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Fire Effects on Wildlife
18 September 2006
Direct Effects
• Few studies, marked re-capture approach ideal
– Body size and mobility, i.e. burrowing, influence direct
mortality
• Life cycle stages are impacted differently
• Depends on fire regime
– Frequency, intensity, extent, and season
– Extent-small area, greater ability to repopulate
• Must look at populations rather than the
individual
Indirect Effects
• Fire severity and resulting successional
patterns dictate wildlife habitats and the
effect on wildlife
• Importance of fire regime
• (+/-) Consumer response is species
dependent, must consider mechanisms at
work
TTYP: What are the indirect effects
of fire on wildlife habitat?
Mechanisms of post-fire population
change
• Availability of food resources and changes
in cover regulate population response
• Sorting out these mechanisms is a
research challenge
Understanding the Consumer
Response to Food Resources
• Fire alters production, species availability,
and food quality
• Migration and immigration
• Short term effects
– Arizona grassland example
• Green vegetation declines while seed availability
increase
• Differential small mammal response
Understanding the Consumer
Response to Food Resources
• Alternatively, shift in food sources
– Ex. Australian eucalypt forest
• Bettongs exploit fire adapted
fungus
– Ex. Primates in Borneo shifting food sources
• Flowers and fruits unavailable→ foliar/herbaceous vegetation
and caterpillars/larvae of wood boring insects
Plant Succession and Animal
Response
• Ex. Browsers in N.A. boreal forest
– Caribou eat lichen, slow growth, easily burned
• Caribou in late successional
– Moose eat woody resprouts (birch, aspen)
• Moose in early
successional
Consumer Response and Food
Quality
• Pulse of higher quality new growth
– Increase in protein (nitrogen content) in new
growth
– New tender shoots with greater digestibility
– Increase in population growth rates?
• Ex. Domestic grazers
Changes in Cover
• Burned vegetation results in drastic change in
both physical and thermal cover
– Ex. Cryptic insects, evolutionary response
• Physical protection from predation
– Structure provides protective habitat
• Structure effects visibility
• Clearing of structure
provides visibility
– Ex. Red-cockaded
woodpecker and loblolly
pine understory
maintenance
Balancing Protective Cover and
Food Availability
• Tallgrass prairie example
• Bird response
• Increase in seed/insect availability
• Decrease in cover, nesting habitat, and predator
protection
• Small mammal response
• Some small rodents, i.e. prairie vole, are small
navigate litter layer and find seed
• Other larger rodents, prefer burned area with
easier seed access
Structural Diversity
• Interspersion of food resources and
cover
• Positive or negative effects depending on
the severity and extent and the wildlife
considered
• Reduced habitat heterogeneity by large
extent, severe fires
Example: Structural Diversity
• Habitat diversity
and complexity,
each supports a
specific faunal
community
– Ex. Snags
important for birds,
mammals, reptiles,
amphibians, and
invertebrates
Structural Diversity and Patchiness
• Refugia for migration
and nucleus for
recovery
• Mature cover and
adjacent high quality
growth
• Mosaics of food
resources and cover
create structural
diversity
– Ecotones - boundaries
Landscape Diversity Example:
Mississippi Alluvial Valley
• Landscape complexity through burning
– Rice and waterfowl management
– Mississippi rice fields, interspersion of open
water and emergent vegetation (Kross 2006)