou指数与FEve指数的相关性较强,最优拟合方程为指数函数;(4)高寒草甸的初级生产力分别与物种丰富度指数Patrick、功能离散指数FDiv具有较强的相关性;而高寒草原的初级生产力与4个物种多样性指数间均具有较强的相关性,与功能离散指数FDiv具有较强的相关性,最佳拟合方程均为二次多项式函数。研究的总体结论为:物种多样性、功能多样性、二者之间的关系以及二者与生态系统服务功能(以初级生产力为例)之间的关系在高寒草甸和高寒草原群落中表现迥异,因此在研究青藏高原高寒草地的生态功能时,不能仅仅测度传统的物种多样性,还应测度与物种多样性、生态功能密切相关的功能多样性。

Relationship between plant species diversity and functional diversity in alpine grasslands

The relationship between species diversity and functional diversity is currently one of the hot topics in ecology research. Determining the relationships between species and functional diversity in typical ecosystems of different regions can contribute to the development of biodiversity conservation theory. In this study, the main grassland ecosystems on the Qinghai-Tibetan Plateau, an alpine meadow and an alpine steppe, were selected to examine the relationships among species diversity, functional diversity, and primary productivity by using four species diversity indices, including the Patrick richness index, Shannon-Weiner diversity index, Pielou evenness index, and Simpson dominance index, as well as nine functional diversity indices, including the FAD functional trait distance index, MFAD functional trait mean distance index, FDp functional tree map index based on plots, FDc functional tree map index based on community, FRic functional volume index, FEve functional evenness index, Rao functional division two-times entropy index, FDiv functional division index, and FDis dispersion index. The aims of the study were to answer the following three questions:(1) what are the differences in plant species diversity and plant functional diversity between different types of alpine grasslands? (2) what are the relationships between plant species diversity and plant functional diversity in the alpine grasslands? (3) are there differences between the species diversity-ecosystem functioning (primary productivity) and plant functional diversity-ecosystem functioning relationships in the alpine grasslands? The results indicated that the alpine meadow showed higher species diversity, functional richness, and functional division than that by the alpine steppe. Furthermore, in the alpine meadow, the Patrick richness index was highly correlated with the functional indices FAD, MFAD, FDp, and FDc, as well as with the FDiv functional division index, and their correlations could be respectively expressed using a power function and two polynomial functions. In the alpine steppe, the Patrick richness index was strongly correlated with the functional indices FAD, MFAD, FDp, FDc, and FRic, and the Shannon diversity index and Simpson dominance index were highly correlated with the functional evenness index FEve; their correlations could be expressed by two polynomial functions. Moreover, the Pielou evenness index was highly correlated with the functional evenness index FEve, and their correlations could be expressed as an exponential function. Primary productivity of the alpine meadow was highly correlated with the Patrick richness index and FDiv functional division index, whereas primary productivity of the alpine steppe was highly correlated with all four biodiversity indices and the FDiv functional division index; all of their correlations could be expressed by two polynomial functions. Based on the results of this study, it can be concluded that plant species diversity, plant functional diversity, and their relationships with each other and with ecosystem function of primary productivity all varied between the different types of alpine grasslands. Therefore, in order to accurately evaluate the ecosystem functions of the alpine grasslands on the Qinghai-Tibetan Plateau, it is imperative to not only measure the plant species diversity but also the plant functional diversity, which is highly correlated with ecosystem function.