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The urgent need to develop a new grassland map in China:based on the consistency and accuracy of ten land cover products

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Science China(Life Sciences) 2023年第2期66卷 385-405页

作者： Mengjing Hou Jing Ge Yangjing Xiu Baoping Meng Jie Liu Qisheng Feng Tiangang Liang State Key Laboratory of grassland Agro-Ecosystems Key Laboratory of Grassland Livestock Industry InnovationMinistry of Agriculture and Rural AffairsEngineering Research Center of Grassland IndustryMinistry of EducationCollege of Pastoral Agriculture Science and TechnologyLanzhou UniversityLanzhou 730000China Institute of Fragile Eco-Environment Nantong UniversityNantong 226007China

grasslands are the most dominant terrestrial ecosystem in China, but few national grassland maps have been generated. The grassland resource map produced in the 1980s is widely used as background data, but it has not been updated for almost 40 years.Therefore, a reliable map depicting the current spatial distribution of grasslands across the country is urgently needed. In this study, we evaluated the grassland consistency and accuracy of ten land cover datasets(GLC2000, GlobCover, CCI-LC,MCD12Q1, CLUD, GlobeLand30, GLC-FCS30, CGLS-LC100, CLCD, and FROM-GLC) for 2000, 2010, and 2020 based on extensive fieldwork. We concluded that the area of these ten grassland products ranges from 107.80×10^(4)to 332.46×10^(4)km^(2), with CLCD and MCD12Q1 having the highest area consistency. The spatial and sample consistency is highest in the regions of eastcentral Inner Mongolia, the Qinghai-Tibet Plateau and northern Xinjiang, while the distribution of southern grasslands is scattered and differs considerably among the ten products. MCD12Q1 is significantly more accurate than the other nine products,with an overall accuracy(OA) reaching 77.51% and a kappa coefficient of 0.51;CLCD is slightly less accurate than MCD12Q1(OA=73.02%, kappa coefficient=0.45) and is more conducive to the fine monitoring and management of grassland because of its30-meter resolution. The highest accuracy of grassland was found in the Inner Mongolia-Ningxia region and Qinghai-Tibet Plateau, while the accuracy was worst in the southeastern region. In the future grassland mapping, cartographers should improve the accuracy of the grassland distribution in South China and regions where grassland is confused with forest, cropland and bare land. We specify the availability of valuable data in existing land cover datasets for China’s grasslands and call for researchers and the government to actively produce a new generation of grassland maps.

关键词： grassland land use and land cover MCD12Q1 CLCD consistency comparison accuracy assessment

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Effects of Enclosure on grassland Ecological and Economic Benefits in Northern China

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Chinese Geographical Science 2024年第1期34卷 67-78页

作者： HU Bo WEN Qingke XI Fengjiang LI Mengyao WANG Libing REN Yuejuan Aerospace Information Research Institute Chinese Academy of SciencesBeijing100094China University of Chinese Academy of Sciences Beijing100049China Inner Mongolia Remote Sensing Center Co. Ltd.Huhhot010000China Xilinhot the Maodeng pasture Xilinhot026000China China University of Mining and Technology Xuzhou221116China Shanxi Provincial Key Lab of Resources Environment and Disaster MonitoringCoal Geological Geophysical Exploration Surveying&Mapping Institute of Shanxi ProvinceJinzhong030600China

grasslands in northern China serve the country as both an ecological barrier and a livestock production base.There,installing enclosures has been becoming the major grassland restoration measure adopted by many local governments.However,the effects of restoration on both ecological and production benefits of grassland remain unclear for implemented grassland restoration policies.Therefore,a representative rangeland in northern China,the Maodeng pasture in Inner Mongolia Autonomous Region was selected as the study area,and remote sensing monitoring analyses were carried out to quantify the ecological benefits and economic benefits from 2015 to 2021.The results showed that:1) in terms of ecological benefits,the grassland area with a grassland coverage rate of more than 60% accounts for 32.3% of the regional area,and 86.4% of its grassland grew significantly better than the same period in2015,showing a significant improvement in grassland growth.Using the average amount of carbon per unit area as the ecological benefit evaluation index,it increased by 27.1% to 32.48Tg C/yr from 2015 to 2021.2) In terms of economic benefits,both theoretical grass production and livestock carrying capacity increased from 2015 to 2021.Compared to 2015,the theoretical grass production in 2021 increased by 24.8% to 71 900 t.The livestock carrying capacity reached 52 100 sheep units in 2021,nearly 11 000 sheep units more than that in 2015.During the study period,multiple economic indicators(on a per capita basis of permanent residents) for the pastoral area of Xilinhot City to which the Maodeng pasture belongs,have grown steadily.Per capita total income rose from 29 630 yuan(RMB) in2015 to 62 859 yuan(RMB) in 2021.Relying on grassland resources to develop the pastoral ecology also broadens the potential economic development space.Overall,the establishment of the reserve and the experiment of implanting an enclosure policy have had a significant and positive impact on Maodeng pasture’s development from both an ecological and economic persp

关键词： enclosure grassland ecological benefit economic benefit Maodeng pasture Inner Mongolia northern China

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Impacts of Extreme Droughts on Ecosystem Water Use Efficiency Diverge between Forest and grassland

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Journal of Meteorological Research 2023年第5期37卷 710-721页

作者： Mengtian HUANG Panmao ZHAI State Key Laboratory of Severe Weather and Institute of Global Change and Polar Meteorology Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

Ecosystem-scale water use efficiency (WUE),as a quantification of the coupling between carbon and water cycle,determines whether vegetation could survive under severe drought stress.Nevertheless,how extreme droughts affect ecosystem-scale WUE and its difference among regions and biomes are still poorly understood.In this study,using data-oriented gridded products of gross primary productivity (GPP) and evapotranspiration (ET),we assessed the ecosystem WUE change during extreme drought years over China,and further compared drought impacts on WUE between forest and grassland ecosystems.We found a spatial heterogeneity of WUE change in response to extreme droughts across regions.Particularly,grassland WUE was substantially reduced concurrent with suppressed photosynthesis,while most of forest exhibited slightly decreased or even increased WUE under extreme droughts.In addition,we demonstrated that drought characteristics and environmental conditions modulated drought impacts on WUE.Temperature anomalies during droughts and leaf area were found to be the predominant factors driving WUE change for both forest and grassland.With increasing occurrence of compound dry and hot extremes,our results,therefore,would be an insightful supplement to the current understanding of the influence of extreme events on terrestrial ecosystems.

关键词： extreme droughts water use efficiency terrestrial ecosystems forest grassland China

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Effects of different forms of nitrogen addition on microbial extracellular enzyme activity in temperate grassland soil

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Ecological Processes 2022年第1期11卷 483-490页

作者： Lili Dong Björn Berg Weiping Gu Zhengwen Wang Tao Sun Erguna Forest-Steppe Ecotone Research Station Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China Department of Forest Sciences University of Helsinki00014 HelsinkiFinland Section of Biology University of Gävle80176 GävleSweden Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China

Background:Nitrogen(N)deposition alters litter decomposition and soil carbon(C)sequestration by influencing the microbial community and its enzyme activity.Natural atmospheric N deposition comprises of inorganic N(IN)and organic N(ON)compounds.However,most studies have focused on IN and its effect on soil C cycling,whereas the effect of ON on microbial enzyme activity is poorly understood.Here we studied the effects of different forms of externally supplied N on soil enzyme activities related to decomposition in a temperate steppe.Ammonium nitrate was chosen as IN source,whereas urea and glycine were chosen as ON sources.Different ratios of IN to ON(Control,10:0,7:3,5:5,3:7,and 0:10)were mixed with equal total amounts of N and then used to fertilize the grassland soils for 6 years.Results:Our results show that IN deposition inhibited lignin-degrading enzyme activity,such as phenol oxidase(POX)and peroxidase(PER),which may restrain decomposition and thus induce accumulation of recalcitrant organic C in grassland soils.By contrast,deposition of ON and mixed ON and IN enhanced most of the C-degrading enzyme activities,which may promote the organic matter decomposition in grassland soils.In addition,theβ-N-acetyl-glucosaminidase(NAG)activity was remarkably stimulated by fertilization with both IN and ON,maybe because of the elevated N availability and the lack of N limitation after long-term N fertilization at the grassland site.Meanwhile,differences in soil pH,soil dissolved organic carbon(DOC),and microbial biomass partially explained the differential effects on soil enzyme activity under different forms of N treatments.Conclusions:Our results emphasize the importance of organic N deposition in controlling soil processes,which are regulated by microbial enzyme activities,and may consequently change the ecological effect of N deposition.Thus,more ON deposition may promote the decomposition of soil organic matter thus converting C sequestration in grassland soils into a C source.

关键词： Inorganic N deposition Organic N deposition Soil microbial biomass Microbial enzyme activity Decomposition grassland

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Modeling the influence of livestock grazing pressure on grassland bird distributions

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Ecological Processes 2020年第1期9卷 488-498页

作者： Rachel R.Fern Michael L.Morrison William E.Grant Hsiaohsuan Wang Tyler A.Campbell Department of Wildlife and Fisheries Sciences Texas A&M UniversityWFES Building2258 TAMU534 John Kimbrough BlvdCollege StationTX 77843-2258USA East Foundation San AntonioTX 78216USA

Background:The influence of vegetative changes due to livestock grazing on grassland birds is well-recognized because these birds are heavily influenced by vegetative structure.Traditionally,species distribution models(SDMs)use direct variables,resources that the animal consumes or requires to persist in an area(e.g.,water)to define and project a species’niche and distribution.Indirect variables,which are features the animal does not consume or require for persistence but with which it may still interact,are often excluded.Our objective was to improve the traditional SDMs projecting the distribution of three summer resident South Texas grassland birds(Northern Bobwhite Colinus virginianus,Eastern Meadowlark Sturnella magna,and Cassin’s Sparrow Peucaea cassinii)by incorporating livestock grazing pressure,an indirect variable,into five SDM algorithms:BioClim,generalized linear model,MaxEnt,boosted regression tree,and random forest.We collected data from the Coloraditas Grazing Research and Demonstration Area(CGRDA),a 7684-ha area located on the San Antonio Viejo Ranch(SAV)in South Texas.We used several relevant environmental characteristics to build SDMs and compared model performance(AUC and TSS)with and without grazing pressure as an indirect variable.Results:Machine learning models(MaxEnt and random forest)had the highest predictive performance for all species,with random forest being the most consistent for each analysis.BioClim and generalized linear model remained constant or only marginally improved with the addition of the grazing pressure.Conclusions:Our findings suggest that model selection for SDM should include consideration of species prevalence,and machine-learning algorithms should be preferred when the target species is of low or unknown prevalence.Further,livestock grazing has measurable influence on grassland bird species’distributions and should be included in SDMs as an indirect variable in addition to associated vegetative changes.

关键词： Birds grassland Grazing Livestock Species distribution model Texas

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Responses of soil microbial communities and functions associated with organic carbon mineralization to nitrogen addition in a Tibetan grassland

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Pedosphere 2020年第2期30卷 214-225页

作者： Ruyi LUO Jiafa LUO Jianling FAN Deyan LIU Jin-Sheng HE Nazia PERVEEN Weixin DING State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 10049China AgResearch Limited Ruakura Research CentreHamilton 3240New Zealand Department of Ecology College of Urban and Environmental SciencesKey Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Alpine grasslands with a high soil organic carbon(SOC)storage on the Tibetan Plateau are experiencing rapid climate warming and anthropogenic nitrogen(N)deposition;this is expected to substantially increase the soil N availability,which may impact carbon(C)cycling.However,little is known regarding how N enrichment influences soil microbial communities and functions relative to C cycling in this region.We conducted a 4-year field experiment on an alpine grassland to evaluate the effects of four different rates of N addition(0,25,50,and 100 kg N ha^-1 year^-1)on the abundance and community structure(phospholipid fatty acids,PLFAs)of microbes,enzyme activities,and community level physiological profiles(CLPP)in soil.We found that N addition increased the microbial biomass C(MBC)and N(MBN),along with an increased abundance of bacterial PLFAs,especially Gram-negative bacterial PLFAs,with a decreasing ratio of Gram-positive to Gram-negative bacteria.The N addition also stimulated the growth of fungi,especially arbuscular mycorrhizal fungi,reducing the ratio of fungi to bacteria.Microbial functional diversity and activity of enzymes involved in C cycling(β-1,4-glucosidase and phenol oxidase)and N cycling(β-1,4-N-acetyl-glucosaminidase and leucine aminopeptidase)increased after N addition,resulting in a loss of SOC.A meta-analysis showed that the soil C/N ratio was a key factor in the response of oxidase activity to N amendment,suggesting that the responses of soil microbial functions,which are linked to C turnover relative to N input,primarily depended upon the soil C/N ratio.Overall,our findings highlight that N addition has a positive influence on microbial communities and their associated functions,which may reduce soil C storage in alpine grasslands under global change scenarios.

关键词： alpine grassland C cycling C turnover community level physiological profiles(CLPP) enzyme activity microbial community composition microbial function N input

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Identification of Concealed Faults in a grassland Area in Inner Mongolia, China, Using the Temperature Vegetation Dryness Index

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Journal of Earth Science 2019年第4期30卷 853-860页

作者： Chengbin Wang Jianguo Chen Xi Chen Jinhui Chen State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China Faculty of Earth Resources、China University of Geosciences Wuhan 430074China Hubei Geological Survey Wuhan 430034China

Fault identification in vegetated area(e.g.,grassland) is a major challenge compared to that in outcrop areas. To identify concealed faults in a grassland covered area,a hybrid method combining the temperature vegetation dryness index(TVDI) and the singularity index was proposed in this paper to extract TVDI anomalies associated with concealed fractures in the Sonid Left Banner grassland,Inner Mongolia,North China. In the triangle space of LST/NDVI(land surface temperature/normalized difference vegetation index),scattered points were concentrated in the areas of partial and full cover,while few data points were in the areas of bare soil with low values of NDVI and high values of LST;this result is consistent with the semiarid grassland landscape of the study area. Although TVDI imaging shows an obvious linear pattern with an NE-NNE trend,which indicates the existence of concealed faults,the surrounding background weakened and reduced the significance of the anomalies.To better delineate the concealed faults,the singularity index was employed to remove the influence of the background and enhance the TVDI anomalies associated with the concealed faults. The TVDI imaging and singularity index mapping showed NNE and NE orientations;this finding is consistent with the regional tectonic framework. Geological mapping footprints showed that the hybrid method is useful to identify concealed faults in covered areas of grassland.

关键词： concealed fracture TVDI grassland Inner Mongolia singularity index

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Assessing the Dynamics of grassland Net Primary Productivity in Response to Climate Change at the Global Scale

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Chinese Geographical Science 2019年第5期29卷 725-740页

作者： LIU Yangyang YANG Yue WANG Qian KHALIFA Muhammad ZHANG Zhaoying TONG Linjing LI Jianlong SHI Aiping Department of Ecology School of Life ScienceNanjing UniversityNanjing210046China Nanjing Institute of EnvironmentalSciences Ministry of Environmental Protection of the People抯Republic of ChinaNanjing210042China Institute for Technologyand Resources Management in the Tropics and Subtropics(ITT) Technische Hochschule K鰈n-Cologne University of Applied SciencesCologne50679Germany Department of Geography University of CologneAlbertus-Magnus-PlatzD-50923CologneGermany International Institute for Earth System Sciences Jiangsu Provincial Key Laboratory of Geographic Information Science andTechnologyNanjing UniversityNanjing210023China School of Agricultural Equipment Engineering Jiangsu UniversityZhenjiang212013China

Understanding the net primary productivity(NPP) of grassland is crucial to evaluate the terrestrial carbon cycle. In this study, we investigated the spatial distribution and the area of global grassland across the globe. Then, we used the Carnegie-Ames-Stanford Approach(CASA) model to estimate global grassland NPP and explore the spatio-temporal variations of grassland NPP in response to climate change from 1982 to 2008. Results showed that the largest area of grassland distribution during the study period was in Asia(1737.23 × 104 km^2), while the grassland area in Europe was relatively small(202.83 × 10~4 km^2). Temporally, the total NPP increased with fluctuations from 1982 to 2008, with an annual increase rate of 0.03 Pg C/yr. The total NPP experienced a significant increasing trend from 1982 to 1995, while a decreasing trend was observed from 1996 to 2008. Spatially, the grassland NPP in South America and Africa were higher than the other regions, largely as a result of these regions are under warm and wet climatic conditions. The highest mean NPP was recorded for savannas(560.10 g C/(m^2·yr)), whereas the lowest was observed in open shrublands with an average NPP of 162.53 g C/(m^2·yr). The relationship between grassland NPP and annual mean temperature and annual precipitation(AMT, AP, respectively) varies with changes in AP, which indicates that, grassland NPP is more sensitive to precipitation than temperature.

关键词： Carnegie-Ames-Stanford Approach(CASA) net primary productivity(NPP) spatio-temporal dynamic climate variation grassland ecosystems

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Soil Properties and Plant Growth Response to Litter in a Prolonged Enclosed grassland of Loess Plateau, China

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Journal of Earth Science 2019年第5期30卷 1041-1048页

作者： Yunwu Xiong Bing Yu Mengting Bai Xueyang Zhang Guanhua Huang Alex Furman College of Water Resources & Civil Engineering China Agricultural University Beijing 100083 China Chinese-Israeli International Center for Research and Training in Agriculture China Agricultural University Beijing 100083 China Civil and Environmental Engineering Technion-Israel Institute of Technology Haifa 32000 Israel

The enclosure and ungrazing practices for grassland management result in accumulation of plant litter on soil surface thus affecting the available soil water and nutrients for plant production. We experimentally investigated the effects of litter on soil properties and plant growth in a prolonged enclosure grassland of Loess Plateau, China. Three different litter manipulations were conducted including removal of all litter, an untreated in-situ control with original litter levels, and a double litter treatment. Litter treatment experiments demonstrated that plant litter affected the superficial soil water. Soil water content in plots with in-situ or double litter is generally higher than that with litter removal. The depletion of soil water up to five days post rainfall is fastest in litter removal plots for the top soil, but no evident difference for the deep ones. Different litter treatments have no significant impact on soil total carbon, nitrogen as well as carbon/nitrogen ratio for consecutive two years experiments. Both above-and below-ground biomasses in plots of litter removal were less than those in the plots of in-situ and double litter treatment. Litter affects plant production mainly through the mechanical barrier regulating root zone soil moisture. Therefore, prolonged litter manipulation experiments are desirable to understand the long-term response of plant growth on litter from nutrient aspect.

关键词： soil moisture ungrazed grassland Stripa bungeana litter manipulation

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Comparison of leaf area index inversion for grassland vegetation through remotely sensed spectra by unmanned aerial vehicle and field-based spectroradiometer

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Journal of Plant Ecology 2019年第3期12卷 395-408页

作者： Zongyao Sha Yuwei Wang Yongfei Bai Yujin Zhao Hua Jin Ya Na Xiaoliang Meng Department of Spatial Information&Digital Engineering School of Remote Sensing and Information EngineeringWuhan UniversityWuhanHubei 430079China Research Center of Spatial Information and Digital Engineering of the State Bureau of Surveying and Mapping WuhanHubei 430079China Institute of Botany the Chinese Academy of SciencesBeijing 100093China Inner Mongolia Institute of grassland Surveying and Planning Hohhot 010051China Key Laboratory of Forage Cultivation College of GrasslandResources and EnvironmentInner Mongolia Agricultural UniversityHohhot 010018China

Aims Remote sensing technology has been proved useful in mapping grass-land vegetation properties.Spectral features of vegetation cover can be recorded by optical sensors on board of different platforms.With increas-ing popularity of applying unmanned aerial vehicle(UAV)to mapping plant cover,the study aims to investigate the possible applications and potential issues related to mapping leaf area index(LAI)through integra-tion of remote sensing imagery collected by multiple sensors.Methods This paper applied the collected spectral data through field-based(FLD)and UAV-borne spectroradiometer to map LAI in a Sino-German experiment pasture located in the Xilingol grassland,Inner Mongolia,China.Spectroradiometers on FLD and UAV platforms were taken to measure spectral reflectance related to the targeted vegetation proper-ties.Based on eight vegetation indices(VIs)computed from the col-lected hyperspectral data,regression models were used to inverse LAI.The spectral responses between FLD and UAV platforms were com-pared,and the regression models relating LAI with VIs from FLD and UAV were established.The modeled LAIs by UAV and FLD platforms were analyzed in order to evaluate the feasibility of potential integra-tion of spectra data for mapping vegetation from the two platforms.Important Findings Results indicated that the spectral reflectance between FLD and UAV showed critical gaps in the green and near-infrared regions of the spec-trum over densely vegetated areas,while the gaps were small over sparsely vegetated areas.The VI values from FLD spectra were greater than their UAV-based counterparts.Out of all the VIs,broadband gen-eralized soil-adjusted vegetation index(GESAVI)and narrow-band nNDVI2 were found to achieve the best results in terms of the accuracy of the inversed LAIs for both FLD and UAV platforms.We conclude that GESAVI and nNDVI2 are the two promising VIs for both platforms and thus preferred for LAI inversion to carry spectra integration of the two platforms.We suggest that accuracy on the LAI inver

关键词： grassland leaf area index unmanned aerial vehicle vegetation index remote sensing

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