College of Ecology and Environment, Xinjiang University, Urumqi, 830046, China.
Key Laboratory of Oasis Ecology, Xinjiang University, Urumqi, 830046, China.
Oecologia. 2024 May;205(1):107-119. doi: 10.1007/s00442-024-05555-6. Epub 2024 May 2.
Community weighted mean trait, i.e., functional composition, has been extensively used for upscaling of individual traits to the community functional attributes and ecosystem functioning in recent years. Yet, the importance of intraspecific trait variation relative to species turnover in determining changes in CWM still remains unclear, especially under nutrient enrichment scenarios. In this study, we conducted a global data synthesis analysis and three nutrient addition experiments in two sites of alpine grassland to reveal the extent to which species turnover and ITV contribute to shift in CWM in response to nutrient enrichment. The results consistently show that the importance of ITV relative to species turnover in regulating CWM in response to nutrient enrichment strongly depends on trait attributes rather than on environmental factors (fertilization type, climatic factors, soil properties, and light transmittance). For whole plant traits (height) and leaf morphological traits, species turnover is generally more important than ITV in determining CWM following most treatments of nutrient addition. However, for leaf nutrient traits, ITV outweighed species turnover in determining shifts in CWM in response to almost all treatments of nutrient addition, regardless of types and gradients of the nutrient addition. Thus, our study not only provides robust evidence for trait-dependent importance of ITV in mediating community functional composition, but also highlights the need to consider the nature of functional traits in linking ITV to community assembly and ecosystem functioning under global nutrient enrichment scenarios.
近年来，群落加权平均性状（即功能组成）已被广泛用于将个体性状放大为群落功能属性和生态系统功能。然而，相对于物种更替，种内性状变异在决定 CWM 变化方面的重要性仍不清楚，特别是在养分富集的情况下。本研究通过全球数据综合分析和两个高山草地站点的三个养分添加实验，揭示了物种更替和 ITV 相对于养分富集条件下 CWM 变化的贡献程度。结果一致表明，相对于物种更替， ITV 在调节 CWM 对养分富集的响应方面的重要性强烈依赖于性状属性，而不是环境因素（施肥类型、气候因素、土壤特性和透光率）。对于整个植物性状（高度）和叶片形态性状，在大多数养分添加处理后，物种更替通常比 ITV 更重要，决定 CWM。然而，对于叶片养分性状， ITV 在决定 CWM 对几乎所有养分添加处理的响应方面都超过了物种更替，无论养分添加的类型和梯度如何。因此，本研究不仅为 ITV 在介导群落功能组成方面的性状依赖性重要性提供了有力证据，还强调了在全球养分富集情景下，需要考虑功能性状的性质，将 ITV 与群落组装和生态系统功能联系起来。
