Li Jiwei, Deng Lei, Peñuelas Josep, Wu Jianzhao, Shangguan Zhouping, Sardans Jordi, Peng Changhui, Kuzyakov Yakov
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Soil and Water Conservation Science and Engineering (Institute of Soil and Water Conservation), Northwest A&F University, Yangling, China.
Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, China.
Glob Chang Biol. 2023 Dec;29(24):7051-7071. doi: 10.1111/gcb.16959. Epub 2023 Oct 3.
Precipitation changes modify C, N, and P cycles, which regulate the functions and structure of terrestrial ecosystems. Although altered precipitation affects above- and belowground C:N:P stoichiometry, considerable uncertainties remain regarding plant-microbial nutrient allocation strategies under increased (IPPT) and decreased (DPPT) precipitation. We meta-analyzed 827 observations from 235 field studies to investigate the effects of IPPT and DPPT on the C:N:P stoichiometry of plants, soils, and microorganisms. DPPT reduced leaf C:N ratio, but increased the leaf and root N:P ratios reflecting stronger decrease of P compared with N mobility in soil under drought. IPPT increased microbial biomass C (+13%), N (+15%), P (26%), and the C:N ratio, whereas DPPT decreased microbial biomass N (-12%) and the N:P ratio. The C:N and N:P ratios of plant leaves were more sensitive to medium DPPT than to IPPT because drought increased plant N content, particularly in humid areas. The responses of plant and soil C:N:P stoichiometry to altered precipitation did not fit the double asymmetry model with a positive asymmetry under IPPT and a negative asymmetry under extreme DPPT. Soil microorganisms were more sensitive to IPPT than to DPPT, but they were more sensitive to extreme DPPT than extreme IPPT, consistent with the double asymmetry model. Soil microorganisms maintained stoichiometric homeostasis, whereas N:P ratios of plants follow that of the soils under altered precipitation. In conclusion, specific N allocation strategies of plants and microbial communities as well as N and P availability in soil critically mediate C:N:P stoichiometry by altered precipitation that need to be considered by prediction of ecosystem functions and C cycling under future climate change scenarios.
降水变化改变了碳、氮和磷循环，而这些循环调节着陆地生态系统的功能和结构。尽管降水变化会影响地上和地下的碳氮磷化学计量比，但在降水增加（IPPT）和降水减少（DPPT）情况下，植物-微生物养分分配策略仍存在相当大的不确定性。我们对来自235项田间研究的827个观测数据进行了荟萃分析，以研究IPPT和DPPT对植物、土壤和微生物碳氮磷化学计量比的影响。DPPT降低了叶片碳氮比，但提高了叶片和根系氮磷比，这反映出在干旱条件下，与土壤中氮的移动性相比，磷的移动性下降得更强烈。IPPT增加了微生物生物量碳（+13%）、氮（+15%）、磷（26%）以及碳氮比，而DPPT降低了微生物生物量氮（-12%）和氮磷比。植物叶片的碳氮比和氮磷比对中等程度的DPPT比IPPT更敏感，因为干旱增加了植物氮含量，特别是在湿润地区。植物和土壤碳氮磷化学计量比对降水变化的响应并不符合双不对称模型（IPPT下为正不对称，极端DPPT下为负不对称）。土壤微生物对IPPT比DPPT更敏感，但对极端DPPT比极端IPPT更敏感，这与双不对称模型一致。土壤微生物保持化学计量稳态，而在降水变化情况下，植物的氮磷比随土壤的氮磷比变化。总之，植物和微生物群落的特定氮分配策略以及土壤中氮和磷的有效性，通过降水变化关键地调节了碳氮磷化学计量比，这在预测未来气候变化情景下的生态系统功能和碳循环时需要加以考虑。
