Fire-dependent Forests Research Articles

The fire history of a 416-year-old western larch tree in southeastern British Columbia

The fire history obtained from pre-settlement fire-scarred trees provides useful benchmarks for the restoration of dry interior, fire-dependent forest ecosystems. In the Rocky Mountain Trench of southeast British Columbia, historical benchmarks obtained from periods prior to significant European influence (i.e., pre-1850) are common reference points for forest ecosystem restoration. This extension note discusses the fire history of a 416-year-old western larch (Larix occidentalis) whose growth rings recorded 268 years of fire history before 1850. The study tree's estimated mean fire interval (MFI) is 34.1 years, and its fire intervals ranged from 19 years to 51 years. The tree did not record a fire during the last 130 years of its life. This extension note also discusses the development of a network of cross-dated benchmark sites across the landscape that would create a master fire chronology for the region. Such a chronology would reflect the natural variability of historical fire patterns, helping policy-makers, managers, recovery teams, and restoration practitioners understand the spatial and temporal distribution of landscape-scale disturbances that historically have created fire-dependent ecological communities (many of which include wildlife and plant species now at risk). The creation of a benchmark network would also refine dry interior forest restoration/conservation programs and improve their efficacy.

Old-growth definitions and management: A literature review

Over the past two decades, scientific discoveries have altered how forest management is viewed, including the understanding of late-successional or old-growth forest communities. Some accept that old-growth forests should be managed, but the process of identification and management of these forests has proven to be very difficult. This review examines literature on old growth and old-growth management from a broad North American base with a focus on the special issues associated with high-frequency forest disturbance regimes. The purpose of this paper is to: examine the various old-growth definitions and management approaches; review the importance of old-growth management and conservation; and draw conclusions and make recommendations based on the information reviewed. Old-growth definitions were divided into three categories: conceptual functional, conceptual structural, and quantitative working. The relative merits and challenges of each category are discussed using examples from different forest types across North America, but the focus is on northern fire-dependent forest ecosystems. The authors recommend the establishment of landscape-level objectives for old-growth retention that include: approaching management from an ecological perspective; recognizing the importance of varied natural disturbance patterns; increasing funds for detailed inventories (especially in more contentious or ecologically sensitive areas); developing a regional old-growth attribute scoring theme or index; using a top-down approach to old-growth management; and developing a monitoring plan to determine the effectiveness of established objectives.

Changes in stand structure and composition after restoration treatments in low elevation dry forests of northeastern Oregon

In many fire-dependent forests in the United States, changes occurring in the last century have resulted in overstory structures, conifer densities, down woody structure and understory plant communities that deviate from those described historically. With these changes, many forests are presumed to be unsustainable. Broad-scale treatments are proposed to promote stand development on trajectories toward more sustainable structures. Yet little research to date has identified the effects of these restoration treatments, especially in low elevation dry ponderosa pine ( Pinus ponderosa) and Douglas-fir ( Pseudotsuga menziesii) forests of northeastern Oregon. We report changes in tree structure, coarse woody debris (logs), and understory composition from an operational-scale, replicated ( N = 4), completely randomized experiment. Treatments included a single entry thin from below conducted in 1998, a late season burn conducted in 2000, a thin followed by burning (thin + burn), and a no action treatment which served as a control. Changes in live and dead tree structure and understory vascular plant community composition were compared between pre-treatment and 2004. Tree seedling density and composition and coarse woody debris structure were evaluated in 2004. Thin, burn, and thin + burn treatments reduced the density but not the basal area of live overstory trees. Thinning reduced the number of medium-diameter trees, and tended to decrease the abundance of shade tolerant, moist-site understory species yet increased the dominance of several rhizomatous species such as Calamagrostis rubescens, Symphoricarpos albus, and Spiraea betulifolia. Burning alone had little effect on large trees but reduced the number of small Douglas-fir and logs. Shade tolerant perennial species associated with fine textured soils such as S. albus, Spiraea betulifolia, C. rubescens, Carex geyeri, and Arnica cordifolia increased in frequency and average cover with burning. Conversely, cover of the bunch grass Festuca idahoensis was reduced while non-native invasive species establishment was little affected. Ordination scores suggested that burning increased the abundance of species representing greater shade tolerance and finer-textured soils. The thin + burn treatment left both ponderosa pine and Douglas-fir with modal or normal diameter distributions, and increased the abundance of understory species representing shallow, coarse texture soils. These results are discussed in the context of management options for restoration of ecosystem health in similar low elevation dry ponderosa pine and Douglas-fir forests.

Wildfire Policy and Fire Use on Public Lands in the United States

ABSTRACT Current wildfire management policy succeeds in suppressing 99% of all fires on public lands. Indirect costs of this achievement include the development of dense vegetation in the absence of fire, and increasingly more intense fires when they do erupt. The result is a fire management system with rising costs and fire-dependent forests that are frequently characterized by declining health. Wildland fire use (WFU), the use of fire to accomplish specific pre-stated resource management objectives, is considered appropriate in many remote wildlands where a naturally ignited fire may safely be used to improve forest health. Ecological benefits associated with WFU include improved watershed conditions, enhanced wildlife habitat, and more resilient forested ecosystems. Economic benefits include reduced suppression and fuels treatment costs over the long term. Policy challenges are complex, however; land management agencies face increased planning requirements as well as the need to develop both institutional and public support before the full potential of wildland fire use can be realized.

Fire history data as reference information in ecological restoration

Fire plays a fundamental role in the ecology of Araucaria-Nothofagus forests. This paper highlights the utility of dendrochronological techniques in providing the historical reference conditions to guide ecological restoration. In the Araucarian region human activity has dramatically changed the fire frequency in the Araucaria-Nothofagus forest ecosystems. Although further critical evaluation is required, our preliminary data show that, compared with the Native American period (pre-1883), there was widespread burning of forests associated with the subsequent Euro-Chilean settlement phase. Vast areas of subalpine forest were deliberately burned to increase pasture for cattle ranching. This process is documented by a major increase in the frequency of fires in the forested Araucaria-Nothofagus landscape during the 20th century. Prior to the 1880s the fire regime was characterized by infrequent catastrophic fires with long intervening periods of stability. The immediate reduction of human-induced fire is necessary to move these altered forest ecosystems towards the range of natural structural conditions and reestablish the historical variability of this ecological process. A better understanding of the fire ecology seems crucial in developing strategies for the restoration and management of these fire-dependent forest ecosystems.

Fire and vegetation dynamics: studies from the North American boreal forest

It is almost dogma that the boreal forest in North America is a fire-dependent forest, yet ecologists often do not consider in any technical detail how forest fires produce effects on individual plants and on plant populations. Consequently, the causal connection between the behaviour of fire and its ecological consequences is poorly understood. This book sets out to correct this deficiency by assembling the relevant studies of fire intensity, rate of spread, fuel consumption, fire frequency and fire weather in the North American boreal forest. The central thesis is that the North American boreal forest has at least four wildfire characteristics that are important in understanding the dynamics of its plant populations: the large size of the burns with respect to dispersal distances, the short recurrence time of fire with respect to tree lifespans, the high mortality of plants due to the predominance of crown fires, and a good germination surface due to the large area of the forest floor which is covered by ash.

Fire-dependent forests in the Northern Rocky Mountains

One objective of wilderness and parkland fire-ecology research is to describe the relationships between fire and unmanaged ecosystems, so that strategies can be determined that will provide a more nearly natural incidence of fire. More than 50 yr of efforts directed toward exclusion of wildland fires in the Northern Rocky Mountains (western Montana and northern Idaho) have resulted in a definite and observable impact on the forest ecosystems in this region. Fire-ecology investigations in Glacier National Park and the Selway-Bitterroot Wilderness have helped to reveal the nature of this impact and to provide a better understanding of the natural role of fire within these coniferous ecosystems. Such areas provide a unique opportunity to study and test approaches designed to perpetuate unmodified ecosystems. However, we still don't understand all of the long-term consequences of fire control in those forest communities that have evolved fire-dependent characteristics.