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Combining gradual and abrupt analysis to detect variation of vegetation greenness on the loess areas of China

Frontiers of Earth Science 2022年第2期16卷 368-380页

作者： Panxing HE Zongjiu SUN Dongxiang XU Huixia LIU Rui YAO Jun MA Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology College of Grassland and Environment SciencesXinjiang Agricultural UniversityUrumqi 830000China ministry of education key laboratory for Biodiversity Science and Ecological Engineering Institute of Biodiversity ScienceFudan UniversityShanghai 200438China School of Earth and Environmental Sciences University of QueenslandQueensland 4072Australia Hubei key laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China

The annual peak growth and trend shift of vegetation are critical in characterizing the carbon sequestration capacity of ecosystems.As the well-known area with the fastest vegetation growth in the world,the Loess Plateau(LP)lands find an enhanced greening trend in the annual and growing-season.However,the spatiotemporal dynamics of vegetation peak growth and breakpoints characteristics on time series still needs to be explored.Here,we performed tendency analysis to characterize recent variations in annual peak vegetation growth through a satellite-derived vegetation index(NDVI_(max),Maximum Normalized Difference Vegetation Index)and then applied breakpoint analysis to capture abrupt points on the time series.The results demonstrated that the vegetation peak trend had been significantly increasing,with a growth rate at 0.68×10^(-2)·a^(-1) during 2001-2018,and most pixels(70.81%)have a positive linear greening trend over the entire LP.In addition,about 83%of the breakpoint type on the monthly NDVI time series is a monotonic increase at the pixel level,and most pixels(57%)have detected breakpoints after 2010.Our results also showed that the growth rate accelerates in the northwest and decelerates in the southeast after the breakpoint.This study indicates that combining abrupt analysis with gradual analysis can describe vegetation dynamics more effectively and comprehensively.The findings highlighted the importance of breakpoint analysis for monitor timing and shift using time series satellite data at a regional scale,which may help stakeholders to make reasonable and effective ecosystem management policies.

关键词： vegetation greenness gradual trend breakpoint BFAST algorithm the Loess Plateau area

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Crepis desertorum(Asteraceae,Cichorieae),a new species from northern Xinjiang(China)based on morphological and molecular data

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Plant Diversity 2020年第2期42卷 74-82页

作者： Juan Qiu Jianwen Zhang Tiangang Gao Dunyan Tan Xinjiang key laboratory of grassland resources and ecology and Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology College of Grassland and Environment SciencesXinjiang Agricultural UniversityUriimqi 830052China CAS key laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of BotanyChinese Academy of SciencesKunming 650201China State key laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of SciencesBeijing 100093China College of Biology and Environmental Sciences Jishou UniversityJishou 416000China

Crepis desertorum from the Junggar Basin of no rthern Xinjiang,northwestern China,is described as a new species.Molecular studies indicate that the species is closely related to Crepis frigida.Morphological studies indicate that it is similar to Crepis sancta subsp.bifida but differs from the latter taxon in having glandular hairs on the stem,a flat receptacle and dimorphic achenes.Chromosome features and pollen and achene ultrastructure also are described for the new species.

关键词： Karyotype Micro-morphology Pericarp Pollen Taxonomy

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Relationship between multi-scale climate factors and performance of ecological engineering on the Loess Plateau, China

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Journal of Forestry Research 2022年第3期33卷 789-800页

作者： Panxing He Jun Ma Zhiming Han Mingjie Shi Dongxiang Xu Zongjiu Sun ministry of education key laboratory for Biodiversity Science and Ecological EngineeringNational Observations and Research Station for Wetland Ecosystems of the Yangtze EstuarySchool of Life SciencesFudan UniversityShanghai200438People’s Republic of China Ministry of Education Key Laboratory for Western Arid Region Grassland Resources and Ecology College of Grassland and Environment SciencesXinjiang Agricultural UniversityUrumqi830052People’s Republic of China State key laboratory Base of Eco-Hydraulic Engineering in arid Areas Xi’an University of TechnologyXi’an710077People’s Republic of China School of Earth and Environmental Sciences University of QueenslandSt Lucia4072Australia

The long-term “Grain-to-Green Program” (GGP) on China’s Loess Plateau is a major global ecological engineering project which has significantly boosted vegetation renewal. Some studies have found that the rate of restoration is quite rapid during the implementation of ecological engineering, however, the influence of multi-scale climatic conditions on the performance of ecological engineering is unclear. In this study, multiple sources of remote sensing data were used to estimate the dynamics of vegetation structural and functional indicators, water-related local climatic factors, and atmospheric circulation factors. These datasets were also used to detect possible causes for vegetation restoration on the Loess Plateau over the past 20 years. The results show that widespread increases in rates of normalized difference vegetation indexes (NDVI), leaf area indexes (LAI), gross primary production (GPP), and aboveground biomass carbon (ABC) during 2000–2016 were significantly higher than before 2000. GPP was significantly correlated with rainfall and surface runoff on a monthly scale, and there were significant positive correlations between GPP and atmospheric circulation. Our results demonstrate that both vegetation structural and functional indicators rapidly increase, and ecological engineering greatly accelerated vegetation restoration after 2000. Local climatic conditions and atmospheric circulation patterns enhance vegetation growth and impact of ecological engineering.

关键词： Vegetation restoration Ecological engineering Water-related climatic factors Atmospheric circulation and sunspot Loess Plateau

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Effects of water stress and NaCl stress on different life cycle stages of the cold desert annual Lachnoloma lehmannii in China

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Journal of arid Land 2019年第5期11卷 774-784页

作者： Jannathan MAMUT TAN Dunyan Carol C BASKIN Jerry M BASKIN Xinjiang key laboratory of grassland resources and ecology and ministry of education Key Laboratory for Western Arid Region Grassland Resources and EcologyCollege of Grassland and Environment SciencesXinjiang Agricultural UniversityUrumqi 830052China College of Biology and Environmental Sciences Jishou UniversityJishou 416000China Department of Biology University of KentuckyLexingtonKY 40506USA Department of Plant and Soil Sciences University of KentuckyLexingtonKY 40546USA

For a plant species to complete its life cycle in arid and saline environments,each stage of the life cycle must be tolerant to the harsh environmental conditions.The aim of the study was to determine the effects of water stress(water potentials of–0.05,–0.16,–0.33,–0.56,–0.85 and–1.21 MPa)and NaCl stress(50,100,200,300,400,500 and 600 mmol/L NaCl)on seed germination percentage,seedling survival and growth,juvenile growth and plant reproduction of Lachnoloma lehmannii Bunge(Brassicaceae),an cold desert annual that grows in the Junggar Basin of Xinjiang,China in 2010.Results indicated that low water stress(–0.05 and–0.16 MPa)had no significant effect on seed germination percentage.With a decrease in water potential,germination percentage decreased,and no seeds germinated at–0.85 and–1.21 MPa water stresses.Germination percentage of seeds was significantly affected by NaCl stress,and higher germination percentages were observed under non-saline than saline conditions.An increase in NaCl concentrations progressively inhibited seed germination percentage,and no seeds germinated at ≥400 mmol/L NaCl concentration.Non-germinated seeds were transferred from both PEG(polyethylene glycol-6000)and NaCl solutions to distilled water for seed germination recovery.The number of surviving seedlings and their heights and root lengths significantly decreased as NaCl stress increased.About 30% of the plants survived and produced fruits/seeds at 200 mmol/L NaCl concentration.Thus,seed germination,seedling establishment and reproductive stage in the life cycle of L.lehmannii are water-and salt-tolerant,with seedlings being the least tolerant.These tolerances help explain why this species can survive and produce seeds in arid and saline habitats.

关键词： drought stress Lachnoloma lehmannii salinity tolerance seed germination seedling growth

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Holocene Moisture Variation Recorded by Aeolian Sand-Palaeosol Sequences of the Gonghe Basin, Northeastern Qinghai-Tibetan Plateau, China

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Acta Geologica Sinica(English Edition) 2020年第3期94卷 668-681页

作者： LIU Bing ZHAO Hui JIN Heling CHEN Fahu key laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of ScienceLanzhou 730000China key laboratory of western China's Environmental Systems Ministry of EducationLanzhou 73000China key laboratory of Alpine ecology Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

The northeastern Qinghai-Tibetan Plateau(QTP) of China is located at the triple junction of the Asian winter and summer monsoons and the westerlies, where paleoclimatic evolution has an important scientific significance for recognizing the spatial-temporal pattern of Asian monsoons in the past and predicting environmental change in the future. Nevertheless, the framework of the Holocene moisture variation and related mechanisms remain controversial, owing to complex hydroclimatic conditions triggered by the landform of the large mountain-arid basin. Here, we employed geochemical proxies from typical aeolian sand-palaeosol sequences in the Gonghe Basin, northeastern QTP, together with Optically Stimulated Luminescence(OSL) dating, to reconstruct the pattern of effective moisture variation and associated mechanisms in this region. Our results indicate that the regional effective moisture was at its lowest until 9–8 ka, and approached a maximum during 8–4/3 ka of the middle Holocene. Afterwards, the climate became relatively dry in general, but with a transient humid interval around 2–1 ka. Our geochemical evidence indicates that the dry early Holocene probably can be attributed to a strong winter monsoon forced by remnant ice sheet, combined with the high evaporation caused by solar insolation. Also, shifts of humid-dry are closely linked to the Asian summer monsoonal strength and therefore the balance of evaporation-precipitation in the middle and late Holocene. Thus, the pattern of the Holocene effective moisture variation is characterized as the ‘monsoon model’ in a closed intermontane arid and semi-arid basin near the western Asian monsoonal limit.

关键词： effective moisture geochemical analysis aeolian deposits Holocene Gonghe Basin

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Influence of ammonium and nitrate supply on growth, nitrate reductase activity and N-use efficiency in a natural hybrid pine and its parents

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Journal of Plant ecology 2011年第4期4卷 275-282页

作者： Buqing Yao Jing Cao Changming Zhao Zed Rengel key laboratory of arid and grassland ecology Ministry of EducationSchool of Life SciencesLanzhou UniversityLanzhou 730000GansuPeople’s Republic of China School of Earth and Environment The University of Western Australia35 Stirling HighwayCrawleyWA 6009Australia

Selection of tree species with a high capacity to assimilate N and efficiently utilize N resources would facilitate the success of initial tree seedling establishment in infertile soils.The preference for N forms was tested using three pine species(Pinus densata,Pinus tabuliformis and Pinus yunnanensis).Pinus densata is a natural diploid hybrid between P.tabuliformis and P.yunnanensis.Methods Seedlings of three pine species were supplied with nitrate-N,ammonium-N(at two different pH regimes)or combined ammonium and nitrate as a nitrogen source in perlite culture in a controlled environment.Important Findings Seedlings of P.densata had higher total biomass and net photosynthesis when supplied with nitrate-N and ammonium nitrate than with ammonium-N.In parental species,total biomass and net photosynthesis for P.yunnanensis seedlings was higher in ammonium-N than in nitrate-N,whereas the other parental species P.tabuliformis had the highest total biomass among species for all treatments except ammonium with CaCO_(3).Most morphological traits in P.densata seedlings were intermediate between its two parental species.However,N-use efficiency and photosynthetic N-use efficiency of P.densata significantly exceeded both parents when supplied with nitrate-N and ammonium nitrate.The results suggested that the diploid hybrid tree species P.densata has a preference for nitrate and is not well adapted to ammonium-N as a sole nitrogen source regardless of the growth medium pH.Based on changes in environmental conditions,such as predicted future temperature increases in high altitude areas associated with climate change,P.densata is likely to be increasingly competitive and have wide adaptation in high altitude regions.

关键词： diploid hybrid Pinus densata N forms rootshoot characteristics photosynthetic N-use efficiency nitrate reductase

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Evaluation of the water conservation function in the Ili River Delta of Central Asia based on the InVEST model

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Journal of arid Land 2023年第12期15卷 1455-1473页

作者： CAO Yijie MA Yonggang BAO Anming CHANG Cun LIU Tie College of Geography and Remote Sensing Sciences Xinjiang UniversityUrumqi 830046China Xinjiang key laboratory of Oasis ecology Xinjiang UniversityUrumqi 830046China College of ecology and Environment Xinjiang UniversityUrumqi 830046China Xinjiang Jinghe Observation and Research Station of Temperate Desert Ecosystem Ministry of EducationJinghe 833300China key laboratory of Oasis ecology of education ministry Urumqi 830046China State key laboratory of Desert and Oasis ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China key laboratory of GIS&RS Application Xinjiang Uygur Autonomous RegionUrumqi 830011China

The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.

关键词： water conservation function water yield Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model climate change land use/land cover change(LUCC) Ili River Delta Lake Balkhash

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中国目前和未来水文气候模态的变化特征

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Science Bulletin 2020年第13期65卷 1061-1063,M0003页

作者：黄伟刘畅曹金秋陈建徽冯松 key laboratory of western China’s Environmental Systems(ministry of education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Department of Geosciences University of ArkansasFayettevilleAR 72701USA

过去千年我国暖季的干湿变化呈现出三极子模态,即新疆地区和华南地区的干湿变化趋势与华北地区相反.本文利用中国的台站观测资料及CMIP5的模拟数据构建干燥度指数(AI),对目前和未来中国水文气候三级子模态的变化特征及归因进行了分析.... 详细信息

过去千年我国暖季的干湿变化呈现出三极子模态,即新疆地区和华南地区的干湿变化趋势与华北地区相反.本文利用中国的台站观测资料及CMIP5的模拟数据构建干燥度指数(AI),对目前和未来中国水文气候三级子模态的变化特征及归因进行了分析.结果表明,1993~2015年期间,长期存在的三极子模态已经消失.在未来RCP8.5排放情景下,21世纪中期当全球升温低于2℃时,该模态可以恢复;但是在21世纪末,三级子模态将再次消失.归因分析表明,未来气温升高将导致新疆和华南地区变干.除温度外,相对湿度的变化也是造成未来华南地区变干的重要因子.而华北地区AI对全球变暖的响应则取决于升温程度.当未来升温低于2℃时,降水的增加使得华北地区变湿,而在21世纪末,升温高于2℃时,温度的升高将导致华北地区变干.

关键词：全球升温干燥度指数全球变暖水文气候华北地区台站观测排放情景归因分析

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Discussion of the“warming and wetting”trend and its future variation in the drylands of Northwest China under global warming

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Science China Earth Sciences 2023年第6期66卷 1241-1257页

作者： Fahu CHEN Tingting XIE Yujie YANG Shengqian CHEN Feng CHEN Wei HUANG Jie CHEN Group of Alpine Paleoecology and Human Adaptation(ALPHA) State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and Resources(TPESER)Institute of Tibetan Plateau Research(ITPCAS)Chinese Academy of Sciences(CAS)Beijing 100101China key laboratory of western China’s Environmental Systems(ministry of education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Yunnan key laboratory of International Rivers and Transboundary Eco-Security Institute of International Rivers and Eco-SecurityYunnan UniversityKunming 650500China key laboratory of Tree-Ring Physical and Chemical Research of the Chinese Meteorological Administration Xinjiang Laboratory of Tree-Ring EcologyInstitute of Desert MeteorologyChinese Meteorological AdministrationUrumqi 830002China College of Atmospheric Sciences Lanzhou UniversityLanzhou 730000China

Since Shi et al.proposed that the climate in the drylands of Northwest China experienced a significant transition from a“warming and drying”trend to a“warming and wetting”trend in the 1980s,researchers have conducted numerous studies on the variations in precipitation and humidity in the region and even in arid Central Asia.In particular,the process of the“warming and wetting”trend by using obtained measurement data received much attention.However,there remain uncertainties about whether the“warming and wetting”trend has paused and what its future variations may be.In this study,we examined the spatiotemporal variations in temperature,precipitation,the aridity index(AI),vegetation,and runoff during 1950-2019.The results showed that the climate in the drylands of Northwest China and the northern Tibetan Plateau is persistently warming and wetting since the 1980s,with an acceleration since the 1990s.The precipitation/humidity variations in North China,which are mainly influenced by summer monsoon,are generally opposite to those in the drylands of Northwest China.This reverse change is mainly controlled by an anomalous anticyclone over Mongolia,which leads to an anomalous easterly wind,reduced water vapor output,and increased precipitation in the drylands of Northwest China.While it also causes an anomalous descending motion,increased water vapor divergence,and decreased precipitation in North China.Precipitation is the primary controlling factor of humidity,which ultimately forms the spatiotemporal pattern of the“westerlies-dominated climatic regime”of antiphase precipitation/humidity variations between the drylands of Northwest China and monsoonal region of North China.The primary reasons behind the debate of the“warming and wetting”trend in Northwest China were due to the use of different time series lengths,regional ranges,and humidity indices in previous analyses.Since the EC-Earth3 has a good performance for simulating precipitation and humidity in Northwest and North China.By using its simulated results,we fo

关键词： The drylands of Northwest China “Warming and wetting”transition Sustained“warming and wetting” Westerliesdominated climatic regime Moderate warming

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Spatial distribution and risk assessments of mercury in topsoils of Central Asia

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Geoscience Frontiers 2023年第4期14卷 270-279页

作者： Zhengzheng Yang Junming Guo Shiwei Sun Dingming Ni Pengfei Chen Dipesh Rupakheti Huhu Kang Sabur F Abdullaev Salamat Abdyzhapar uulu Shichang Kang key laboratory of western China's Environmental Systems(ministry of education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China State key laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Jiangsu key laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China S.U.Umarov Physical Technical Institute of the National Academy of Sciences of Tajikistan Dushanbe 734063Tajikistan Research Center for ecology and Environment of Central Asia(Bishkek) 720001Kyrgyzstan Geography Department Geology InstituteNational Academy of Sciences720001Kyrgyzstan

Central Asia is one of the largest arid areas on earth,yet little is known about the concentration levels and risks of mercury(Hg)in the soils of this region.In this study,extensive sampling of topsoils(0-10 cm)from representative landscapes was carried out over Central Asia(i.e.,Tajikistan,Uzbekistan,and Kyrgyzstan).The total mercury(THg)concentrations in topsoils varied widely from 1.6 to 908.0 ng/g,with high values observed in samples collected in the capital cities and urban areas.Topsoil THg concentrations among different landscapes showed a decreasing order of urban(79.8±184.0 ng/g)>woodland(27.3±28.9 ng/g)>grassland(20.6±15.9 ng/g)>farmland(18.3±9.5 ng/g)>desert(12.3±8.0 ng/g).High THg concentrations were found in the capital cities/urban clusters,followed by a gradual decrease towards the peripheries.THg concentrations were found to be negatively correlated with the distance from the sampling sites to their nearest cities,indicating that anthropogenic emissions significantly influenced the spatial distribution of topsoil Hg.A significant correlation between THg concentrations and topsoil total organic carbon(TOC)contents was also observed,suggesting that TOC played an essential role in the spatial distribution of topsoil Hg.The assessments of pollution and potential ecological risk suggested that topsoils in highly densely-populated areas were contaminated by Hg and had higher degrees of potential ecological risks.The health risk assessment results showed that the exposure risk of topsoil Hg to children was higher than that to adults.Fortunately,there was no unacceptable human health risk of topsoil Hg.This study clarified the spatial distribution and risks of Hg in the Central Asian topsoils,offering new insight into the risk prevention and control of soil Hg.

关键词： Mercury Topsoil Landscape Spatial distribution Risk assessment Central Asia

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