Is regulated even-aged management the right strategy for the Canadian boreal forest?

2004 ◽  
Vol 80 (4) ◽  
pp. 458-462 ◽  
Author(s):  
Yves Bergeron

Over the past decade, there has been an increasing interest in the development of forest management approaches that are based on an understanding of historical natural disturbance dynamics. The rationale for such an approach is that management to favour landscape compositions and stand structures similar to those of natural ecosystems should also maintain biological diversity and essential ecological functions. In fire-dominated landscapes, this approach is possible only if current and future fire frequencies are sufficiently low, in comparison to pre-industrial fire frequency, that we can substitute fire with forest management. I address this question by comparing current and future fire frequency to historical reconstruction of fire frequency from studies in the Canadian boreal forest. Current and simulated future fire frequencies using 2× and 3×CO2 scenarios are lower than the historical fire frequency for most sites, suggesting that forest management could potentially be used to recreate the forest age structure of fire-controlled pre-industrial landscapes. Current even-aged management, however, tends to reduce forest variability: for example, fully regulated, even-aged management will tend to truncate the natural forest stand age distribution and eliminate overmature and old-growth forests from the landscape. The development of silvicultural techniques that maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain this variability. Key words: boreal forest, even aged management, fire regime, old-growth forests, climate change, partial cutting

2007 ◽  
Vol 83 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Annie Belleau ◽  
Yves Bergeron ◽  
Alain Leduc ◽  
Sylvie Gauthier ◽  
Andrew Fall

It is now recognized that in the Canadian boreal forest, timber harvesting activities have replaced wildfires as the main stand-replacing disturbance. Differences in landscape patterns derived from these two sources of disturbance have, however, raised concerns that the way forest harvesting has been dispersed is potentially shifting patterns away from the natural range. In the context of natural disturbance-based management, we used a spatially explicit model designed to capture general fire regimes in order to quantify temporal variability associated with regenerating areas (burnt areas of 25 years or younger), and to develop strategic objectives for harvest agglomeration sizes and dispersion. We first evaluated temporal variability in the proportion of stands younger than 100 years (assumed to be even-aged stands) for various fire regimes (seven fire cycles: 50 to 400 years, and three mean fires sizes: 3000, 15 000 and 60 000 ha). Secondly, we quantified the size distribution and dispersion of regenerating areas for each fire regime. As expected by theoretical fire frequencies and size distributions, the importance of even-aged stands at the forest management unit level was found to decrease with longer fire cycles. However, the temporal variability associated with these proportions is shown to increase with mean fire size. It was also observed that the size distribution and dispersion of regenerating areas was primarily influenced by mean fire size. Based on these observations, natural disturbance-based management objectives were formulated, providing guidelines on harvest agglomeration size and dispersion. Key words: temporal variability, boreal forest, fire regime, forest management, age distribution, fire size distribution, clearcut agglomeration size distribution


AMBIO ◽  
2004 ◽  
Vol 33 (6) ◽  
pp. 356-360 ◽  
Author(s):  
Yves Bergeron ◽  
Mike Flannigan ◽  
Sylvie Gauthier ◽  
Alain Leduc ◽  
Patrick Lefort

2001 ◽  
Vol 9 (4) ◽  
pp. 223-260 ◽  
Author(s):  
D J McRae ◽  
L C Duchesne ◽  
B Freedman ◽  
T J Lynham ◽  
S Woodley

Emulation silviculture is the use of silvicultural techniques that try to imitate natural disturbances such as wildfire. Emulation silviculture is becoming increasingly popular in Canada because it may help circumvent the political and environmental difficulties associated with intensive forest harvesting practices. In this review we summarize empirical evidence that illustrates disparities between forest harvesting and wildfire. As a rule, harvesting and wildfire affect biodiversity in different ways, which vary a great deal among ecosystem types, harvesting practices, and scale of disturbance. The scales of disturbance are different in that patch sizes created by logging are a small subset of the range of those of wildfire. In particular, typical forestry does not result in the large numbers of small disturbances and the small number of extremely large disturbances created by wildfires. Moreover, the frequency of timber harvesting is generally different from typical fire return intervals. The latter varies widely, with stand-replacing fires occurring in the range of 20 to 500 years in Canada. In contrast, harvest frequencies are dictated primarily by the rotational age at merchantable size, which typically ranges from 40 to 100 years. Forest harvesting does not maintain the natural stand-age distributions associated with wildfire in many regions, especially in the oldest age classes. The occurrence of fire on the landscape is largely a function of stand age and flammability, slope, aspect, valley orientation, and the location of a timely ignition event. These factors result in a complex mosaic of stand types and ages on the landscape. Timber harvesting does not generally emulate these ecological influences. The shape of cut blocks does not follow the general ellipse pattern of wind driven fires, nor do harvested stands have the ragged edges and unburned patches typically found in stand-replacing fires. Wildfire also leaves large numbers of snags and abundant coarse woody debris, while some types of harvesting typically leave few standing trees and not much large debris. Successional pathways following logging and fire often differ. Harvesting tends to favor angiosperm trees and results in less dominance by conifers. Also, understory species richness and cover do not always recover to the pre-harvest condition during the rotation periods used in typical logging, especially in eastern Canada and in old-growth forests. As well, animal species that depend on conifers or old-growth forests are affected negatively by forest harvesting in ways that may not occur after wildfire. The road networks developed for timber extraction cause erosion, reduce the areas available for reforestation, fragment the landscape for some species and ecological functions, and allow easier access by humans, whereas there is no such equivalency in a fire-disturbed forest. Key words: silviculture, forest management, clearcutting, forest conservation, wildfire, biodiversity.


2003 ◽  
Vol 108 (D3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Marcy Litvak ◽  
Scott Miller ◽  
Steve C. Wofsy ◽  
Michael Goulden

Author(s):  
Marilyn W. Walker ◽  
Mary E. Edwards

Historically the boreal forest has experienced major changes, and it remains a highly dynamic biome today. During cold phases of Quaternary climate cycles, forests were virtually absent from Alaska, and since the postglacial re-establishment of forests ca 13,000 years ago, there have been periods of both relative stability and rapid change (Chapter 5). Today, the Alaskan boreal forest appears to be on the brink of further significant change in composition and function triggered by recent changes that include climatic warming (Chapter 4). In this chapter, we summarize the major conclusions from earlier chapters as a basis for anticipating future trends. Alaska warmed rapidly at the end of the last glacial period, ca 15,000–13,000 years ago. Broadly speaking, climate was warmest and driest in the late glacial and early Holocene; subsequently, moisture increased, and the climate gradually cooled. These changes were associated with shifts in vegetation dominance from deciduous woodland and shrubland to white spruce and then to black spruce. The establishment of stands of fire-prone black spruce over large areas of the boreal forest 5000–6000 years ago is linked to an apparent increase in fire frequency, despite the climatic trend to cooler and moister conditions. This suggests that long-term features of the Holocene fire regime are more strongly driven by vegetation characteristics than directly by climate (Chapter 5). White spruce forests show decreased growth in response to recent warming, because warming-induced drought stress is more limiting to growth than is temperature per se (Chapters 5, 11). If these environmental controls persist, projections suggest that continued climate warming will lead to zero net annual growth and perhaps the movement of white spruce to cooler upland forest sites before the end of the twenty-first century. At the southern limit of the Alaskan boreal forest, spruce bark beetle outbreaks have decimated extensive areas of spruce forest, because warmer temperatures have reduced tree resistance to bark beetles and shortened the life cycle of the beetle from two years to one, shifting the tree-beetle interaction in favor of the insect (Chapter 9).


2007 ◽  
Vol 83 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Laurence Bourgeois ◽  
Daniel Kneeshaw ◽  
Louis Imbeau ◽  
Nicolas Bélanger ◽  
Stephen Yamasaki ◽  
...  

In order to receive forest certification and to respond to societal desires, many forest companies are attempting to demonstrate that their forest activities are «sustainable». The main objective of this paper is to qualitatively evaluate the ways in which forestry-related provincial regulations in the three provinces (Alberta, Ontario and Quebec) that contain most of the Canadian boreal forest help forest companies achieve certification with respect to ecological criteria. In the process of continually evolving towards sustainable forest management, we evaluate how these provincial regulations governing forest operations can be helpful in maintaining three criteria: biodiversity, the aquatic environment and soils. This study shows that the regulations evaluated have varied in their approach and thus have different strengths that must be underlined: (1) Ontario's approach is the strongest in terms of biodiversity, (2) Alberta and Ontario provide measures to abandon roads after harvesting, (3) Quebec provides the greatest specific measures for protecting waterways and aquatic species, (4) Alberta shows the greatest consideration for maintaining the most soil properties and functions. Better links between different regulations are necessary in all jurisdictions. The continual improvement of Canadian forest rules is often slow and advances at a different pace depending on regulators but it should be supported in all provinces. Key words: sustainable forest management, biodiversity, aquatic environment, soils, Alberta, Ontario, Quebec


2008 ◽  
Vol 38 (4) ◽  
pp. 711-720 ◽  
Author(s):  
Anne-Hélène Mathey ◽  
Emina Krcmar ◽  
John Innes ◽  
Ilan Vertinsky

The intensification of forest management in Canada has been advocated as a possible solution to the conundrum that increasing demand for conservation areas and increasing pressure for timber production have created. The benefits and disadvantages of intensive forest management in the context of the Canadian boreal forest are unclear and reaching conclusions about its general value from stand analyses may be difficult. In this study, a boreal forest in Ontario has been used to investigate the potential of intensive management to generate financial revenues and meet management constraints on volume flow and old-growth retention. Two aspects of intensive forest management are considered: intensive silviculture and concentrated harvest activities. The plans are generated with a decentralized planning approach based on cellular automata. The results for the case study show that increasing silviculture intensity can help fulfill high timber flow requirements under strict conservation requirements. This comes at the cost of reduced net revenues but from a smaller timber harvesting landbase. The main trade-offs found were those between harvest flow and financial benefits. Clustering both protected areas and harvest operations could help achieve the conservation and timber-related objectives simultaneously by improving the habitat value of conserved areas and decreasing the operational costs in harvested areas.


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