Systematic Botany and Functional Biodiversity, Institute of Biology, Leipzig University, Johannisallee 21, Leipzig, 04103, Germany.
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany.
Ecology. 2020 Jan;101(1):e02905. doi: 10.1002/ecy.2905. Epub 2019 Nov 6.
Locally, plant species richness supports many ecosystem functions. Yet, the mechanisms driving these often-positive biodiversity-ecosystem functioning relationships are not well understood. Spatial resource partitioning across vertical resource gradients is one of the main hypothesized causes for enhanced ecosystem functioning in more biodiverse grasslands. Spatial resource partitioning occurs if species differ in where they acquire resources and can happen both above- and belowground. However, studies investigating spatial resource partitioning in grasslands provide inconsistent evidence. We present the results of a meta-analysis of 21 data sets from experimental species-richness gradients in grasslands. We test the hypothesis that increasing spatial resource partitioning along vertical resource gradients enhances ecosystem functioning in diverse grassland plant communities above- and belowground. To test this hypothesis, we asked three questions. (1) Does species richness enhance biomass production or community resource uptake across sites? (2) Is there evidence of spatial resource partitioning as indicated by resource tracer uptake and biomass allocation above- and belowground? (3) Is evidence of spatial resource partitioning correlated with increased biomass production or community resource uptake? Although plant species richness enhanced community nitrogen and potassium uptake and biomass production above- and belowground, we found that plant communities did not meet our criteria for spatial resource partitioning, though they did invest in significantly more aboveground biomass in higher canopy layers in mixture relative to monoculture. Furthermore, the extent of spatial resource partitioning across studies was not positively correlated with either biomass production or community resource uptake. Our results suggest that spatial resource partitioning across vertical resource gradients alone does not offer a general explanation for enhanced ecosystem functioning in more diverse temperate grasslands.
在局部范围内，植物物种丰富度支持着许多生态系统功能。然而，驱动这些通常为正的生物多样性-生态系统功能关系的机制还没有被很好地理解。在垂直资源梯度上的空间资源分配是增强更多生物多样性草地生态系统功能的主要假设原因之一。如果物种在获取资源的位置上存在差异，就会发生空间资源分配，而且这种差异既可以发生在地上，也可以发生在地下。然而，研究草地中空间资源分配的研究提供了不一致的证据。我们提出了对来自草地物种丰富度梯度的 21 个实验数据集的元分析结果。我们检验了这样一个假设，即在垂直资源梯度上增加空间资源分配会增强多样化草地植物群落的生态系统功能，无论是地上还是地下。为了检验这个假设，我们提出了三个问题。（1）物种丰富度是否会在整个地区增加生物量生产或社区资源吸收？（2）是否有证据表明存在空间资源分配，如资源示踪剂的吸收和地上和地下的生物量分配？（3）空间资源分配的证据是否与增加的生物量生产或社区资源吸收相关？尽管植物物种丰富度增强了地上和地下的群落氮和钾吸收和生物量生产，但我们发现，植物群落没有达到我们的空间资源分配标准，尽管它们在混合种植中比在单一种植中显著增加了上层树冠层的地上生物量。此外，跨研究的空间资源分配程度与生物量生产或社区资源吸收没有正相关关系。我们的结果表明，仅在垂直资源梯度上的空间资源分配并不能为更具多样性的温带草地中增强的生态系统功能提供一般性解释。
