Department of Ecology, Evolution, and Environmental Biology, Columbia University, 1200 Amsterdam Avenue, New York, NY, 10027, USA.
Rubenstein School of the Environment and Natural Resources, University of Vermont, 81 Carrigan Drive, Burlington, VT, 05405, USA.
Oecologia. 2020 Mar;192(3):671-685. doi: 10.1007/s00442-019-04586-8. Epub 2020 Feb 12.
Warming-induced nutrient enrichment in the Arctic may lead to shifts in leaf-level physiological properties and processes with potential consequences for plant community dynamics and ecosystem function. To explore the physiological responses of Arctic tundra vegetation to increasing nutrient availability, we examined how a set of leaf nutrient and physiological characteristics of eight plant species (representing four plant functional groups) respond to a gradient of experimental nitrogen (N) and phosphorus (P) enrichment. Specifically, we examined a set of chlorophyll fluorescence measures related to photosynthetic efficiency, performance and stress, and two leaf nutrient traits (leaf %C and %N), across an experimental nutrient gradient at the Arctic Long Term Ecological Research site, located in the northern foothills of the Brooks Range, Alaska. In addition, we explicitly assessed the direct relationships between chlorophyll fluorescence and leaf %N. We found significant differences in physiological and nutrient traits between species and plant functional groups, and we found that species within one functional group (deciduous shrubs) have significantly greater leaf %N at high levels of nutrient addition. In addition, we found positive, saturating relationships between leaf %N and chlorophyll fluorescence measures across all species. Our results highlight species-specific differences in leaf nutrient traits and physiology in this ecosystem. In particular, the effects of a gradient of nutrient enrichment were most prominent in deciduous plant species, the plant functional group known to be increasing in relative abundance with warming in this ecosystem.
变暖引起的北极养分富集可能导致叶片水平生理特性和过程的变化，从而对植物群落动态和生态系统功能产生潜在影响。为了探索北极苔原生态系统植被对增加养分供应的生理反应，我们研究了一套 8 种植物物种（代表 4 种植物功能群）的叶片养分和生理特征如何响应实验氮（N）和磷（P）富集梯度。具体来说，我们在阿拉斯加布鲁克斯山脉北麓的北极长期生态研究站点的实验养分梯度上，检查了一组与光合作用效率、性能和胁迫有关的叶绿素荧光测量值，以及两个叶片养分特征（叶片 %C 和 %N）。此外，我们明确评估了叶绿素荧光与叶片 %N 之间的直接关系。我们发现物种之间和植物功能群之间存在生理和养分特征的显著差异，并且我们发现一个功能群（落叶灌木）内的物种在高养分添加水平下具有显著更高的叶片 %N。此外，我们发现所有物种的叶片 %N 与叶绿素荧光测量值之间存在正相关和饱和关系。我们的研究结果突出了该生态系统中叶片养分特征和生理学的物种特异性差异。特别是，养分富集梯度的影响在落叶植物物种中最为明显，而这些物种是已知在该生态系统变暖过程中相对丰度增加的植物功能群。
