Abstract
Persistent fire refugia, which are forest stands that have survived multiple fires, play an important ecological role in the resilience of mountainous forest ecosystems following disturbances. The loss of numerous refugia patches to large, high-severity fires in recent years is prompting the need to better understand drivers of fire refugia endurance. We investigate the role of topographic features on fire refugia survivorship based on pre-1950 fire regime conditions. Mapped refugia patches (n = 557) covering 28% of the forested landscape were used to develop three predictive models based on patch size (all sizes, <30 ha, <10 ha), as a function of explanatory variables describing several components of topography. Five topographic variables consistently favoured persistent fire refugia occurrence, though the ranking of explanatory variable importance varied among patch-size models. For the all-refugia model, elevation (23.7%), proportion of non-fuel at a 5000-m scale (20.3%), solar radiation (14.6%), Topographic Position Index at a 2000-m scale (10.1%), and distance from rivers (10.1%) were the top variables. The models’ predictive abilities were high, but decreased with larger patch sizes. We conclude that many suitable areas are currently unoccupied by fire refugia; that random elements affect their survivorship; and that additional environmental factors not considered in this study may contribute to their persistence. With changing climate and fire-regime conditions, careful fire and forest management considerations will be needed to limit future losses of persistent fire refugia forests.
Highlights
The simple definition of a forest fire refugium is a forested area, big or small, that has escaped burning
As a complement to the variable importance, we evaluated the relationships of likelihood of fire refugia to the top explanatory variables for each refugia-size model
Given the unique perspective stemming from a rich data set covering a large-sized territory, our study provides a valuable contribution to understanding persistent fire refugia in the Canadian
Summary
The simple definition of a forest fire refugium is a forested area, big or small, that has escaped burning. Various studies define the state of what qualifies as refugia, or fire refugia, differently. Franklin et al [1] define refugia as areas persisting through a disturbance that contain biological legacies, such as organisms, organic materials, and organically generated patterns, which can be incorporated into the recovering ecosystem. Fire refugia are the result of site characteristics and spatial locations favouring lower fire susceptibilities [2,3]. Some consider residual island remnants within a recent fire to be refugia [4,5], whereas others are more concerned with persistences in which some patches of forests can survive multiple fires [2,3]. In the context of this study, persistent fire refugia are examined. Persistent fire refugia patches are common in the Canadian
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