Habitat or fuel? Implications of long‐term, post‐fire dynamics for the development of key resources for fauna and fire

Abstract

Summary1. Managing fire to achieve hazard reduction while providing for biodiversity conservation is complex in fire-prone regions. This challenge is exacerbated by limited understanding of post-fire changes in habitat and fuel attributes over time-scales commensurate with their development, and a paucity of empirical research integrating the effects of fire on these attributes. 2. We used a 110-year post-fire chronosequence to investigate temporal development in habitat resources used by fauna, and fuels for fire in semi-arid Mallee vegetation, south-eastern Australia. Fire-history mapping previously limited investigation to 35 years post-fire. The patterns of temporal change over 110 years for 13 variables, representing key attributes of habitat and fuel, were explored using nonlinear mixed models and data from 549 sites. 3. Most habitat and fuel attributes exhibited changes in abundance and rate of development over extended periods, emphasizing the importance of documenting post-fire dynamics over long timeframes. Further, developmental patterns were mostly nonlinear, indicating that a shorter temporal perspective (e.g. 20-30 years post-fire) may obscure, or provide an inaccurate understanding of, long-term changes. 4. There were striking differences in the post-fire dynamics of some habitat and fuel attributes. Leaf litter and spinifex grass Triodia scariosa, which function as both habitat and fuel, increased rapidly after fire followed by a plateau or slow decline after 20-30 years. In contrast, live tree stems were not predicted to develop hollows until 40 years, after which time the density of live hollow-bearing stems, an important habitat feature, increased steadily. 5. Synthesis and applications. Fire affects the development and abundance of resources over substantially longer periods than can be examined using fire-mapping based on satellite imagery. Our results demonstrate that post-fire changes in mallee vegetation influence fire hazard and faunal habitat in different ways. Critically, the cover ⁄ abundance of most primary fuel sources did not increase substantially beyond around 30 years post-fire; whereas important habitat attributes changed in ways that affect faunal occurrence for over a century. Fire management must explicitly acknowledge the potential for fire to affect fauna and fuel differently, and for these effects to operate over time-frames that may extend well beyond current understanding.

Reptile responses to fire and the risk of post-disturbance sampling bias

“…Over half of the mallee on the Eyre Peninsula has been cleared, mostly before 1939, leaving a small number of very large mallee reserves and many small remnants (Australian Native Vegetation Assessment 2001; State of the Environment Report 2003). Natural fire regimes in mallee communities are poorly understood, but fire return intervals of less than 15 years are regarded as short (Bradstock and Cohn 2002), and mallee may remain unburnt for more than a century (Haslem et al 2011). …”

The impacts of fire on birds in Australia's tropical savannas

“…Although this approach has been widely used elsewhere in Australia (e.g. Haslem et al 2011), there are few examples of its use in the Australian tropical savannas, perhaps because frequent fire mercurially shifts fire histories across this landscape, because there are few sites in the landscape that are long-unburnt, rendering most potential contrasts in fire history rather muted, and because, at most sites, with contrasting fire history there are conflating influences relating to topography or land-use. A variation on this research design is a monitoring approach that samples every site twice or more, and compares the divergence between the results of the baseline and subsequent sampling of each site with the fire history that occurred at that site in the between-sampling interval.…”

Multi-century dynamics of ant communities following fire in Mediterranean-climate woodlands: Are changes congruent with vegetation succession?

“…As vegetation recovers after disturbances such as fire its composition and structure systematically changes (Bond and van Wilgen, 1996;Haslem et al, 2011;Gosper et al, 2012), affecting the availability of resources for fauna and mediating physical conditions such as temperature and exposure to sunlight (Whelan, 1995). According to the habitat accommodation model (Fox, 1982), these changes drive a succession of animal species, which enter and leave according to their habitat requirements and competitive interactions.…”