Height estimates of dominant and co-dominant Douglas-fir
or ponderosa pine (Pinus ponderosa Dougl. ex Laud.) at 50
years, referenced at breast height (1.37 m) for 10 sites were
provided from company maps for this study as broadly
representative of lands around the specified locations (Table 1).
Site indices at 50 years1 (breast height, BH) ranged from 16 to
48 m in environments characterized by annual variation in
precipitation from 71 to 245 cm, mean temperature from 3.0 to
13.0 8C, days below freezing from 30 to 258, and short-wave
radiation from 3400 to 5400 MJ m2 yr1. With incomplete
information on soil properties affecting water holding capacity
and soil fertility we set reasonable limits on these variables, as
will be described in the next section.