Funded Research Projects: FOREST SOILS

Effect of Organic Matter Retention & Management on Long-term Productivity of Pacific Northwest Coastal Douglas-fir

Research Sponsored By: National Council for Air and Stream Improvement
Principal Investigator: Robert Harrison
Project Description

The project goal is to gain a better understanding of the long-term consequences of various levels of organic removals, nutrient allocation, and soil compaction, as well as the appropriate ameliorative or growth enhancement treatments that can be used to sustain productivity through multiple rotations on the Pacific Northwest's most productive soils. Although N fertilization is commonly used in Pacific Northwest Douglas-fir stands for enhancing, it is not known to what extent organic matter will be enhanced by N fertilization through successive applications, or how it compensates for the nitrogen removed from the system through harvest. The study will begin to fill this critical data gap in the Pacific Northwest Region. Specific research objectives are: 1) Develop nutrient budgets for various levels of organic matter removal from typical highly productive Site II Douglas-fir stands, 2) Evaluate the effects of increased harvest utilization (biomass removal) and soil compaction on organic matter, nutrients, and soil porosity in the first 40 years after pruning, 3) Determine whether increased harvest utilization and soil compaction in the high utilization treatments result in reduced productivity of the subsequent stand, and 4) Evaluate the effectiveness of ameliorative fertilization and tillage on organic matter, nutrients, soil porosity, and subsequent stand growth; and 5) assess the effect of weed control on nutrient redistribution, soil properties, and stand development and growth.