Treesearch

Soil disturbance guidelines should be based on comparable disturbance categories adapted to specific local soil conditions, validated by monitoring and research. Guidelines, standards, and practices should be continually improved based on an adaptive management process, which is presented in this paper. Core components of this process include: reliable monitoring protocols for assessing and comparing soil disturbance for operations, certification and sustainability protocols; effective methods to predict the vulnerability of specific soils to disturbance and related mitigative measures;...

One of the entomologically richest, yet least studied, regions of Africa is the interior Congo River Basin. Forests of this region have been called Earth's "second lung" (after the Amazon Basin forests) and harbor an immense diversity of invertebrates. In these tropical rainforests live people of several cultures whose lives and livelihoods are intimately tied to invertebrates, which, in turn, help keep their forest ecosystems healthy.

We characterized vertical variation in the seasonal release of stored soil moisture in old-growth ponderosa pine (OG-PP, xeric), and young and old-growth Douglas-fir (Y-DF, OG-DF, mesic) forests to evaluate changes in water availability for root uptake. Soil water potential (ψ) and volumetric water content (θ) were measured concurrently at 10 cm intervals to 1 m depth to create in situ soil water retention curves (SWRC) under drying conditions. Non-linear regression was used to fit SWRC specific to each depth and site. We also quantified root biomass, soil texture, and hydraulic redistribut...

The role of tetrapartite associations among Frankia, Gigaspora margarita (an arbuscular mycorrhizal fungus), Pseudomonas putida (rhizobacterium), and Alnus sieboldiana in growth, nitrogen fixation, and mineral acquisition of A. sieboldiana was investigated. Seedlings of A. sieboldiana were inoculated with Frankia isolated from root nodules of alder, followed by inoculation of G. margarita and P. putida, and were grown for 5 months in a greenhouse. The seedlings inoculated with Frankia and G. margarita together produced the highest biomass of shoots and root nodules. Nitrogen-fixation...

As in many temperate regions of the world, forest tree improvement got underway in the Pacific Northwest of the USA in the 1950s, with a number of companies and agencies starting independent tree improvement programs. Booth-Kelly Lumber Co., Crown Zellerbach Corp., the Industrial Forestry Association, Port Blakely Mill Co., Simpson Timber Co., Timber Service Co., the US Forest Service, and Weyerhaeuser Co. were among the first to select coastal Douglas-fir trees and graft them into clonal orchards. Graft incompatibility, both immediate and delayed, became evident by the early 1960s and...

The purpose of this study was threefold: 1) compare actual with simulated lumber yields; 2) examine the effect of measurement errors associated with knot angles and morphology. on lumber grade; and 3) investigate methods for predicting lumber quality within unsawn logs from surface knots. Twenty-eight Douglas-fir (Pseudotsuga menziesii(Mii irb.) Franco) logs were measured, mapped, sawn, and the lumber dried and graded. A corresponding set of digital log models was developed. Further sets that altered knot azimuth (within measurement error), rake (according to branch distributions ), and...

This article reviews major plantation silvicultural practices used in the westside Douglas-fir region of Oregon and Washington: origin, growth and yield impacts, and the region's global competitive status for productivity, tree-growing costs, and returns. Two main messages emerge: (1) there has been great progress in the region to increase wood yield and shorten rotations; and (2) opportunity remains strong for this region to become even more competitive, although it will require challenging current beliefs and norms and an increased collective will and focused sense of urgency.

The possibility of early testing coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) for Swiss needle cast (SNC; caused by Phaeocryptopus gaeumannii (Rohde) Petrak) tolerance was investigated using 55 Douglas-fir families from western Oregon. Seedlings were inoculated with P. gaeumannii naturally in the field and were visually scored for a variety of SNC symptom traits (i.e., needle and foliage color, and retention) at the seedling stage (age 2) and in "mature" (ages 10 and 12) trees at two test sites for both the seedling and mature ages. Seedlings were also assessed...

Management indicator species (MIS) often are selected because their life history and demographics are thought to reflect a suite of ecosystem conditions that are too difficult or costly to measure directly. The northern flying squirrel (Glaucomys sabrinus) has been proposed as an MIS of temperate rain forest of southeastern Alaska based on previous studies in the Pacific Northwest that demonstrated its habitat is multi-factorial, i.e., an emergent property of old-growth forest. We evaluated the suitability of flying squirrels as MIS in temperate rain forests of Alaska by modeling seasonal...

Two recent studies provide alternative views of the current state and future prospects of southern forests and timber supply: the Southern Forest Resource Assessment (SOFRA) and the Fifth Resources Planning Act Timber Assessment (RPA). Using apparently comparable data but different models and methods, the studies portray futures that in some aspects are quite similar and in others markedly different. This article focuses on what the differences and commonalities between the reports suggest about the key factors that help shape our views of the future of southern timber supply. What inputs...