Jennings Michael D, Williams John W, Stromberg Mark R
National Center for Ecological Analysis and Synthesis/Donald Bren School of Environmental Science and Management, University of California, Santa Barbara, CA, USA.
Oecologia. 2005 May;143(4):607-18. doi: 10.1007/s00442-005-0011-x. Epub 2005 Mar 10.
No definitive explanation for the form of the relationship between species diversity and ecosystem productivity exists nor is there agreement on the mechanisms linking diversity and productivity across scales. Here, we examine changes in the form of the diversity-productivity relationship within and across the plant communities at three observational scales: plots, alliances, and physiognomic vegetation types (PVTs). Vascular plant richness data are from 4,760 20 m2 vegetation field plots. Productivity estimates in grams carbon per square meter are from annual net primary productivity (ANPP) models. Analyses with generalized linear models confirm scale dependence in the species diversity-productivity relationship. At the plot focus, the observed diversity-productivity relationship was weak. When plot data were aggregated to a focus of vegetation alliances, a hump-shaped relationship was observed. Species turnover among plots cannot explain the observed hump-shaped relationship at the alliance focus because we used mean plot richness across plots as our index of species richness for alliances and PVTs. The sorting of alliances along the productivity gradient appears to follow regional patterns of moisture availability, with alliances that occupy dry environments occurring within the increasing phase of the hump-shaped pattern, alliances that occupy mesic to hydric environments occurring near the top or in the decreasing phase of the curve, and alliances that occupy the wettest environments having the fewest species and the highest ANPP. This pattern is consistent with the intermediate productivity theory but appears to be inconsistent with the predictions of water-energy theory.
对于物种多样性与生态系统生产力之间关系的形式，目前尚无定论性的解释，而且在跨尺度联系多样性和生产力的机制方面也未达成共识。在此，我们在三个观测尺度上研究了植物群落内部及之间多样性 - 生产力关系形式的变化：样地、植被群丛和外貌植被类型（PVTs）。维管植物丰富度数据来自4760个20平方米的植被野外样地。每平方米克碳的生产力估计值来自年净初级生产力（ANPP）模型。广义线性模型分析证实了物种多样性 - 生产力关系中的尺度依赖性。在样地尺度上，观测到的多样性 - 生产力关系较弱。当将样地数据汇总到植被群丛尺度时，观察到呈驼峰状的关系。样地间的物种周转无法解释在群丛尺度上观测到的驼峰状关系，因为我们使用样地间的平均样地丰富度作为群丛和PVTs的物种丰富度指标。群丛沿生产力梯度的分类似乎遵循区域水分可利用性模式，占据干旱环境的群丛出现在驼峰状模式的增加阶段，占据中生至水生环境的群丛出现在曲线顶部附近或下降阶段，而占据最湿润环境的群丛物种最少且ANPP最高。这种模式与中等生产力理论一致，但似乎与水 - 能量理论的预测不一致。
