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Exceptional Warmth, More than Extreme Rainfall Alternations Directly Stimulate Co2 and Water Vapor Exchanges of Semi-Arid Alpine Grasslands on the Northeastern Qinghai-Tibetan Plateau

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SSRN 2023年

作者： Li, Hongqin Zhang, Fawei Wang, Junbang Guo, Xiaowei Li, Jiexia Yang, Yongsheng Zhou, Huakun Li, Yingnian College of Life Sciences Luoyang Normal University Henan Luoyang471934 China Key Laboratory of Adaptation and Evolution of Plateau Biota Northwest Institute of Plateau Biology Chinese Academy of Sciences Qinghai Xining810001 China Qinghai Provincial Key Laboratory of Restoration Ecology in Cold Region Northwest Institute of Plateau Biology Chinese Academy of Sciences Qinghai Xining810001 China Synthesis Research Center of Chinese Ecosystem Research Network Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China

Discrete extreme heat, deluges, and droughts become more frequent and disproportionately affect grassland ecosystem processes and functions. Here, we pair-compared the changes of CO2 and heat fluxes to natural extreme events between an alpine meadow and adjoining shrubland on the northeastern Qinghai-Tibetan Plateau. Unlike insensitive sensible heat fluxes, latent heat fluxes (LE) were promoted by 21.8% in the meadow and by 56.4% in the shrubland during a dry and subsequent compound dry hot period, respectively. The changes (Δ, data in 2016 minus the corresponding mean from the other years) of heat fluxes were both determined by the changes of solar radiation (ΔSwin). And the open-canopy shrubland has a higher sensitivity of ΔLE with ΔSwin, reflecting a stronger evaporative cooling capacity to buffer climate anomalies. CO2 fluxes responded weakly to extreme wet or dry events until those events were accompanied by hot events. During a single or compound hot event, the mean changes of total ecosystem respiration (ΔTER) were both promoted by about 30%, with a higher sensitivity of ΔTER against the changes of topsoil temperature in the more productive meadow. The mean changes of gross primary productivity (ΔGPP) fluctuated by less than 10% in the warmer meadow while were promoted by 29.3% in the cooler shrubland, likely due to different canopy structures and consequent high-temperature stress on vegetation photosynthesis. The changes of net ecosystem CO2 exchanges (ΔNEE) were significantly related to ΔTER and thus increased by 55.8% in the meadow, while it was mainly controlled by ΔGPP and then decreased by 22.4% in the shrubland. Overall, semi-arid alpine grasslands are resistant to rainfall alterations and susceptible to exceptional warmth. And the differential response was probably associated with canopy structures. Our results provide helpful insights into predicting the ecological functions of alpine grasslands in future climate changes. © 2023, The Authors. All ri

关键词： Carbon dioxide

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Response of soil microbial biomass C, N, and P and microbial quotient to agriculture and agricultural abandonment in a meadow steppe of northeast China

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SOIL & TILLAGE RESEARCH 2022年 223卷

作者： Yan, Yuchun Wang, Chu Zhang, Jingmin Sun, Yu Xu, Xingliang Zhu, Na Cai, Yurong Xu, Dawei Wang, Xu Xin, Xiaoping Chen, Jinqiang Chinese Acad Agr Sci Inst Agr Resources & Reg Planning Beijing 100081 Peoples R China Chinese Acad Sci Northeast Inst Geog & Agroecol Key Lab Mollisols Agroecol Changchun 130102 Peoples R China Chinese Acad Sci Inst Geog Sci & Nat Resources Res Key Lab Ecosystem Network Observat & Modeling Datun Rd Beijing 100101 Peoples R China

The carbon and nutrients in the soil microbial biomass (SMB) and their proportion in soil elements, namely soil microbial quotient (SMQ), are the key indicators of the soil quality and quickly respond to the shift in the landuse pattern. However, the degree of the land-use shift influences on the soil microbial biomass, and the soil microbial quotient in the meadow steppe is not well-understood. The soil microbial biomass carbon (MBC), nitrogen (MBN), phosphorous (MBP), and SMQ were determined separately in grassland, cropland, and abandoned cropland in four sites within 50 km at a meadow steppe in northeast China. The results showed that the soil MBC, MBN, and MBP declined significantly as soil depth increased among the three land-use patterns. Agriculture has resulted in a significant decrease in the soil MBC, MBN, MBP, and SMQ compared to their corresponding values in grassland. The soil MBC content significantly was increased at the 0-10 cm soil layer after agriculture abandonment, but the SMQ had no significant improvement in the entire profile when compared to cropland. Besides, for the three types of land-use patterns, the C, N, and P stoichiometry of the soil microbial biomass was relatively stable, except for the stoichiometry in the relatively deep soil layer. Overall, the present agricultural abandonment (similar to 19 years) got a certain of restoration in soil microbial biomass. Their corresponding values, however, were significantly lower than those found in native grassland. This highlighted that the restoration of the poor soil quality caused by the long term agriculture cultivation is a slow and hard process;it is important to maintain natural grasslands for protecting and maintaining soil microbial biomass and SMQ in the meadow steppe of northeast China.

关键词： Soil microbial biomass Soil microbial quotient Microbial C:N:P stoichiometry Meadow steppe Land-use shift

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Variations of nitrogen transport in the mainstream of the Yellow River,China

Variations of nitrogen transport in the mainstream of the Ye...

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中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Zhimin Wang Xianfang Song Guomin Li Jianfeng Zhang Guirui Yu Xiaomin Sun Key Laboratory of Engineering Geomechanics Institute of Geology and GeophysicsChinese Academy of Sciences Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of Sciences Key Laboratory of Engineering Gcomcchanics Institute of Geology and GeophysicsChinese Academy of Sciences Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of Sciences

Three sections along the mainstream of the Yellow River were chosen as sites for monitoring the concentration variations of nitrogen species. First,the nitrogen in the water was mainly dissolved and dominated by ***,the nitrogen concentrations in the middle stream were much higher than those in the upper stream,and close to those in the lower ***,the nitrogen species in the upper stream were mainly related to fertiliser,mostly connected with domestic sewage and fertiliser in the middle stream,and principally induced by industrial wastewater in the lower stream. Fourth,the amount of total nitrogen,dissolved nitrogen,solid nitrogen,and nitrate nitrogen transported to the Bohai Sea by the Yellow River averaged 101.2,94.6,6.6,and 81.8 thousand tons,respectively,during the period of 2005 to ***,water and sediment regulation had important effects on the nitrogen transport in the Yellow River.

关键词： Yellow River nitrogen flux monitoring Bohai Sea China

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Divergent Responses of Nitrogen Availability to Drought Stress in Drylands

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SSRN 2022年

作者： Wang, Jing Wen, Xuefa Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing101408 China Beijing Yanshan Earth Critical Zone National Research Station University of Chinese Academy of Sciences Beijing101408 China

Dryland ecosystems are generally drought-stressed and have low soil fertility. While the negative effects of drought on vegetation productivity are undisputed, it is unclear whether drought limits vegetation productivity alone or in combination with nitrogen (N) deficiency. To address this unknown, we used a combination of N-isotopic observations and model simulations for three aridity transects (Loess Plateau, LP;Inner Mongolia Plateau, MP;Tibetan Plateau, TP). We found that soil N content decreased and δ 15 N soil increased with increasing aridity, demonstrating that soil N supply for plant decreased with increasing aridity. δ 15 N leaf increased with increasing aridity, however, δ 15 N leaf-soil exhibited an increasing trend in MP and TP only. δ 15 N leaf-soil in LP was large and showed no clear spatial pattern. These results indicated that N availability (defined as the balance between soil N supply for plant and plant N demand) increased with increasing aridity in MP and TP but remained low due to high vegetation productivity in LP. Our results showed that δ 15 N leaf-soil was more closely related to N availability than δ 15 N leaf . Gross ecosystem primary productivity (GPP) was significantly associated with drought stress, but not with N availability along aridity gradients, indicating that GPP in these ecosystems was constrained by drought stress rather than low N availability. Overall, our study demonstrated that the response of N availability to drought stress depends mainly on the amount of vegetation that can be maintained by available water, and that high N availability in drought stress conditions may alleviate the limiting effect of future drylands expansion on GPP. © 2022, The Authors. All rights reserved.

关键词： Soils

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Accuracy Assessment and Inconsistency Diagnosis of 30-Meter Land Cover Datasets in China

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SSRN 2024年

作者： Xu, Xiaolin Li, Dan D. Liu, Hongxi Zhao, Guang Cui, Baoshan Yi, Yujun Yang, Wei Du, Jizeng School of Environment Beijing Normal University State Key Joint Laboratory of Environmental Simulation and Pollution Control Beijing100875 China Advanced Institute of Natural Sciences Beijing Normal University Zhuhai Campus Zhuhai519087 China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China

Accurate and detailed land cover information is fundamental for environmental studies, including regional climate change, sustainable development, and land resource management. With higher resolution and longer records, land cover datasets with a 30-meter resolution are widely used to evaluate land cover changes and consequent impacts on carbon storage, land-atmosphere energy balance, and water cycle processes. However, existing data products employ different classification methods, leading to substantial classification inconsistency and thus reducing the confidence of related studies. Here, we compared four mainstream land cover products in China, including GLC_FCS30, CLCD, Globeland30, and CNLUCC. The result shows that only 50.4% of the classification results were consistent across the four datasets. The differences between pairs of datasets ranged from 21.10% to 37.53%, with most inconsistency occurring in transitional zones among land cover types and regions with complex terrain or severe landscape fragmentation. Based on accuracy evaluation, CLCD is significantly more accurate than the other products, with an overall accuracy reaching 86.98%, followed by CNLUCC (with an overall accuracy of 81.38%) and GLC_FCS30 (77.83%). The Globeland30 had a lowest accuracy (75.24%), primarily due to misclassification between cropland and forests. Misclassification diagnoses revealed that overlapping NDVI values among land cover types contributed significantly to misclassifications, followed by slope, cloud cover, and landscape fragmentation, which affected satellite observation angles, data availability, and mixed pixels. Automated classification methods using the random forest algorithm can perform better than those that depend on traditional hunam-machine interactive interpretation or object-based approaches. However, their classification accuracy depends more on the quality of training samples and feature variables. This study quantitatively supports the selection and opti

关键词： Sustainable development

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Climatic Changes Dominant Interannual Trend in Net Primary Productivity of Alpine Vulnerable ecosystems

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Journal of Resources and Ecology 2019年第4期10卷 379-388页

作者： YANG Yihan WANG Junbang LIU Peng LU Guangxin LI Yingnian Key Lab of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101 China University of Chinese Academy of Sciehces Beijing 100049 China Henan Academy of Land and Resources Sciences Zhengzhou 450053 China Qinghai University Xining 810016 China Northwest Institute of Plateau Biology Chinese Academy of Sciences Xining 81000& China

The Three-River Headwaters(TRH), which is the source area of Yangtze River, Yellow River and Lancang River, is vulnerable and sensitive, and its alpine ecosystem is considered an important barrier for China’s ecological security. Understanding the impact of climate changes is essential for determining suitable measures for ecological environmental protection and restoration against the background of global climatic changes. However, different explanations of the interannual trends in complex alpine ecosystems have been proposed due to limited availability of reliable data and the uncertainty of the model itself. In this study, the remote sensing-process coupled model(GLOPEM-CEVSA) was used to estimate the net primary productivity(NPP) of vegetation in the TRH region from 2000 to 2012. The estimated NPP significantly and linearly correlated with the above-ground biomass sampled in the field(the multiple correlative coefficient R2 = 0.45, significant level P < 0.01) and showed better performance than the MODIS productivity product, i.e. MOD17 A3,(R2 = 0.21). The climate of TRH became warmer and wetter during 1990-2012, and the years 2000 to 2012 were warmer and wetter than the years1990–2000. Responding to the warmer and wetter climate, the NPP had an increasing trend of 13.7 g m^–2(10 yr)^–1 with a statistical confidence of 86%(P = 0.14). Among the three basins, the NPP of the Yellow River basin increased at the fastest rate of 17.44 g m^–2(10 yr)^–1(P = 0.158), followed by the Yangtze River basin, and the Lancang River, which was the slowest with a rate of 12.2 g m^–2(10 yr)^–1 and a statistical confidence level of only 67%. A multivariate linear regression with temperature and precipitation as the independent variables and NPP as the dependent variable at the pixel level was used to analyze the impacts of climatic changes on the trend of NPP. Both temperature and precipitation can explain the interannual variability of 83% in grassland NPP in the whole region, and

关键词： Three-River Headwaters alpine ecosystems net primary productivity climate changes

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A Synthetic Analysis of ecosystem Carbon Exchange Across China's Coastal Wetlands: Magnitudes, Patterns, and Mechanisms

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SSRN 2023年

作者： Wang, Jilong Yu, Guirui Han, Lang Yao, Yuan Sun, Mingyu Yan, Zhifeng Institute of Surface-Earth System Science School of Earth System Science Tianjin University Tianjin300072 China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China

Coastal wetlands are of great importance for global carbon cycle and climate regulation for its strong carbon uptake capacity. However, the magnitudes, spatial patterns, and potential mechanisms for ecosystem carbon exchange of coastal wetlands at national scale remain poorly understood. Herein, we synthesized ecosystem C fluxes and variables from previous studies to explore their spatial patterns, drivers, and mechanisms of C exchange in China’s coastal wetlands. Our results reveal that China's coastal wetlands absorb 1.38 TgC yr-1, exhibiting a large net CO2 uptake with GPP (gross primary production), NEP (net ecosystem production), and ER (ecosystem respiration) values of 1451 ± 442, 413 ± 240, and 991 ± 297 gC m-2 yr-1, respectively. Significant spatial variations in GPP, NEP, and ER across the coastal wetlands were found, with the highest values in the tropics, followed by subtropics and temperate. Generally, the spatial patterns of carbon exchange exhibited decreasing trend with elevated latitude. With the increase in latitude for each 1°, GPP, NEP and ER decreased by 61.12, 29.19 and 27.14 gC m-2 yr-1, respectively. Meteorological factors including MAT and MAP were the dominating factors for the spatial patterns of ecosystem carbon exchange with respective explanatory power of 31~75% and 36~73%. Moreover, the botanic factors including LAI (leaf area index), FVC (fractional vegetation coverage), and BIOM (biomass) could shift the physiological processes, and thus control the spatial patterns of carbon exchange. The SOC (soil organic carbon) acts as both indicator and factor for the C dynamics. Meanwhile, we found the external disturbances of coastal wetlands could exert more influence on ER than GPP, leading to different responses of GPP and ER to environmental drivers. Our findings highlight the strong carbon uptake capacity and significant spatial variabilities of C exchange in China's coastal wetlands, which were controlled by multifaceted factors and compl

关键词： ecosystems

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Loss of Soil Total Carbon from 2010s to 2020s in Northern Tibetan Plateau

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SSRN 2023年

作者： Wu, Wenjuan Zhao, Guang Zhao, Bo Huang, Ke Brandt, Martin Zhu, Juntao Zhang, Yangjian Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China CAS center for excellence in Tibetan Plateau Earth Sciences Beijing100101 China College of Resources and Environment University of Chinese Academy of Science Beijing100190 China Department of Geosciences and Natural Resource Management University of Copenhagen Copenhagen1350 Denmark

As the largest and highest plateau in the world, ecosystems on the Tibetan Plateau (TP) imply fundamental ecological significance to the globe. Among the variety, ecosystem carbon on the TP forms a critical part of the global ecosystem. Soil carbon accounts over nine tenths of grassland ecosystem carbon on the TP. Revealing soil carbon dynamics and the underlying driving forces is vital for corroborating ecosystem carbon sequestration capacity on the TP. By selecting northern TP, the core region of the TP, this study investigates spatial-temporal dynamics of soil total carbon and the driving forces based on two phases of soil sampling data from the 2010s to the 2020s. The research findings show that soil total carbon density (STCD) in 2010s (8.85±3.08 kg C m-2) significantly decreased to 2020s (7.15±2.90 kg C m-2), with a decreasing rate (ΔSTCD) of -0.17±0.39 kg C m-2 yr-1. Moreover, STCD in both periods gradually increased with deepening soil depth, while ΔSTCD loss magnitude gradually decreased with deepening soil depth. Spatially, ΔSTCD loss in alpine desert grassland was significantly higher than that in alpine grassland or alpine meadow. The STCD in 2010s explained the largest part of variances in ΔSTCD among the set of covariates. Moreover, rising temperature aggravates ΔSTCD loss in alpine desert grassland, while enhanced precipitation alleviate ΔSTCD loss in alpine meadow. These findings further broaden our understanding on carbon cycling in alpine ecosystems and are valuable for achieving long-term carbon management goals in compliance with national carbon peak and neutrality objectives. © 2023, The Authors. All rights reserved.

关键词： Soils

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Linking leaf elemental traits to biomass across forest biomes in the Himalayas

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Science China Earth Sciences 2024年第5期67卷 1518-1528页

作者： Nita DYOLA Eryuan LIANG Josep PEÑUELAS J.Julio CAMARERO Shalik Ram SIGDEL Sugam ARYAL Wentao LIN Xiang LIU Yongwen LIU Xingliang XU Sergio ROSSI State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Laboratoire sur lesécosystèmes terrestres boréaux Département des Sciences FondamentalesUniversitédu QuébecàChicoutimi555Boulevard de l′UniversitéChicoutimi(QC)G7H2B1Canada CSIC Global Ecology Unit CREAF-CSIC-UABBellaterraE-08193 CataloniaSpain CREAF Cerdanyola del VallèsE-08193 CataloniaSpain Instituto Pirenaico de Ecología(IPE-CSIC) Avenida Montañana 1005Zaragoza 50059Spain Friedrich-Alexander-Universität Erlangen-Nürnberg Institut für GeographieErlangen 91058Germany State Key Laboratory of Grassland Agro-Ecosystems College of EcologyLanzhou UniversityLanzhou 730000China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Plants require a number of essential elements in different proportions for ensuring their growth and *** elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental ***,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational *** examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements(C,N,P,K,Ca,Mg,Zn,Fe,Cu,and Mn)in tree communities situated every 100 meters along an extensive elevation gradient,ranging from the tropical forest(80 meters above sea level)to the alpine treeline(4200 meters above sea level)in the Kangchenjunga Landscape in eastern Nepal *** calculated communityweighted averages(reflecting dominant traits governing biomass,i.e.,mass-ratio effect)and functional divergence(reflecting increased trait variety,i.e.,complementarity effect)for leaf elements in a total of 1,859 trees representing 116 *** increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation.A combination of elements together with elevation explains biomass(52.2%of the variance)better than individual elemental trait diversity(0.05%to 21%of the variance).Elevation modulates trait diversity among plant species in biomass *** promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and *** interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation *** research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation *** higher trait variation enhances the adaptation of species to environmental changes,it reduces

关键词： ecosystem function Elevational gradient Functional diversity Functional traits Leaf elements Niche complementarity

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Evolutionary history resolves global organization of root functional traits (vol 555, pg 94, 2018)

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NATURE 2019年第7759期570卷 E25-E25页

作者： Ma, Zeqing Guo, Dali Xu, Xingliang Lu, Mingzhen Bardgett, Richard D. Eissenstat, David M. McCormack, M. Luke Hedin, Lars O. Center for Forest Ecosystem Studies and Qianyanzhou Ecological Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Department of Ecology and Evolutionary Biology Princeton University New Jersey USA School of Earth and Environmental Sciences The University of Manchester Manchester UK Department of Ecosystem Science and Management The Pennsylvania State University University Park USA Department of Plant and Microbial Biology University of Minnesota St Paul USA

We thank reader Joseph Craine for pointing out three inadvertent errors in this Letter. First, 4 of the 71 divergence dates extracted from ref. of this Amendment and used in Fig. 1b of the original Letter were overestimated. The correct values are 45 million years ago (Ma) for Apocynaceae, 51 Ma for Anacardiaceae, 40 Ma for Primulaceae, and 53 Ma for Amaryllidaceae. These errors had little influence on the overall trend of Fig. 1b (r is now 0.48 rather than 0.54, with no change to P < 0.001) and do not change our conclusion and inferences. Second, we neglected to note that since refs. and of this Amendment considered only angiosperms, our Fig. 1b necessarily did not include gymnosperm taxa. The in-text reference to Fig. 1b should therefore read "all major angiosperm plant families in our dataset" rather than "all major vascular plant families in our dataset". Third, in Fig. 1c the trait value of mycorrhizal colonization for Machilus kwangtungensis was erroneously given the value 0.25 instead of 1.0. This error had little influence on the overall Fig. 1c trend, reducing r from 0.64 to 0.63 (with no change to P < 0.001).

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