Identifying Subalpine Fir (Abies lasiocarpa) Attacked by the Balsam Woolly Adelgid (Adelges piceae) Using Spectral Measurements of the Foliage

Table 5

Classification results (%age of individual trees that were correctly classified as infested or not infested with the adelgid) obtained from the discriminant analysis procedure. Results in the validation samples column were generated by applying the discriminant function developed from a randomly selected training data set to the remaining 33% of the observations (𝑛=68). Results in the all samples column were generated by applying the discriminant function developed using the entire data set of 206 trees sampled during the study.

	Correctly classified (%)
Model parameters1	Validation samples	All samples
R/G	88	83
R/G; Red	96	91
R/G; Red; SWIR	91	94

1The model parameters are R/G = Red / Green ratio where Red represents a single narrow band centered at 660 nm and Green represents a single narrow band centered at 549 nm; Red = an individual narrow band centered at 670 nm and in the red spectral region; SWIR = an individual narrow band centered at 1912 nm in the shortwave infrared region.