Treesearch

Visibility impairment from regional haze is a significant problem throughout the continental United States. A substantial portion of regional haze is produced by smoke from prescribed and wildland fires. Here we describe the integration of four simulation models, an array of GIS raster layers, and a set of algorithms for fire-danger calculations into a modeling framework for simulating regional-scale smoke dispersion. We focus on a representative fire season (2003) in the Northwestern USA, on a 12-km domain, and track the simulated dispersion and concentration of PM2.5 over the course of...

We compared hydraulic architecture, photosynthesis, and growth in Douglas-fir with that of a shade-tolerant western hemlock. The study was conducted in a site that had been thinned to release suppressed trees, and one that remained unthinned. Release seemed to be constrained initially by photosynthetic capacity in both species. After released trees increased their photosynthetic capacity, hydraulic architecture appeared to constrain further release from suppression in Douglas-fir, and to a lesser extent, western hemlock. There were no significant differences between the above-ground...

Provides current information on lumber and plywood production and prices; employment in forest industries; international trade in logs, lumber, and plywood; volumes and average prices of stumpage sold by public agencies; and other related items. Current data and downloadable Excel files are available online.

EMDS 3.0 is implemented as an ArcMap® extension and integrates the logic engine of NetWeaver® to perform landscape evaluations, and the decision modeling engine of Criterium DecisionPlus® for evaluating management priorities. Key features of the system's evaluation component include abilities to (1) reason about large, abstract, multifaceted ecosystem management problems, (2) perform useful evaluations with incomplete information, (3) evaluate the influence of missing information, and (4) determine priorities for missing information. A key feature of the planning component is the ability...

We assessed differences in growth-ring width, specific conductivity (Ks), tracheid dimensions, moisture content, and wood density in suppressed Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) trees and trees released from suppression. Growth-ring width was 370 percent higher for Douglas-fir and 300 percent higher for western hemlock trees released from suppression, and Ks was 182 percent higher for Douglas-fir and 42 percent higher for western hemlock trees released from suppression. Earlywood width was approximately four times...

Fire planners and other resource managers need to examine a range of potential fuel and vegetation treatments to select options that will lead to desired outcomes for fire hazard and natural resource conditions. A new approach to this issue integrates concepts and tools from silviculture and fuel science to quantify outcomes for a large number of treatment options in dry forest stands in the Western United States. Five silvicultural options (thinning from below to 50 trees per acre [tpa], 100, 200, and 300 tpa; or no thinning) are considered in combination with three surface fuel treatments...

We evaluated the effects of vegetation control and organic matter (OM) removal on soil water content (SWC) in a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation from age 3 through age 5. Treatments were presence versus absence of vegetation control through year 5 and bole only harvest of the previous stand versus total-tree harvest of the previous stand including removal of all coarse woody residues. In the presence of vegetation control, SWC was approximately 0.02 to 0.04 m3•m-3 greater between depths of 10 and 60 cm; the effect was greatest from July to September. Soil water...

A little-known fire-maintained anthropogenic ecosystem in the southeastern Olympic Peninsula of Washington is documented. Owing to cessation of burning, most of these areas have succeeded to forest. We present cultural, historical, and ecological data to describe the structure and function of this ecosystem. We believe that native peoples maintained this system for the provision of culturally important plants and animals through repeated burning. The overstory was dominated by Douglas-fir and the understory by beargrass. Shade-intolerant prairie species persist where openings have been...

Habitat models address only 1 component of biodiversity but can be useful in addressing and managing single or multiple species and ecosystem functions, for projecting disturbance regimes, and in supporting decisions. I review categories and examples of habitat models, their utility for biodiversity conservation, and their roles in making conservation decisions. I suggest the use of influence diagrams in structuring causal webs and structural equation modeling to quantify relations, as a general framework for building models of habitat from which a known degree of inference can be made to...

Tree height is an important variable in forest inventory programs but is typically time-consuming and costly to measure in the field using conventional techniques. Airborne light detection and ranging (LIDAR) provides individual tree height measurements that are highly correlated with field-derived measurements, but the imprecision of conventional field techniques does not allow for definitive assessments regarding the absolute accuracy of LIDAR tree height measurements and the relative influence of beam divergence setting (i.e., laser footprint size), species type, and digital terrain...