Shelterbelts do recover after fire

10 August 2019

On Saturday 3rd August, 35 landholders from the Western Port catchment and Bunyip fire affected area attended a workshop at Bunyip North focussing on post fire shelterbelt design, fire ecology and environmental weeds.

At the event, ecologist Gidja Walker, spoke about how plants respond to fire in the Australian context, what fire hazardous characteristics to avoid, and what characteristics to encourage. She also spoke about how to structure your shelterbelt to avoid the rapid movement of fire across your property.

The best orientation for your shelterbelt is east west orientation as the prevailing winds are usually northerly and have a tendency to swing around to the south west says Gidja. Avoid having shelterbelts running up a slope particularly on a drier northern slope but rather run across a slope and have gaps between them to impede the wicking effect from the fire. The structure of the shelterbelt vegetation is also critical.

Gidja recommends removing hanging bark and fine fuels in your shelterbelt prior to the fire season as these create fuses for fire the travel up the trunk to the canopy and cause fire spotting elsewhere once they are picked up by the wind and transported ahead of the fire front. Also create clumps of mid storey vegetation which can impede the movement of fire within the shelterbelt, other factors that determine how a fire spreads are wind, slope and aspect. Remember that fire travels faster uphill, faster through grassland than forest and there is a difference between fire intensity and severity, she said.

Some of the characteristics to avoid when designing your shelterbelt are summer dry annual winter growing grasses, high biomass of dead fine material, species with a high oil content or loose candling bark, dense woody weed understorey, even age stands that are starting to reach the end of their natural life (senescence) and plants that look sick (remove them).
On the plus side, characteristics to encourage are indigenous summer growing grasses, sheoaks and cherry ballart, long lived wattles such as Blackwoods, low growing ground cover and herbs, maintain moss and ground layer. Swamp gums have a relatively low oil content unlike some of the other eucalypt species and can be grown in a number of situations, she said.

Gidja also spoke about post fire rehabilitation of your shelterbelt and the process of weed prioritisation and alternative weed removal techniques. She recommends you minimise disturbance to your burnt area and monitor for regeneration and weeds. If weeds do start to emerge then non-chemical means of weed removal are best.

This event was organised by the Bunyip Fire Natural Environment Subcommittee which includes representatives from local Councils, the Port Phillip & Westernport CMA, Landcare, Melbourne Water, Victorian Farmers Federation and AgVic. The subcommittee meets fortnightly to ensure that fire affected landholders have access to relevant information and services to support the recovery from the March bushfire. The event was also supported by the Smart Farming for Western Port project, supported by the National Landcare Program.

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