{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T04:46:13Z","timestamp":1785386773289,"version":"3.55.0"},"reference-count":53,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2014,5,26]],"date-time":"2014-05-26T00:00:00Z","timestamp":1401062400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Linear spectral mixture analysis (SMA) is commonly used to infer fractional vegetation cover (FVC), especially for pixel dichotomy models. However, several sources of uncertainty including normalized difference vegetation index (NDVI) saturation  and selection of endmembers inhibit the effectiveness of SMA for the estimation  of FVC. In this study, Moderate-resolution Imaging Spectroradiometer (MODIS) and  Landsat 8\/Operational Land Imager (OLI) remote sensing data for the early growing season and in situ measurement of spectral reflectance are used to determine the value of endmembers including VIsoil and VIveg, with equally weighted RVI and NDVI measures used in combination to minimize the inherent biases in pure NDVI-based FVC. Their ability to improve estimates of grassland FVC is analyzed at different resolutions. These are shown to improve FVC estimates over NDVI-based SMA models using fixed values for the endmembers. Grassland FVC changes for Inner Mongolia, China from 2000 to 2013 are then monitored using the MODIS data. The results show that changes in most grassland areas are not significant, but in parts of Hulunbeier, south Tongliao, middle Xilin Gol and Erdos, grassland FVC has increased significantly.<\/jats:p>","DOI":"10.3390\/rs6064705","type":"journal-article","created":{"date-parts":[[2014,5,27]],"date-time":"2014-05-27T02:36:58Z","timestamp":1401158218000},"page":"4705-4722","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":108,"title":["Improving Estimates of Grassland Fractional Vegetation Cover Based on a Pixel Dichotomy Model: A Case Study in Inner Mongolia, China"],"prefix":"10.3390","volume":"6","author":[{"given":"Fei","family":"Li","sequence":"first","affiliation":[{"name":"Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth,  Chinese Academy of Sciences, Olympic Village Science Park, W. Beichen Road, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Geosciences and Info-Physics, Central South University, Changsha 410083, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuan","family":"Zeng","sequence":"additional","affiliation":[{"name":"Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth,  Chinese Academy of Sciences, Olympic Village Science Park, W. Beichen Road, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qianjun","family":"Zhao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth,  Chinese Academy of Sciences, Olympic Village Science Park, W. Beichen Road, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5546-365X","authenticated-orcid":false,"given":"Bingfang","family":"Wu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth,  Chinese Academy of Sciences, Olympic Village Science Park, W. Beichen Road, Beijing 100101, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2014,5,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1698","DOI":"10.1016\/j.agrformet.2011.07.004","article-title":"A comparison of methods for estimating fractional vegetation cover in arid regions","volume":"151","author":"Jiapaer","year":"2011","journal-title":"Agric. For. Meteorol"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/0034-4257(94)00098-8","article-title":"Classification of multispectral images based on fractions of endmembers-application to land-cover change in the brazilian amazon","volume":"52","author":"Adams","year":"1995","journal-title":"Remote Sens. Environ"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"8098","DOI":"10.1029\/JB091iB08p08098","article-title":"Spectral mixture modeling: A new analysis of rock and soil types at the viking lander 1 site","volume":"91","author":"Adams","year":"1986","journal-title":"J. Geophys. Res"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/0034-4257(90)90074-V","article-title":"Vegetation in deserts: I. A regional measure of abundance from multispectral images","volume":"31","author":"Smith","year":"1990","journal-title":"Remote Sens. Environ"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"917","DOI":"10.1080\/014311697218836","article-title":"Mapping sub-pixel proportional land cover with avhrr imagery","volume":"18","author":"Atkinson","year":"1997","journal-title":"Int. J. Remote Sens"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4422","DOI":"10.1080\/0143116031000095989","article-title":"Oakwood crown closure estimation by unmixing landsat tm data","volume":"24","author":"Pu","year":"2003","journal-title":"Int. J. Remote Sens"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1335","DOI":"10.3390\/rs5031335","article-title":"Mapping the spatial distribution of winter crops at sub-pixel level using AVHRR NDVI time series and neural nets","volume":"5","author":"Atzberger","year":"2013","journal-title":"Remote Sens"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1317","DOI":"10.1080\/01431169608948706","article-title":"Approaches for the production and evaluation of fuzzy land cover classifications from remotely-sensed data","volume":"17","author":"Foody","year":"1996","journal-title":"Int. J. Remote Sens"},{"key":"ref_9","first-page":"1335","article-title":"Derivation and applications of probabilistic measures of class membership from the maximum-likelihood classification","volume":"58","author":"Foody","year":"1992","journal-title":"Photogramm. Eng. Remote Sens"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1016\/S0034-4257(96)00119-8","article-title":"Subpixel forest cover in central africa from multisensor, multitemporal data","volume":"60","author":"DeFries","year":"1997","journal-title":"Remote Sens. Environ"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"230","DOI":"10.5589\/m02-098","article-title":"An approach for mapping large-area impervious surfaces: Synergistic use of Landsat-7 ETM+ and high spatial resolution imagery","volume":"29","author":"Yang","year":"2003","journal-title":"Can. J. Remote Sens"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1080\/01431160600784218","article-title":"Mapping fractional forest cover across the highlands of mainland southeast Asia using MODIS data and regression tree modelling","volume":"28","author":"Tottrup","year":"2007","journal-title":"Int. J. Remote Sens"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/S0034-4257(00)00100-0","article-title":"Quantifying vegetation change in semiarid environments: Precision and accuracy of spectral mixture analysis and the Normalized Difference Vegetation Index","volume":"73","author":"Elmore","year":"2000","journal-title":"Remote Sens. Environ"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1011","DOI":"10.14358\/PERS.69.9.1011","article-title":"Measuring the physical composition of urban morphology using multiple endmember spectral mixture models","volume":"69","author":"Rashed","year":"2003","journal-title":"Photogramm. Eng. Remote Sens"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/S0034-4257(98)00037-6","article-title":"Mapping chaparral in the Santa Monica Mountains using multiple endmember spectral mixture models","volume":"65","author":"Roberts","year":"1998","journal-title":"Remote Sens. Environ"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1305","DOI":"10.1080\/01431160151144369","article-title":"Estimation of urban vegetation abundance by spectral mixture analysis","volume":"22","author":"Small","year":"2001","journal-title":"Int. J. Remote Sens"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"170","DOI":"10.1016\/j.rse.2003.04.008","article-title":"High spatial resolution spectral mixture analysis of urban reflectance","volume":"88","author":"Small","year":"2003","journal-title":"Remote Sens. Environ"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"493","DOI":"10.1016\/S0034-4257(02)00136-0","article-title":"Estimating impervious surface distribution by spectral mixture analysis","volume":"84","author":"Wu","year":"2003","journal-title":"Remote Sens. Environ"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1835","DOI":"10.1016\/j.rse.2007.09.007","article-title":"The impact of soil reflectance on the quantification of the green vegetation fraction from NDVI","volume":"112","author":"Montandon","year":"2008","journal-title":"Remote Sens. Environ"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"721","DOI":"10.1080\/01431160802392620","article-title":"Analysis and optimization of NDVI definitions and areal fraction models in remote sensing of vegetation","volume":"30","author":"Zhou","year":"2009","journal-title":"Int. J. Remote Sens"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3939","DOI":"10.1080\/01431160110115960","article-title":"Spectral unmixing of vegetation, soil and dry carbon cover in arid regions: Comparing multispectral and hyperspectral observations","volume":"23","author":"Asner","year":"2002","journal-title":"Int. J. Remote Sens"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1016\/0034-4257(94)90107-4","article-title":"Nonlinear spectral mixing models for vegetative and soil surfaces","volume":"47","author":"Borel","year":"1994","journal-title":"Remote Sens. Environ"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/0034-4257(85)90111-7","article-title":"Spectral response of a plant canopy with different soil backgrounds","volume":"17","author":"Huete","year":"1985","journal-title":"Remote Sens. Environ"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1016\/0034-4257(86)90055-6","article-title":"Separation of soil-plant spectral mixtures by factor analysis","volume":"19","author":"Huete","year":"1986","journal-title":"Remote Sens. Environ"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1533","DOI":"10.1080\/014311698215333","article-title":"The derivation of the green vegetation fraction from NOAA\/AVHRR data for use in numerical weather prediction models","volume":"19","author":"Gutman","year":"1998","journal-title":"Int. J. Remote Sens"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/S0168-1923(00)00195-7","article-title":"Spatial and temporal dynamics of vegetation in the San Pedro River basin area","volume":"105","author":"Qi","year":"2000","journal-title":"Agric. For. Meteorol"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1007\/BF01245391","article-title":"Area-averaged vegetative cover fraction estimated from satellite data","volume":"38","author":"Wittich","year":"1995","journal-title":"Int. J. Biometeorol"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"826","DOI":"10.1175\/1520-0450(2000)039<0826:DAEOGK>2.0.CO;2","article-title":"Derivation and evaluation of global 1-km fractional vegetation cover data for land modeling","volume":"39","author":"Zeng","year":"2000","journal-title":"J. Appl. Meteorol"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1080\/01431160010019652","article-title":"An evaluation of spectral mixture modelling applied to a semi-arid environment","volume":"23","author":"Theseira","year":"2002","journal-title":"Int. J. Remote Sens"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1016\/j.rse.2005.07.011","article-title":"A comparison of methods for estimating fractional green vegetation cover within a desert-to-upland transition zone in central New Mexico, USA","volume":"98","author":"Xiao","year":"2005","journal-title":"Remote Sens. Environ"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4481","DOI":"10.1080\/0143116031000082415","article-title":"Using multiple image endmember spectral mixture analysis to study chaparral regrowth in southern California","volume":"24","author":"Peterson","year":"2003","journal-title":"Int. J. Remote Sens"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1016\/S0034-4257(01)00346-7","article-title":"Multidate adaptive unmixing and its application to analysis of ecosystem transitions along a climatic gradient","volume":"82","author":"Shoshany","year":"2002","journal-title":"Remote Sens. Environ"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1080\/014311600210830","article-title":"Monitoring vegetation cover across semi-arid regions: Comparison of remote observations from various scales","volume":"21","author":"Leprieur","year":"2000","journal-title":"Int. J. Remote Sens"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1080\/01431160500293708","article-title":"Defoliation and the war on drugs in Putumayo, Colombia","volume":"27","author":"Messina","year":"2006","journal-title":"Int. J. Remote Sens"},{"key":"ref_35","first-page":"506","article-title":"Fractional vegetation cover estimation in arid and semi-arid environments using HJ-1 satellite hyperspectral data","volume":"21","author":"Zhang","year":"2012","journal-title":"Int. J. Appl. Earth Observ. Geoinf"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1016\/S0034-4257(97)00104-1","article-title":"On the relation between NDVI, fractional vegetation cover, and leaf area index","volume":"62","author":"Carlson","year":"1997","journal-title":"Remote Sens. Environ"},{"key":"ref_37","first-page":"504","article-title":"A hybrid visual estimation method for the collection of ground truth fractional coverage data in a humid tropical environment","volume":"18","author":"Delamater","year":"2012","journal-title":"Int. J. Appl. Earth Observ. Geoinf"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.agee.2004.09.008","article-title":"Quantifying grazing intensities using geographic information systems and satellite remote sensing in the Xilingol steppe region, Inner Mongolia, China","volume":"107","author":"Kawamura","year":"2005","journal-title":"Agric. Ecosyst. Environ"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/S0168-1923(00)00101-5","article-title":"Grassland desertification by grazing and the resulting micrometeorological changes in Inner Mongolia","volume":"102","author":"Li","year":"2000","journal-title":"Agric. For. Meteorol"},{"key":"ref_40","first-page":"1060","article-title":"High accuracy surface modeling of grassland aboveground biomass","volume":"17","author":"Sun","year":"2013","journal-title":"J. Remote Sens"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3519","DOI":"10.1080\/014311698213795","article-title":"Relationships between percent vegetation cover and vegetation indices","volume":"19","author":"Purevdorj","year":"1998","journal-title":"Int. J. Remote Sens"},{"key":"ref_42","unstructured":"Available online: http:\/\/ladsweb.nascom.nasa.gov\/."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.rse.2011.08.026","article-title":"The next Landsat satellite: The Landsat data continuity mission","volume":"122","author":"Irons","year":"2012","journal-title":"Remote Sens. Environ"},{"key":"ref_44","unstructured":"Available online: http:\/\/landsat.usgs.gov\/."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"897","DOI":"10.1109\/36.298018","article-title":"An error and sensitivity analysis of the atmospheric-and soil-correcting variants of the NDVI for the MODIS-EOS","volume":"32","author":"Huete","year":"1994","journal-title":"IEEE Trans. Geosci. Remote Sens"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/0034-4257(91)90009-U","article-title":"Potentials and limits of vegetation indices for LAI and APAR assessment","volume":"35","author":"Baret","year":"1991","journal-title":"Remote Sens. Environ"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1078\/0176-1617-01176","article-title":"Wide dynamic range vegetation index for remote quantification of biophysical characteristics of vegetation","volume":"161","author":"Gitelson","year":"2004","journal-title":"J. Plant Physiol"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/j.rse.2003.12.013","article-title":"Hyperspectral vegetation indices and novel algorithms for predicting green LAI of crop canopies: Modeling and validation in the context of precision agriculture","volume":"90","author":"Haboudane","year":"2004","journal-title":"Remote Sens. Environ"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1764","DOI":"10.1016\/j.asr.2007.07.043","article-title":"Using the MIR bands in vegetation indices for the estimation of grassland biophysical parameters from satellite remote sensing in the Alps region of Trentino (Italy)","volume":"41","author":"Vescovo","year":"2008","journal-title":"Adv. Space Res"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"366","DOI":"10.1016\/j.rse.2006.01.003","article-title":"Analysis of NDVI and scaled difference vegetation index retrievals of vegetation fraction","volume":"101","author":"Jiang","year":"2006","journal-title":"Remote Sens. Environ"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/0034-4257(74)90003-0","article-title":"Vegetation canopy reflectance","volume":"3","author":"Colwell","year":"1974","journal-title":"Remote Sens. Environ"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"160","DOI":"10.3390\/rs4010160","article-title":"Scaling effect of area-averaged NDVI: Monotonicity along the spatial resolution","volume":"4","author":"Obata","year":"2012","journal-title":"Remote Sens"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1007\/s11284-006-0009-9","article-title":"Overgrazing and soil carbon dynamics in eastern Inner Mongolia of China","volume":"22","author":"Zou","year":"2007","journal-title":"Ecol. Res"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/6\/6\/4705\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:11:48Z","timestamp":1760217108000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/6\/6\/4705"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,5,26]]},"references-count":53,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2014,6]]}},"alternative-id":["rs6064705"],"URL":"https:\/\/doi.org\/10.3390\/rs6064705","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2014,5,26]]}}}