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Effects of Elevated Air Temperatures on Soil Thermal and Hydrologic Processes in the Active Layer in an Alpine Meadow Ecosystem of the Qinghai-Tibet Plateau

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Journal of Mountain Science 2012年第2期9卷 243-255页

作者： BAI Wei wang genxu LIU Guangsheng School of Environmental and Municipal Engineering Lanzhou Jiaotong UniversityLanzhou 730070China College of Resource and Environmental Science Lanzhou UniversityLanzhou 730000China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

In this study,effects of elevated air temperatures on thermal and hydrologic process of the shallow soil in the active layer were investigated. Open-top chambers(OTCs)were utilized to increase air temperatures 1-2℃ in OTC-1 and 3-5℃ in OTC-2 in the alpine meadow ecosystem on the Qinghai- Tibetan *** show that the annual air temperatures under OTC-1 and OTC-2 were 1.21℃ and 3.62℃ higher than the Control,*** entirely-frozen period of shallow soil in the active layer was shortened and the fully thawed period was prolonged with temperature *** maximum penetration depth and duration of the negative isotherm during the entirely-frozen period decreased, and soil freezing was retarded in the local scope of the soil profile when temperature ***, the positive isotherm during the fully-thawed period increased,and the soil thawing was *** moisture under different manipulations decreased with the temperature increase at the same depth. During the early freezing period and the early fully- thawed period,the maximum soil moisture under the Control manipulation was at 0.2 m deep,whereas under OTC-1 and OTC-2 manipulations,the maximum soil moisture were at 0.4-0.5 m deep. These results indicate that elevated temperatures led to a decrease of the moisture in the surface *** coupled relationship between soil temperature and moisture was significantly affected by the temperature *** the freezing and thawing processes, the soil temperature and moisture under different manipulations fit the regression model given by the equationθV=a/{1+exp[b(TS+c)]}+d.

关键词： Thermal and hydrologic process Temperature Open-top chambers Alpine meadow Qinghai-Tibetan Plateau

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Linkage between permafrost distribution and river runoff changes across the Arctic and the Tibetan Plateau

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Science China Earth Sciences 2020年第2期63卷 292-302页

作者： Chunlin SONG genxu wang Tianxu MAO Junchen DAI Daqing YANG Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China College of Forestry Guizhou UniversityGuiyang 550025China National Hydrology Research Centre Environment CanadaSaskatoon SK S7N 3H5Canada

River runoff in the Arctic and the Tibetan Plateau(TP) change significantly in recent decades. However, the mechanisms of the physical processes of permafrost river runoff change remain uncertain across large scale. This study investigated the mainstreams and tributaries of main Arctic and TP rivers dominated by permafrost and assessed the linkage between hydrological regime change and permafrost. The results show that the effects of permafrost on river runoff are highly dependent on the permafrost coverage of a watershed. For the past decades, the majority of the Arctic and TP basins showed increased discharge, while all of the studied basins showed increased baseflow, with faster increasing speed than total *** total discharge and baseflow annual change rate(ΔQ and ΔBF) increased with permafrost coverage, indicating the increments of streamflow are enhanced with high permafrost coverage. Meanwhile, the annual change of precipitation showed weak connection with total discharge and baseflow change. The high permafrost coverage basins showed high annual maximum/minimum discharge ratio(Qmax/Qmin), while the Qmax/Qminchanged slightly in low permafrost cover basins. Our results highlight the importance of permafrost coverage on streamflow regime change for permafrost basins across the northern hemisphere. Due to these linkage between permafrost extent and runoff regime change and the increasing changes of permafrost, more attention should be paid to the change of hydrological processes in permafrost-underlain basins.

关键词： Permafrost hydrology Arctic rivers Tibetan Plateau rivers Permafrost degradation Runoff change

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Short-term effects of nitrogen deposition on soil respiration components in two alpine coniferous forests, southeastern Tibetan Plateau

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Journal of Forestry Research 2019年第3期30卷 1029-1041页

作者： Jian wang genxu wang Yu Fu Xiaopeng Chen Xiaoyan Song Land and Resource College China West Normal University Nanchong 637002SichuanPeople’s Republic of China Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of Sciences#9Block 4 Renminnanlu RoadWuhou DistrictChengdu 610041 People’s Republic of China Department of Politics and Administration China West Normal UniversityNanchong 637002SichuanPeople’s Republic of China Graduate University of Chinese Academy of Sciences Beijing 100049People’s Republic of China

Nitrogen (N) deposition to alpine forest ecosystems is increasing gradually, yet previous studies have seldom reported the effects of N inputs on soil CO2 flux in these ecosystems. Evaluating the effects of soil respiration on N addition is of great significance for understanding soil carbon (C) budgets along N gradients in forest ecosystems. In this study, four levels of N (0, 50, 100, 150 kg N ha^-1 a^-1) were added to soil in a Picea baifouriana and an Abies georgei natural forest on the Tibetan Plateau to investigate the effect of the N inputs on soil respiration. N addition stimulated total soil respiration (Rt) and its components including heterotrophic respiration (Rh) and autotrophic respiration (Ra);however, the promoted effects declined with an increase in N application in two coniferous forests. Soil respiration rate was a little greater in the spruce forest (1.05 μmol CO2 m^-2 s^-1) than that in the fir forest (0.97 μmol CO2 m^-2 s^-1). A repeated measures ANOVA indicated that N fertilization had significant effects on Rt and its components in the spruce forest and Rt in the fir forest, but had no obvious effect on Rh or Ra in the fir forest. Rt and its components had significant exponential relationships with soil temperature in both forests. N addition also increased temperature sensitivity (Q10) of Rt and its components in the two coniferous forests, but the promotion declined as N in put increased. Important, soil moisture had great effects on Rt and its components in the spruce forest (P0.05). Following N fertilization, Ra was significantly and positively related to fine root biomass, while Rh was related to soil enzymatic activities in both forests. The mechanisms underlying the effect of simulated N deposition on soil respiration and its components in this study may help in forecasting C cycling in alpine forests under future levels of reactive N deposition.

关键词： N addition Heterotrophic soil respiration Autotrophic soil respiration Q10 Alpine forest ecosystem

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Influences of the degradation of swamp and alpine meadows on CO_2 emission during growing season on the Qinghai-Tibet Plateau

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Chinese Science Bulletin 2007年第18期52卷 2565-2574页

作者： wang JunFeng wang genxu wang YiBo LI YuanShou College of Earth and Environment Sciences Lanzhou University Lanzhou 730000 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Cold and Arid Regions Environment and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

CO2 emission fluxes of two types of ecosystem, swamp meadow and alpine meadow, in the Fenghuo- shan region of the Qinghai-Tibet Plateau were studied by the static chamber-portable infrared chro- matographic method. The results showed that there was large difference in the CO2 emission fluxes between the two ecosystems and in the same ecosystem of different degradation degrees. CO2 emis- sion flux of the swamp meadow gradually decreased with increasing degradation degree, while that of the alpine meadow gradually increased with increasing degradation degree except in May. The CO2 emission flux of undegraded swamp meadow was 65.1%―80.3% higher than that of undegraded alpine meadow; and the CO2 emission flux of moderately degraded swamp meadow was 22.1%―67.5% higher than that of alpine meadow; but the CO2 emission flux of severely degraded alpine meadow was 14.3%―29.5% higher than that of swamp meadow. The soil moisture content and temperature in the upper 5 cm soil layer and above-ground biomass were significantly correlated with the CO2 emission fluxes and regarded as the main environment factors to control the CO2 emission.

关键词：青藏高原沼泽草甸高山草甸生长季节二氧化碳释放量降解

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Influence of short-term experimental warming on heat-waterprocesses of the active layer in a swamp meadow ecosystemof the Qinghai-Tibet Plateau

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Research in Cold and Arid Regions 2016年第2期8卷 125-134页

作者： GuangSheng Liu genxu wang College of Environmental Science and Engineering Xiamen University of TechnologyXiamenFujian 361024China Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengduSichuan 610041China

Climate change is now evident in the Qinghai-Tibet Plateau(QTP), with impacts on the alpine ecosystem, particularly on water and heat balance between the active layer and the atmosphere. Thus, we document the basic characteristics of changes in the water and heat dynamics in response to experimental warming in a typical alpine swamp meadow ecosystem. Data sets under open top chambers(OTC) and the control manipulations were collected over a complete year. The results show that annual(2008) air temperatures of OTC-1 and OTC-2 were 6.7 °C and 3.5 °C warmer than the control. Rising temperature promotes plant growth and development. The freeze-thaw and isothermal days of OTCs appeared more frequently than the control, owing to comparably higher water and better vegetation conditions. OTCs soil moisture decreased with the decrease of soil depth; however, there was an obviously middle dry aquifer of the control, which is familiar in QTP. Moreover, experimental warming led to an increase in topsoil water content due to poorly drained swamp meadow ecosystem with higher organic matter content and thicker root horizons. The results of this study will have some contributions to alpine cold ecosystem water-heat process and water cycle under climate change.

关键词： experimental warming open top chamber Qinghai-Tibet Plateau soil moisture soil temperature alpine swamp meadow ecosystem

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Response of Biomass Spatial Pattern of Alpine Vegetation to Climate Change in Permafrost Region of the Qinghai-Tibet Plateau,China

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Journal of Mountain Science 2010年第4期7卷 301-314页

作者： ZHANG Yu wang genxu wang Yibo College of Resources & Environment Lanzhou UniversityLanzhou 730000China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

Alpine ecosystems in permafrost region are extremely sensitive to climate *** determine spatial pattern variations in alpine meadow and alpine steppe biomass dynamics in the permafrost region of the Qinghai-Tibet Plateau,China,calibrated with historical datasets of above-ground biomass production within the permafrost region's two main ecosystems,an ecosystem-biomass model was developed by employing empirical spatialdistribution models of the study region's precipitation,air temperature and soil *** model was then successfully used to simulate the spatio-temporal variations in annual alpine ecosystem biomass production under climate *** a 0.44°C decade-1 rise in air temperature,the model predicted that the biomasses of alpine meadow and alpine steppe remained roughly the same if annual precipitation increased by 8 mm per decade-1,but the biomasses were decreased by 2.7% and 2.4%,respectively if precipitation was *** a 2.2°C decade-1 rise in air temperature coupled with a 12 mm decade-1 rise in precipitation,the model predicted that the biomass of alpine meadow was unchanged or slightly increased,while that of alpine steppe was increased by 5.2%.However,in the absence of any rise in precipitation,the model predicted 6.8% and 4.6% declines in alpine meadow and alpine steppe biomasses,*** response of alpine steppe biomass to the rising air temperatures and precipitation was significantly lesser and greater,respectively than that of alpine meadow biomass.A better understanding of the difference in alpine ecosystem biomass production under climate change is greatly significant with respect to the influence of climate change on the carbon and water cycles in the permafrost regions of the Qinghai-Tibet Plateau.

关键词： Permafrost change Qinghai-TibetanPlateau Alpine ecosystem Grassland biomass Climate change Response model

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Energy Balance of Irrigated Intercropping Field in the Middle Reaches of Heihe River Basin

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Chinese Geographical Science 2006年第3期16卷 243-248页

作者： WU Jinkui DING Yongjian wang genxu SHEN Yongping Yusuke YAMAZAKI Jumpei KUBOTA Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China The Laboratory of Climate Study of China Meteorological Administration Beijing 100041 China Research Institute for Humanity and Nature Kyoto 602-0778 Japan

Based on the experiments conducted in an irrigated intercropping field in Zhangye Oasis in the middle reaches of Heihe River basin in 2004, the characteristics of radiation budget are analyzed. Furthermore, energy balance is cal- culated by using Bowen-Ratio Energy Balance (BREB) method. The results show that the ratio of the absorbed radiation to the incoming short radiation in intercropping crop canopy-soil system is increasing with growing stages, from 0.81 in the initial growing stage (IGS) to 0.86 in the late growing stage (LGS). The net radiation, which is smaller in IGS, in- creases rapidly in the first period of the middle growing stage (MGS) and reaches the maximum value in the second period of MGS. It then somewhat decreases in LGS. The ratio of net radiation to total radiation has a similar trend with the net radiation. In the whole growing stages, latent heat flux, which takes up 70% or so of the net radiation, is the dominant item in energy balance. Sensible heat flux shares 20% of the net radiation and soil heat flux has a percentage of 10%. The characteristics of heat balance vary distinctly in different growing stages. In IGS, the ratios of latent heat flux, sensible heat flux and soil heat flux to net radiation are 44.5%, 23.8% and 31.7% respectively. In MGS, with the in- creasing of latent heat flux and the decreasing of sensible heat flux and soil heat flux, the ratios turn into 84.4%, 6.3% and 9.3%. In LGS, the soil heat flux maintains 0W/m2 or so, and latent heat flux and sensible heat flux take up 61.4% and 38.6% respectively. The energy balance also shows an obvious daily variation characteristic.

关键词： radiation budget energy balance intercropping field Heihe River basin

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Response of soil heat-water processes to vegetation cover on the typical permafrost and seasonally frozen soil in the headwaters of the Yangtze and Yellow Rivers

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Chinese Science Bulletin 2009年第7期54卷 1225-1233页

作者： HU HongChang wang genxu wang YiBo LIU GuangSheng LI TaiBing REN DongXing College of Resources and Environment Lanzhou University Lanzhou 730000 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China

The response of soil temperature and moisture to vegetative cover in the active layer of permafrost and seasonally frozen soil were assessed and compared. Soil temperature and moisture, under a range of vegetation covers (92%, 65% and 30%) in the permafrost and vegetation covers (95%, 70%―80%, 40%―50% and 10%) in the seasonally frozen soil, were measured on a daily basis. A decline in vege-tation cover led to a decrease in the integral of freezing depth of active permafrost layer, but an increase in seasonally frozen soil. The maximum invasion depth and duration of the negative isotherm during the frozen period and of the positive isotherm during the non-frozen period clearly increased when vegetation cover declined. With a reduction of vegetation cover, the soil moisture in the active layer of the permafrost decreased for depths of 0.20―0.60 m, but increased for depths of 0.60―0.80 m, while for seasonally frozen soil, soil moisture of the entire profile (0.10―1.20 m) increased. Variation in vegetation cover alters soil heat-water processes, but the response to it is different between permafrost and seasonally frozen soil.

关键词：季节性冻土植被覆盖度永久冻土层土壤水分土壤热进程黄河长江

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Seasonal dynamics of suprapermafrost groundwater and its response to the freeing-thawing processes of soil in the permafrost region of Qinghai-Tibet Plateau

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Science China Earth Sciences 2015年第4期58卷 727-738页

作者： CHANG Juan wang genxu LI ChunJie MAO TianXu College of Earth and Environment Science Lanzhou University Institute of Mountain Hazards and Environment Chinese Academy of Sciences

The suprapermafrost groundwater in permafrost region not only is an important component of the water cycle and land surface process, but also is closely associated with the charges of ecological environment in cold region. However, the seasonal dynamics, driving factors, and mechanism of suprapermafrost groundwater are not well understood. Based on observation at slope scale on suprapermafrost groundwater dynamics of typical alpine meadows in the Qinghai-Tibet Plateau, the seasonal dynamics, spatial distribution and driving factors of suprapermafrost groundwater were analyzed. The results showed that there were close relationships between the seasonal dynamics of suprapermafrost groundwater and the freezing-thawing processes of active soil in permafrost region. The seasonal dynamics of suprapermafrost groundwater and its slope distribution pattern were controlled by soil temperature of active layers. The phase and range of the suprapermafrost groundwater dynamics are determined by deep soil(below 60 cm depth) moisture and groundwater recharging sources. The relationship between active soil temperatures and dynamics of suprapermafrost groundwater levels was better described by Boltzmann functions. However, the influencing thresholds of soil temperature on groundwater dynamics varied at different depths of active layers and in different slope positions, which resulted in the significant spatial heterogeneity of suprapermafrost groundwater dynamics in slope scale. Land cover change and global warming certainly altered the dynamics of suprapermafrost groundwater and the hydraulic interaction between groundwater and rivers, and consequently altered the overall hydrologic cycle of watershed scale.

关键词： suprapermafrost groundwater seasonal dynamics soil hydrothermal characteristics freezing-thawing process

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Estimates of net primary productivity and actual evapotranspiration over the Tibetan Plateau from the Community Land Model version 4.5 with four atmospheric forcing datasets

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Journal of Plant Ecology 2024年第4期17卷 70-89页

作者： Shan Lin Kewei Huang Xiangyang Sun Chunlin Song Juying Sun Shouqin Sun genxu wang Zhaoyong Hu State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu 610065China Hubei Key Laboratory of Basin Water Security Changjiang SurveyPlanningDesign and Research Co.Ltd.Wuhan 430010China Research Unit Forest Dynamics Swiss Federal Research Institute for ForestSnow and Landscape Research WSLBirmensdorf 8903Switzerland

The accuracy of the simulation of carbon and water processes largely relies on the selection of atmospheric forcing datasets when driving land surface models(LSM).Particularly in high-altitude regions,choosing appropriate atmospheric forcing datasets can effectively reduce uncertainties in the LSM ***,this study conducted four offline LSM simulations over the Tibetan Plateau(TP)using the Community Land Model version 4.5(CLM4.5)driven by four state-of-the-art atmospheric forcing *** performances of CRUNCEP(CLM4.5 model default)and three other reanalysis-based atmospheric forcing datasets(***,GSWP3 and WFDEI)in simulating the net primary productivity(NPP)and actual evapotranspiration(ET)were evaluated based on in situ and gridded reference *** with in situ observations,simulated results exhibited determination coefficients(R2)ranging from 0.58 to 0.84 and 0.59 to 0.87 for observed NPP and ET,respectively,among which GSWP3 and ITPCAS showed superior *** the plateau level,CRUNCEP-based simulations displayed the largest bias compared with the reference NPP and ***3-based simulations demonstrated the best performance when comprehensively considering both the magnitudes and change trends of TP-averaged NPP and *** simulated ET increase over the TP during 1982-2010 based on ITPCAS was significantly greater than in the other three simulations and reference ET,suggesting that ITPCAS may not be appropriate for studying long-term ET changes over the *** results suggest that GSWP3 is recommended for driving CLM4.5 in conducting long-term carbon and water processes simulations over the *** study contributes to enhancing the accuracy of LSM in water-carbon simulations over alpine regions.

关键词： land surface model carbon cycle water cycle high altitude Community Land Model version 4.5

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