Fire severity may decrease as number/extent of wildfires increase

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More wildfires and greater areas burned is the forecast for the future as climate change continues. Recently, a new study published in the “Environmental Research Letters” expects fire severity to decrease.

Fire severity is the extent of change in the local vegetation one year after a major fire. For example, if brushes and shrubs took over the burned area where previously pines or hardwoods dominated, extreme fire severity occurs.

Although the study expects longer fire seasons and larger fires, it is the water deficit and deficient precipitation that will encourage and permit the vegetative change to begin before a fire or to enhance the change after a fire, according to the authors.

“Fire severity generally decreased with [water deficit] and increased with [precipitation],” they reported. Consequently, they believe the severity of fires will be greater in the Pacific Northwest and northern Rockies and less severe in the warmer and drier forest of Arizona and New Mexico. This is how climate change affects fire severity.

Also, as the number of fires increases, the amount of biomass available to burn will decrease, which will also reduce fire severity.

The authors concluded that a passive management approach would most likely be more effective. They argued that activities such as mechanical thinning can be limited for legal reasons, such as a wilderness designation, or geographical, such as steep slopes. Consequently, they recommended that greater reliance on managing wildfires would be more effective.

Regardless, the cumulative effect will be more and larger fires, but sudden and dramatic changes will be less likely since the water environment already will be ushering in these changes.

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