Wang Zhong, Wu Zhigang, Wang Yang, Yu Dan
Department of Ecology, College of Life Sciences, Wuhan University, Wuhan, China.
Front Plant Sci. 2018 Jun 22;9:870. doi: 10.3389/fpls.2018.00870. eCollection 2018.
The variations in nitrogen (N) and phosphorus (P) stoichiometry between species and along environmental gradients reflects plant growth and survival under certain conditions. Exploring the determinants of plant N and P stoichiometry at species level could help us understand the mechanisms of plant distribution. Temperature is considered a driving factor in forming the geographical patterns of plant N and P stoichiometry at the community level. Here we selected four common aquatic plants to explore the divergence of plant N and P stoichiometry between species and the species-level variations across large geographical gradients on the Tibetan Plateau. We found that plant N and P concentrations and N:P ratios were significantly different among the four species/groups. Charophytes had the lowest N and P concentrations, but the N:P ratio did not differ significantly from those of angiosperms. All four species/groups plant N concentrations were positively correlated with P concentrations. The temperature was also the primary explanatory variable, while the habitats properties showed weak and inconsistent effects on plant N and P stoichiometry. Plant N and P concentrations increased, but N:P ratios decreased, with decreasing temperature. Altitude, rather than latitude, determined the environmental patterns of plant N and P stoichiometry by affecting the temperature. These findings indicated that, after removing the influences of species replacement at the community level, temperature still plays a primary role in forming the geographical patterns of plant N and P stoichiometry at species level. Plants of each species could optimize their investment strategies of elements under different environmental conditions. The Tibetan Plateau is recognized as an area that is sensitive to global warming. Our results provided evidence, in terms of N and P stoichiometry, of potential variations among aquatic plants in nutrient absorption and element cycling under climatic warming.
物种之间以及沿环境梯度的氮（N）和磷（P）化学计量比变化反映了特定条件下植物的生长和存活情况。探索物种水平上植物N和P化学计量比的决定因素有助于我们理解植物分布的机制。温度被认为是在群落水平上形成植物N和P化学计量比地理格局的驱动因素。在此，我们选择了四种常见水生植物，以探究物种间植物N和P化学计量比的差异以及青藏高原大地理梯度上的物种水平变化。我们发现，这四个物种/类群之间的植物N和P浓度以及N:P比存在显著差异。轮藻的N和P浓度最低，但其N:P比与被子植物的N:P比没有显著差异。所有四个物种/类群的植物N浓度均与P浓度呈正相关。温度也是主要的解释变量，而栖息地特性对植物N和P化学计量比的影响较弱且不一致。随着温度降低，植物N和P浓度增加，但N:P比降低。海拔而非纬度通过影响温度决定了植物N和P化学计量比的环境格局。这些发现表明，在消除群落水平上物种替代的影响后，温度在物种水平上形成植物N和P化学计量比地理格局方面仍起主要作用。每个物种的植物都可以在不同环境条件下优化其元素投资策略。青藏高原被认为是对全球变暖敏感的地区。我们的结果从N和P化学计量比的角度提供了气候变暖下水生植物在养分吸收和元素循环方面潜在变化的证据。
