Luo Yahuang, Liu Jie, Tan Shaolin, Cadotte Marc W, Xu Kun, Gao Lianming, Li Dezhu
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
Plant Divers. 2016 Nov 15;38(6):303-311. doi: 10.1016/j.pld.2016.11.002. eCollection 2016 Dec.
Characterizing trait variation across different ecological scales in plant communities has been viewed as a way to gain insights into the mechanisms driving species coexistence. However, little is known about how changes in intraspecific and interspecific traits across sites influence species richness and community assembly, especially in understory herbaceous communities. Here we partitioned the variance of four functional traits (maximum height, leaf thickness, leaf area and specific leaf area) across four nested biological scales: individual, species, plot, and elevation to quantify the scale-dependent distributions of understory herbaceous trait variance. We also integrated the comparison of the trait variance ratios to null models to investigate the effects of different ecological processes on community assembly and functional diversity along a 1200-m elevational gradient in Yulong Mountain. We found interspecific trait variation was the main trait variation component for leaf traits, although intraspecific trait variation ranged from 10% to 28% of total variation. In particular, maximum height exhibited high plasticity, and intraspecific variation accounted for 44% of the total variation. Despite the fact that species composition varied across elevation and species richness decreased dramatically along the elevational gradient, there was little variance at our largest (elevation) scale in leaf traits and functional diversity remained constant along the elevational gradient, indicating that traits responded to smaller scale influences. External filtering was only observed at high elevations. However, strong internal filtering was detected along the entire elevational gradient in understory herbaceous communities, possibly due to competition. Our results provide evidence that species coexistence in understory herbaceous communities might be structured by differential niche-assembled processes. This approach -- integrating different biological scales of trait variation -- may provide a better understanding of the mechanisms involved in the structure of communities.
刻画植物群落中不同生态尺度下的性状变异，被视为一种深入了解驱动物种共存机制的方法。然而，对于种内和种间性状在不同地点的变化如何影响物种丰富度和群落组装，我们知之甚少，尤其是在林下草本群落中。在此，我们将四个功能性状（最大高度、叶片厚度、叶面积和比叶面积）的变异，在四个嵌套的生物尺度上进行划分：个体、物种、样地和海拔，以量化林下草本性状变异的尺度依赖性分布。我们还将性状变异比与零模型进行比较，以研究不同生态过程对玉龙雪山1200米海拔梯度上群落组装和功能多样性的影响。我们发现，种间性状变异是叶片性状的主要性状变异组成部分，尽管种内性状变异占总变异的10%至28%。特别是，最大高度表现出高可塑性，种内变异占总变异的44%。尽管物种组成随海拔变化，且物种丰富度沿海拔梯度急剧下降，但在我们最大的（海拔）尺度上，叶片性状的变异很小，功能多样性沿海拔梯度保持不变，这表明性状对较小尺度的影响做出了响应。外部筛选仅在高海拔地区观察到。然而，在林下草本群落的整个海拔梯度上都检测到了强烈的内部筛选，这可能是由于竞争所致。我们的结果提供了证据，表明林下草本群落中的物种共存可能由不同的生态位组装过程构建。这种整合性状变异不同生物尺度的方法，可能会更好地理解群落结构所涉及的机制。
