Treesearch

Biological legacies left by natural disturbances provide ecological functions throughout forest stand development, but their influences on processes of ecological succession are not completely understood. We investigated the successional role of one type of biological legacy: remnant old-growth trees persisting in mature Pseudotsuga menziesii (Douglas-fir) forests in the U.S. Pacific Northwest. We tested the hypothesis that remnant old-growth Tsuga heterophylla (western hemlock) and Thuja plicata (western red cedar) trees enhance the reestablishment of shade-tolerant conifers by increasing...

1. We employed standardized measurement techniques and protocols to describe the size dependence of whole-tree water use and cross-sectional area of conducting xylem (sapwood) among several species of angiosperms and conifers. 2. The results were not inconsistent with previously proposed 314-power scaling of water transport with estimated above-ground biomass. However, for a given size, angiosperms transported considerably greater quantities of water than conifers. 3. In the angiosperms studied, the scaling of water transport with sapwood area, stem diameter and above-ground biomass was...

ASTM standard sizes for bending tests (either 50 x 50 mm or 25 x 25 mm in cross-section) are not always suitable for research purposes that characterize smaller sections of wood. Moreover, the ASTM standards specify loading the sample on the longitudinal-tangential surface. If specimens are small enough, then the effects of both growth-ring orientation and whether earlywood or latewood is on the upper and lower surfaces could affect values of modulus of elasticity (MOE) and modulus of rupture (MOR). The objectives of this study were to assess the effects of growth-ring orientation and...

1. The obligate symbiosis formed between ectomycorrhizal fungi (EMF) and roots of tree species in the Pinaceae influences nutrient uptake and surrounding soil structure. Understanding how EMF respond to prescribed fire and thinning will assist forest managers in selecting fuel-reducing restoration treatments that maintain critical soil processes and site productivity. 2. The response of EMF species richness, live fine root biomass and duff levels to various forms and combinations of thinning and burning was investigated in mixed ponderosa pine and Douglas fir stands in the Blue Mountains...

In forest reserves of the U.S. Pacific Northwest, management objectives include protecting late-semi habitat structure by reducing the threat of large-scale disturbances like wildfire. We simulated how altering within- and among-stand structure with silvicultural treatments of differing intensity affected late-seral forest (LSF) structure and fire threat (FT) reduction over 30 years in a 6070-ha reserve. We then evaluated how different financial requirements influenced the treatment mix selected for each decade, the associated effects on FT reduction and LSF structure in the reserve, and...

An intertemporal spatial equilibrium model of the eastern Oregon softwood log market was employed to estimate the market and economic welfare impacts of restoration thinning programs established on national forests in the region. Programs treated only lands with sawtimber thinning volume and varied by the extent of public subsidies for costs, the types of costs that could be subsidized, and the form of the subsidy payment. Impacts on private harvest timing, numbers of mills, and postprogram log prices in the region were found to vary markedly with the form of the program. Log consumers...

The authors present a brief description of a 1.5-dimensional thunderstorm model with a lightning parameterization that utilizes an explicit microphysical scheme to model lightning-producing clouds. The main intent of this work is to describe the basic microphysical and electrical properties of the model, with a small illustrative section to show how the model may be used to determine the electrical properties of clouds.

Major changes in federal forest policy in Alaska have resulted in a dramatic downsizing of the state's forest industry. These changes have driven efforts for economic restructuring and improved support for Alaskan communities. The University of Alaska Sitka Forest Products program at the University of Alaska Southeast is one example of efforts to better support the Alaskan forest industry. In an effort to best target educational programs, an industry needs assessment was conducted. Despite the fact that the Alaskan forest industry is different in many ways from the industry in the lower 48...

The condition of aquatic habitat and the health of species dependent on that habitat are issues of significant concern to land management agencies, other organizations, and the public at large in southeastern Alaska, as well as along much of the Pacific coastal region of North America. We develop and test a set of effectiveness monitoring procedures for measuring change in floodplain channel habitat in southeastern Alaska. Variables include measures of channel morphology, pool size, pool spatial density, and bed surface grain size distribution. These procedures provide methods of data...

Invasive plants are now recognized as a serious threat to most extensive management systems, such as forests, meadows, deserts, and riparian areas [1-3]. Vitousek et al. [3] described exotic plant invasion as a significant element of global environmental change because exotic plants can alter primary productivity, decomposition, hydrology, nutrient cycling, and natural disturbance regimes. Non-native plants also impact landscapes by changing the structure, composition, and successional pathways of native communities [3-8].