Responses of Pond-Breeding Amphibians to Wildfire: Short-Term Patterns in Occupancy and Colonization

Abstract

Abstract. Wildland fires are expected to become more frequent and severe in many ecosystems, potentially posing a threat to many sensitive species. We evaluated the effects of a large, stand-replacement wildfire on three species of pond-breeding amphibians by estimating changes in occupancy of breeding sites during the three years before and after the fire burned 42 of 83 previously surveyed wetlands. Annual occupancy and colonization for each species was estimated using recently developed models that incorporate detection probabilities to provide unbiased parameter estimates. We did not find negative effects of the fire on the occupancy or colonization rates of the long-toed salamander (Ambystoma macrodactylum). Instead, its occupancy was higher across the study area after the fire, possibly in response to a large snowpack that may have facilitated colonization of unoccupied wetlands. Naı¨ve data (uncorrected for detection probability) for the Columbia spotted frog (Rana luteiventris) initially led to the conclusion of increased occupancy and colonization in wetlands that burned. After accounting for temporal and spatial variation in detection probabilities, however, it was evident that these parameters were relatively stable in both areas before and after the fire. We found a similar discrepancy between naı¨ve and estimated occupancy of A. macrodactylum that resulted from different detection probabilities in burned and control wetlands. The boreal toad (Bufo boreas) was not found breeding in the area prior to the fire but colonized several wetlands the year after they burned. Occupancy by B. boreas then declined during years 2 and 3 following the fire. Our study suggests that the amphibian populations we studied are resistant to wildfire and that B. boreas may experience short-term benefits from wildfire. Our data also illustrate how naı¨ve presence-non-detection data can provide misleading results.

Effects of Timber Harvest on Amphibian Populations: Understanding Mechanisms from Forest Experiments

“…Thus, we predict that other species requiring early successional or open habitats for reproduction (e.g., chorus frogs, narrow-mouthed toads, spadefoot toads) would benefit from the presence of breeding pools in clearcuts (e.g., use of skidder ruts; Cromer et al 2002). Hossack and Corn (2007) reported that disturbance created by wildfire can also benefit some pond-breeding amphibians, especially if fire creates or mimics early successional habitats. This does not mean that all stages of these species would benefit from clearcut or early successional habitat.…”

“…Thus, the larval aquatic stage presumably benefits from the presence of pools in small clearcuts, but juvenile and adult treefrogs must find suitable forested habitat nearby (Johnson et al 2007. Hossack and Corn (2007) found that toads (Bufo boreas) increased the use of wetlands up to two to three years after wildfires, and suggested that this species was adapted to disturbance created by fire. However, some species, such as the wood frog in Maine, benefited little from breeding pools in clearcuts; these most likely represent species with a strongly forest-dependent life history (Blomquist and Hunter 2009).…”

Spatiotemporally variable management by grazing and burning increases marsh diversity and benefits amphibians: A field experiment

“…Habitat management for amphibians includes creating or restoring breeding ponds, increasing the connectivity between ponds, and establishing and maintaining shallow open water habitats by grazing or fire management (Bisson et al 2003;Hazell et al 2004;Pilliod et al 2003). Although there is a growing body of knowledge on how controlled and natural fires affect amphibian communities, the issue is far from settled due to the complexity of species-specific effects that depend on the local habitat structure and populations (Hossack and Corn 2007). Short-term negative effects include increased solar and UV-B radiation, high surface temperatures, aridification, and increased predation (Pilliod et al 2003).…”

Meta-analysis of avian and small-mammal response to fire severity and fire surrogate treatments in U.S. fire-prone forests

“…However, despite high management and policy interest in wildlife, faunal response to fire has received substantially less attention. Much of this is due to the difficulty of studying fire-wildlife interactions; consequently, a great deal of the literature is based upon convenience sampling of wildfires that burned preexisting sample points (e.g., Smucker et al 2005, Hossack and Corn 2007, Kotliar et al 2007. Reviewing global fire literature on the birds, the best-studied vertebrate taxon, Leidolf and Bissonette (2009) found just over 500 documents, of which ,50% were journal articles containing original research and of which .50% had been published since 1990.…”