Persistence of obligate-seeding species at the population scale: effects of fire intensity, fire patchiness and long fire-free intervals
Mark K. J. Ooi A B C , Robert J. Whelan A and Tony D. Auld BA Institute for Conservation Biology, School of Biological Sciences, University of Wollongong, NSW 2522, Australia.
B Biodiversity Conservation Science Section, Department of Environment and Conservation (NSW), PO Box 1967, Hurstville, NSW 2220, Australia.
C Corresponding author. Email: mark.ooi@environment.nsw.gov.au
International Journal of Wildland Fire 15(2) 261-269 https://doi.org/10.1071/WF05024
Submitted: 23 March 2005 Accepted: 15 February 2006 Published: 31 May 2006
Abstract
Understanding how a species persists under a particular fire regime requires knowledge of the response to fire of individual plants. However, categorising the fire response of a species solely based on known responses of individual plants can be misleading when predicting a population response. In the present study, we sought to determine the fire responses of several Leucopogon species at the population level, including the threatened L. exolasius. We found that, whilst all species studied were obligate seeders, the population responses of species to fire were dependent upon fire intensity and patchiness. Results showed first that low intensity fires were significantly patchier than higher intensity fires. Second, the proportion of plants killed within a population decreased with increased fire patchiness. We also assessed how populations were structured and found that stands were multi-aged at most sites, and did not have a single-aged structure, which is often assumed for obligate seeders. Both spatial complexity within the fire regime leading to adult plant persistence, and inter-fire recruitment, contributed to the multi-aged structure. It is possible that these Leucopogon species are gap recruiters, and may tolerate fire rather than be specifically adapted to it. Inter-fire recruitment may enable L. exolasius populations to persist for a much longer fire-free period than many other species in the region.
Additional keywords: Epacridaceae; Ericaceae; Leucopogon; rarity; soil seed bank; south-eastern Australia; threatened species.
Auld TD (1987) Population dynamics of the shrub Acacia suaveolens (Sm.) Willd.: survivorship throughout the life cycle, a synthesis. Australian Journal of Ecology 12, 139–151.
Bell TL, Pate JS , Dixon KW (1996) Relationships between fire response, morphology, root anatomy and starch distribution in south-west Australian Epacridaceae. Annals of Botany 77, 357–364.
| Crossref | GoogleScholarGoogle Scholar |
Bradstock RA , O’Connell MA (1988) Demography of woody plants in relation to fire: Banksia ericifolia L.f. and Petrophile pulchella (Schrad) R.Br. Australian Journal of Ecology 13, 505–518.
Cheney NP (1990) Quantifying bushfires. Mathematical and Computer Modelling 13, 9–15.
| Crossref | GoogleScholarGoogle Scholar |
Clarke PJ (2002) Habitat insularity and fire response traits: evidence from a sclerophyll archipelago. Oecologia 132, 582–591.
| Crossref | GoogleScholarGoogle Scholar |
Hobbs RJ , Atkins L (1988) Spatial variability of experimental fires in south-west Western Australia. Australian Journal of Ecology 13, 295–299.
Keeley JE (1987) Role of fire in seed germination of woody taxa in California chaparral. Ecology 68, 434–443.
| Crossref |
Kron KA, Judd WS, Stevens PF, Crayn DM, Anderberg AA, Gadek PA, Quinn CJ , Luteyn JL (2002) Phylogenetic classification of Ericaceae: molecular and morphological evidence. Botanical Review 68, 335–423.
Lamont BB, le Maitre DC, Cowling RM , Enright NJ (1991) Canopy seed storage in woody plants. Botanical Review 57, 277–317.
Stern H, de Hoedt G , Ernst J (2000) Objective classification of Australian climates. Australian Meteorological Magazine 49, 87–96.
Whelan RJ, de Jong N , von der Burg S (1998) Variation in bradyspory and seedling recruitment without fire among populations of Banksia serrata (Proteaceae). Australian Journal of Ecology 23, 121–128.
Williams JE, Whelan RJ , Gill AM (1994) Fire and environmental heterogeneity in southern temperate forest ecosystems: implications for management. Australian Journal of Botany 42, 125–137.
| Crossref | GoogleScholarGoogle Scholar |