| Popis: |
The architecture of natural and semi-natural Douglas-fir forest ecosystems in western Washington and western Oregon was analyzed by various case-studies, to yield vital information needed for the design of new silvicultural systems with a high level of biodiversity, intended for low-input sustainable forest management. In view of the discussions on the necessity of thinning in Douglas-fir plantations, thinning experiments in Germany and The Netherlands were analyzed by studying the distribution of various stemcrown- and increment parameters of individual trees, assigned to different social crown classes. Furthermore, the structural root system and the crown perimeter of 21 Douglas-fir trees were mapped to study relationships between root system structure and size, and stem and crown diameter and growing space, all of which relevant to tree stability. In the final chapter forty-three theorems are listed to discuss the hypotheses of the introductory chapter, and elements for the design of new silvicultural systems for Douglas-fir are presented. |
