The effects of biodiversity on community function and services are frequently studied in the history of ecology, while the response of individual species to biodiversity remains great elusive. In this study, we determined the biodiversity effects on community productivity as well as species level plant mass and carbon (C) and nitrogen (N) metabolism of eight submerged plants. These macrophytes in Lake Erhai were selected and planted in a water depth of one meter along a diversity gradient of 1, 2, 4 or 8 species. Then, the community productivity or species level plant mass, soluble protein, free amino acid and soluble carbohydrate were correlated to species richness to determine the biodiversity effects on community and single species. The results showed that the community level biomass was positively correlated to plant species richness although the species level plant mass of individual species responded differently to the overall plant species richness. Namely, only one plant mass positively correlated to species richness and the others decreased or showed no significant correlation with the increase of species richness. The soluble proteins of most macrophytes were positively correlated to species richness; however, both the free amino acid and soluble carbohydrate of the plants were negatively or not significantly correlated to species richness. These results indicated that the selection effects might dominate in our aquatic communities and the negative impacts of biodiversity on C and N metabolism of the macrophytes increased with the increase of species richness, which might result from the strong competition among the studied species. The biodiversity effects on the plant mass, and C and N metabolism of individual submerged species were first reported in this study, while more such field and control experiments deserve further research.

中文翻译：

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生物多样性梯度对沉水植物个体质量和代谢的影响

生态学史上经常研究生物多样性对社区功能和服务的影响，而个体物种对生物多样性的反应仍然难以捉摸。在这项研究中，我们确定了生物多样性对群落生产力以及八种沉水植物的物种水平植物质量和碳 (C) 和氮 (N) 代谢的影响。洱海的这些大型植物被选择并种植在1米水深的1、2、4或8种多样性梯度上。然后，将群落生产力或物种水平的植物质量、可溶性蛋白质、游离氨基酸和可溶性碳水化合物与物种丰富度相关联，以确定生物多样性对群落和单一物种的影响。结果表明，群落水平生物量与植物物种丰富度呈正相关，尽管单个物种的物种水平植物质量对整体植物物种丰富度的反应不同。即，只有一种植物群与物种丰富度呈正相关，其他植物群与物种丰富度的增加呈下降或不显着相关。大多数大型植物的可溶性蛋白与物种丰富度呈正相关；然而，植物的游离氨基酸和可溶性碳水化合物均与物种丰富度呈负相关或不显着相关。这些结果表明，选择效应可能在我们的水生群落中占主导地位，生物多样性对大型植物碳氮代谢的负面影响随着物种丰富度的增加而增加，这可能是由于研究物种之间的激烈竞争造成的。本研究首次报道了生物多样性对单个沉水物种的植物质量和碳氮代谢的影响，而更多此类现场和对照实验值得进一步研究。