Treesearch

In this study, we investigated the effect of drought stress on ethanol production and accumulation in tissues from seedlings of three conifers (Douglas-fir, lodgepole pine, and ponderosa pine) with increasing degrees of tolerance to drought stress. Significant ethanol accumulation was only observed in their aerial tissues when severely stressed (water potential < -3.0 mpa or water content < 0.4 g g-1 dry mass), with needles accumulating greater quantities than the sapwood or phloem. All species had the same predawn water potentials when sampled, but they were experiencing different levels...

Designing policies that harness the motivations of landowners is essential for conserving threatened habitats on private lands. Our goal was to understand how to apply ethnographic information about family-forest owners to the design of conservation policy for Oregon white oak (Quercus garryana) in the Willamette Valley, Oregon (U.S.A.). We examined owners' knowledge, beliefs, values, and socioeconomic contexts through indepth Individual and focus-group interviews to understand their motivations to conserve oak. We then used Schneider and Ingram's (1990) policy analysis framework to...

Making input decisions under climate uncertainty often involves two-stage methods that use expensive and opaque transfer functions. This article describes an alternative, single-stage approach to such decisions using forecasting methods. The example shown is for preseason fire suppression resource contracting decisions faced by the United States Forest Service. Two-stage decision tools have been developed for these decisions, and we compare the expected gains to the agency, in terms of reduced personnel costs, of the single-stage model over the two-stage model, existing hiring decisions,...

Over the past two decades, sets of timber harvesting guidelines designed to mitigate the deleterious environmental impacts of tree felling, yarding, and hauling have become known as "reduced-impact logging" (RIL) techniques. Although none of the components of RIL are new, concerns about destructive logging practices and worker safety in the tropics stimulated this recent proliferation of semicoordinated research and training activities related to timber harvesting. Studies in Southeast Asia, Africa, and South and Central America have clearly documented that the undesired impacts of...

Species of conservation concern, which we define as species with rare or declining populations or habitats, often number in the hundreds or even thousands within a given ecosystem. Moreover, these species typically span a wide spectrum of taxa and are associated with a broad set of ecological characteristics and diverse management challenges. Management designed to fully meet the needs of large numbers of species is by definition impossible; each species occupies its own niche, and explicitly addressing each of these multidimensional niches would far exceed resources available to managers....

Recent studies predict that projected climate change will lead to significant reductions in summer streamflow in the mountainous regions of the Western United States. Hydrologic modeling directed at quantifying these potential changes has focused on the magnitude and timing of spring snowmelt as the key control on the spatial temporal pattern of summer streamflow. We illustrate how spatial differences in groundwater dynamics can also play a significant role in determining streamflow responses to warming. We examine two contrasting watersheds, one located in the Western Cascades and the...

Simulation models of disturbance and succession are being increasingly applied to characterize landscape composition and dynamics under natural fire regimes, and to evaluate alternative management strategies for ecological restoration and fire hazard reduction. However, we have a limited understanding of how landscapes respond to changes in fire frequency, and about the sensitivity of model predictions to assumptions about successional pathways and fire behavior. We updated an existing landscape dynamics model (LADS) to simulate the complex interactions between forest dynamics, fire...

A modeling experiment was designed to investigate the impact of fire management, CO2 emission rate, and the growth response to CO2 on the response of ecosystems in the conterminous United States to climate scenarios produced by three different general circulation models (GCMs) as simulated by the MCl Dynamic General Vegetation Model (DGVM). Distinct regional trends in response to projected climatic change were evident across all combinations of the experimental factors. In the eastern half of the United States, the average response to relatively large increases in temperature and decreases...

1. Recent increases in fire frequency in North America have focused interest on potential effects on adjacent ecosystems, induding streams. Headwaters could be particularly affected because of their high connectivity to riparian and downstream aquatic ecosystems through aquatic invertebrate drift and emergence. 2. Headwater streams from replicated burned and control catchments were sampled in 2 years following an intense forest fire in northeastern Washington (U.S.A.). We compared differences in benthic, drift, and emergent macroinvertebrate density, biomass, and community composition...

In central Oregon, management of western juniper (Juniperus occidentalis var. occidentalis Hook.) has included use of prescribed fire and mechanical removal. After these treatments, several species of bark and wood-boring beetles have been observed on treated trees and also occasionally on trees outside management areas, suggesting that these insects might contribute to juniper mortality. In this 2-year (2002-2003) study, we identified bark and wood-boring beetles that attack western juniper along with associated beetle predators and examined whether these insects can be manipulated for...