高寒草甸植物群落中物种多样性与生产力关系研究

RELATIONSHIP BETWEEN PRODUCTIVITY AND SPECIES DIVERSITY IN ALPINE MEADOW PLANT COMMUNITY

通过对高寒草甸植物群落中物种多样性 (Shannon多样性指数 )与生产力 (地上生物量 )的关系的研究表明 :多样性与生产力的总体关系呈对数线性增加关系 ,随着观测时间和环境条件 (生境 )的改变 ,多样性与生产力的关系会发生一些变化 ,这是因为当观测时间和环境条件不同时 ,物种丰富度和物种构成以及其它的生物或非生物条件发生了相应的变化 ,而它们对多样性和生产力各自造成的影响是非同步性的 (这种非同步实际上就是物种在时间和空间生态位上的分化 ) ;而可能由于高寒草甸生态系统的生长季较短 ,环境条件的改变比观测时间改变对多样性与生产力关系造成的影响更显著。观测时间和环境条件的不同可能是造成许多实验研究中得不到一个一致的多样性与生产力关系的主要原因。此外 ,通过对各种多样性指标进行综合分析可以对多样性与生产力的关系有一个更加全面的了解 。

Through studying the relationship pattern between productivity (aboveground biomass) and species diversity (Shannon diversity index) of plant communities in typical alpine meadow of the eastern QingHai_Tibetan Plateau, this paper suggested that the relationship between productivity and Shannon diversity index can be well described by log_linear increase model. As the observed time and environmental conditions changed, the diversity_productivity relationship would change. This change may be caused by the differences in the species richness and species composition or other biotic and abiotic conditions; whereas those differences had an asynchronous influence on diversity and productivity respectively. These types of asynchronous influences could be attributed to species niche differentiations in time and space. Due to the shorter growth season in alpine meadow ecosystem, the changes in environmental conditions had more significant influences on the diversity_productivity relationship than those in the observed time. The differences in observed time and environmental conditions may be the major factors which caused the controversial diversity_productivity relationship. Besides, the synthetical analysis of various diversity indices may deepen the understanding of the diversity_productivity relationship and get some insights into the underlying mechanisms of the relationship.