Drivers of understorey biomass: tree species identity is more important than richness in a young forest
Drivers of understorey biomass: tree species identity is more important than richness in a young forest
复制标题
DOI：
10.1093/jpe/rtab004
复制
发表时间：
2021-06
影响因子：
2.7
通讯作者：
Markus S. Germany;H. Bruelheide;Alexandra Erfmeier
中科院分区：
文献类型：
--
作者：
Markus S. Germany;H. Bruelheide;Alexandra Erfmeier
积极的生物多样性与生态系统功能关系已被广泛报道，主要来自草原生态系统。然而，这不一定适用于更复杂的情况，例如跨越不同垂直层的森林。例如，已证明上层树种丰富度与下层生产力较低有关。树种丰富度效应是否通过增加（即由于栖息地异质性）或减少资源可用性（即通过增加竞争）来增加林下生产力，以及林下生产力是否确实受到树种特性的更强烈控制，都可能随着时间的推移而发生变化。此外，研究还表明，丰富度与生产力的关系随着环境背景的变化而变化。这项研究利用一个具有可操纵树种丰富度的实验性人工林，研究了跨层的时间和环境动态。在中国亚热带生物多样性-生态系统功能项目（BEF-China）的背景下，我们利用了在3年时间内沿着树种丰富度梯度重复收集的林下生物量样本。研究了不同环境处理下树种丰富度、树种特性和时间对林下生物量的影响。虽然我们发现树层特征对林下生物量有显着且一致的影响，但树种丰富度没有遇到这种影响。我们的结果还表明，在森林的结构层中，可能不存在单一的、可概括的上层物种丰富度与林下生产力关系，并且与上层相关的环境因素（例如透光率）对林下生产力的影响程度随时间而变化。总的来说，我们证明在研究森林结构层之间的关系时应考虑时间动态。
Positive biodiversity–ecosystem functioning relationships have been widely reported, predominately from grassland ecosystems. However, this does not necessarily have to apply accordingly in more complex situations such as in forests across different vertical strata. For instance, overstorey tree species richness has been shown to be associated with a lower understorey productivity. Whether or not tree species richness effects add to understorey productivity by increasing (i.e. due to habitat heterogeneity) or reducing resource availability (i.e. through increasing competition) and whether understorey productivity is indeed being governed more strongly by tree species identity are likely to change over time. Moreover, studies also suggested that richness–productivity relationships change with the environmental context. Using an experimental forest plantation with manipulated tree species richness, this study examined these temporal and environmental dynamics across strata. In the context of the Biodiversity-Ecosystem Functioning project in subtropical China (BEF-China), we made use of understorey biomass samples repeatedly collected over a time period of 3 years along a tree species richness gradient. The effects of tree species richness, tree species identities and time were studied across different environmental treatments for their impact on understorey biomass. While we found significant and consistent tree layer identity effects on understorey biomass, no such effect was encountered for tree species richness. Our results also indicate that among structural layers in forests, there might not be a single, generalizable overstorey species richness–understorey productivity relationship, and that the extent as to which overstorey-related environmental factors such as light transmittance contribute to understorey productivity change with time. Overall, we demonstrate that temporal dynamics should be considered when studying relationship among structural layers in forests.