Nitrogen addition delays the emergence of an aridity-induced threshold for plant biomass  

作　　者：Hailing Li César Terrer Miguel Berdugo Fernando T.Maestre Zaichun Zhu Josep Peñuelas Kailiang Yu Lin Luo Jie-Yu Gong Jian-Sheng Ye 

机构地区：[1]State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems,College of Ecology,Lanzhou University,Lanzhou 730000,China [2]Department of Civil and Environmental Engineering,Massachusetts Institute of Technology,Cambridge,MA 02139,USA [3]Instituto Multidisciplinar para el Estudio del Medio“Ramón Margalef,”Universidad de Alicante,Alicante 03690,Spain [4]Institut de Biologia Evolutiva(CSIC-UPF),Barcelona 08003,Spain [5]Departamento de Ecología,Universidad de Alicante,Alicante 03690,Spain [6]School of Urban Planning and Design,Peking University Shenzhen Graduate School,Peking University,Shenzhen 518055,China [7]CSIC,Global Ecology Unit CREAF-CSIC-UAB,Barcelona 08193,Spain [8]CREAF,Cerdanyola del Vallès,Barcelona 08193,Spain [9]High Meadows Environmental Institute,Princeton University,Princeton,NJ 08544,USA

出　　处：《National Science Review》2023年第11期143-154,共12页国家科学评论（英文版）

基　　金：supported by the Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0305);the Fundamental Research Funds for the Central Universities (lzujbky-2022-ct01);‘111’ Project (BP0719040);‘Innovation Star’project of Gansu Province’s outstanding graduate students in2023 (2023CXZX-132);supported by Generalitat Valenciana (CIDEGENT/2018/041);the Spanish Ministry of Science and Innovation (EUR2022-134048);supported by the National Natural Science Foundation of China(41 901 122);the Shenzhen Fundamental Research Program(GXWD20201231165807007-20200814213435001);supported by the Spanish Government grant TED2021-132627B-I00funded by MCIN;AEI/10.13039/501 100 011 033;the European Union Next Generation EU/PRTR,the Fundación Ramón Areces grant CIVP20A6621;the Catalan Government grant SGR2021-1333

摘　　要：Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity,potentially causing land degradation and desertification.It is largely unknown,however,whether these thresholds can be altered by other key global change drivers known to affect the water-use efficiency and productivity of vegetation,such as elevated CO_(2) and nitrogen(N).Using>5000 empirical measurements of plant biomass,we showed that crossing an aridity(1–precipitation/potential evapotranspiration)threshold of∼0.50,which marks the transition from dry sub-humid to semi-arid climates,led to abrupt declines in aboveground biomass(AGB)and progressive increases in root:shoot ratios,thus importantly affecting carbon stocks and their distribution.N addition significantly increased AGB and delayed the emergence of its aridity threshold from 0.49 to 0.55(P<0.05).By coupling remote sensing estimates of leaf area index with simulations from multiple models,we found that CO_(2) enrichment did not alter the observed aridity threshold.By 2100,and under the RCP 8.5 scenario,we forecast a 0.3%net increase in the global land area exceeding the aridity threshold detected under a scenario that includes N deposition,in comparison to a 2.9%net increase if the N effect is not considered.Our study thus indicates that N addition could mitigate to a great extent the negative impact of increasing aridity on plant biomass in drylands.These findings are critical for improving forecasts of abrupt vegetation changes in response to ongoing global environmental change.

关 键 词：aboveground biomass root:shoot ratios elevated CO_(2) nitrogen fertilization ecosystem threshold 

分 类 号：Q945[生物学—植物学]