Transcript Slide 1
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)