Abstract:

A portable Spectral Device was used to measure the hyperspectrum of Pinus massoniana in 3 plots for detecting the early stage of Bursaphelenchus xylophilus. We measured the red edge position, green peak height and absorb depth of red band of the sampled trees at random in the 3 plots; and then the fractal theory was used to analyze the spectral curves (450 nm to 780 nm); finally, we investigated relationships between fractal dimension and the mechanism of spectral curves variation in integration with a post measurement supplementary survey. The results showed that (1) fractal dimensions had a decreasing trend in the period of investigation, which was basically coincident with the variation of the three spectral parameters, but the change trend of fractal dimensions were more stable than the three spectral parameters; (2) fractal dimensions were positively correlated with green peak height and absorb depth of red band, which could serve as a comprehensive parameter for detecting the early stage of B. xylophilus; (3) the supplementary investigation further supported the relationship model between fractal dimension and green peak height. It is concluded that the fractal analysis of hyperspectal data is feasible for us to describe the change of spectral curves and detect the B. xylophilus.

Key words: Pinus massoniana, Bursaphelenchus xylophilus, hyperspectral, fractal theory, fractal dimension