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Diversity loss and light limitation threaten the sustainability of ecosystem productivity gains under nitrogen enrichment

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Science of the Total Environment 2025年 958卷 177960页

作者： Zhang, Wenshuo Li, Tingting Li, Jiawen Zhang, Ruiyang Xu, Li Wang, Jinsong Hu, Jian Niu, Shuli Tian, Dashuan Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research CAS Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China College of Life Sciences China West Normal University Nanchong637009 China Sichuan Zoige Alpine Wetland Ecosystem National Observation and Research Station Southwest Minzu University Chengdu610041 China

Plant photosynthesis significantly regulates atmospheric CO₂ but is often limited by nitrogen (N) availability. While N deposition could alleviate this limitation and enhance gross ecosystem productivity (GEP), its long-term effects are uncertain due to potential negative impacts like biodiversity loss and soil acidification. Yet, many long-term N addition experiments emphasize community biomass over gross GEP. Here, we conducted a six-year N addition experiment in an alpine meadow, frequently monitoring GEP, community structure, aboveground net primary productivity (ANPP)and plant traits. We found that N addition significantly enhanced GEP in the first three years, but during 4–6 years this effect disappeared. We further disentangled the mechanisms affecting GEP into biomass-based and non-biomass-based processes. The latter is expressed as biomass-specific GEP, defined as GEP per unit biomass. Differing with GEP, biomass-specific GEP provides a metric of carbon assimilation efficiency normalized to biomass. Unlike previous studies, we found that it was not ANPP, but specific GEP that determined the loss of the short-term N effect. ANPP showed a consistent increase under N addition, whereas specific GEP decreased in the last three years. This specific GEP reduction was primarily regulated by biodiversity loss and increased light limitation under N addition. Overall, our findings suggest that short-term benefits of N deposition on GEP are not sustained in long term, highlighting the need to explore the non-biomass-based mechanisms to better predict ecosystem responses to prolonged N enrichment. © 2024 Elsevier B.V.

关键词： Anthropogenic

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Analysis of Methane Emission Characteristics and Environmental Response in Natural Wetlands

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SSRN 2023年

作者： Li, Jinshuai Hao, Tianxiang Yang, Meng Chen, Zhi Zhu, Jianxing Wang, Qiufeng Guirui, Yu Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China College of Resources and Environment University of Chinese Academy of Sciences Beijing China

Wetlands are the most important natural source of methane emissions. Methane emission from wetlands is the result of the synergy of biotic and abiotic factors, and there are three main forms of emission: diffusion, ebullition and plant-mediated. Among them, the plant-mediated methane emission process is an important carbon exchange pathway at the land‒air interface. However, there is a lack of direct observations and side-by-side comparisons of methane emissions from different vegetation types. The environmental response characteristics of methane emissions from different vegetation types are still poorly understood. Based on the FLUXNET-CH4 dataset and the Global Standard Soil Database, we analyzed the environmental response characteristics of methane emissions from wetlands and clarified the important role of wetland plants in methane emission. The analysis results showed that water table depth (WTD) and temperature were the main determinants of wetland methane emissions, but plant-mediated emission processes were the main reason for the high heterogeneity of methane emissions. We categorized wetlands into vascular plant wetlands (VPWs) and moss plant wetlands (MPWs). VPW methane emissions were typically higher and more heterogeneous, whereas MPW methane emissions were lower and less variable. Radiation was the main factor affecting VPW methane emissions, and temperature was the main factor affecting MPW methane emissions. Finally, we constructed a structural equation model of methane emissions from wetlands, and our results suggested that warming increases wetland methane emissions via multiple pathways. These findings highlight the important role of wetland vegetation in methane emissions, which should be seriously considered to help further reduce uncertainty in the assessment of wetland methane emissions. © 2023, The Authors. All rights reserved.

关键词： Methane

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Plant use of water across soil depths regulates species dominance under nitrogen addition

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Plant Diversity 2025年第03期 479-488页

作者： Fu-Qiang Huang Josep Pe?uelas Jordi Sardans Scott L.Collins Kai-Liang Yu Man-Qiong Liu Jiu-Ying Pei Wen-Bin Ke Jian-Sheng Ye State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems College of Ecology Lanzhou University CSIC Global Ecology Unit CREAF-CSIC-UAB CREAF Cerdanyola del Vallès Department of Biology University of New Mexico Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

The primary mechanism driving plant species loss after nitrogen（N） addition has been often hypothesized to be asymmetric competition for light, resulting from increased aboveground biomass. However, it is largely unknown whether plants' access to soil water at different depths would affect their responses,fate, and community composition under nitrogen addition. In a semiarid grassland exposed to 8-years of N addition, we measured plant aboveground biomass and diversity under four nitrogen addition rates(0,4, 10, and 16 g m-2year-1), and evaluated plant use of water across the soil profile using oxygen *** biomass increased significantly, but diversity and shallow soil-water content decreased,with increasing rate of nitrogen addition. The water isotopic signature for both plant and soil water at the high N rate indicated that Leymus secalinus（a perennial grass） absorbed 7% more water from the subsurface soil layer（20-100 cm） compared to Elymus dahuricus（a perennial grass） and Artemisia annua（an annual forb）. L. secalinus thus had a significantly larger biomass and was more abundant than the other two species at the high N rate but did not differ significantly from the other two species under ambient and the low N rate. Species that could use water from deeper soil layers became dominant when water in the shallow layers was insufficient to meet the demands of increased aboveground plant biomass. Our study highlights the importance of water across soil depths as key driver of plant growth and dominance in grasslands under N addition.

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Variations of Vegetation Phenology Extracted from Remote Sensing Data over the Tibetan Plateau Hinterland during 2000–2014

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Journal of Meteorological Research 2020年第4期34卷 786-797页

作者： Ya LIU Junbang WANG Jinwei DONG Shaoqiang WANG Hui YE Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural ResourcesChinese Academy of SciencesBeijing 100101 Key Laboratory of Watershed Geographic Sciences Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008

How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day moderate resolution imaging spectroradiometer(MODIS) normalized difference vegetation index(NDVI) data for 2000-2014 in the Three-River Source Region(TRSR) of Qinghai Province, China, i.e., the hinterland of the Tibetan Plateau, we extracted relevant vegetation phenological information(e.g., start, end, and length of growing season) and analyzed the changes in the TRSR vegetation in response to climate change. The results reveal that, under the increasingly warm and humid climate, the start of vegetation growing season(SOS) advanced 1.03 day yr-1 while the end of vegetation growing season(EOS) exhibited no significant changes, which led to extended growing season length. It is found that the SOS was greatly affected by the preceding winter precipitation, with progressively enhanced precipitation facilitating an earlier SOS. Moreover, as the variations of SOS and its trend depended strongly on topography, we estimated the elevation break-points for SOS. The lower the elevations were, the earlier the SOS started. In the areas below 3095-m elevation, the SOS delay changed rapidly with increasing elevation;whereas above that, the SOS changes were relatively minor. The SOS trend had three elevation break-points at 2660, 3880, and 5240 m.

关键词： Three-River Source Region(TRSR) start of vegetation growing season(SOS) spatiotemporal change elevation climate change China

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Changes in leaf stomatal traits of different aged temperate forest stands

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Journal of Forestry Research 2021年第3期32卷 927-936页

作者： Qian Li Jihua Hou Nianpeng He Li Xu Zihao Zhang Beijing Key Laboratory of Forest Resources and Ecosystem Processes Beijing Forestry UniversityBeijing 100083People’s Republic of China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China College of Resources and Environment University of Chinese Academy of SciencesBeijingPeople’s Republic of China Key Laboratory of Vegetation Ecology Ministry of EducationNortheast Normal UniversityChangchunPeople’s Republic of China

Stomata control carbon and water vapor exchange between the leaves and the atmosphere,thus infl uencing photosynthesis and *** of forest patches with different stand ages are common in nature,however,information of which stomatal traits vary among these stands and how,remains ***,seven different aged forest stands(6,14,25,36,45,55,and 100 years)were selected in typical temperate,mixed broadleaf-conifer forests of northeast *** density,size and relative area of 624 species,including the same species in stands of different ages were *** density,size and relative area were distributed log-normally,differing across all species and plant functional *** density ranged from 4.2 to 1276.7 stomata mm^(–2),stomatal size ranged from 66.6 to 8315.7μm^(2),and stomatal relative area 0.1–93.3%.There was a significant negative relationship between density and size at the species and functional group levels,while the relative stomatal area was positively correlated with density and *** traits of dominant species were relatively stable across different stand ages but were significantly different for *** results suggest that stomatal traits remain relatively stable for dominant species in natural forests and therefore,spatial variation in stomatal traits across forest patches does not need to be incorporated in future ecological models.

关键词： Forest restoration Stomatal traits Stand age Plant functional groups Variation

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Vertical distribution changes in land cover between 1990 and 2015 within the Koshi River Basin,Central Himalayas

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Journal of Geographical Sciences 2021年第10期31卷 1419-1436页

作者： WU Xue PAUDEL Basanta ZHANG Yili LIU Linshan WANG Zhaofeng XIE Fangdi GAO Jungang SUN Xiaomin Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Texas A&M AgriLife Blackland Res&Extens CtrTempleTX 76502USA

The study of mountain vertical natural belts is an important component in the study of regional *** areas are especially sensitive to climate change and have indicative function,which is the core of three-dimensional zonality ***,based on high precision land cover and digital elevation model(DEM)data,and supported by MATLAB and ArcGIS analyses,this paper aimed to study the present situation and changes of the land cover vertical belts between 1990 and 2015 on the northern and southern slopes of the Koshi River Basin(KRB).Results showed that the vertical belts on both slopes were markedly different from one *** vertical belts on the southern slope were mainly dominated by cropland,forest,bare land,and glacier and snow *** contrast,grassland,bare land,sparse vegetation,glacier and snow cover dominated the northern *** found that the main vertical belts across the KRB within this region have not changed substantially over the past 25 *** contrast,on the southern slope,the upper limits of cropland and bare land have moved to higher elevation,while the lower limits of forest and glacier and snow cover have moved to higher *** upper limit of alpine grassland on the northern slope retreated and moved to higher elevation,while the lower limits of glacier and snow cover and vegetation moved northward to higher *** in the vertical belt were influenced by climate change and human activities over *** was mainly controlled by human activities and climate warming,and the reduced precipitation also led to the abandonment of cropland,at least to a certain *** in grassland and forest ecosystems were predominantly influenced by both human activities and climate *** the same time,glacier and snow cover far away from human activities was also mainly influenced by climate warming.

关键词： vertical belt land cover Central Himalayas Koshi River Basin climate change

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Strong Inhibiting Effect of Daytime Warming But Weak Promoting Effect of Nighttime Warming on Carbon Use Efficiency in Northern Hemisphere

SSRN

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SSRN 2023年

作者： Sun, Yihan Zhang, Yangjian Zheng, Zhoutao Zhao, Guang Zhu, Yixuan Gao, Jie Zhang, Yu 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 Beijing100190 China

Asymmetric diurnal warming broadly affects terrestrial ecosystem carbon cycling in the Northern Hemisphere. Vegetation photosynthesis mostly occurs in the daytime and respiration occurs during the whole day. Then the asymmetrical diurnal warming will certainly affect the ratio between net ecosystem productivity (NPP) against gross ecosystem productivity (GPP), i.e. vegetation carbon use efficiency (CUE). However, this kind of study has rarely been reported on a global scale. Using long-term productivity datasets from MODIS and land surface models, we investigated spatiotemporal response patterns of CUE to daytime (Tmax) and nighttime (Tmin) temperature changes across the Northern Hemisphere (>30°N) spanning 2000-2019. Regions exhibiting a positive correlation between Tmax and CUE were extensive throughout the growing season in most northern ecosystems, with a greater magnitude in summer than in spring and autumn. Tmin tended to cause a positive impact on CUE in spring and autumn, while being correlated negatively with summer CUE, resulting in a weak positive relationship between CUE and Tmin. Divergences in the strength and direction of productivity and respiratory responses to diurnal warming lead to spatial and seasonal patterns between CUE and Tmax or Tmin, which is regulated by soil moisture. Our findings provide an in-depth understanding of how the interaction between asymmetric diurnal warming and water limitations regulates the spatiotemporal variations of vegetation product allocation, which is vital for predicting future carbon dynamics under climate warming. © 2023, The Authors. All rights reserved.

关键词： Vegetation

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Regional coupled C-N-H2O cycle processes and associated driving mechanisms

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Science China Earth Sciences 2020年第9期63卷 1227-1236页

作者： Yang GAO Gui-Rui YU Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

From a molecular level to an ecosystem scale,different coupling mechanisms take place during coupled carbonnitrogen-water(C-N-H2O)cycle,of which essential are water flux and related biogeochemical processes through physicochemical reactions associated with terrestrial and aquatic ***,regional coupled C-N-H2O cycle will subsequently impact regional gross primary productivity(GPP)and C and N exchanges during air-water interactions that occur downstream of *** study aimed to first synthetically analyze the regional dynamics of C,N and H2O cycles in ecosystems and determine their interactional relationships;second,to specify regional C-N-H2O coupled relationships of ecosystems and their theoretical ecological principles;third,to classify coupled regional response and adaptation of the C-N-H2O cycle to climatic and environmental changes under anthropogenic activities,providing a theoretical basis to fully understand and make adjustments to interactional C,N and H2O cycling relationships at different ecosystem scales and under associated coupling processes.

关键词： Regional C-N-H2O cycle Coupled relationship C cycle N cycle Water cycle Driving mechanisms

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Significant Difference between Temporal and Spatial Scales Regarding the Response of Soil Respiration to Temperature and Precipitation in China's Terrestrial ecosystems

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SSRN 2023年

作者： Zhao, Wei Yang, Meng Yu, Guirui Chen, Zhi Wang, Qiufeng 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

In the context of increasing CO2 concentrations and climate warming, there are large uncertainties regarding the regulatory mechanisms of soil respiration and its accurate assessment. As an area sensitive to global climate change, China covers a broad range of longitudes, latitudes, and altitudes, and it is of great significance to study the spatial and temporal patterns of soil respiration and its environmental response in China's terrestrial ecosystems to clarify the mechanisms of regional and global carbon balance processes and their assessment. Based on the expanded annual soil respiration dataset from 1993 to 2020, we re-evaluated soil respiration in China's terrestrial ecosystems and its responses to environmental factors. The mean annual soil respiration in China's terrestrial ecosystems was 777.90 ± 489.43 g C m-2 yr-1, with soil respiration in wetlands being higher than that of the forest, grassland, shrubland, cropland, and desert. Soil respiration showed a significant upward trend between 1993 and 2020, which was mainly caused by a significant increase in soil respiration in grasslands due to increasing precipitation. In addition, we found differences in the environmental factors influencing the interannual and spatial variability of soil respiration. MAP dominated the interannual variability of soil respiration in China, whereas MAT and MAP jointly controlled the spatial variability of soil respiration in China. The response sensitivity of soil respiration to interannual climate variability was significantly higher than its response sensitivity to spatial variability, possibly one of the reasons for the relatively low accuracy of the present statistical models, which do not distinguish between temporal and spatial responses. More studies are needed to quantify the response of soil respiration to environmental changes at temporal and spatial scales and to construct soil respiration models considering two-dimensional responses in time and space. © 2023, Th

关键词： Climate change

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人为管理措施诱导土壤微生物磷与土壤微生物碳氮内稳态解耦的代谢证据

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Journal of Plant Ecology 2023年第6期16卷 185-196页

作者： Lihua Zhang Lizhi Jia Liyuan He David A.Lipson Yihui Wang Shunzhong Wang Xiaofeng Xu College of Life and Environmental Sciences Minzu University of ChinaBeijing 100081China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Biology Department San Diego State UniversitySan DiegoCA 92182USA

微生物化学计量学理论能够预测微生物对碳(C)、氮(N)、磷(P)的同化作用具有比例耦合性。这种耦合性被量化为稳态值,用于计算内稳性系数(H)。C、N、P的H值协变量表明,微生物对C、N、P的同化作用是耦合的。因此,在本文中我们利用全球数据... 详细信息

微生物化学计量学理论能够预测微生物对碳(C)、氮(N)、磷(P)的同化作用具有比例耦合性。这种耦合性被量化为稳态值,用于计算内稳性系数(H)。C、N、P的H值协变量表明,微生物对C、N、P的同化作用是耦合的。因此,在本文中我们利用全球数据集研究微生物C、N、P的H值在不同生物群落中的时空动态变化。研究结果表明,土地利用和人为管理措施导致P与C、N的代谢在时间和空间上解耦,并且我们利用结构方程模型(SEM)分析结果表明,土壤因子主导P的微生物动态平衡,而土壤元素含量则主导C和N的微生物动态平衡。利用机器学习算法得出的微生物P与微生物C和N的对比因子也证实了这一结果。总的来说,我们的研究强调了在营养循环中人为管理措施对微生物角色转变具有重要的影响。

关键词：碳氮磷微生物的内稳性管理措施

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