How many common reptile species are fire specialists? A replicated natural experiment highlights the predictive weakness of a fire succession model

Abstract

Species with strong preferences for early or late successional stages after fire may be extinction prone under current fire regimes. However, the extent of specialisation to time since fire is poorly understood, and, for reptiles, succession models for predicting responses are in the development phase. In this study we tested predictions of a reptile succession model, and identified species that may be fire specialists. Reptiles were sampled in five burnt and unburnt mallee Eucalyptus woodlands, Australia. Two, 400 m transects within each burn treatment were sampled using 11 pairs of pitfall-traps that were opened for five weeks over two summers. A habitat accommodation model of succession that was previously developed for mallee reptiles correctly predicted the observed responses of three of 16 common reptile species. A further four species showed non-significant trends in the predicted direction. However, eight other species showed unexpected responses. One species showed a strong interaction between burn age and location, requiring a two-dimensional successional model in contrast with the usual linear models explaining reptile responses to fire. One third of common species were not affected by fire and so may not have increased risks of extinction due to the fire suppression/incineration cycle. However, approximately half to two-thirds of common reptiles did have a fire response, so the risk of deterministic extinction in small fragments may be substantial. Further model development is needed to better predict fire responses and to assist the design of fire mosaics that can accommodate early and late successional fire specialists.

Ecological succession and habitat attributes affect the postfire response of a Mediterranean reptile community

“…All reptile species living in the Natural Park do not follow the same postfire response, this conclusion confirming previous findings in Australia (Caughley 1985;Driscoll and Henderson 2008) and USA (Perry et al 2009). Several of our results support this conclusion:…”

“…However, GLM analyses did not find differences in species richness between eastern and western areas, whereas old and recent fires marginally did. These differences between the commonest reptiles are similar to those reported in other postfire succession studies (Pianka 1996;Letnic et al 2004;Driscoll and Henderson 2008). In our case, P. hispanica and P. algirus differed at macrohabitat and microhabitat scales and also with regard to burnt and unburnt sites.…”

“…This positive response has been observed in some reptile communities (e.g., Pianka 1996; Rugiero and Luiselli 2006). However, Caughley (1985) and Driscoll and Henderson (2008) reported that the response of reptiles to fire is not homogeneous within a single community. These authors recognized different succession trajectories for reptile species in Australian burnt areas, during the vegetation structure recovery.…”

Is there an inherent conflict in managing fire for people and conservation?

“…A fire regime considers the frequency, intensity, extent, seasonality, heterogeneity and size of fires in a given landscape (Gill 1975;Whelan 1995). Changes to natural fire regimes (or the variability therein) can result in significant ecological impacts on some populations, species and communities (Fox 1982;Russell-Smith et al 2003;Andersen et al 2005;Clarke 2008;Driscoll and Henderson 2008;Nimmo et al 2012;Nimmo et al 2014;Sitters et al 2014).…”

Fire impacts recruitment more than survival of small‐mammals in a tropical savanna

“…There are limited data on the demographic processes that are responsible for observed changes in abundance under different fire regimes, and the majority of research on the effects of fire on animal populations has focussed on change in relative abundance (Friend 1993, Whelan 1995, Sutherland and Dickman 1999, Whelan et al 2002, Griffiths and Brook 2014. A reliance on changes in abundance to draw generalisations, or for making predictions about fire effects, is problematic because of idiosyncratic differences in fire history, fire and habitat characteristics, biotic interactions, climatic influences, and siteto-site variation in an organism's life history (Whelan 1995, Whelan et al 2002, Driscoll and Henderson 2008, Lindenmayer et al 2008). …”