Forest in the central interior of British Columbia, Canada are accustom to beetle outbreaks and wildfire. However, the most recent outbreak produced unprecedented mortality, and created a forest legacy that will be present for decades to come.
These forest have both economic and intrinsic value.
• A loss of over 50% merchantable timber since the onset of the beetle outbreak
• Declines in recreation affecting local economies
• Forest once served as carbon sinks
• Now forests are a net carbon source that will release an ~270 megatonnes of carbon between 2000-2020 (Kurz et al. 2008).
• Changes in forest fuels have raised management concerns about the potential fire severity and forest resiliency.
Because of the extent of the outbreak, it is not a question of if these forests will burn but when.
This overview of outbreak severity, wildfire severity, and forest recovery is centered on three fires that burned in Tweedsmuir and Entiako provincial parks. Although the outbreak is widespread, due to the active and pervasive forest harvest tenures in central interior, this region and these fires provided a rare opportunity to study beetle-fire interactions without the interference of salvage logging and forest management.
The last major wildfires in the region occurred between 1880 and 1920, which has allowed Lodgepole pine to mature over the last century. The combination of abundant mature lodgepole pine and warmer winters associated with anthropogenic climate change have resulted in 50-100% lodgepole pine mortality in Tweedsmuir and Entiako Provincial Parks, and over 18 million hectares of forest with tree mortality.
| Beetle Outbreak |
Provincial Parks |
Wildfire |
Sub-boreal forests cover vast areas in central interior British Columbia. Forests provide vital services across the region. The forests provide economic value in terms of timber harvest. They provide ecosystems services such as carbon sequestration and watershed management. Forests provide critical wildlife habitat.
Lodgepole pine are a dominant species in the forests of the central interior. Historically, forest life cycles are influenced by disturbance regimes of wildfire and beetle outbreaks. wildfire return is typically 100-150 year intervals. Wildfire results in tree mortality and forest initiation. It diversifies the landscape by initiating early successional habitat.
Mountain pine beetles are endemic to North American forest often killing older, weaker trees, which create canopy gaps. Outbreak conditions are associated with eruptions in beetle population that result in large tree mortality events.
| Lodgepole Pine |
Spruce Hybrid |
White Spruce |
| Spruce |
Aspen |
Forest |
Mountain pine beetles are a natural part of forest ecosystems in western North America. Lodgepole pine trees are the primary host for mountain pine beetles. Warmer winters and and abundance of mature lodgepole pine trees have created ideal conditions for the eruption in beetle populations that have resulted in millions of hectares of tree mortality.
The epicenter of the beetle outbreak occurred in the central interior of British Columbia. Beetles have killed 50-100% of mature lodgepole pine. Forest regeneration is slow in the wake of the beetle outbreak, because pines continue to hold seeds in sealed serotinous cones awaiting the heat from wildfire.
| Low Mortality |
Moderate Mortality |
High Mortality |
Wildfires is often associated with the initiation of new growth for lodgepole pine forests. These ecosystems are often reliant on wildfire to release seeds from fire cue serotinous cones that are held in tree canopies. Without wildfire, cones retain seeds, and new growth is limited.
These landscapes tend to be characterized by stand replacing fire when forest are alive at time of fire. When dead forests burn much of the landscape is still characterized by moderate to high severity fire, based on this burn severity map generated from Landsat imagery.
The post fire burn mosaic will diversify the composition and structure of the landscape.
Forest resiliency has been a concern for land managers when dead forest from beetle outbreak burn during wildfire. Although some areas have low seedling recruitment, generally wildfire is a good mechanism to release seeds and allow the forest to regenerate.
Field work has shown some influence of outbreak conditions on seedling recruitment. Here we are using Landsat imagery to characterize forest recovery after sequential disturbances of beetle outbreak and wildfire.
Wildfire initiates a variety of plant growth either by cuing seedbanks and/or freeing up available resources. The beauty of the post fire landscape presents itself in both plant life and wildlife. The influx of herbaceous plants such as fireweed and Geranium bicknellii attract humming birds, while increased insect and charred trees provide both food and shelter for black backed woodpeckers.
| Unchanged |
Low recovery Rate |
| Moderate Recovery Rate |
High Recovery Rate |
Wildfire breaths new life into forest killed by beetle outbreak. Post wildfire early succession produces an influx of new plant species that attract and provide food and habitat for a diversity of species including blacked backed wood peckers, humming birds, and grizzly bears. Lodgepole pine regeneration may vary across the landscape but is generally resilient because wildfire releases seeds that are held in cones after trees were killed by beetles.
Created by Michael Cook and Anna Talucci from Oregon State University