Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades.

Abstract

Fire has been an important ecological process in eastside Cascade ecosystems for millennia. Fire regimes ranged from low severity to high severity, and historic fire return intervals ranged from less than a decade to greater than 300 years. Fire history and effects are described for grassland and shrubland ecosystems, and the range of forested communities by plant series: Ponderosa Pine, Douglas-fir/White fir/Grand fir, Lodgepole pine, Western hemlock/Western redcedar, and subalpine fir/Mountain hemlock. The riparian zones within these communities may be more or less impacted by fire. The effects of extreme weather events, including unusual temperature, wind, or moisture have generally had less significant impact than fire. Management practices, including fire suppression, timber harvesting, and livestock grazing, have altered historical fire regimes, in some cases irreversibly. The management issues for the 1990s include both management and research issues, at a grand scale with which we have little experience. Ecosystem and adaptive management principles will have to be applied.

Examining Spatial Variation in the Effects of Japanese Red Pine (Pinus densiflora) on Burn Severity Using Geographically Weighted Regression

“…In general, the influence of topography on burn severity is greater on steep slopes, ridgetops, and southerly aspects [20,33,71]. Thus, it is generally assumed that burn severity is higher at higher than at lower elevations, and many studies have reported a strong positive association between burn severity and elevation.…”

Effect of fuels reduction on American martens and their prey.

“…Fire suppression and insect outbreaks in the last 25 years have resulted in high fuel loadings in some stands in northeastern Oregon (Agee 1994). The risk of wildfire in these stands has generated concern among managers, and various methods of removing some of these fuels are being used.…”

Historical and current forest landscapes of eastern Oregon and Washington Part I: Vegetation pattern and insect and disease hazards.

“…Land-use practices over the last 100 years have altered the natural disturbance regime and reduced ecosystem resistance to disturbances. Fire suppression, timber harvest, and livestock grazing are among the management practices that have contributed to changes in ecosystem character that are conducive to insect outbreaks and severe wildfires (Agee 1993, Gast and others 1991, Hessburg and others 1993, Martin and others 1976 (fig. 1).…”

“…Surface fires tend to occur in dry and warm vegetation series, such as ponderosa pine 1 and dry Douglas-fir series, at relatively frequent intervals of 3 to 35 years (see Agee 1993 for review). These low-intensity fires influence vegetation composition and structure primarily at a stand scale.…”

“…1). Other potentially negative effects of ecosystem change include local extinction of wildlife and native plants, and deterioration of ecosystem health (Agee 1993). These conditions are not pervasive, however, and some forests remain healthy and productive (Gast and others 1991).…”