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The desertification process alters soil microbial metabolic limitations and their effects on soil carbon sequestration in a Tibetan alpine steppe

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Journal of Integrative Agriculture 2025年第03期 845-858页

作者： Jialuo Yu Peili Shi Ning Zong Yongxing Cui Ge Hou Xueying Chen Tiancai Zhou Xiaofang Huang key laboratory of ecosystem network Observation and modelling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences College of Resources and Environment University of Chinese Academy of Sciences Institute of Biology Free University of Berlin State key laboratory of Tibetan Plateau Earth System Resources and Environment (TPESRE) Institute of Tibetan Plateau Research Chinese Academy of Sciences

Tibetan alpine steppes are large and sensitive terrestrial carbon(C) reservoirs that are experiencing desertification due to global change and overgrazing, which can lead to stronger resource limitations for both above-and belowground communities. Soil nutrients, especially nitrogen(N) and phosphorus(P), are the crucial resources for plant growth and microbial metabolism. However, whether both plant and soil microbial communities in the degraded alpine steppes are limited by these soil nutrients remains unclear, which limits our understanding of the mechanisms of desertification and subsequent ecosystem restoration. Here, we evaluated potential nutrient limitations of the plant and soil microbial communities in the alpine steppe across five stages of desertification using stoichiometry-based approaches. Our results showed that soil microbial metabolism was mainly limited by C and P, and the plant N limitation and microbial C limitation were intensified while the microbial P limitation was relieved during ***–soil–microbe interactions had significant impacts on the microbial C and P limitations, explaining 72 and 61% of the variation, respectively. Specifically, desertification ultimately affected microbial metabolic limitations by regulating soil pH, soil nutrients, and the plant N limitation. Moreover, the microbial C limitation further reduced microbial C use efficiency(CUE) with desertification, which is detrimental for organic C retention in the degraded soil. Overall, this study revealed that microbial metabolic limitations through plant–microbe interactions were the key drivers affecting soil microbial CUE, and it provided insights that can advance our knowledge of the microbial regulation of nutrient cycles and C sequestration.

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Patterns of Soil ^(15)N and Total N and Their Relationships with Environmental Factors on the Qinghai-Tibetan Plateau

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Pedosphere 2014年第2期24卷 232-242页

作者： ZHOU Lei SONG Ming-Hua WANG Shao-Qiang FAN Jiang-Wen LIU Ji-Yuan ZHONG Hua-Ping YU Gui-Rui GAO Lu-Peng HU Zhong-Min CHEN Bin WU Wei-Xing SONG Ting key laboratory of ecosystem network Observation and modelling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences University of Chinese Academy of Sciences

The patterns of soil nitrogen （N） isotope composition at large spatial and temporal scales and their relationships to environmental factors illustrate N cycle and sources of N, and are integrative indicators of the terrestrial N cycle and its response to global change. The objectives of this study were： i） to investigate the patterns of soil N content and natural abundance of 15N （δ15N） values in different ecosystem types and soil profiles on the Qinghai-Tibetan Plateau; ii） to examine the effects of climatic factors and soil characteristics on the patterns of soil N content and soil δ15N values; and iii） to test the relationship between soil δ15N values and soil C/N ratios across ecosystems and soil profiles. Soil profiles were sampled at 51 sites along two transects 1 875 km in length and 200 km apart and distributed in forest, meadow and steppe on the Qinghai-Tibetan Plateau. Each site was sampled every 10 cm from a soil depth of 0 to 40 cm and each sample was analyzed for soil N content and δ15N values. Our results indicated that soil N and 515N values （0-40 cm） in meadows were much higher than in desert steppe. Soil N decreased with soil depth for each ecosystem, while variations of soil ~15N values along soil profiles were not statistically significant among most ecosystems but for mountain meadow, lowland meadow, and temperate steppe where soil δ15N values tended to increase with soil depth. The parabolic relationship between soil δ15N values and mean annual precipitation indicated that soil δ15N values increased with increasing precipitation in desert steppe up to 500 mm, and then decreased with increasing precipitation across all other ecosystems. Moreover, the parabolic relationship between δ15N values and mean annual temperature existed in all individual ecosystem types. Soil N and δ15N values （0-0 cm） increased with an increase in soil silt and clay contents. Furthermore, a threshold of C/N ratio of about 11 divided the parabolic relationship between soi

关键词： desert steppe nitrogen isotope composition nutrient availability soil nitrogen

Biomass Allocation Patterns of Alpine Grassland Species and Functional Groups along a Precipitation Gradient on the Northern Tibetan Plateau

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Journal of Mountain Science 2013年第6期10卷 1097-1108页

作者： WU Jian-shuang SHEN Zhen-xi ZHANG Xian-zhou SHI Pei-li Lhasa National Ecological Research Station Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of sciences

Variations in the fractions of biomass allocated to functional components are widely considered as plant responses to resource availability for grassland plants. Observations indicated shoots isometrically relates to roots at the community level but allometrically at the species level in Tibetan alpine grasslands. These differences may result from the specific complementarity of functional groups between functional components, such as leaf, root, stem and reproductive organ. To test the component complementary responses to regional moisture variation, we conducted a multi-site transect survey to measure plant individual size and component biomass fractions of common species belonging to the functional groups： forbs, grasses, legumes and sedges on the Northern Tibetan Plateau in peak growing season in 2010. Along the mean annual precipitation （MAP） gradient, we sampled 7o species, in which 2o are in alpine meadows, 20 in alpine steppes, 15 in alpine desert-steppes and 15 in alpine deserts, respectively. Our results showed that the size of alpine plants is small with individual biomass mostly lower than 1.0 g. Plants keep relative conservative component individual responses moisture functional fractions across alpine grasslands at the level. However, the complementary between functional components to variations specifically differ among groups. These results indicate that functional group diversity may be an effective tool for scaling biomass allocation patterns from individual up to community level. Therefore, it is necessary andvaluable to perform intensive and systematic studies on identification and differentiation the influences of compositional changes in functional groups on ecosystem primary services and processes.

关键词： Biomass fractions Complementaryresponse Functional components Functional groups Changtang Plateau

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China,2004-2010

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Journal of Environmental Sciences 2013年第5期25卷 1007-1014页

作者： Xinyu Zhang Zhiwei Xu Xiaomin Sun Wenyi Dong Deborah Ballantine key laboratory of ecosystem network Observation and modelling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences National Institute of Water and Atmospheric Research HamiltonNew Zealand

The nitrate-nitrogen（NO 3-N） concentrations from shallow groundwater wells situated in 29 of the Chinese ecosystem Research network field stations,representing typical agroand forest ecosystems,were assessed using monitoring data collected between 2004 and *** from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater,and allow linkages between nitrate concentrations in groundwater and broad land use categories to be *** indicated that most of the NO 3--N concentrations in groundwater from the agroand forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard：Quality Standard for Ground Water（≤ 20 mg/L）.Over the study period,the average NO 3--N concentrations were significantly higher in agro-ecosystems（4.1 ± 0.33 mg/L） than in forest ecosystems（0.5 ± 0.04 mg/L）.NO 3-N concentrations were relatively higher（〉 10 mg N /L） in 10 of the 43 wells sampled in the agricultural *** elevated concentrations occurred mainly in the Ansai,Yucheng,Linze,Fukang,Akesu,and Cele field sites,which were located in arid and semiarid areas where irrigation rates are *** suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

关键词： Chinese ecosystem Research network shallow groundwater agricultural forest ecosystems nitrate concentration

The Altitudinal Belts of Subalpine Virgin Forest on *** Simulated by a Succession Model

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Journal of Mountain Science 2014年第6期11卷 1560-1570页

作者： CHENG Gen-wei SUN Jian SHA Yu-kun FAN Ji-hui key laboratory of Mountain Surface Process and Ecological Regulation Institute of Mountain Hazard and EnvironmentChinese Academy of Sciences Synthesis Research Centre of Chinese ecosystem Research network Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences

How to accurately simulate the distribution of forest species based upon their biological attributes has been a traditional biogeographical *** gap models are very useful tools for examining the dynamics of forest succession and revealing the species structure of *** the present study,the GFSM(Gongga Forest Succession Model) was developed and applied to simulate the distribution,composition and succession process of forests in 100 m elevation *** results indicate that the simulated results of the tree species,quantities of the different types of trees,tree age and differences in DBH(diameter at breast height) composition were in line with the actual situation from 1400 to 3700 MASL(meters above sea level) on the eastern slope of ***,the dominant species in the simulated results were the same as those in the surveyed ***,the GFSM model can best simulate the features of forest dynamics and structure in the natural conditions of *** work provides a new approach to studying the structure and distribution characteristics of mountain ecosystems in varied ***,the results of this study suggest that the biogeochemistry mechanism model should be combined with the forestsuccession model to facilitate the ecological model in simulating the physical and chemical processes involved.

关键词： Subalpine forests Altitudinal belts Succession processes Forest gap model

Seasonal patterns of root and shoot interactions in an alpine meadow on the Tibetan Plateau

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Journal of Plant Ecology 2012年第2期5卷 182-190页

作者： Minghua Song Qiwu Hu Yuqiang Tian Hua Ouyang key laboratory of ecosystem network Observation and modelling Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China

Aims Numerous studies have showed that the balance between negative and positive plant–plant interactions shifted along environmental *** little is known how the positive or negative plant–plant interactions varied with temporal fluctuating habitat conditions and plant ontogenetic *** In a 2-year experiment,the four perennial grasses(Kobresia humilis,Stipa aliena,Elymus nutans and Saussurea superba)were grown under four interaction treatments(no root or shoot interaction,only shoot interaction,only root interaction,root and shoot interaction).Intensity of above-and belowground interactions is proposed to vary with the fluctuation of seasonal climatic conditions and soil available *** we report measurements of above-and belowground interactions during entire growing *** between plant interaction intensity and seasonal soil available N as well as habitat climate conditions was also *** findings Our experiment found that root interactions had negative effect on plant growth for the four species during growing ***,both negative and positive shoot interactions occurred among the four *** there being shoot facilitative effect for *** and ***,the full interaction was negative,suggested that root interaction take more important role on plant growth than that of shoot *** interaction between root and shoot effect varied as a function of species identity and growth *** weak correlation of plant interaction intensity to habitat environmental factors suggested that plant ontogenetic characteristics may be primary factors causing temporal variation in plant interaction.

关键词： competition facilitation growing season ontogenetic phase habitat environmental conditions

Carbon Balance in an Alpine Steppe in the Qinghai-Tibet Plateau

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Journal of Integrative Plant Biology 2009年第5期51卷 521-526页

作者： Zhi-Yong Pei Hua Ouyang Cai-Ping Zhou Xing-Liang Xu The Administrative Center for China's Agenda 21 Beijing 100038 China key laboratory of ecosystem network Observation and modelling Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China

Carbon fluxes were measured using a static chamber technique in an alpine steppe in the Qinghai-Tibet Plateau from July 2000 to July 2001. It was shown that carbon emissions decreased in autumn and increased in spring of the next year, with higher values in growth seasons than in winters. An exponential correlation （Ecarbon = 0.22（exp（0.09T）＋ In（0.31P ＋ 1））, R^2 = 0.77, P 〈 0.001） was shown between carbon emissions and environmental factors such as temperature （T） and precipitation （P）. Using the daily temperature （T） and total precipitation （R）, annual carbon emission from soil to the atmosphere was estimated to be 79.6 g C/m^2, 46% of which was emitted by microbial respiration. Considering an average net primary production of 92.5 g C/m^2 per year within the 2 year experiment, alpine steppes can take up 55.9 g CO2-C/m^2 per year. This indicates that alpine steppes are a distinct carbon sink, although this carbon reservoir was quite small.

关键词： alpine grassland carbon balance carbon flux net primary productivity Qinghai-Tibet Plateau

Drought Impacts on Vegetation Indices and Productivity of Terrestrial ecosystems in Southwestern China During 2001–2012

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Chinese Geographical Science 2018年第5期28卷 784-796页

作者： ZHOU Lei WANG Shaoqiang CHI Yonggang WANG Junbang College of Geography and Environmental Sciences Zhejiang Normal University key laboratory of ecosystem network Observation and modelling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences School of Earth & Atmospheric Sciences Georgia Institute of Technology

Drought, as a recurring extreme climate event, affects the structure, function, and process of terrestrial ecosystems. Despite the increasing occurrence and intensity of the drought in the past decade in Southwestern China, the impacts of continuous drought events on vegetation in this region remain unclear. During 2001–2012, Southwestern China experienced the severe drought events from 2009 to 2011. Our aim is to characterize drought conditions in the Southwestern China and explore the impacts on the vegetation condition and terrestrial ecosystem productivity. The Standardized Precipitation Index(SPI) was used to characterize drought area and intensity and a light-use efficiency model was used to explore the effect of drought on the terrestrial ecosystem productivity with Moderate Resolution Imaging Spectrometer(MODIS) data. The SPI captured the major drought events in Southwestern China during the study period, indicated that the 12-year period of this study included both ‘normal' precipitation years and two severe drought events in 2009–2010 and 2011. Results showed that vegetation greenness(Normalized Difference Vegetation Index, NDVI and Enhanced Vegetation Index, EVI) both declined in 2009/2010 drought, but the 2011 drought resulted in less declines of vegetation greenness and productivity due to shorten drought duration and rising temperature. Meanwhile, it was about 5 months lapse between drought events and maximum declines in vegetation greenness for 2009/2010 drought events. In addition, forest, grassland and cropland revealed significant different ecosystem responses to drought. It indicated that grassland showed an early sensitivity to drought, while cropland was the most sensitive to water deficit and forest was more resilient to drought. This study suggests that it is necessary to detect the difference responses of ecosystem to drought in a regional area with satellite data and ecosystem model.

关键词： drought Standardized Precipitation Index(SPI) vegetation indices Net Primary Productivity(NPP) Southwestern China

Carbon Sequestration in Two Alpine Soils on the Tibetan Plateau

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Journal of Integrative Plant Biology 2009年第9期51卷 900-905页

作者： Yu-Qiang Tian Xing-Liang Xu Ming-Hua Song Cai-Ping Zhou Qiong Gao Hua Ouyang College of Resources Science & Technology State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing 100875 China key laboratory of ecosystem network Observation and modelling Institute of Geographic Sciences and Natural Resources Research the Chinese Academy of Sciences Beijing 100101 China

Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon- 14 radioactive label provided by thermonuclear weapon tests （known as bomb-^14C）. Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb-^14C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil. Based on the depth of the bomb-^14C spike, the carbon sequestration rate was determined to be 38.5 g C/m^2 per year for the forest soil and 27.1 g C/m^2 per year for the alpine meadow soil. Considering that more than 60% of soil organic carbon （SOC） is stored in the heavy fraction and the large area of alpine forests and meadows on the Tibetan Plateau, these alpine ecosystems might partially contribute to ＂the missing carbon sink＂.

关键词： alpine soils bomb carbon carbon sequestration soil organic carbon.