Stephen F. Arno

Restoring Fire-Dependent Ponderosa Pine Forests in Western Montana

| suppression. M any foresters and ecologists recognize that disruption of the historic pattern of frequent fires in ponderosa pine forests has resulted in major ecological changes, including increasingly severe wildfires and insect and disease epidemics (Weaver, 1943; Covington and Moore, 1992; Mutch and others, 1993; Everett, 1994). In response to this realization, there is increasing interest among natural resource managers, biologists, and the public in restoring ponderosa pine forests to more natural and sustainable conditions (American Forests, 1995). The Intermountain Research Station and the University of Montana’s School of Forestry, in cooperation with the Bitterroot and Lolo National Forests have been testing the effectiveness of different silvicultural and prescribed-fire treatments for restoring ponderosa pine forests, and we will report some observations and initial findings here. But first we will summarize ecological changes that have occurred and describe our restoration treatments. For thousands of years fire shaped the composition and structure of North American forests, favoring species such as ponderosa pine (Pinus ponderosa) that are fireresistant and require fire to regenerate and compete successfully with other species (Pyne, 1982, Agee, 1993). In the inland West, pure ponderosa pine and mixed ponderosa pine-fir types are the most extensive of the fire-dependent forests. Non-fire-dependent species associated with ponderosa pine are interior Douglas-fir (Pseudotsuga menziesii var. glauca), grand fir (Abies grandis), white fir (A. concolor), and incensecedar (Calocedrus decurrens). Pure and mixed ponderosa pine types cover about 40 million acres (16 million hectares) in the western United States, an area equal to that of the state of Washington (van Hooser and Keegan, 1988). Prior to the early 1900s these forests were characterized by frequent lowto moderate-intensity fires, mostly underbums that killed few overstory pines. Historically, fires at intervals averaging five to 30 years in most areas thinned small trees and helped produce open, park-like, fire-resistant stands (Amo, 1988). Today many of these forests have changed dramatically and are experiencing critical health problems as a result of 60-80 years of fire exclusion and logging of overstory pines. For example, more than a million acres in eastern Oregon’s Blue Mountains now consist mostly of dead or dying trees, primarily fir thickets impacted by insect and disease epidemics (Mutch and others, 1993). Also, large stand-destroying wildfires, formerly rare in the open ponderosa pine forests, have become common in the dense stands that have developed as a result of fire exclusion. Dense stands also provide fuel ladders that cause fires to increase in intensity and climb into tree crowns. Severe fires in ponderosa pine made up a large portion of the three million acres that burned in the inland West during 1994. Past logging, which selectively removed large pines and left understory trees has allowed rapid development of conifer thickets (Habeck, 1990). Extensive coni-

The use of fire in forest restoration

The 26 papers in this document address the current knowledge of fire as a disturbance agent, fire history and fire regimes, applications of prescribed fire for ecological restoration, and the effects of fire on the various forested ecosystems of the north-western United States. The main body of this document is organized in three sections: Assessing Needs for Fire in Restoration; Restoration of Fire in Inland Forests; and Restoration in Pacific Westside Forests. These papers comprise the proceedings from a general technical conference at the 1995 Annual Meeting of the Society for Ecological Restoration, held at the University of Washington, Seattle, September 14-16, 1995.

Eighty-eight years of change in a managed ponderosa pine forest

This publication gives an overview of structural and other ecological changes associated with forest management and fire suppression since the early 1900s in a ponderosa pine forest, the most widespread forest type in the Western United States. Three sources of information are presented: (1) changes seen in a series of repeat photographs taken between 1909 and 1997 at 13 camera points; (2) knowledge from 19 authors who have investigated effects of recent ecosystem-based management treatments; integrated with (3) findings of forest changes related to earlier treatments and to succession. The contributing authors discuss effects of historical silviculture and recent ecosystem-based management treatments, including an evaluation of various burning prescriptions in terms of tree response, undergrowth, soils, wildlife habitat, and esthetics and public acceptance.

Wildland Fire in Ecosystems Effects of Fire on Flora

____________________________________ Brown, James K.; Smith, Jane Kapler, eds. 2000. Wildland fire in ecosystems: effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 257 p. This state-of-knowledge review about the effects of fire on flora and fuels can assist land managers with ecosystem and fire management planning and in their efforts to inform others about the ecological role of fire. Chapter topics include fire regime classification, autecological effects of fire, fire regime characteristics and postfire plant community developments in ecosystems throughout the United States and Canada, global climate change, ecological principles of fire regimes, and practical considerations for managing fire in an ecosytem context.

The Complexity of Managing Fire-dependent Ecosystems in Wilderness: Relict Ponderosa Pine in the Bob Marshall Wilderness

Isolated wilderness ecosystems with a history of frequent, low-severity fires have been altered due to many decades of fire exclusion and, as a result, are difficult to restore for philosophical and logistical reasons. In this paper, we describe the successional conditions of ponderosa pine (Pinus ponderosa) communities along the South Fork of the Flathead River in the Bob Marshall Wilderness following decades of fire suppression, and then summarize the first-year effects of the 2003 fires on these communities. We found that at least 34 percent of the large ponderosa pine trees were dead or dying as a result of the fires, with much of this mortality due to cambial girdling following the burning of duff and litter buildup around the base of the trees. We explore possible strategies for, and barriers to, the restoration of deteriorating ecosystems in wilderness and other similarly managed natural areas that historically depended on frequent, low-intensity fires. We also discuss the complexity of managing fire-dependent ecosystems in wilderness.