Analysis of forest fire patterns and their relationship with climate variables in Alberta's natural subregions

Abstract

Forest fires are significant ecological and environmental phenomena that can be influenced by various climatic factors. This study used fire point records from the Canadian National Fire Database (CNFDB) and interpolated climate data, which include the minimum and maximum air temperature, the average relative humidity, and the precipitation for each subregion of Alberta, Canada, to analyze the patterns and relationships of forest fires and climate variables using trend analysis and anomaly detection methods. The trend analysis was based on the Mann-Kendall test and Sen's slope, which were used to detect the presence and magnitude of monotonic trends in the monthly aggregated data from 1955 to 2022. The anomaly detection is based on the RobustSTL method, which was used to decompose the monthly aggregated data into seasonal, trend, and remainder components, and to identify the periods of significantly high or low values for each component. Most subregions showed a significant increase in temperature and a decrease in humidity, indicating a warming and drying trend due to climate change. Precipitation change was variable across subregions. Human-caused or prescribed forest fires increased significantly in Central Mixedwood, Dry Mixedwood, Lower Foothills, Montane, and Upper Foothills, while lightning-caused forest fires had mixed trends in Dry Mixedwood, Upper Foothills, Central Mixedwood, and Lower Boreal Highlands. The fire occurrence and source were affected by the climate variables in different ways across subregions. The fire occurrence in the Athabasca Plain subregion changed with the air temperature. It was low when the temperature was significantly low, and it was high due to lightning when the temperature was significantly high. The Central Mixedwood subregion had three peaks of lightning-induced fires when the relative humidity was significantly low, and several peaks of fires from human activities and lightning when the air temperature was significantly high. The study also revealed some other interesting patterns and relationships between the climate and fire variables and the forest fire distribution in different subregions, which may help to understand and manage the climate and fire interactions and their implications for forest fire understanding and management in the context of climate change.