Climate Change and Fire Behavior

Question 1

Drought

Answer 1

Droughts are increasing under climate change
- Forests are struggling to survive and grow in a hotter, drier climate
- Wildfires burning more acres in recent decades
- High aridity is triggering more and bigger wildfires at increasingly unprecedented rates

Question 2

Double Whammy Effect

Answer 2

Fire + climate change on forests = limited vegetation survival, growth, and regeneration potential

Question 3

Resilience

Answer 3

The ability of a forest to absorb disturbances and re-organize, while still maintaining fundamental structure and functions
- shifting disturbance regimes are eroding forest resilience; people are really worried about trees and fire

Question 4

Forest adaptation in the Pacific Northwest (Jesse Halofsky case study)

Answer 4

Assessment of stakeholder needs; relationship between fire and climate came out as a top priority

Stats:
- In 2014, record was set for the largest wildfire in Washington State history (256, 100-acre Carlton Complex Fire)
- In 2015, 1.7 million acres burned in Oregon and Washington, with over 9 million acres burning in western US
- Several fires in 2015 occurred in west-side conifer forests, including a rare fire even tin coastal temperate rainforest on Olympic Peninsula

Question 5

Wildfire collision

Answer 5

Fires have burned some areas 3 times in last few decades

Short fire return interval: places can burn multiple times in one place
- How are fuel loads changing, how does short return affect these areas, etc.

Grasses: have come back, but there is no tree regeneration
- Our lifespan is incongruent with the lifespan of trees

Question 6

Information sources for climate change effects on fire

Answer 6

• Paleoecological record
• Tree ring records of fire
• Observed trends with recent warming
• Model projections

Question 7

Drier fuels

Answer 7

Earlier and longer periods of dry fuels; Several weeks of high temp and low rainfall are sufficient to dry fuels and cause extreme fire hazard

Question 8

Projections for changes in summers water-balance deficit

Answer 8

Strong relationships in future between water deficit and fire area burned in future projections

Question 9

Extremes matter

Answer 9

• Frequency, extent, and severity of wildfire may be affected by climate change, altering the mean and variability of wildfire properties

Question 10

Rapid forest change: insects

Answer 10

During the past 30 years, bark beetle-caused
tree mortality in the western U.S. has exceeded
that of wildfire.

Question 11

What does this mean for forests in the West and beyond?

Answer 11

• High-severity “reburns” may occur before forests recover from most recent high-severity fire
• Large fires are creating larger and more homogeneous patches of stand-replacing fire
• Post-fire regeneration is very sensitive to climate
• Drought, bark beetle outbreaks, and fires will likely interact
• Forests will change in species composition and structure, and in some places will transition to non-forest; Managers must now consider where to
  try to forestall change and where they may need to allow conversions to occur

Question 12

Resist, Accept, Direct framework

Answer 12

We may be able to resist some changes, we may be able to accept some changes, redirect toward a different state; use management

Question 13

Legacy effects matter

Answer 13

If things survive, there’s a better chance for forest recovery
- Localized effects: combustion of logs heating soil and removing shade

Question 14

Managing for resilient ecosystems in a warmer climate (strategies)

Answer 14

• Increase landscape diversity
• Manage stand density (and fuels)
• Climate adaptation options in forests with stand-replacing fire regimes
• Treat large disturbances as an opportunity
• Think about seed zones under future climate scenarios
• Implement risk assessment

Question 15

Increase landscape diversity

Answer 15

• Diversify spatial distribution of vegetation age and structure
• Orient location of treatments in large patches to modify fire severity and spread

Ex. Implement thinning and fuel treatments across large landscapes

Question 16

Manage stand density (and fuels)

Answer 16

• Thin dense stands to reduce competitions
• Consider removing surface and understory fuels to reduce intensity
• Manage forest density and fuels across landscapes (collaborate with neighbors)

Question 17

Climate adaptation options in forests with stand-replacing fire regimes

Answer 17

• Big events are part of system
• Pre-disturbance climate adaptation management options are relatively few, or ineffective (e.g., fuel management)
• Fire suppression may be a reasonable strategy (in these systems)
• Have post-disturbance plans in place

Question 18

Treat large disturbances as an opportunity

Answer 18

• Develop management strategies and on-the-ground actions for implementation following wildfire and insect outbreaks
• Plant trees in areas that are far from seed sources, but plant spaced out in high-severity fire regimes
• Include long-term experimentation
• Get the plans approved

Question 19

Characteristics of climate-tolerant species

Answer 19

• High seed production
• High seed dispersal
• Tolerant of low soil moisture
• Tolerant of high air temp
• Tolerant of wildfire
• High competitive ability
• Broad environmental tolerance
• High genetic diversity

→ idea is to plant these plants in fire-prone areas

Question 20

Implement risk assessment

Answer 20

• Quantify or at least estimate risk of fire and other climate stressors on natural resources
• Use risk assessment to guide adaptation responses (risk management)