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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
