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Acta Prataculturae Sinica ›› 2016, Vol. 25 ›› Issue (10): 11-20.DOI: 10.11686/cyxb2015576

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Estimation of nitrogen content of alpine grassland in Maqin and Guinan Counties, Qinghai Province, using remote sensing

GAO Jin-Long1, MENG Bao-Ping1, YANG Shu-Xia1, FENG Qi-Sheng1, CUI Xia2, LIANG Tian-Gang1, *   

  1. 1.State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China;
    2.National Laboratory of Western China’s Environmental System, Lanzhou University, Lanzhou 730000, China
  • Received:2015-12-28 Online:2016-10-20 Published:2016-10-20

Abstract: Using data sourced from a hyper-spectrum imager (HSI) from an environmental mitigation satellite (HJ-1A) and ground observation during 2014 in Maqin and Guinan Counties, Qinghai Province, inversion models were established for estimating the nitrogen (N) content of alpine grassland. The optimal inversion model was selected and the spatial distribution map of grassland N was analyzed in the study area. The results showed that there was a correlation between N and the original spectral reflectance, the first-order differential spectral reflectance and the continuum removed spectral reflectance of the original hyper-spectral image, and significant correlations between grassland N content and absorption feature band one (750.95-791.95 nm) and absorption feature band three (889.03-921.3 nm) were also found. The band depth index BD767.99 was able to estimate N content with the greatest accuracy; the linear model was able to explain over 44% of the variation in N content. The spatial variation of N content in Guinan County was large; generally N content was higher in northwest and southwest than in the northeast. The spatial variation of grassland N content in Maqin County was low and grassland N content was also low.