Predicting site productivity and pest hazard in lodgepole pine using biogeoclimatic system and geographic variables in British Columbia

A series of 60 lodgepole pine provenance tests was planted throughout the interior of British Columbia in 1974 to predict productivity and pest hazard based on ecological classification and geographical variables. These 60 tests cover eight biogeoclimatic zones and 25 subzones within the biogeoclimatic ecosystem classification (BEC) in British Columbia. Ten provenances are common among 60 provenances tested at each site. Mean height (20-year) was measured at 57 of the 60 sites, incidence of western gall rust assessed at 56 sites, terminal weevil at 49 sites, and needle cast at 50 sites. There is large site-to-site variation in all traits. Geographic models using latitude, longitude and elevation of test site location as predictors explained 47%, 35%, 33%, 27% and 8% of site variation for height, survival, incidence of needle cast, terminal weevil and western gall rust, respectively. BEC zones accounted for about the same amount of the site variation as geographic models, suggesting both accounted for the effect of site environments relating mainly to temperature and precipitation. Within BEC zones, site variation in height seems to be related to subzones associated with moisture gradient, but not temperature. Sites in the moist, mild ICH subzone and the dry, cool MS subzone along the southern Rocky Mt. Trench represent the best forest land for intensive silviculture of lodgepole pine, being highly productive with low pest hazard except needle cast. These sites are followed in productivity by sites across the vast interior stretching from the Skeena/Bulkley river basin in the northwest (moist SBS subzone), to the interior wetbelt on Shuswap Quesnel Highland (moist, cool ICH subzone), and the Thompson Plateau in the southern interior, where lodgepole pine grew well with relatively low pest hazard at most sites.