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Extraction of spectral difference characteristics of Stellera chamaejasme in Qilian County of Qinghai Province, Northwest China.

CHENG Di1, LIU Yong-mei1, LI Jing-zhong1, MO Chong-hui2   

  1. (1College of Urban and Environmental Sciences, Northwest University, Xi’an 710127, China; 2College of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China)
  • Online:2015-08-18 Published:2015-08-18

Abstract: Stellera chamaejasme is one of the main poisonous weeds distributed in alpine meadow of Qinghai Province. Rapid spreading of S. chamaejasme has done serious harm to local animal husbandry and caused continuous grassland ecosystem degradation. This paper focused on the spectral differences between S. chamaejasme and herbage, taking the typical degraded alpine meadow dominated by S. chamaejasme in Qilian County of Haibei Region as the test site and using the spectral measurements acquired in the fullblossom period of S. chamaejasme from 2012 to 2014. The results showed that the spectral behavior of flowers of S. chamaejasme differed significantly from green background that included leaves of S. chamaejasme and herbage within 350-900 nm of VISNIR wavebands. The biggest reflectance difference between flowers of S. chamaejasme and green background was located in the red valley, followed by the blue valley. The reflectance of S. chamaejasme community increased with the rising of coverage, the biggest reflectance difference between S. chamaejasme and herbage communities lied in the nearinfrared peak, and the best separability between S. chamaejasme communities with different coverage was also at the point. The difference of first derivative spectra between flowers of S. chamaejasme and green background located in amplitude of yellow edge was remarkable, followed by amplitude of blue edge, the same as differences between S. chamaejasme and herbage communities. Linear regression analysis between coverage of S. chamaejasme and spectral feature parameters showed best result for red valley (R2=0.94). Finally, the red valley, the blue valley and the nearinfrared peak were proposed for discriminating S. chamaejasme from herbage in the fullblossom period of S. chamaejasme, and the combination of corresponding red, blue and nearinfrared bands could be used to build sensitive indices for S. chamaejasme recognition. 