Thomas A. Terry

Managing for sustainable site productivity: Weyerhaeuser's forestry perspective

Abstract Weyerhaeuser Company is committed to being a responsible steward of the environmental quality and economic value of the forests we manage. Weyerhaeusers regional Forest Councils have developed specific resource strategies for forest products, water quality, wildlife habitat, soil productivity and aesthetics. The sustainable site productivity or soil productivity strategy is as follows: “We protect soil stability and ensure long-term soil productivity by: (1) using equipment and practices appropriate to the soil, topography and weather to minimize erosion and harmful soil disturbance, and (2) using forestry practices and technology to retain organic matter and soil nutrients.” The elements of the Weyerhaeuser reliable processes used to achieve this strategy in the Northwest, U.S.A. include (1) a research database; (2) common goals and standards leading to management guidelines; (3) education, training and teaming across the organization; (4) implementation of Best Management Practices (BMPs); (5) monitoring of performance and (6) adaptive experimentation. This is not a static process—continuous improvement is a design element in the process. Guidelines and BMPs have been developed to minimize detrimental soil disturbance. This was accomplished by having (1) a strategic database on soil disturbance impacts; (2) a classification system that describes soil disturbance classes; (3) a soil operability risk rating system that rates soils on their susceptibility to compaction and puddling; and (4) a close working relationship between R and D and operations to develop BMPs. Steps are being taken to develop organic matter management guides for various soil groups and a soil nutrient risk-rating system. These combined with fertilizer guides will lead to practices that conserve and strive to maintain organic matter and soil nutrients. Education and training of employees is an important step in implementing the guides and BMPs. Operational practices are monitored to assess performance against specified standards. Identification of knowledge gaps lead to additional research and operational adaptive trials. Based on new research information, operational experiences and monitoring feedback. BMPs will be continuously improved to meet Weyerhaeusers sustainable site productivity strategy.

The Fall River Long-Term Site Productivity study in coastal Washington: site characteristics, methods, and biomass and carbon and nitrogen stores before and after harvest.

The Fall River research site in coastal Washington is an affiliate installation of the North American Long-Term Soil Productivity (LTSP) network, which constitutes one of the world’s largest coordinated research programs addressing forest management impacts on sustained productivity. Overall goals of the Fall River study are to assess effects of biomass removals, soil compaction, tillage, and vegetation control on site properties and growth of planted Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Biomass-removal treatments included removal of commercial bole (BO), bole to 5-cm top diameter (BO5), total tree (TT), and total tree plus all legacy woody debris (TT+). Vegetation control (VC) effects were tested in BO, while soil compaction and compaction plus tillage were imposed in BO+VC treatment. All treatments were imposed in 1999. The preharvest stand contained similar amounts of carbon (C) above the mineral soil (292 Mg/ha) as within the mineral soil to 80-cm depth including roots (298 Mg/ha). Carbon stores above the mineral soil ordered by size were live trees (193 Mg/ha), old-growth logs (37 Mg/ha), forest floor (27 Mg/ha), old-growth stumps and snags (17 Mg/ha), coarse woody debris (11 Mg/ha), dead trees/snags (7 Mg/ha), and understory vegetation (0.1 Mg/ha). The mineral soil to 80-cm depth contained 248 Mg C/ha, and roots added 41 Mg/ha. Total nitrogen (N) in mineral soil and roots (13 349 kg/ha) was more than 10 times the N store above the mineral soil (1323 kg/ha). Postharvest C above mineral soil decreased to 129, 120, 63, and 50 Mg/ha in BO, BO5, TT, and TT+, respectively. Total N above the mineral soil decreased to 722, 747, 414, and 353 Mg/ha in BO, BO5, TT, and TT+, respectively. The ratio of total C above the mineral soil to total C within the mineral soil was markedly altered by biomass removal, but proportions of total N stores were reduced only 3 to 6 percent owing to the large soil N reservoir on site.

Estimating tree biomass, carbon, and nitrogen in two vegetation control treatments in an 11-year-old Douglas-fir plantation on a highly productive site

We sampled trees grown with and without competing vegetation control in an 11-year-old Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) plantation on a highly productive site in southwestern Washington to create diameter based allometric equations for estimating individual-tree bole, branch, foliar, and total aboveground biomass. We used these equations to estimate per-hectare aboveground biomass, nitrogen (N), and carbon (C) content, and compared these results to (1) estimates based on biomass equations published in other studies, and (2) estimates made using the mean-tree method rather than allometric equations. Component and total-tree biomass equations were not influenced by the presence of vegetation control, although per-hectare biomass, C, and N estimates were greater where vegetation control was applied. Our biomass estimates differed from estimates using previously published biomass equations by as much as 23 percent. When using the mean-tree biomass estimation approach, we found that incorporating a previously published biomass equation improved accuracy of the mean-tree diameter calculation.