McKenzie, D., Z. Gedalof, D.L. Peterson and P. Mote. 2004. Climate change, wildfire, and conservation. Conservation Biology 18: 890-902.
RELEVANT TO: |
FIRE |
TREE CUTTING |
|
SPECIES |
DESCRIPTION
This article discusses historic, current, and future relationships between climate variability and the extent and severity of wildland fire in western forest ecosystems, including the anticipated effects of global warming on the amplitude and duration of burning seasons, fire behavior, dominant vegetation, and sensitive species habitats. Authors quantify 20 th century relationships between climate and fire extent and use those relationships to infer the effects of predicted climate change scenarios on future fire extent. The article also discusses how modifying fuels structures may change the impacts of global warming and associated changes in wildland fires in some vegetation types and the incompatibility of those treatments with habitat requirements of some imperiled species.
MAJOR FINDINGS
- The most important factor affecting wildfire extent is summer temperatures.
- Global warming is expected to result in higher summer temperatures and longer, more severe fire seasons.
- Area burned is expected to at least double by 2100 in western states; there is no reason to believe it will decrease.
- Increased fire frequency resulting from global warming may decrease habitat quality in high severity/low frequency fire forests and savannah, shrublands, and interior chaparrals while increasing overall habitat quality in forests with moderate severity/frequency and low severity/high frequency where fire has been excluded during the past century.
- Reduced amount and duration of snow pack will likely extend the annual period of moisture deficit in water limited systems, increasing stress to plants and making them more vulnerable to (sometimes synergistic) disturbances including fire, insect attack, and/or stress-induced mortality.
- Increased fire extent and severity may reduce the extent and connectivity of late-successional refugia, especially in mesic sites that have survived past disturbance and in areas where those refugia are already limited in quality or extent by anthropogenic forces. Resulting spatiotemporal habitat bottlenecks could negatively impact the viability of species dependent on those habitats including spotted owl and northern goshawk.
- Mitigating impacts of global warming with preemptive fuels reduction activities is possible, however treatments that reduce overstory, understory, or surface fuels may preclude habitat requirements of the species vulnerable to global warming impacts. Authors recommend a case-by-case approach to management of those habitats.
QUESTIONS RAISED FOR THE THREE FORESTS
- Do the three Forests plan to manage forest uses and habitats in anticipation of global warming and increasingly frequent and severe fire regimes with more in mind than timber production? If so, how?
RELEVANCE TO FOREST MANAGEMENT
- Fire management planning should plan now for probable, perhaps inevitable, coming changes.
- Over time, use of naturally ignited fires should be accommodated where it will improve overall habitat quality in mixed and high frequency fire regime forests where fire has been excluded during the past century.
- Impacts of fire use and fuels reduction to imperiled or declining species should be assessed on a case-by-case basis.
- Identification of mesic or late seral refugia that may be vulnerable to changing climate and fire regime should be identified and, wherever possible, mitigation plans should be developed to avoid spatiotemporal habitat bottlenecks. Retention of redundancy in high quality habitats is essential.
- Spruce-fir and other high-severity, low frequency forest types (pinyon-juniper, mesic mixed conifer), shrublands, and interior chaparral will be most severely impacted by changing climate and fire regimes. These impacts may be unavoidable. Mitigation measures may include conserving additional habitat outside these types where it is suitable for imperiled species.