Transcript Fire and Wildlife

Fire’s Effects on Wildlife
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
Mechanisms of post-fire population
change
• Population response to fire regulated by:
– Availability of food resources
– Changes in cover
– Movement of populations in/out of
burned/unburned areas (migration,
immigration)
Understanding the Consumer
Response to Food Resources
• Fire alters production, species availability,
and food quality
• Migration and immigration
• Short term effects
– Deer mice in prairies or grasslands
• Some mortality during fire may decrease
populations
• Adapted to postfire environment: insects, winddispersed seeds, soil seed bank
• Populations may increase several-fold in burned
areas
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
• Shift to foliar/herbaceous vegetation and
caterpillars/larvae of wood boring insects
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
– Grasshoppers – decline after fire, require a welldeveloped litter layer for habitat
– Earthworms – found 10-20 cm below soil surface,
direct affects only with severe fires; may increase
postfire due to increased plant productivity
• Physical protection from predation
– Structure provides protective habitat
– Affects visibility
Red-cockaded woodpecker in loblolly
pine forests
• Forage behavior of woodpeckers:
– Foraged at greater heights in areas of tall and dense
midstory vegetation
– Concentrate foraging activities in forest stands or
openings with reduced midstory vegetation
• Fire regime in Loblolly pine
– Fire-maintained, frequent surface fires
– Changes in fire regime: fire suppression
TTYP
• Why do red-cockaded
woodpeckers require fire in
order for long-term survival of
their populations in loblolly
pine forests?
• What are the specific
mechanisms?
Mortality of Cavity Trees
• Disturbance by prescribed burning,
thinning, winds, and southern pine beetle
increases cavity tree mortality.
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
Plant Succession and Animal Response:
moose & caribou in boreal forests
• Discuss the following questions:
– How are moose/caribou affected by fire?
– How would you design a management plan to
manage for moose OR caribou?
– How would you design a management plan to
manage for moose AND caribou?
Plant Succession and
Animal Response
• Browsers in North
American boreal forest
– Caribou eat lichen, slow
growth, easily burned
• Caribou in late
successional
– Moose eat woody
resprouts (birch, aspen)
• Moose in early
successional
Structural Diversity and Patchiness
• Mature cover
provides refuge for
migration
• Adjacent high quality
growth in burned
areas
• Mosaics of food
resources and cover
create structural
diversity
– Ecotones boundaries