Burn Severity and Forest Resiliency

With the increases in wildfire activity in British Columbia and world wide, it is crucial to understand how resilient forests are after wildfire events. One of the key factors in forest resiliency after disturbances, such as wildfires, is forest regrowth. Forest regrowth is an important part of forest resiliency, particularly to the reorganization and exploitative phases of resiliency. Understanding how wildfires have impacted forest regrowth is crucial for forest management practices.

The use of remote sensing offers a cost-effective approach to monitoring wildfires, particularly for inaccessible areas. Using remote sensing techniques, this study aims to address how the burn severity of the Little Bobtail Lake wildfire in North-Central British Columbia impacted forest regrowth several years later.

To understand how burn severity of the Little Bobtail Lake wildfire has impacted forest regrowth  Landsat-8  satellite imagery was used to characterize burn severity and vegetation health over a seven-year time period. The pre-fire conditions of this area are important as they define a baseline for the forest regeneration. This was done by using a Landsat-8 image that was acquired one year before the wildfire event. The changes in the post-fire conditions are understood by characterizing burn severity and vegetation health immediately after the wildfire and every year after that to monitor the return to the pre-fire state.

The burn severity of the Little Bobtail Lake wildfire had an impact on vegetation health. The higher the burn severity the greater the decrease in vegetation health from pre-fire to post-fire conditions. Higher burn severity areas also showed a slower return to a pre-fire state. Additionally, it is important to note that different measures of vegetation health showed slightly different results in this return.

When looking at the spatial patterns of burn severity and vegetation health over time some of the classes showed changes while others did not. For the Core Area pattern metric the Sparse Vegetation (vegetation health) class showed a 3.72 hectare increase in Core Area every year. This was the most drastic change and shows the initial influx of new vegetation occurring in the first years after the wildfire. The Healthy Vegetation class showed no change, while the Moderately Healthy and No Vegetation classes showed only slight changes.

The High-Severity class showed the most drastic change, for burn severity, in Core Area with a decrease of 2.63 hectares every year. The Low-Severity class had a 1.48 hectare increase every year; while the Moderate-Severity and Unburned classes showed only slight increases. This was to be expected because as the vegetation regrows in the High-Severity class it changes to a lesser severity.

To have a better understanding of the changes in forest regrowth as impacted by burn severity one should consider a longer time period. This would allow for a further return to a pre-fire state. Another consideration would be to have a classification of the land cover in the area impacted by the wildfire. The species composition pre-fire and the return to this post-fire is crucial to forest resiliency studies. Future work in this area is of vital importance to have improved management practices after wildfire events, as well as for a better understanding of the impacts of wildfires on forest resiliency.