Canadian Forest Service Publications
Accounting for spatial autocorrelation improves the estimation of climate, physical environment and vegetation’s effects on boreal forest’s burn rates. 2018. Portier, J.; Gauthier, S.; Robitaille, A.; Bergeron, Y. Ecol. 33: 19-34.
Issued by: Laurentian Forestry Centre
Catalog ID: 38958
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Context. Wildfires play a crucial role in maintaining ecological and societal functions of North American boreal forests. Because of their contagious way of spreading, using statistical methods dealing with spatial autocorrelation has become a major challenge in fire studies analyzing how environmental factors affect their spatial variability.
Objectives. We aimed to demonstrate the performance of a spatially explicit method accounting for spatial autocorrelation in burn rates modelling, and to use this method to determine the relative contribution of climate, physical environment and vegetation to the spatial variability of burn rates between 1972 and 2015.
Methods. Using a 482,000 km2 territory located in the coniferous boreal forest of eastern Canada, we built and compared burn rates models with and without accounting for spatial autocorrelation. The relative contribution of climate, physical environment and vegetation to the burn rates variability was identified with variance partitioning.
Results. Accounting for spatial autocorrelation improved the models’ performance by a factor of 1.5. Our method allowed the unadulterated extraction of the contribution of climate, physical environment and vegetation to the spatial variability of burn rates. This contribution was similar for the three groups of factors. The spatial autocorrelation extent was linked to the fire size distribution.
Conclusions. Accounting for spatial autocorrelation can highly improve models and avoids biased results and misinterpretation. Considering climate, physical environment and vegetation altogether is essential, especially when attempting to predict future area burned. In addition to the direct effect of climate, changes in vegetation could have important impacts on future burn rates.
Plain Language Summary
In this study, the researchers concluded that accounting for spatial autocorrelation in burn rate modelling could greatly improve its accuracy and prevent biased results and misinterpretations.
The researchers compared two burn rate models using a territory located in the boreal forest of eastern Canada for the 1972-2015 period: a method accounting for spatial autocorrelation, and another that did not. Fires are considered to be spatially autocorrelated since they are more likely to spread to neighbouring areas if they occur in a given part of a territory. The other factors taken into account were climate, physical environment and vegetation type.