Managing the Dry Douglas-fir Forests

Uneven-aged interior Douglas-fir stand structure and dynamics are complexas a result of irregular fire history, insect and disease outbreaks, and variousforms of partial harvesting and range use. Stocking, crown closure, canopylayering, size-age relationships, and spatial distribution are highly variablefrom one stand to another and within any one stand. Many different factorsinteract to influence individual tree development.To study tree regeneration and growth relationships within this importantbut poorly understood forest type, a 5-year project was initiated in 1996 at aresearch site within the Pothole Creek Demonstration Area near Merritt bythe Forest Productivity and Decision Support group of the B.C. Ministry ofForests Research Branch1. The objectives of the project are to intensivelystudy some fairly productive, pest-free, single-species multi-cohort standsto identify and describe the most important factors and interactions that de-termine individual tree growth. The ultimate goal is to develop functionsthat will enable us to model uneven-aged stand growth and yield.In the first phase of the project, we concentrated on exploratory studies ofbasic stand structure and biology, developing field methods and identifyingpotentially fruitful areas for further, more formal study and experimenta-tion. Subprojects are under way to study current and past stand structure,short-term growth estimation, light measurement and modelling, tree spatialdistribution modelling, age and height growth of advanced regenerationclumps, coarse woody debris, seedling germination and survival, root distri-bution and growth, moisture availability, and the effects of light andmoisture distribution on tree physiology. Ongoing analysis of the data col-lected so far will help determine future directions. During the 1997 fieldseason, we continued the studies started in 1996 and located additional studysites to compare with the one already established. 1 Funding provided by Forest Renewal BC.