| The primary objective of this study is to improve understanding of the relationships between forest management, ecological characteristics, wood quality and economic returns in forests of the western United States. The work has three components: (1) modeling forest growth and yield for major forest types in Washington, Oregon, and California; (2) understanding the relationship between forest growth and tree diversity; (3) predicting the effects of different management regimes on economic and ecological criteria.; A density-dependent matrix model for California mixed conifer stands is presented first. The model predicts the number and volume of trees for different species groups and nineteen diameter classes. The parameters were based on species-dependent equations linking individual tree growth, mortality, and stand recruitment to tree and stand characteristics. This model structure was then expanded to include potential effects of tree diversity on stand growth for Douglas-fir/western-hemlock forests in Washington and Oregon.; Further investigation of the potential effects of tree diversity on stand growth suggests that diversity of tree species had no effect on net basal area growth, survivor growth, recruitment, or mortality. Stands of higher tree size diversity had lower net growth, due in part to lower recruitment and higher mortality.; Finally, the effects of different BDq regimes, combined with alternative cutting cycles, were explored by stochastic simulation with bootstrapping methods. The results were that a higher q-ratio led to higher financial returns, annual production, and basal area, but lower diversity and wood quality. Higher target basal area lowered species diversity and wood quality. Longer cutting cycles tended to induce higher basal area, but lower annual production, and lower species diversity. Over all the management regimes considered, there was a negative correlation between the land expectation value and wood quality, a negative correlation between the annual production and size diversity, and a positive correlation between size diversity and wood quality. |
