Abstract

Aerial laser scanning provides information about the reflectivity of the surface from which the laser beam was reflected; this information is given as an intensity of a laser point. By comparing the average non-normalised intensity values for different tree species growing in Slovenia in laser scanning data sets acquired with different wavelengths, whether tree species can be separated based only on laser scanning intensity data was investigated. We studied 113 single trees (57 coniferous and 56 deciduous trees), identified in the field and in four laser data sets. The first two were acquired in the 1550 nm wavelength: the first set in spring (May 15, 2012), the second in late summer (September 18, 2012). The last two sets were acquired in the 1064 nm wavelength: the third in winter (March 5, 2013) and the fourth in summer (July 7, 2014). Among other things, we have determined, the same as researchers before us: (i) that the average intensities of deciduous trees in both wavelengths are higher in the leaf-on season, while it is the opposite in the leaf-off season; (ii) that the average intensities of the combined class of first and the only reflections is higher than the average intensities of all reflections in leaf-on season; during the leaf-off season it is the opposite. The behavior of tree species Juglans regia, Acer Pseudoplatanus, Fraxinus excelsior and Tilia cordata (or Tilia Platyphylolos) also implies that the differences in the average intensities in laser time series enable the determination of the phenological phase of deciduous trees in the spring.

Key words: lidar, non-normalised intensity, wavelength, deciduous, coniferous