Regeneration after fire in Triodia R. Br.

Abstract

Hummock grasses in the genus Triodia R. Br. were examined at 116 recently burned locations across mainland Australia, and were recorded as regenerating by resprouting, or by seed only. Prior to this survey it was known that the capacity to resprout varies considerably in Triodia, but it was unclear whether some species might be entirely resprouting and other species entirely fire-killed; whether this might be associated with particular traits of species or particular landscape types; or whether resprouting might be more common in particular regions such as the northern monsoonal grasslands. Seven species had both fire-killed and resprouting populations represented among the sites examined. Three species [T. basedowii E. Pritzel, T. marginata N.T. Burbidge and T. melvillei (C.E. Hubbard) Lazarides] were recorded as fire-killed at all sites examined, and five species [T. bynoei (C.E. Hubbard) Lazarides, T. bunicola (S.W.L. Jacobs) Lazarides, T. intermedia Cheel, T. molesta N.T. Burbidge and T. spicata N.T.Burbidge] were recorded as resprouting at all sites. Another seven species were recorded at one site only. There was no clear overall trend for fire-killed populations to be more prevalent in south rather than north, or east vs west, or coastal vs inland parts of the continent. No clear relationships were found between regeneration strategy and site attributes. Considered as a group, resprouting species were more likely to have an open growth form than a dense growth form, whereas the opposite was true for fire-killed species. Given that no trait either of species or of landscape was found to be a consistent correlate of resprouting, a likely inference is that resprouting might vary between different fires, even for a given population at a given site. Against this inference, fire-killed populations had substantial densities of seedlings much more often. Longitudinal studies would be needed to demonstrate directly whether resprouting varied between different fires at a site, and to investigate the implications of this for maintenance or extinction of local populations.

Harvesting as an Alternative to Burning for Managing Spinifex Grasslands in Australia

“…Therefore, we examined how harvesting, compared to burning, impacts on the regeneration of spinifex grasslands in north-west Queensland. Spinifex grasslands in northern Australia, including the study region, receive reliable monsoon rains in summer, resulting in shorter fire-return intervals than grasslands in central/southern regions that receive less reliable winter rains [15,16]. While spinifex can regenerate from seeds and burned hummock bases, other species within spinifex dominated ecosystems are not fire dependent (i.e., fire is not required for regeneration) which includes grasses (e.g., Aristida spp.)…”

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

“…Processes in addition to fire must therefore influence spinifex re-establishment and subsequently the rate at which C. atlas populations increase after fire. Candidate processes include the rate of re-sprouting (Rice and Westoby 1999), possible interactions with grazing (Cohn and Bradstock 2000;Legge et al 2008) and the influence of fire frequency on plant survival (Bradstock et al 1998;Regan et al 2003). Conceivably a state and transition model like that proposed for small mammals in the Australian arid zone (Letnic et al 2004) may be a more useful concept than succession for describing changes in abundance of species that depend on a flammable habitat component (Fig.…”

Evidence for the equal resilience of Triodia spp. (Poaceae), from different functional groups, to frequent fire dating back to the late Pleistocene

“…Taxa within Triodia provide ideal model species because they are reliant on fire for reproduction (Burbidge, 1943;Noble, 1989;Rice and Westoby, 1999) and encompass several functional groups, including obligate seeders (Casson and Fox, 1987), facultative resprouters and obligate resprouters (Wells, 1999). As with other species of obligate seeders, the resilience of obligate seeding Triodia spp.…”

“…As with other species of obligate seeders, the resilience of obligate seeding Triodia spp. to short fire return intervals, as occurs in northern Australia, has been questioned (Rice and Westoby, 1999). However, as with all other predictions regarding the resilience of particular functional groups to particular fire regimes, the evidence is based on short-term observations.…”