Fire Ecology

1
Fire Ecology

• Betty Harper
• bjh17_at_psu.edu

2
Take home message

• Fire frequency vs. intensity
• Fire as a disturbance mechanism
• Role of fire in succession
• Evolution of fire policy
• Plant adaptations to fire
• Fire is not simply good or bad
• Economic concerns may way as heavily as science
  in making decisions

3
Forest fires in the news

• http//www.nytimes.com/college
• Forestry search 6 out of 10 articles about
  forest fires
• Los Alamos fires in 2000
• Florida fires particularly bad in 1997
• Consistent fire problems in Western US

4
Fire is a certainty

• Fire WILL occur in most ecosystems
• In 2002 the federal government spent 1.6 billion
  on fire suppression and still 6,937,584 acres
  burned in the US.
• Natl Interagency Fire Center BLM, BIA, FWS,
  USFS, NPS, NOAA, OAS, NASF
• The only question is the effect of these fires.

5
Fires ecological role

• Disturbance is any relatively discrete event in
  time that disrupts ecosystem, community, or
  population structure and changes resources,
  substrate availability, or the physical
  environment
• Other examples?

6
Succession
How does a lawn stay a lawn?
7
Roles

• Reduce fuel load
• Open understory
• Increase light reaching forest floor
• Favors fire-tolerant species
• Release nutrients back into the soil or sterilize
  soil

8
Other possible effects

• Fisheries increase water temp sedimentation,
  decrease water quality, change water chemistry
• Destroy/create critical habitat
• Invasive plants
• Disease/insect infestations

9
Fire regime characteristics

• Frequency
• Size
• Fire type (crown, surface, light surface)
• Fire intensity (how hot, how long)
• High intensity results in uniform burn
• Low intensity effected by small-scale variability
  in fuel moisture, leaving a patchy landscape
• All dependent variables

10
Frequency vs. Intensity

• Inverse correlation between frequency and
  intensity
• Prescribed/controlled fire is frequently used to
  reduce fuel loads
• Result can be a relatively large number of cool
  burns

11
Historic perspective

• Fire occurred periodically due to lightning, dry
  conditions, etc.
• Native people altered the N. American landscape
  with fire
• Took advantage of natural fire
• Also capable of very precise controlled burns
• Resulted in altered vegetation patterns

12
Post-European Colonization

• Early Euro-Americans use fire use to clear land
• 1600s current Use fire to create habitat
  favored by quail, turkey, and deer
• Early 20th century cut out and get out
  lumbering left large loads of fuel on the ground
• Resulting fires could be devastating and fire
  rather than poor timber harvesting practices was
  blamed

13
Policy of fire suppression

• Fire viewed as something to be controlled
• Aggressive fire suppression policy in wildland
  areas since the beginning of the 20th century
• Goals of suppression
• Protect public/private property
• Prevent destruction of forests, grasslands, etc.
• Protect timber resource

14
Results of suppression

• Unprecedented fuel loads
• More intense fires
• Spread of invasive/non-native species
• Ecosystem shifts
• Suppression does not recognize the ecological
  role of fire

15
Americas most wanted
16
Todays Federal Wildland Fire Policy

• Recognizes dangers of suppression
• Recognizes fire as a critical natural process
• Calls for reintroduction of fire on an
  ecologically significant scale
• Proactive approach to reduce threat of wildfire
• http//www.fs.fed.us/land/wdfire.htm

17
Why do we use fire?

• Fire prevention
• Conservation
• Habitat improvement for species of interest
• Restore natural or historic landscape
• How do we define what is natural?

18
Prescribed Fire

• Where to start?

19
Factors to consider

• Weather (Temp, Rain, Wind)
• Fuel load
• Habitat type
• Proximity to private and/or developed property
  and roads
• Natural and human-created fire barriers

20
Fire seasonality

• Management cool season burns are easiest to
  control, but not always best
• Ecology if natural fire season is during the
  summer, plants may be adapted to this
• Example wiregrass (Aristida sp.) reproduction is
  stimulated by a summer burn

21
Mortality due to fire

• Plant susceptibility to damage/death increases
  with decreasing size
• Herbs, seedlings, and small saplings may be
  killed by low intensity fire that has no effect
  on trees
• Low intermediate fires may produce selective
  mortality
• High intensity fires may kill many plants

22
Plant defenses adaptations

• Bark
• Height
• Roots
• Thick, leathery leaves with cuticle
• Serotinous cones

23
Fire and ecosystems

• Pennsylvania
• Prairie grassland
• Southeast US

24
Fire and Pennsylvania forests

• Prior to European settlement periodic fire
  believed to have maintained forests dominated by
  oak, hickory, and American chestnut in Central PA
• Red maple relegated to swamps due to fire
  sensitivity (soft maple)
• 1700s and 1800s logging, charcoal industry,
  wildfire encouraged oak growth

25

• Oaks favored by fire, relative to many other
  Northeastern, mid-Atlantic species
• Thick bark
• Sprouting ability
• Resistance to rot after scarring
• Suitability of fire-created seedbeds for acorn
  germination

26

• Now were suppressing fire and logging less ?
  succession is moving along again
• Theory Historic PA forests represented a early
  to mid-successional stage prior to domination by
  more shade-tolerant, later successional species
  (such as red maple)

27
Fire and grassland ecosystems

• Fire reduces shade, eliminates thatch layer,
  increases seed germination, releases nutrients
  into the soil
• Fire prevents establishment of trees and shrubs
  that would eventually out-compete and shade out
  the grasses
• Fire adaptation many grassland plants have no
  permanent aboveground parts

28
Fire in the southeast

• Wet and dry seasons
• Fire adapted plants
• Sand pine (Pinus clausa) serotinous cones
• Wiregrass meristem is 1-1.5 underground
• Long leaf pine (Pinus palustra) large
  underground root system, rapid growth, thick bark

29
(No Transcript)
30
All other things similar

• Frequent, low intensity fires ? Sandhill open
  stands of longleaf or slash pine (Pinus
  elliottii) with grassy understory
• Less frequent, more severe fires ? Sand pine
  scrub closed canopy of sand pine with dense
  understory
• Absence of fire ? Xeric hardwoods dominated by
  evergreen oaks and hickories

31
Yellowstone, 1988

• Driest summer in Parks history
• 9000 fire fighters, 120 million
• gt 3 million dollars in property damage
• Fires not extinguished until autumn snow began
• 1.2 million acres in the Greater Yellowstone area
  burned

32
(No Transcript)
33

• Post 1988 ? ample precipitation combined with ash
  and nutrient influx from fire resulted in
  abundant wildflowers
• Lodgepole pine seed densities of 50,000 to 1
  million per acre beginning new cycle of forest
  growth
• Stable ecosystems can recover from even
  catastrophic fire

34
(No Transcript)
35
Healthy Forest Initiative

• Catastrophic fires due to fuel buildup
• Goal is to reduce fuel load with
• Thinning
• Prescribed burning
• Forest restoration projects
• Remove administrative obstacles to timber
  projects
• Balance environmental needs w/ community needs

36
Opposition to the plan

• An excuse for more logging
• Logging companies will leave saplings and brush
• Degrades habitat
• Will actually result in more fuel
• Eliminates checks balances
• http//www.wildrockies.org/wildfire/Chad_oped.html