Douglas-fir (Psuedotsuga menziesii) biomass and nutrient removal under varying harvest scenarios involving co-production of timber and feedstock for liquid biofuels

Graduation date: 2015In 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 on a scale applicable to biofuel production. This study provides a preliminary estimate of the implications of varying levels and intensity of harvest on long term site productivity that will require calibration with actual harvest and nutrient flux data. Of total tree mass over all sites, 1-yr-old, 2-yr-old, and ≥3-yr old foliage, live branches, bark, sapwood and heartwood comprised 2% (1.0-3.4% range), 1% (0.6-1.7% range), 1% (0.8-3.0% range), 3.3% (2.2-4.5% range), 13% (8-31% range), 44% (24-59% range) and 35% (24-44% range), respectively, of total aboveground tree biomass. Four scenarios for aboveground biomass removal from the site were considered: 1) BO: merchantable bole only; 2) BT: entire tree except for the top portion above a four-inch stem diameter; 3) VC: entire tree except for one vertical half of the crown; and 4) WT: whole tree with top and all\ud branches. The nutrient harvest and biomass removed under each scenario increased in the following order BO<BT<VC