Shi Lina, Lin Zhenrong, Wei Xiaoting, Peng Cuoji, Yao Zeying, Han Bing, Xiao Qing, Zhou Huakun, Deng Yanfang, Liu Kesi, Shao Xinqing
College of Grassland Science and Technology, China Agricultural University, Beijing, China.
Institute of Ecological Protection and Restoration, Chinese Academy of Forestry, Beijing, China.
Front Plant Sci. 2022 Nov 2;13:1044173. doi: 10.3389/fpls.2022.1044173. eCollection 2022.
Temperature and precipitation are expected to increase in the forthcoming decades in the northeastern Qinghai-Tibetan Plateau, with uncertain effects of their interaction on plant and soil carbon:nitrogen:phosphorus (C:N:P) stoichiometry in alpine ecosystems. A two-year field experiment was conducted to examine the effects of warming, precipitation increase, and their interaction on soil and plant C:N:P stoichiometry at functional groups and community level in an alpine meadow. Warming increased aboveground biomass of legumes and N:P ratios of grasses and community, but did not affect soil C:N:P stoichiometry. The piecewise structural equation model (SEM) indicated that the positive effect of warming on community N:P ratio was mainly resulted from its positive influence on the aboveground biomass of functional groups. Precipitation increase reduced C:N ratios of soil, grasses, and community, indicating the alleviation in soil N-limitation and the reduction in N use efficiency of plant. SEM also demonstrated the decisive role of grasses C:N:P stoichiometry on the response of community C:N:P stoichiometry to precipitation increase. The interaction of warming and precipitation increase did not alter plant community and soil, N:P and C:P ratios, which was resulting from their antagonistic effects. The stable soil and plant community C:N:P stoichiometry raised important implications that the effect of warming was offset by precipitation increase. Our study highlights the importance of considering the interaction between warming and precipitation increase when predicting the impacts of climate change on biogeochemical cycles in alpine meadow ecosystems.
预计在未来几十年里，青藏高原东北部的气温和降水量将会上升，它们之间的相互作用对高山生态系统中植物和土壤的碳氮磷（C:N:P）化学计量比的影响尚不确定。我们进行了一项为期两年的田间试验，以研究升温、降水增加及其相互作用对高山草甸中功能组和群落水平上土壤和植物C:N:P化学计量比的影响。升温增加了豆科植物的地上生物量以及禾本科植物和群落的氮磷比，但并未影响土壤C:N:P化学计量比。分段结构方程模型（SEM）表明，升温对群落氮磷比的积极影响主要源于其对功能组地上生物量的积极影响。降水增加降低了土壤、禾本科植物和群落的碳氮比，这表明土壤氮限制得到缓解，植物的氮利用效率降低。SEM还证明了禾本科植物C:N:P化学计量比对群落C:N:P化学计量比响应对降水增加的决定性作用。升温和降水增加的相互作用并未改变植物群落和土壤的氮磷比和碳磷比，这是由它们的拮抗作用导致的。稳定的土壤和植物群落C:N:P化学计量比具有重要意义，即升温的影响被降水增加所抵消。我们的研究强调了在预测气候变化对高山草甸生态系统生物地球化学循环的影响时，考虑升温和降水增加之间相互作用的重要性。
