Abstract
Very high-severity fires are a component of many fire-prone ecosystems, yet are often viewed as detrimental to vegetation. However, species in such systems are likely to have adapted to persist under a fire regime that includes high-severity fires. We examined how fire severity affects post-fire recruitment and residual seed banks of Acacia species and whether severity may affect plant responses to fire intervals. Nine sites of either high or low burn severity were identified after a large-scale mixed-severity fire in Warrumbungle National Park, south-eastern Australia. Transects were used to sample above-ground woody plant density. Seed bank size was surveyed by soil extraction from two depths and manual searching for seeds. Residual soil seed bank and recruitment were compared across the two burn severities. Acacia seedling density was higher in areas burnt at high severity, indicating that increased severity triggers increased germination from the seed bank. Size of residual seed bank was smaller after high-severity fire, but varied between species, with few Acacia cheelii seeds remaining despite high above-ground abundance. In contrast, A. penninervis retained a small residual seed bank. There was little evidence of negative effects on populations of Acacia species after high-severity burns. However, we found that high fire severity may impact on the ability of a species to persist in response to a subsequent short fire interval. Fire management for maintaining biodiversity needs to consider other key aspects of the fire regime, including severity and season, rather than focusing solely on fire frequency.
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References
Abu-Hamdeh NH, Reeder RC (2000) Soil thermal conductivity effects of density, moisture, salt concentration, and organic matter. Soil Sci Soc Am J 64:1285
Auld TD, Denham AJ (2005) A technique to estimate the pre-fire depth of burial of Grevillea seeds using seedlings after fire. Aust J Bot 53:401–405
Auld TD, Denham AJ (2006) How much seed remains in the soil after a fire? Plant Ecol 187:15–24
Auld TD, O’Connell MA (1991) Predicting patterns of post-fire germination in 35 eastern Australian Fabaceae. Aust J Ecol 16:53–70
Auld TD, Keith DA, Bradstock RA (2000) Patterns in longevity of soil seedbanks in fire-prone communities of south-eastern Australia. Aust J Bot 48:539–548
Auld TD, Denham AJ, Turner K (2007) Dispersal and recruitment dynamics in the fleshy-fruited Persoonia lanceolata (Proteaceae). J Veg Sci 18:903–910
Bond WJ, van Wilgen BW (1996) Fire and plants. Chapman and Hall, London
Bond WJ, Honig M, Maze KE (1999) Seed size and seedling emergence: an allometric relationship and some ecological implications. Oecologia 120:132–136
Bowman DMJS, MacDermott HJ, Nichols SC, Murphy BP (2014a) A grass-fire cycle eliminates an obligate-seeding tree in a tropical savanna. Ecol Evol 4:4185–4194
Bowman DMJS, Murphy BP, Neyland DLJ, Williamson GJ, Prior LD (2014b) Abrupt fire regime change may cause landscape-wide loss of mature obligate seeder forests. Glob Change Biol 20:1008–1015
Bradstock RA, Auld TD (1995) Soil temperatures during experimental bushfires in relation to fire intensity: consequences for legume germination and fire management in south-eastern Australia. J Appl Ecol 32:76–84
Bradstock RA, Auld TD, Ellis MV, Cohn JS (1992) Soil temperatures during bushfires in semi-arid, mallee shrublands. Aust J Ecol 17:433–440
Chafer CJ, Noonan M, Macnaught E (2004) The post-fire measurement of fire severity and intensity in the Christmas 2001 Sydney wildfires. Int J Wildland Fire 13:227–240
Cohn JS, Lunt ID, Ross KA, Bradstock RA (2011) How do slow-growing, fire-sensitive conifers survive in flammable eucalypt woodlands? J Veg Sci 22:425–435
DECC (2002) NSW Flora fire response database Version 1.3. NSW Department of Environment and Climate Change, Hurstville
DellaSala DA, Lindenmayer DB, Hanson CT, Furnish J (2015) In the aftermath of fire: logging and related actions degrade mixed- and high-severity burn areas. In: DellaSala DA, Hanson CT (eds) The ecological importance of mixed-severity fires. Elsevier, Amsterdam, pp 313–347
Denham AJ, Vincent BE, Clarke PJ, Auld TD (2016) Responses of tree species to a severe fire indicate major structural change to Eucalyptus-Callitris forests. Plant Ecol 217:617–629
Enright NJ, Fontaine JB, Bowman DMJS, Bradstock RA, Williams RJ (2015) Interval squeeze: altered fire regimes and demographic responses interact to threaten woody species persistence as climate changes. Front Ecol Environ 13:265–272
Fairman TA, Nitschke CR, Bennett LT (2016) Too much, too soon? A review of the effects of increasing wildfire frequency on tree mortality and regeneration in temperate eucalypt forests. Int J Wildland Fire 25:831–848
Fenner M, Thompson K (2005) The ecology of seeds. CAB International, Wallingford
Gibson MR, Richardson DM, Marchante E et al (2011) Reproductive biology of Australian acacias: important mediator of invasiveness? Divers Distrib 17:911–933
Gordon CE, Price OF, Tasker EM, Denham AJ (2017) Acacia shrubs respond positively to high severity wildfire: implications for conservation and fuel hazard management. Sci Total Environ 575:858–868
Hanley ME, Unna JE, Darvill B (2003) Seed size and germination response: a relationship for fire-following plant species exposed to thermal shock. Oecologia 134:18–22
Herranz JM, Ferrandis P, Martinez-Sanchez JJ (1998) Influence of heat on seed germination of seven Mediterranean Leguminosae species. Plant Ecol 136:95–103
Hunter JT (2008) Vegetation and floristics of Warrumbungle National Park. Report to NSW National Parks and Wildlife Service, Coonabarabran
Jeffery DJ, Holmes PM, Rebelo AG (1988) Effects of dry heat on seed germination in selected indigenous and alien legume species in South Africa. S Afr J Bot 54:28–34
Keeley JE (2009) Fire intensity, fire severity and burn severity: a brief review and suggested usage. Int J Wildland Fire 18:116–126
Keeley JE, Meyers A (1985) Effect of heat on seed germination of southwestern Yucca species. Southwestern Nat 30:303–304
Keith DA (1996) Fire-driven extinction of plant populations: a synthesis of theory and review of evidence from Australian vegetation. P Linn Soc NSW 116:37–78
Keith DA (2004) Ocean shores to desert dunes: the native vegetation of New South Wales. Department of Environment and Conservation (NSW), Hurstville
Knox KJE, Morrison DA (2005) Effects of inter-fire intervals on the reproductive output of resprouters and obligate seeders in the Proteaceae. Austral Ecol 30:407–413
Liyanage GS, Ooi MKJ (2015) Intra-population level variation in thresholds for physical dormancy-breaking temperature. Ann Bot Lond 116:123–131
Liyanage GS, Ooi MKJ (2018) Seed size-mediated dormancy thresholds: a case for the selective pressure of fire on physically dormant species. Biol J Linn Soc 123:135–143
Mackenzie BDE, Auld TD, Keith DA, Hui FKC, Ooi MKJ (2016) The effect of seasonal ambient temperatures on fire-stimulated germination of species with physiological dormancy: a case study using Boronia (Rutaceae). PLoS ONE 11:e0156142
Merritt DJ, Turner SR, Clarke S, Dixon KW (2007) Seed dormancy and germination stimulation syndromes for Australian temperate species. Aust J Bot 55:336–344
Mondal NS, Sukumar R (2014) Fire and soil temperatures during controlled burns in seasonally dry tropical forests of southern India. Curr Sci India 107:1590–1594
Moreno JM, Oechel WC (1991) Fire intensity effects on germination of shrubs and herbs in southern California chaparral. Ecology 72:1993–2004
Morrison DA, Auld TD, Rish S, Porter C, McClay K (1992) Patterns of testa-imposed seed dormancy in native Australian legumes. Ann Bot Lond 70:157–163
Odion DC, Davis FW (2000) Fire, soil heating, and the formation of vegetation patterns in chaparral. Ecol Monogr 70:149–169
Ooi MJK (2007) Dormancy classification and potential dormancy-breaking cues for shrub species from fire-prone south-eastern Australia. In: Adkins SA, Ashmore SE, Navie SC (eds) Seeds: biology, development and ecology. CAB International, New York, pp 205–216
Ooi MKJ (2010) Delayed emergence and post-fire recruitment success: effects of seasonal germination, fire season and dormancy type. Aust J Bot 58:248–256
Ooi MKJ, Auld TD, Whelan RJ (2007) Distinguishing between persistence and dormancy in soil seed banks of three shrub species from fire-prone southeastern Australia. J Veg Sci 18:405–412
Ooi MKJ, Denham AJ, Santana VM, Auld TD (2014) Temperature thresholds of physically dormant seeds and plant functional response to fire: variation among species and relative impact of climate change. Ecol Evol 4:656–671
Penman TD, Towerton AL (2008) Soil temperatures during autumn prescribed burning: implications for the germination of fire responsive species? Int J Wildland Fire 17:572–578
Stoof CR, De Kort A, Bishop TFA, Moore D, Wesseling JG, Ritsema CJ (2011) How rock fragments and moisture affect soil temperatures during fire. Soil Sci Soc Am J 75:1133–1143
Storey M, Price O, Tasker E (2016) The role of weather, past fire and topography in crown fire occurrence in eastern Australia. Int J Wildland Fire 25:1048–1060
Thaxton JM, Platt WJ (2006) Small-scale fuel variation alters fire intensity and shrub abundance in a pine savanna. Ecology 87:1331–1337
Tozer MG (1998) Distribution of the soil seedbank and influence of fire on seedling emergence in Acacia saligna growing on the central coast of New South Wales. Aust J Bot 46:743–755
Van Wijk WR (1963) Physics of plant environment. North-Holland Publishing Company, Amsterdam
Vivian LM, Cary GJ, Bradstock RA, Gill AM (2008) Influence of fire severity on the regeneration, recruitment and distribution of eucalypts in the Cotter River Catchment, Australian Capital Territory. Austral Ecol 33:55–67
Whelan RJ (1995) The ecology of fire. Cambridge University Press, Cambridge
Wright BR, Latz PK, Zuur AF (2016) Fire severity mediates seedling recruitment patterns in slender mulga (Acacia aptaneura), a fire-sensitive Australian desert shrub with heat-stimulated germination. Plant Ecol 217:789–800
Acknowledgements
We thank Martin Henery and Justin Collette for field assistance, Lisa Metcalfe for laboratory assistance, Craig Wall and the National Parks and Wildlife Service Coonabarabran office for permission to work in Warrumbungle NP and Jessica Meade for assistance with drafting figures. The project was supported by funding from the NSW Office of Environment and Heritage, and as part of the Australian Government’s National Environmental Science Programme (NESP), Threatened Species Recovery Hub (1.3).
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Communicated by Stephen Brewer.
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Palmer, H.D., Denham, A.J. & Ooi, M.K.J. Fire severity drives variation in post-fire recruitment and residual seed bank size of Acacia species. Plant Ecol 219, 527–537 (2018). https://doi.org/10.1007/s11258-018-0815-5
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DOI: https://doi.org/10.1007/s11258-018-0815-5