检索结果-南通市图书馆

The Influence of Seasonal Snow on Soil Thermal and Water Dynamics under Different Vegetation Covers in a Permafrost Region

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2014年第3期11卷 727-745页

作者： HANG Juan wang gen-xu GAO Yong-heng wang Yi-bo College of Earth and Environmental Sciences Lanzhou University Institute of Mountain Hazards and Environment Chinese Academy of Sciences

Seasonal snow is one of the most important influences on the development and distribution of permafrost and the hydrothermal regime in surface soil. Alpine meadow, which constitutes the main land type in permafrost regions of the Qinghai-Tibet Plateau, was selected to study the influence of seasonal snow on the temperature and moisture in active soil layers under different vegetation coverage. Monitoring sites for soil moisture and temperature were constructed to observe the hydrothermal processes in active soil layers under different vegetation cover with seasonal snow cover variation for three years from 2010 to 2012. Differences in soil temperature and moisture in areas of diverse vegetation coverage with varying levels of snow cover were analyzed using active soil layer water and temperature indices. The results indicated that snow cover greatly influenced the hydrothermal dynamics of the active soil layer in alpine meadows. In the snow manipulation experiment with a snow depth greater than 15 cm, the snow cover postponed both the freeze-fall and thawrise onset times of soil temperature and moisture in alpine LC(lower vegetation coverage) meadows and of soil moisture in alpine HC(higher vegetation coverage) meadows; however, the opposite response occurred for soil temperatures of alpine HC meadows,where the entire melting period was extended by advancing the thaw-rise and delaying the freeze-fall onset time of the soil temperature. Snow cover resulted in a decreased amplitude and rate of variation in soil temperature, for both alpine HC meadows and alpine LC meadows, whereas the distinct influence of snow cover on the amplitude and rate of soil moisture variation occurred at different soil layers with different vegetation coverages. Snow cover increased the soil moisture of alpine grasslands during thawing periods. The results confirmed that the annual hydrothermal dynamics of active layers in permafrost were subject to the synergistic actions of both snow cover

关键词： Permafrost Snow cover Vegetationcover Active soil layer Hydrothermal dynamics Synergistic action

Exploring the influence of environmental factors in partitioning evapotranspiration along an elevation gradient on Mount Gongga, eastern edge of the Qinghai-Tibet Platea, China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2020年第2期17卷 384-396页

作者： SUN Ju-ying SUN Xiang-yang HU Zhao-yong wang gen-xu Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China

Evapotranspiration(ET) is a crucial part of the global hydrological cycle, and quantifying ET components is significant for understanding the global water cycle and energy balance. However, there is no consensus on the value of ET components, especially in topographic abrupt change zone, such as eastern margin of the Qinghai-Tibet Platea, where values of ET changes along the altitudinal gradients. Our aim is to explore the influencing factors in partitioning evapotranspiration and how ET components change with increasing elevations. A novel approach was proposed to estimate ET components by adding net solar radiation(Rn) instead of the vapor pressure deficit(VPD) into the underlying water use efficiency(u WUE) model based on one-year continuous measurements of flux data along the elevation gradient on Mount Gongga. Correlation analysis shows that the u WUE model's performance can be improved significantly by considering Rn instead of VPD, with correlation coefficients increasing by 35%-64%. The ratios of transpiration(T) to ET(T/ET) were 0.47, 0.48, 0.50 and 0.35 for the deciduous broadleaf forest(BF), mixed coniferous and deciduous broadleaf forest(MF), evergreen needle forest(ENF) and shrub land(SL), respectively. Leaf area index(LAI) and air temperature(Ta) were the two main controlling factors in determining T/ET during the growing season and at an annual scale, while Rn and Ta played more important roles during the dormant season. This study highlights the importance of incorporating Rn in partitioning evapotranspiration by using the water use efficiency(WUE) method in a humid mountainous region, which can improve the estimation of T/ET on a global scale.

关键词： Eddy covariance Water use efficiency Radiation Evapotranspiration components

Effect of climate change on seasonal water use efficiency in subalpine Abies fabri

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2017年第1期14卷 142-157页

作者： SUN Xiang-yang wang gen-xu HUANG Mei HU Zhao-yong SONG Chun-lin Institute of Mountain Hazards and Environment Chinese Academy of Sciences Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

Abies fabri is a typical subalpine dark coniferous forest in southwestern China. Air temperature increases more at high elevation areas than that at low elevation areas in mountainous regions,and climate change ratio is also uneven in different seasons. Carbon gain and the response of water use efficiency(WUE) to annual and seasonal increases in temperature with or without CO_2 fertilization were simulated in Abies fabri using the atmospheric-vegetation interaction model(AVIM2). Four future climate scenarios(RCP2.6,RCP4.5,RCP6.0 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5(CMIP5) were selectively investigated. The results showed that warmer temperatures have negative effects on gross primary production(GPP) and net primary production(NPP) in growing seasons and positive effects in dormant seasons due to the variation in the leaf area index. Warmer temperatures tend to generate lower canopy WUE and higher ecosystem WUE in Abies fabri. However,warmer temperature together with rising CO_2 concentrations significantlyincrease the GPP and NPP in both growing and dormant seasons and enhance WUE in annual and dormant seasons because of the higher leaf area index(LAI) and soil temperature. The comparison of the simulated results with and without CO_2 fertilization shows that CO_2 has the potential to partially alleviate the adverse effects of climate warming on carbon gain and WUE in subalpine coniferous forests.

关键词： Climate change Carbon gain Water use efficiency Atmospheric-vegetation interaction model

Soil microbial community composition and its driving factors in alpine grasslands along a mountain elevational gradient

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2016年第6期13卷 1013-1023页

作者： CUI Hai-jun wang gen-xu YANG Yan YANG Yang CHANG Rui-ying RAN Fei Institute of Mountain Hazards and Environment Chinese Academy of Sciences

Understanding the vertical distribution patterns of soil microbial community and its driving factors in alpine grasslands in the humid regions of the Tibet Plateau might be of great significance for predicting the soil microbial community of this type of vegetation in response to environmental change. Using phospholipid fatty acids （PLFA）, we investigated soil microbial community composition along an elevational gradient （3094-4131 m above sea level） on Mount Yajiageng, and we explored the impact of plant functional groups and soil chemistry on the soil microbial community. Except for Arbuscular Mycorrhizal fungi （AM fungi） biomarker 18：2ω6,9 increasing significantly, other biomarkers did not show a consistent trend with the elevational gradient. Microbial biomass quantified by total PLFAs did not show the elevational trend and had mean values ranging from 1.64 to 4.09 ktmol per g organic carbon （OC）, which had the maximum value at the highest site. Bacterial PLFAs exhibited a similar trend with total PLFAs, and its mean values ranged from 0.82 to 1.81 μmol （g OC）-1. The bacterial to fungal biomass ratios had the minimum value at the highest site, which might be related to temperature and soil total nitrogen （TN）. The ratios of Gram-negative to Gram-positive bacteria had a significantly negative correlation with soil TN and had the maximum value at the highest site. Leguminous plant coverage and soil TN explained 58% of the total variation in the soil microbial community and could achieve the same interpretation as the whole model. Other factors may influence the soil microbial community through interaction with leguminous plant coverage and soil TN. Soil chemistry and plant functional group composition in substantial amounts explained different parts of the variation within the soil microbial community, and the interaction between them had no impact on the soil microbial community maybe beeause long-term grazing greatly reduces litter. In sum, although there were o

关键词： Alpine grassland Elevational gradient Soil microbial community Phospholipid fatty acid Plant functional group Soil chemistry Variancepartitioning

Allometric equations of select tree species of the Tibetan Plateau, China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2017年第9期14卷 1889-1902页

作者： RAN Fei CHANG Rui-ying YANG Yang ZHU Wan-ze LUO Ji wang gen-xu Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China

The Tibetan forest is one of the most important national forest zones in China. Despite the potentially important role that Tibetan forest will play in the Earth?s future carbon balance and climate regulation, few allometric equations exist for accurately estimating biomass and carbon budgets of this forest. In the present study, allometric equations,both species-specific and generic, were developed relating component biomass(DW) to diameter at breast height(DBH) and tree height(H) for six most common tree species in Tibetan forest. The 6 species were Abies georgei Orr., Picea spinulosa(Griff.)Henry, Pinus densata Mast., Pinus yunnanensis Franch., Cypresses funebris Endl. and Quercus semecarpifilia Smith.. The results showed that, both DBH-only and DBH2 H based species-specific equations showed a significant fit(Pgeneralized equations of mixed coniferous component biomass against DBH, DBH2 H and DBH-H also showed a significant fit(Pgeneralized equations should only be used when there are too many different tree species, or there is no species-specific model of the same species or similar growth form in adjacent area.

关键词： Tibetan forest Allometric models Species-specific Mixed coniferous forest Model evaluation

Temperature trends and elevation dependent warming during 1965-2014 in headwaters of Yangtze River, Qinghai Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2020年第3期17卷 556-571页

作者： Naveed AHMED wang gen-xu Adeyeri OLUWAFEMI Sarfraz MUNIR HU Zhao-yong Aamir SHAKOOR Muhammad Ali IMRAN Key Laboratory of Mountain Surface Process and Ecological Regulations Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China Institute for Meteorology and Climate Research Atmospheric Environmental Research Karlsruhe Institute of TechnologyCampus Alpine82467Germany Water Resources Engineering University of Kurdistan Hewler 30 Meter Avenue ErbilKurdistan44001Iraq Department of Agricultural Engineering Bahauddin Zakariya UniversityMultan66000Pakistan Beijing Key Laboratory of Water Resources and Environmental Engineering China University of GeosciencesBeijing 100083China

The understanding of temperature trends in high elevation mountain areas is an integral part of climate change research and it is critical for assessing the impacts of climate change on water resources including glacier melt, degradation of soils, and active layer thickness. In this study, climate changes were analyzed based on trends in air temperature variables(Tmax, Tmin, Tmean), and Diurnal Temperature Range(DTR) as well as elevation-dependent warming at annual and seasonal scales in the Headwaters of Yangtze River(HWYZ), Qinghai Tibetan Plateau. The Base Period(1965-2014) was split into two subperiods;Period-Ⅰ(1965-1989) and Period-Ⅱ(1990-2014) and the analysis was constrained over two subbasins;Zhimenda and Tuotuohe. Increasing trends were found in absolute changes in temperature variables during Period-Ⅱ as compared to Period-Ⅰ.Tmax, Tmin, and Tmean had significant increasing trends for both sub-basins. The highest significant trends in annual time scale were observed in Tmin(1.15℃ decade-1) in Tuotuohe and 0.98℃ decade-1 in Zhimenda sub-basins. In Period-Ⅱ, only the winter season had the highest magnitudes of Tmax and Tmin0.58℃ decade-1 and 1.26℃ decade-1 in Tuotuohe subbasin, respectively. Elevation dependent warming analysis revealed that Tmax, Tmin and Tmean trend magnitudes increase with the increase of elevations in the middle reaches(4000 m to 4400 m) of the HWYZ during Period-Ⅱ annually. The increasing trend magnitude during Period-Ⅱ, for Tmax, is 1.77, 0.92, and 1.31℃ decade-1, for Tmin 1.20, 1.32 and 1.59℃ decade-1,for Tmean 1.51, 1.10 and 1.51℃ decade-1 at elevations of4066 m, 4175 m and 4415 m respectively in the winter season. Tmean increases during the spring season for> 3681 m elevations during Period-Ⅱ, with no particular relation with elevation dependency for other variables. During the summer season in Period Ⅱ, Tmax, Tmin, Tmean increases with the increase of elevations(3681 m to 4415 m) in the middle reaches of HWYZ. Elevation dependent wa

关键词： Climate change Elevation dependent warming Mann Kendall Temperature trends Yangtze River Qinghai Tibetan Plateau

EVAPOTRANSPIRATION OF LOW-LYING PRAIRIE WETLAND IN MIDDLE REACHES OF HEIHE RIVER IN NORTHWEST CHINA

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2005年第4期15卷 325-329页

作者： WU Jin-kui DING Yong-jian wang gen-xu SHEN Yong-ping Yusuke YAMAZAKI Jumpei KUBOTA Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 P. R. China The Laboratory of Climate Study of China Metralogical Administration Beijing 100041 P. R. China Research Institute far Humanity and Nature Kyoto 602-0778 Japan

Low-lying prairie wetland, which has characteristics of both grassland and wetland, has irreplaceable ecological functions in inland river basins of Northwest China. Owing to its small-scale distribution, so far, the observation and research on it are rare. The estimation of evapotranspiration is significant to ecological and environmental construction, scientific management of pasture and protection of wetland. For studying the evapotranspiration （ET） of low-lying prairie wetland in the middle reaches of the Heihe River, an inland river, in Northwest China, the automatic weather station in Linze Ecological Experimental Station of Lanzhou University （39°15′ 3″N, 100°03′ 52″ E）, Linze, Gansu Province, was selected as a case study. Based on meteorological data collected, Bowen-Ratio Energy Balance （BREB） method was used to calculate the evapotranspiration （ET） of low-lying prairie wetland. The analysis results showed that in a whole year （September 2003 -August 2004）, the total ET was 611.5mm and mean daily 1.67mm/d. The ET varied with different growing stages. In non-growing stage （NGS）, initial growing stage （IGS）, middle growing stage （MGS） and end growing stage （EGS）, the ET was 0.57, 2.01, 3.82 and 1.49mrrdd, with a percentage of total ET of 18.26%, 9.20%, 61.83% and 10.71% respectively. In March, ET began to increase. But in April, the ET increased most. After that, it increased gradually and got the maximal value in July. From then on, the ET decreased gradually. In September, the ET decreased rapidly. With the ending of growing and the freezing of soil, the ET stopped from the middle of November to February in next year. Hourly ET analysis showed that at 8：00 a.m. （during MGS at 7：00 a.m.）, the evapotranspiration began, at 13：00 p.m. got its maximal value and at 19：00 p.m. （during MGS at 20：00 p.m.）, the evapotranspiration stopped. The intensity of ET in sunny day was much larger than that in cloudy day in the same growing stage.

关键词： evapotranspiration low-lying prairie wetland inland river basin

A modified TOPMODEL introducing the bedrock surface topographic index in Huangbengliu watershed,China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2022年第12期19卷 3517-3532页

作者： QIU An-ni ZHANG Yan-jun wang gen-xu CUI Jun-fang SONG Yuan-xin SUN Xiang-yang CHEN Li State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu 610065China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Key laboratory of Hydrometeorological Simulation Prediction and WarningNanjing University of Information Science and TechnologyNanjing210044China School of Hydrology and Water Resources Nanjing University of Information Scienceand TechnologyNanjing 210044China

Subsurface stormflow is a dominant runoff mechanism in steep humid mountainous *** insite measurement of subsurface stormflow suggests that the bedrock surface plays an important role in the runoff generation and routing process,which was rarely adopted in hydrological modelling *** improve the runoff simulation performance,the bedrock surface topographic index is introduced,and a modified TOPMODEL based on the bedrock surface topographic index is developed to simulate the *** modified TOPMODEL is applied to the Huangbengliu(HBL),a steep watershed in Gongga Mountain,and proved to be more appropriate for the HBL watershed,especially for peak *** Nash-Sutcliffe model efficiency(NSE)is improved from 0.24 to 0.58 in the calibration period and from 0.40 to 0.62 in the verification *** result of this study can advance the understanding of the mechanism of flash floods and contribute flood control and disaster prevention in the HBL watershed and similar areas.

关键词： Subsurface stormflow Flash flood Modified TOPMODEL Bedrock surface topographic index Gongga Mountain

Carbon storage of the forest and its spatial pattern in Tibet,China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2021年第7期18卷 1748-1761页

作者： JIA Long-yu wang gen-xu LUO Ji RAN Fei LI Wei ZHOU Jun YANG Dan-li SHI Wen-bo xu Qian ZHU Kun Key Laboratory of Mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China College of Tourism and Urban-Rural Planning Chengdu University of TechnologyChengdu 610059China

The raising concentration of atmospheric CO_2 resulted in global *** forest ecosystem in Tibet played an irreplaceable role in maintaining global carbon balance and mitigating climate change for its abundant original forest resources with powerful action of carbon *** the present study,the samples of soil and vegetation were collected at a total of 137 sites from 2001 to 2018 in *** on the field survey of Tibet's forest resources and 8^(th) forest inventory data,we estimated the carbon storage and carbon density of forest vegetation(tree layer,shrub,grass,litter and dead wood) and soil(0-50 cm) in *** methods combined with Kriging spatial interpolation and Moran's I were applied to reveal their spatial distribution patterns and variation *** carbon density of forest vegetation and soil in Tibet were 74.57 t ha^(-1) and 96.24 t ha^(-1),*** carbon storage of forest vegetation and soil in Tibet were 344.35 Tg C and 440.53 Tg C,*** density of fir(Abies forest) was 144.80 t ha^(-1) with the highest value among all the forest *** storage of spruce(Picea forest) was the highest with 99.09 Tg C compared with other forest *** carbon density of fir forest and spruce forest both increased with the rising temperature and *** was the main influential *** spatial distribution of carbon density of forest vegetation,soil,and ecosystem in Tibet generally showed declining trends from western Tibet to eastern *** results facilitated the understanding of the carbon sequestration role of forest ecosystem in the *** also implied that as the carbon storage potential of Tibet's forests are expected to increase,these forests are likely to serve as huge carbon sinks in the current era of global warming and climate change.

关键词： Carbon storage Carbon density Spatial distribution Forest ecosystems Climate factors Tibet