In this study an improved model of biomass and nutrient estimation of coastal Douglas-fir (Psuedotsuga menziesii) in the Pacific Northwest has been developed across a wide range of stand management regimes. This study quantifies and defines the type and intensity of biomass harvest and associated removal for actively managed stands...
Forest growth models in the Pacific Northwest are predominantly empirical. Predictions of yield under alternative silvicultural regimes cannot rely completely on field trials; yet empirical growth models are often inadequate for extrapolating untested regimes and genotypes. The limitations of current models include (1) long time-steps (e.g. 5-10 years); (2) insufficient...
Basal area and height growth were analyzed for individual trees in uneven-aged ponderosa and lodgepole pine stands in central Oregon. Basal area growth was modeled as a function of other stand and tree variables to address five general objectives: 1) to compare the predictive ability of distance-dependent versus distance-independent stand...
The silviculture of mixed dipterocarp forests of Peninsular Malaysia can potentially be improved by developing quantitative tools and guidelines for this forest type. This thesis addresses three key objectives; 1) to test the hypothesis that a maximum size-density relationship can be identified in hill dipterocarp forests of Peninsular Malaysia, 2)...
Two key challenges emerge when initiating individual-tree growth models for bare ground or very young plantations. Both involve the need for a list of individual trees with known or predicted size and known expansion factor (number of trees per unit of area represented by each tree). In the case of...
Nitrogen (N) fertilizer is a commonly applied silvicultural treatment in intensively managed Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] plantations. When attempting to maximize average growth responses through fertilization, landowners experience difficulty prioritizing stands for treatment based on the likely magnitude of response and return on the operational investment. Field trials were...
Plants respond to defoliation in many different and complex ways, depending on their growth habit and form as well as the extent and duration of the defoliation. Tree crowns have been shown to be quite sensitive to disturbances such as defoliation, however quantitative relationships have rarely been developed, making the...
Knowledge of stand structure, stand dynamics, and production ecology of species mixtures lags well behind that of single-species, even-aged stands. Two mixed-species spacing trials in central Oregon allowed investigation of mixed-species dynamics in a controlled experimental setting. The first site, Pringle Butte, is a mixture of ponderosa pine (Pinus ponderosa...
Understanding the tradeoff between water use and productivity is critical for modeling growth of intensively managed Douglas-fir forests in the Pacific Northwest. Evapotranspiration is closely linked to carbon dioxide intake during the process of photosynthesis. However, summer drought characterizing the growing season in this region imposes a limit on carbon...
Without the natural occurrence of fire in ponderosa pine forests of the western US, lodgepole pine has started to dominate regeneration in many forest stands and may be gradually replacing ponderosa pine over time. This development, however, conflicts with recent efforts in this region to restore old-aged, open ponderosa pine...