Data from: Greater than the sum of the parts: how the species composition in different forest strata influence ecosystem function

The mechanisms underpinning forest biodiversity-ecosystem function
relationships remain unresolved. Yet, in heterogeneous forests, ecosystem
function of different strata could be associated with traits or
evolutionary relationships differently. Here, we integrate phylogenies and
traits to evaluate the effects of elevational diversity on above-ground
biomass across forest strata and spatial scales. Community-weighted means
of height and leaf phosphorous concentration, and functional diversity in
specific leaf area exhibited positive correlations with tree biomass,
suggesting that both positive selection effects and complementarity occur.
However, high shrub biomass is associated with greater dissimilarity in
seed mass and multidimensional trait space, while species richness or
phylogenetic diversity is the most important predictor for herbaceous
biomass, indicating that species complementarity is especially important
for understory function. The strength of diversity-biomass relationships
increases at larger spatial scales. We conclude that strata- and scale-
dependent assessments of community structure and function are needed to
fully understand how biodiversity influences ecosystem function.

森林生物多样性-生态系统功能关系背后的调控机制尚未完全阐明。然而在异质森林中，不同林层的生态系统功能与功能性状或演化关系的关联模式可能存在差异。本研究整合系统发育（phylogeny）数据与功能性状，探究海拔多样性对不同森林林层及不同空间尺度下地上生物量的影响。树木高度与叶片磷浓度的群落加权均值，以及比叶面积（specific leaf area）的功能多样性（functional diversity）均与乔木生物量呈显著正相关，表明正选择效应与生态位互补效应均存在。但灌木生物量较高则与种子质量及多维性状空间的更大差异相关；而物种丰富度（species richness）或系统发育多样性（phylogenetic diversity）则是草本生物量的最重要预测因子，这表明物种互补效应对林下植被功能的维持尤为关键。多样性-生物量关系的强度随空间尺度扩大而增强。本研究认为，若要全面阐明生物多样性如何影响生态系统功能，需开展依赖于林层与空间尺度的群落结构与功能评估。