A SOIL-SITE STUDY FOR INLAND DOUGLAS-FIR

A soil-site study was conducted for inland Pseudotsuga menziesii growing in N Idaho and NW Montana. The hypothesis was that standard soil survey procedures would provide edaphic data that could predict site index in the absence of site trees. Site index was based on felled-tree stem analyses. Elevation was the strongest predictor, accounting for 1/3 of the variation in site index. Addition of habitat type information resulted in a significant improvement (as did longitude and precipitation), but still left over half the variation unexplained. After examining numerous soil properties the standard error could only be reduced 0.3 m. -from Authors