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 Fire and Ecosystem Effects Interactions

How does fire severity relate to tree mortality, survivorship, and turnover?

The importance of small fire refugia in the central Sierra Nevada, California, USA

Small fire refugia occurred on all landscape positions and within areas burned at all burn severity classes. Individual patches were not significantly related to burn severity, and the authors suggest that refugia may arise within high or low severity burned areas due to different reasons, such as fuel continuity or changes in weather conditions during the fire. However, the authors did find that the amount and distance between refugia decreased with increasing burn severity.

Citation:
Blomdahl, Erika M.; Kolden, Crystal A.; Meddens, Arjan J.H.; Lutz, James A. 2019. The importance of small fire refugia in the central Sierra Nevada, California, USA. Forest Ecology and Management 432:1041-1052.

Low-severity fire increases tree defense against bark beetle attacks

The authors found that frequent, low-severity fire events correlate with increased resin duct defenses in ponderosa pine, which increases protection against bark beetle infestation provided the trees suffer only minor injury. This resin production decreases during long fire-free periods.

Citation:
Hood, Sharon M.; Sala, Anna; Heyerdahl, Emily K.; Boutin, Marion. 2015. Low-severity fire increases tree defense against bark beetle attacks. Ecology 96(7):1846-1855.

Fire severity, size, and climate associations diverge from historical precedent along an ecological gradient in the Pinaleño Mountains, Arizona, USA

Fire severity has also increased by four times that of previous large fires, resulting in high tree mortality and low regeneration in burn scars.

Citation:
O'Connor, Christopher D.; Falk, Donald A.; Lynch, Ann M.; Swetnam, Thomas W. 2014. Fire severity, size, and climate associations diverge from historical precedent along an ecological gradient in the Pinaleño Mountains, Arizona, USA. Forest Ecology and Management 329:264-278.

Climatic stress increases forest fire severity across the western United States

The authors found that long term climatic stress, measured by climatic water deficit, predisposed trees to higher mortality from fire damage. The author suggest that warming temperatures increase fire severity, and ultimately tree mortality, independent of fire intensity.

Citation:
van Mantgem, Phillip J.; Nesmith, Jonathan C.B.; Keifer, MaryBeth J.; Knapp, Eric E.; Flint, Alan L.; Flint, Lorraine E. 2013. Climatic stress increases forest fire severity across the western United States. Ecology Letters 16(9):1151-1156.

Fire effects on Gambel oak in southwestern ponderosa pine-oak forests

Gambel oak is a prolific resprouter and will survive even intense wildfire and may become the dominant species if frequent high-severity wildfire eliminates competing vegetation.

Citation:
Abella, Scott R.; Fulé, Peter Z. 2008. Fire effects on Gambel oak in southwestern ponderosa pine-oak forests. Research Note RMRS-RN-34. Fort Collins, CO: USDA Forest Service, Rocky Mountain Research Station. 6 p.

Survival and sprouting responses of Chihuahua pine after the Rodeo-Chediski fire on the Mogollon Rim, Arizona

Chihuahua pine is one of the few pine species that can resprout from its base after a disturbance. Smaller trees had greater mortality due to fire, however, of the survivors at any age class, these younger trees were more likely to resprout from their base.

Citation:
Baumgartner, Kenneth H.; Fulé, Peter Z. 2007. Survival and sprouting responses of Chihuahua pine after the Rodeo-Chediski fire on the Mogollon Rim, Arizona. Western North American Naturalist 67(1):51-56.

Effects of an intense prescribed forest fire: is it ecological restoration?

Despite issues with pseudoreplication and the limited sample size, the authors found that post-fire conditions moved toward range of natural variation conditions after intense burning. Small trees and fire-susceptible understory trees were preferentially killed by fire and forest floor woody debris was within desired conditions. The sites had adequate regeneration of seedlings with no evidence of any landscape conversion to a non-forest vegetation type.

Citation:
Fulé, Peter Z.; Cocke, Allison E.; Heinlein, Thomas A.; Covington, W. Wallace. 2004. Effects of an intense prescribed forest fire: is it ecological restoration? Restoration Ecology 12(2):220-230.