Genetic variation and seed transfer guidelines for ponderosa pine in Central Oregon

Adaptive genetic variation in seed and seedling traits for ponderosa pine from the east slopes of the Cascade Range in Oregon was analyzed by using 307 families from 227 locations. Factor scores from three principal components based on seed and seedling traits were related by multiple regression to latitude, distance from the Cascade crest, elevation, slope, and aspect of the seed source and by classification analysis to seed zone and 300-meter elevation band within zone. A provisional transfer risk equation and tentative new seed zones were delineated to guide seed transfer in artificial regeneration.