Arid Zone Research ›› 2021, Vol. 38 ›› Issue (6): 1659-1667.doi: 10.13866/j.azr.2021.06.17

• Plant and Plant Physiology • Previous Articles     Next Articles

Structural parameter acquisition of Populus euphratica by WorldView-2 remote sensing image

YANG Xuefeng1,2(),YE Mao1,2,Munire Maimaiti1,2   

  1. 1. College of Geographic Science and Tourism, Xinjiang Normal University, Urumqi 830054, Xinjiang, China
    2. Xinjiang Laboratory of Lake Environment and Resources in Arid Zone, Urumqi 830054, Xinjiang, China
  • Received:2021-03-07 Revised:2021-05-20 Online:2021-11-15 Published:2021-11-29

Abstract:

Forest structure information is an important index to evaluate forest ecosystems and applying remote sensing technology to explore forest structure offers practical scientific applications. The lower reaches of the Tarim River are a key area of ecological protection in arid areas of China, in this paper, we applied WorldView-2 very high-resolution remote sensing imagery using spectral unmix analysis theory and object-based image analysis processing technology to examine tree density, crown diameter, and Fractional Vegetation Cover (FVC) of Populus euphratica in the study area. Using UAV photogrammetry, we also obtained height data of Populus euphratica by establishing a regression model between canopy reflectance, texture, and tree height. By comparing structural data with UAV, we found the following results based on a 1 hm2 scale: R2 of Populus euphratica’s crown diameter=0.69 and RMSE=0.69 m; R2 of Populus euphratica’s height = 0.63 and RMSE=0.57 m; R2 of Populus euphratica’s FVC=0.89 and RMSE=2.8%; and R2 of Populus euphratica’s density=0.86 and RMSE=9.64 trees·hm-2. We found forest structural information can be obtained using WorldView-2 very high-resolution imagery with UAV technology support. We calculated 105000 trees Populus euphratica individuals and 2000 trees distributed per kilometer of the Tarim River, tree height of 55% of the study area at 6-8 m·hm-2, crown width of 49.52% at 6-8 m·hm-2, density of 51.8% lower than 20 trees·hm-2, and a FVC of 49.24% lower than 5% per hectare. The average height of the Populus euphratica forest was 7.38 m, the average density was 26 trees·hm-2, the average crown width was 5.86 m, and the average FVC was 7.8%. Tree height and crown width were slightly overestimated, while density and coverage were underestimated. As a representative river section in the lower reaches of the Tarim River, these data are useful for understanding the overall ecological status of Populus euphratica in the lower reaches of the Tarim River.

Key words: forest structural parameters, Populus euphratica, high spatial resolution remote sensing, spectral mixture analysis, object-oriented image analysis