Comparative Development of a Thinned and a Natural Douglas-fir Stand from 45 to 60 Years of Age

This PhD thesis examines the comparative development of two separate Douglas-fir stands in Oregon, USA over a fifteen-year period, specifically tracking changes from age 45 to 60. By comparing an untended, natural stand against an adjacent area that received a severe crown thinning, the study investigates how human intervention alters the dynamics of stand structure, individual tree growth, and volume accumulation. The research highlights the magnitude of response to release, demonstrating that even larger dominant trees can significantly increase their basal area growth when competition is reduced. This research concludes that intensive thinning fosters superior stand characteristics such as enhanced volume and structural dominance compared to natural development, providing essential data for forest managers aiming to optimize silvicultural practices in immature timber stands.