Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China.
Shanghai Chenshan Botanical Garden, Shanghai, 201602, China.
J Environ Manage. 2021 Sep 1;293:112869. doi: 10.1016/j.jenvman.2021.112869. Epub 2021 May 24.
Urban ecosystems feature intense anthropogenic activities and environmental stressors that filter species with varying life-history traits. The traits therefore provide an essential aspect to understanding how species respond to urban environments. We conducted this study in Chongqing, a mountainous city in southwestern China, and tested the hypothesis that the velocity of urban growth can alter functional compositions of urban plant communities through selection on species' taxonomic distributions and functional traits. We found that for most traits, their values spanned a wide range across the 70 spontaneous species in this study, and seed size and leaf element composition played a key role in contributing to the functional differentiation among species. At the same time, urban growth intensity was negatively correlated with leaf N concentration, the N:P ratio, and specific leaf area (SLA), and positively correlated with the leaf C:N ratio. This suggests that species in urban centers are associated with an acquisitive nutrient-use strategy and may gain strong competitive strategies to be favored by greater selective pressure in those long-term urban centers. Lastly, we show that urbanization as a strong filter tends to reduce the chance of species with unique traits for the spontaneous plant communities. Our study offers insights into mechanisms through which spontaneous plant communities are filtered by urbanization with a special focus on the ecological consequences of the velocity of urban growth.
城市生态系统具有强烈的人为活动和环境压力，这些压力过滤了具有不同生活史特征的物种。因此，这些特征为理解物种如何对城市环境做出响应提供了一个重要方面。我们在重庆进行了这项研究，重庆是中国西南部的一个多山城市，我们检验了这样一个假设，即城市增长的速度可以通过对物种分类分布和功能特征的选择来改变城市植物群落的功能组成。我们发现，对于大多数特征来说，它们的值在本研究中的 70 种自然物种中跨越了很宽的范围，种子大小和叶片元素组成在物种功能分化中起着关键作用。同时，城市增长强度与叶片氮浓度、氮磷比和比叶面积呈负相关，与叶片碳氮比呈正相关。这表明，城市中心的物种与一种获取性养分利用策略有关，它们可能获得了强大的竞争策略，从而在长期的城市中心受到更大的选择压力的青睐。最后，我们表明，城市化作为一个强有力的筛选器，往往会降低具有独特特征的物种在自然植物群落中出现的机会。我们的研究提供了关于城市化如何通过植物群落过滤的机制的见解，特别关注城市增长速度的生态后果。
