Treesearch

A classification of forest vegetation is presented for the Wenatchee National Forest (NF). It is based on potential vegetation, with the plant association as the basic unit. The sample includes about 570 intensive plots and 840 reconnaissance plots distributed across the Wenatchee National Forest and the southwest portion of the Okanogan National Forest from 1975 through 1994. The hierarchical classification includes 10 forest series and 104 types (plant association or community type). Diagnostic keys and descriptions are presented for each tree series and type. Detailed descriptions are...

Giant sequoia [Sequoiadendron giganteum (Lindl.) Buchholz] groves are found entirely within the Sierra Nevada mixed-conifer type. Several of its companion tree species, mainly ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and Jeffrey pine (P. jeffreyi Grev. & Balf.), show foliar injury after exposure to present levels of ozone in the southern Sierra Nevada. Observations at nine giant sequoia groves in Sequoia National Park from August 1983 through September 1986 showed that surviving seedlings in 1986 averaged 18 percent of the original number. These observations did not provide...

There has been much debate about the effect of increased atmospheric CO2 concentrations on plant net primary production1,3 and on net ecosystem CO2 flux3–10. Apparently conflicting experimental findings could be the result of differences in genetic potential11–15 and resource availability16–20, different experimental conditions21–24 and the fact that many studies have focused on individual components of the system2,21,25–27 rather than the whole ecosystem. Here we present results of an in situ experiment on the response of an intact native ecosystem to elevated CO2. An undisturbed patch of...

This report responds to the request by Speaker Foley and Senator Hatfield for a scientific evaluation of the effects of Forest Service management practices on the sustainability of eastern Oregon and Washington ecosystems. The report recommends analysis methods and management practices that can be used to build an experimental approach to the restoration of stressed ecosystems. A total of 113 scientists from universities, Federal and State agencies, and private companies, contributed to this report. Their research provides the basis for a sustainable ecosystem management framework to...

SBexpert version 1.0 is a knowledge-based decision-support system for spruce beetle (Dendroctonus rutipennis (Kby.)) management developed for use in Microsoft Windows with the KnowledgePro Windows development language. The SBexpert users guide provides detailed instructions on the use of all SBexpert features. SBexpert has four main topics (subprograms): Introduction, Analysis, Textbook, and Literature. Introduction is the first of five subtopics in the SBexpert help system. Analysis is an advisory system for spruce beetle management that provides recommendations for reducing spruce beetle...

Tree seedling exposure studies, covering a wide range of experimental conditions in pollutant treatments, species, facilities, and exposure regimes, have been conducted during the past several years to determine acute effects and relative sensitivity of tree species in response to simulated acid precipitation and gaseous pollutants. Because of tile difficulties inherent in conducting controlled exposures with mature trees (e.g., size, variability among experimental units, and costs associated with replication of treatments), seedling exposure studies have been initiated as the quickest way...

We examined the process of fragmentation in a managed forest landscape by comparing rates and patterns of disturbance (primarily clear-cutting) and regrowth between 1972 and 1988 using Landsat imagery. A 2589-km2 managed forest landscape in western Oregon was classified into two forest types, closed-canopy conifer forest (CF) (typically, > 60% conifer cover) and other forest and nonforest types (OT) (typically, < 40 yr old or deciduous forest). the percentage of cf declined from 71 to 58% between 1972 and 1988. declines were greatest on private land, least in wilderness, and intermediate...

Natural disturbances are important to ecosystem processes. Disturbances historically have occurred in the vegetation of the Blue Mountain area of northeastern Oregon and southeastern Washington. The primary modifying events that historically have cycled through most of its plant communities are fire, grazing and browsing, insect and disease epidemics, windthrow, flooding, and erosion. Knowledge of plant successional pathways enables managers to predict the probable course of community development for a disturbance regime. Recommendations for restoring the Blue Mountains area are to...

Patterns of development of mean annual increment in relation to age predicted by the widely used DFSIM, SPS, TASS, and ORGANON simulators were examined. Although predictions differ considerably among simulators for portions of the range of sites, ages, and treatments, comparisons indicated that (1) culmination is relatively late, (2) the curve is relatively flat in the vicinity of culmination, and (3) systematic thinning tends to delay culmination. Harvest ages of 40 to 50 years reduce volume production relative to potential by amounts ranging from moderate to large according to site,...

Adaptive genetic variation in seed and seedling traits was evaluated for 280 families from 220 locations. Factor scores from three principal components were related by multiple regression to latitude, longitude, elevation, slope, and aspect of the seed source, and by classification analysis to seed zone and elevation band in seed zone. Location variance was significant but not large. Multiple regression equations explained less than 50 percent of location variance. Slope-aspect variables were important.