The Nature Conservation Council's biennial 2-day Fire and Restoration conference was a fantastic opportunity to hear practitioners, scientists and agencies share their findings and the latest research on using fire to assist with restoration projects. With a Hazard Reduction Burn for the protection of community assets in preparation for one of our landcare sites at Coal Point, the conference was very relevant.
The Stansfield Reserve is a 5.5ha parcel that is bounded by residences, including land owned by the Progress Association. It has been overrun by a variety of weeds ranging from ground Asparagus fern to Olive and Privet. Manual removal and chemical treatment has been attempted in the past but the resources required to transition the vegetation back to a weed-free system were beyond the capacity of the landcare group. The Asset Protection burn has provided a unique opportunity to gain some environmental outcomes in a reserve that really was in the 'too hard basket'
How Stansfield Reserve got to the state it is in became clearer when one of the speakers Andy Barker, a Vegetation Ecologist, described the transition process of vegetation communities, from treeless ecosystems to forest and open forest to rainforest. He explained how different burning intervals determine what type of vegetation community is retained or changed. For example, a grassland with regular burning will remain a grassland, if burning doesn't happen taller tree species will enter the system. There is then a window where another burn will kill these 'new' species and retain the grassland, if a burn doesn't happen then these new arrivals will be big enough to survive a burn, continue to grow and reproduce, this is the fire resistance threshold. By excluding fire in the landscape this threshold is regularly passed and so we see a transition as new plants, often weeds start to dominate.
More food for thought when Tein McDonald, from the Australian Association of Bush Regenerators, described the impacts of 'mesic weed shift' upon native bushland. When fire exclusion is coupled with long term weed presence a degraded bushland state occurs because native seed and bud banks are depleted. Weeds such as Olives and Privets, because of their fleshy (mesic) leaves, increase the humidity and shade making bushland areas become incombustible and increasing the rate of decomposition which destroys the seed bank. Tein emphasised the aim of bush regeneration should be to reverse the 'mesic shift'. This altered species composition is common in areas that have not been burnt for a long time, at Stansfield Reserve, this means the Spotted Gum Open Forest plant community that should be flourishing is not.
The process of being able to use fire as a tool in the restoration tookbox is a very complicated one. Talks on the operational and planning logistics were enlightening. One exercise to conduct three hazard reduction burns and research on about 3ha at North Head, Sydney, to assist the recovery of the Eastern Suburbs Banksia Scrub, an Endangered Ecological Community required 18 months of extensive planning and multi agency collaboration. Agencies involved were NPWS, Police, Rural Fire Service, and included shutting down the whole North Head reserve for a day, having a ferry on hand in case evacuation of a school group at the Quarantine station was needed, planning in case the harbour had to be shut down for smoke or the nearby biogas facility exploded or smoke entered ventilation tunnels. The exercise cost $250,000. At the other end of the spectrum Hornsby Council's 1st ecological burn in a 3ha reserve bounded by residents cost $5000 plus the support of Rural Fire Service and took eight years of planning.
Why would you go through such protracted and extensive processes to attempt a burn? Because the outcomes are proving to be outstanding. At Hornsby the species have doubled and the risk to adjacent property diminished. The ongoing maintenance of the reserve will be possible by the very small bushcare group.
Other speakers talked of the process to maximise the gains from a burn. The importance of pre-burn preparation and post-burn followup was repeatedly emphasised.
The Hornsby scenario provided lots of ideas to incorporate into the local action at Coal Point. Their site had been undergoing a mesic shift as well so in preparation for the burn they undertook some weed control prior to the event to manipulate the fuel load on the site. A statement repeated at the conference was that pyro-diversity leads to biodiversity. Different plants respond differently to varying fire intensity.
The pattern of vegetation recovery after a fire was discussed with various categories of ‘responders’ now identified. There will be some species that decline, some will increase, some will be lost, new species may emerge, some will be seeding laggards, others resprouting laggards and some plants will be multitaskers. Identifying how different plants respond is important for assisting the recovery of the ecosystem after the fire as targeted weeding strategies can be put in place.
LMCC's Bushfire Management Officer, Craig Holland, has issued the Bush Fire Hazard Reduction Certificate for 2.56ha of land off Stansfield Close, it is valid till March 2018. Although the burn was muted to go ahead last year, and this year, the delay has provided an opportunity to undertake more preparation in order optimize the environmental benefits from the process and assist in the long term environmental recovery of 5.5ha of bushland assets.
The Progress Association is in the fortunate situation of having bush regeneration resources available through the Threatened Species project to undertake preparation activities such as treating the woody weeds before the fire and following up after the burn.
No comments:
Post a Comment