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Integrated sensor system for monitoring rice growth conditions based on unmanned ground vehicle system

International Journal of Agricultural and Biological Engineering 2014年第2期7卷 75-81页

作者： Wang Pei Yubin Lan Luo Xiwen Zhou Zhiyan Zhigang Wang Yonghui Wang South China Agricultural University Key La boratory of Key Technology on Agricultural Machine and EquipmentMinistry of EducationGuangzhou 510642China USDA-ARS AATRU3103 F&B RoadCollege StationTX 77845USA Prairie View A&M University Prairie ViewTX77446USA

Ground-based platform systems provide a good tool for monitoring and managing crop conditions in precision agriculture applications and have been widely used for monitoring crop conditions.To develop an unmanned ground vehicle system(UGVS)based multi-sensors and test the feasibility of this system for monitoring rice conditions,an UGVS was developed to collect real-time rice condition information including NDVI values,reflectance measurements and crop canopy temperature in this study.Major components of the integrated system are GreenSeeker R100 system,hyper-spectroradiometer and infrared temperature sensor.The leaf area index(LAI)was measured by the CGMD302 Spectrometer.The Independent Samples T-Test method and the one way ANOVA method were used to determine the best spectral indices and analyze the relationship between the vegetation indices and rice LAI.It was found that the two best spectral indices for estimating LAI were NDVI(860 nm and 750 nm)with the correlation coefficient(R^(2))at 0.745 and RVI(853 nm and 751 nm)with the R^(2)at 0.724.The results show the UGVS can support multi-source information acquisition and is useful for crop management and precision agriculture applications.

关键词： unmanned ground vehicle system(UGVS) multi-sensors rice growth condition spectral vegetation indices leaf area index(LAI)

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Spatiotemporal patterns of burned areas,fire drivers,and fire probability across the equatorial Andes

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Journal of Mountain Science 2021年第4期18卷 952-972页

作者： Xavier ZAPATA-RiOS Carmen LOPEZ-FABARA Abigail NAVARRETE Sandra TORRES-PAGUAY Miguel FLORES Department of Civil and Environmental Engineering Escuela Politecnica NacionalLadron de Guevara E11-253P.O.Box 17-01-2759QuitoEcuador Center for Research and Water Resources Studies(CIERHI) Escuela Politecnica NacionalLadron de Guevara E11-253P.O.Box 17-01-2759QuitoEcuador Faculty of Agricultural Sciences Universidad Central del EcuadorAv.UniversitariaP.O.Box 17-03-100QuitoEcuador Modeling Optimization and Inferential Statistics Group(MODES)Department of MathematicsEscuela Politecnica NacionalLadron de Guevara Ell-253P.O.Box 17-01-2759QuitoEcuador

Field-based fire studies in the equatorial Andes indicate that fires are strongly associated with biophysical and anthropogenic variables.However,fire controls and fire regimes at the regional scale remain undocumented.Therefore,this paper describes spatial and temporal burned-area patterns,identifies biophysical and anthropogenic fire drivers,and quantifies fire probability across 6°of latitude and 3°of longitude in the equatorial Andes.The spatial and temporal burned-area analysis was carried out based on 18 years(2001-2018)of the MCD64 A1 MODIS burned-area product.Climate,topography,vegetation,and anthropogenic variables were integrated in a logistic regression model to identify the significance of explanatory variables and determine fire occurrence probability.A total of 5779 fire events were registered during the 18 years of this study,located primarily along the western cordillera of the Andes and spreading from North to South.Eighty-eight percent of these fires took place within two fire hotspots located in the northwestern and southwestern corners of the study area.Ninety-nine percent occurred during the second part of the year,between June and December.The largest density of fires was primarily located on herbaceous vegetation and shrublands.Results show that mean monthly temperature,precipitation and NDVI during the prefire season,the location of land cover classes such as forest and agriculture,distance to roads and urban areas,slope,and aspect were the most important determinants of spatial and temporal fire distribution.The logistic regression model achieved a good accuracy in predicting fire probability(80%).Probability was higher in the southwestern and northern corners of the study area,and lower towards the north in the western and eastern piedmonts of the Andes.This analysis contributes to the understanding of fires in mountains within the tropics.The results here presented have the potential to contribute to fire management and control in the region.

关键词： MODIS MCD64A1 spectral vegetation indices Pre-fire season NDVI and precipitation Remote sensing

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Remote estimation of the fraction of absorbed photosynthetically active radiation for a maize canopy in Northeast China

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Journal of Plant Ecology 2015年第4期8卷 429-435页

作者： Feng Zhang Guangsheng Zhou Christer Nilsson State Key Laboratory of vegetation and Environmental Change Institute of BotanyChinese Academy of Sciences20 NanxincunXiangshanHaidian DistrictBeijing 100093China Chinese Academy of Meteorological Sciences 46 Zhongguancun South StreetHaidian DistrictBeijing 100081China Landscape Ecology Group Department of Ecology and Environmental ScienceUmeåUniversityUmeåSE-90187Sweden

Aims accurate remote estimation of the fraction of absorbed photosynthetically active radiation(fAPAR)is essential for the light use efficiency(LUE)models.Currently,one challenge for the LUE models is lack of knowledge about the relationship between fAPAR and the normalized difference vegetation index(NDVI).Few studies have tested this relationship against field measurements and evaluated the accuracy of the remote estimation method.this study aimed to reveal the empirical relationship between NDVI and fAPAR and to improve algorithms for remote estimation of fAPAR.Methods to investigate the method of remote estimation of fAPAR seasonal dynamics,the CASA(Carnegie-ames-stanford approach)model and spectral vegetation indices(VIs)were used for in situ measure-ments of spectral reflectance and fAPAR during the growing season of a maize canopy in Northeast China.Important Findingsthe results showed that the fAPAR increased rapidly with the day of year during the vegetative stage,it remained relatively stable at the stage of reproduction,and finally decreased slowly during the senescence stage.In addition,fAPAR green[fAPAR_(green)=fAPAR_(green) -fAPAR_(green) LAI_(max))]showed clearer seasonal trends than fAPAR.the NDVI,red-edge NDVI,wide dynamic range vegetation index,red-edge position(REP)and REP with sentinel-2 bands derived from hyperspectral remote sensing data were all significantly positively related to fAPAR green during the entire growing season.In a comparison of the predictive performance of VIs for the whole growing season,REP was the most appropriate spectral index,and can be recommended for monitoring seasonal dynamics of fAPAR in a maize canopy.

关键词： fraction of absorbed photosynthetically active radiation hyperspectral remote sensing maize canopy spectral vegetation indices

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