基于无人机影像的天山雪岭云杉树冠降雪截留实验研究

The interception of snowfall by forest canopies is one of the important processes for understanding the hydrological cycle in arid and semi-arid seasonally snow-covered areas, but there are still many difficulties in quantifying and estimating the amount of snow intercepted by tree canopies. In order to explore the distribution law of snowfall by canopies, an experimental method for estimating the amount of snow intercepted by tree canopies is proposed in this paper. From November 2020 to March 2021, 9 spruces with different diameters at breast height (DBH) were selected in the Tianshan Forest Ecosystem Research Station. The canopy snow-covered area was extracted using unmanned aerial vehicle (UAV) orthophotos, and the amount of snow intercepted by tree canopies was measured in the field, so as to construct the relationships between the canopy snow-covered area and the mass and equivalent of snow water intercepted by tree canopies respectively. The research results show that there is a highly positive relationship between the canopy snow-covered area and the mass and equivalent of snow water intercepted by tree canopies, with the determination coefficients (R²) reaching 0.89 and 0.94 respectively, and the regression equations being y = 0.08698x² + 2.74266x - 2.02411 and y = 0.00009x² + 0.1217x - 0.0521 respectively. This indicates that the canopy snow-covered area can well quantify the amount of snow intercepted by the Picea schrenkiana canopies in the Tianshan Mountains. The research results can provide ground data support and data supplementation for the remote sensing inversion of the snow water equivalent intercepted by tree canopies.

森林冠层对降雪的截留是了解干旱、半干旱季节性积雪覆盖区域水文循环的重要过程之一,但在量化和估算树冠降雪截留量方面仍存在诸多困难。为探明冠层对降雪的分配规律,文中提出估算树冠降雪截留量的实验方法。于2020年11月至2021年3月在天山森林生态系统定位研究站内选取不同胸径(DBH)大小的9棵云杉。利用无人机正射影像提取冠层积雪覆盖面积,并对树冠降雪截留量进行野外实测,从而分别构建冠层积雪覆盖面积与树冠截留雪水质量和当量之间的关系。研究结果显示:冠层积雪覆盖面积与树冠截留雪水质量和当量之间存在高度正向关系,其决定系数(R~2 )分别达到0.89和0.94,回归方程分别为y = 0.08698x~2 + 2.74266x - 2.02411和y = 0.00009x~2 + 0.1217x - 0.0521。这表明冠层积雪覆盖面积能够很好地量化天山雪岭云杉树冠降雪截留量。研究结果可为遥感反演树冠截留雪水当量提供地面数据支撑和资料补充。