Site Specific Biodiversity Conservation and Fire Management PBC Todd Dudley President NEBN
Impact of hot burn on understorey diversity Dee Why Headland NSW 1985 -2015 In 1984 first paid bush regeneration work was at Dee Why Headland : coastal vegetation. At the time the vegetation had not been burnt for over 50 years and was dominated by Melaleuca nodosa and Leptospermum laevigatum with only a few understorey species perhaps a dozen in total. In 1985 a fire suspected to be lit by youths burnt the bush. It was a hot fire. Afterwards over 120 species of plants regenerated. I visited the site in 2015 and it had reverted back to its pre fire condition of 1984. Implications drawn were that the seedbank can remain viable for extended periods of time between fires and that hot burns could have positive impacts for understorey diversity.
Restore Skyline Tier project using fire to restore pine plantations back to native forest. Next two slides 1. Mature Radiata Pine Plantation after harvesting and hot ecological burn 2. 7 years later. Biodiverse native forest regeneration including weeding of remaining pine wildlings and some direct seeding of local provenance Eucalypt species (E.sieberi, E.obliqua)
“Planned Burning in Tasmania” (2009) • From a conservation perspective there is a conflict between the regularity, intensity and scale of planned burns required to be effective for fire risk reduction and the conservation of biodiversity including understorey diversity. “Planned Burning in Tasmania” page 54 suggests that for example heathy dry eucalypt forests need to be burnt every 4-8 years in asset protection zones and 4-10 years in strategic management zones to be effective . In addition the scale of burning is of concern in our region ie 8,500ha Mount Pearson 5,000ha Avenue River etc. 60,000ha per year target for burning in Tasmania… Tasmanian Fuel Reduction Burn Unit • 15-30 years heathy forests/woodlands 20-40 years shrubby forests. fire intervals recommended in Tasmanian Bushcare Toolkit
IAN SAUER CHAIR OF THE STATE FIRE MANAGEMENT COUNCIL ABC COUNTRY HOUR 16 th September 2018 In relation to low intensity fuel reduction burning every 7-10 years: “ ecological values of the bush you burn will increase dramatically” In relation to farmers: “ if they want to value add that environmental side of the equation on that farm then the best way to do that is to be able to do fuel reduction burns that are fairly low intensity every 7 to 10 years ,patchwork quilt, and they will find values will increase significantly” GREG ESNOUF Fire consultant working with Tasmanian Fire Service ABC COUNTRY HOUR 24 th September 2018 “for most forest types cool burning and regular cool burning is right………”
UNDERSTOREY VALUES • hosts a great deal of biodiversity • stabilises soil • provides feeding, nesting and shelter habitat for many species • aesthetic beauty • part of our natural heritage • Intrinsic value/for its own sake.
Next slides 1. Diverse understorey in dry sclerophyll forest at Winifred Curtis Reserve Scamander about 10 years after high intensity wildfire. 2. and 3. Coastal heathland unburnt for 25 and 17 years respectively maintained by coastal sea spray and drainage factors north east Tasmania.
Penman 2008 impacts of cool burns on seed bank germination SE NSW “prescribed fires, carried out according to standard practices, in these forests are unlikely to trigger germination in the majority of the soil- stored seed banks. If ecological burns in these forests are aimed at promoting populations of senescing obligate seeder species, they need to be hotter than standard practice if they are to achieve their objectives, although we acknowledge that there are inherent risks associated with hotter burns”
Australian Vegetation 2017 (Edited by David A. Keith) Heathlands and Associated Shrublands , fire regimes that may threaten heathlands include “high frequency fires” and “low intensity, cool season or pre drought fires in the temperate zone that fail to initiate seedling recruitment”. Heathlands cover 1.5% of Australia’s land mass but contain 25% of plant species Dry Sclerophyll Forests “……..degraded by a range of other practices such as deliberate, high frequency (and low intensity) burning…………”
Jamie Kirkpatrick • Jamie Kirkpatrick: A Continent Transformed • p74 Cool burns do not encourage regeneration from seed thereby leading to gradual reduction of those species that do not propagate vegetatively Some bush peas and wattles may be particularly susceptible to elimination through repeated cool burns. These are the main species that fix nitrogen in Australian soils. Cool burns consume the understorey while failing to scorch the tall shrub and tree layers.. The taller plants are thus able to grab more root space and ground cover can be drastically reduced. The reduction of ground cover often leads to accelerated soil erosion." • Jamie Kirkpatrick: The Disappearing Heath Revisited • p111 "The classical "cold" burn adopted to reduce fire hazard while not harming trees will almost certainly prove inappropriate for heath management • p112 "In Tasmania there seems to be more evidence for the deleterious effects of extremely frequent firing than the deleterious effects of extremely infrequent firing
Next five slides 1. E.sieberi forest Mount Pearson State Reserve burnt in hot wildfire about 13 years ago and part of proposed 8,500ha fuel reduction burn for Mount Pearson area. Clearly not in need of another burn and showing symptoms of too many fires (ie bracken fern dominance of understorey) 2. E.sieberi forest with dense understorey of Philotheca virgata (obligate seeder) a relatively rare form of E. sieberi forest given limited distribution of Philotheca and overburning of E. sieberi which impacts adversely on obligate seeders. 3. E. amygdalina forest burnt too many times Humbug Point Nature Recreation Area leading to loss of understorey diversity replaced by mainly bracken fern and lomandra 4. E. amygdalina forest with diverse understorey. 5. Variation in Banksia marginata leaf shape in Tasmania. An example of local variation and adaption which requires closer examination, assessment and protection rather than a generic approach which disregards “common” or “adequately/well reserved communities”. I didn’t include the Banksia slide in my talk on the day but it’s a good example of biodiversity variation within a species as adaptions to locally particular conditions/circumstances.
Burial Point (Four Mile Creek) Fuel Reduction Burn 27 th May 2018 (Photo from October 2018)
Ironstone Point fuel reduction burn May 27 th 2018 (11 years after previous very hot wildfire) Tasmanian Fire Service (TFS) email “The unit was visited many times prior to burning, the assessment of environmental values was undertaken as part of these visits” . North East Bioregional Network “Could you provide evidence of the environmental assessments that were carried out ?” No response from TFS Leigh Walters Tasmanian Land Conservancy (TLC) “ The natural values have been impacted by fire to the extent that the property did not fit TLC guidelines for purchasing land with high ecological values”
Cool burning Cape Barren Island ABC News 15 th October 2017 “We’ve gone up to the Top End and learnt from the traditional burners up there how to “cool burn” properly so we can regenerate our land” said Trowunna (the Aboriginal name for Cape Barren Island) ranger Terry Maynard. J.Kirkpatrick The Disappearing Heath Revisited “…. frequent firing results in ………loss of species that rely on seedling regeneration. Such degradation of heath into sedgeland has been observed on Cape Barren Island and parts of the north east and west of Tasmania”
John Hunter : Fallacies, Complexities and Dangers of Fires in Themeda Grasslands (Restore, Regenerate, Revegetate Conference 2017 Armidale) Firesticks indigenous burning program NSW • Veg communities did not occur anywhere else • Could not have evolved under frequent fire/no evidence of regular burning • Fire would result in homogenisation and loss of landscape richness • Threatened species and obligate seeders would be eliminated by regular fire.
Cultural Burning Ian Thomas : The Holocene Archaeology and Palaeoecology of North Eastern Tasmania “It seems likely that the vegetation structure of the Surrey Hills could have been produced by relatively infrequent intense fires rather than the accepted notion of frequent low intensity bums. The important point to note is that firestick farming is not a formula to be applied uncritically over all of the state”
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