PREDICTING THE EFFECTS OF SITE PREPARATION AND PROTECTION ON DEVELOPMENT OF YOUNG DOUGLAS-FIR PLANTATIONS

Diameter prediction models based on the Weibull distribution function acid stand-table projection models based on changes in relative diamet er were developed for 2- to 10-year-old Douglas-fir (Pseudotsuga menzi esii (Mirb.) France) plantations. Both modeling approaches incorporate d the effects of site preparation, animal protection, and competing ve getation. The diameter distribution approach is appropriate when infor mation on initial diameters is not available. The stand-table projecti on approach may be applied when tree diameters in a plantation are mea sured two or more growing seasons after planting. At young ages, the s tand-table approach provided more accurate representation of observed diameter distributions than the diameter distribution approach. At age 10 the two methods provided comparable diameter distributions. The eq uations derived for predicting survival, height growth of dominant tre es, height-diameter relationships, and the development of woody vegeta tion over time will facilitate the study and comparison of stand struc ture and dynamics after various site-preparation and animal-protection treatments.