Divergent trait responses to nitrogen addition in tall and short species

Asymmetrical light competition and direct detrimental effect of nitrogen have been proposed as two main mechanisms driving species richness declines following nitrogen (N) addition. N addition is also known to alter functional trait composition towards increased dominance of tall and fast-growing species. However, whether trait changes vary between species and, in particular, how the traits of tall and short species respond to N addition has rarely been studied. Understanding whether different trait changes occur for tall and short species would provide insight into mechanisms underlying N addition effects.
Based on a long-term N addition experiment, we measured the natural height of 44 plant species and the photosynthetic active radiation (PAR) at seven heights in the vegetation and identified a clear stratification of the plant community into tall species (>30cm tall), which experienced high light conditions, and short species that grew under the canopy. We also measured four funct..., ,

不对称光竞争与氮的直接有害效应，被认为是驱动氮（N）添加后植物群落物种丰富度下降的两大核心机制。已有研究表明，氮添加还会改变植物群落的功能性状（functional trait）组成，提升高大速生物种的群落优势度。然而，不同物种间的性状变化是否存在差异，尤其是高矮物种的性状对氮添加的响应模式，迄今尚未得到充分研究。明确高矮物种的性状变化差异，可为解析氮添加产生生态效应的潜在机制提供关键视角。本研究依托长期氮添加野外控制实验，测定了44种植物的自然株高，并在植被群落的7个高度层级测量了光合有效辐射（PAR），据此将植物群落清晰划分为两类：株高大于30cm的高大物种（处于高光环境），以及生长于冠层下方的矮小物种。本研究同时测定了4项功能……，，