10 0417 294 778 A Touch of Grass Garden Care GARDEN CLEANUPS / REJUVENATION & MAKEOVERS A SPECIALTY We offer an experienced, professional and reliable service Call Jeremy on ... Est. Gold Coast since 2001 Let us create your new and rejuvenated garden where you can sit back, relax and enjoy your tranquil surroundings ... Specialising Garden Makeovers & Rejuvenation * Garden Care * Plant Selection * Soft Landscaping The terrible damage caused to trees, and by trees to homes, sheds, fences, roads, and the power network during the recent destructive Ex Cyclone Alfred reminds me of the long list of often complex reasons that may lead to tree failure. It’s a while since I’ve had cause to look up significant research that followed cyclones including Tracey in 1974, Winifred in 1986, and Yasi in 2011. Each of these studies has led to an important and growing information base. It is clear when viewing these reports that there is no single factor but there are known causes. Here are just a few, which I hope might lead readers to look up the report ‘An assessment of tree susceptibility and resistance to cyclones A study based on Severe Tropical Cyclone Yasi 2nd February 2011 Greening Australia and Ergon Energy” City of Townsville; Author Dr G. Calvert. The estate we live in had major tree losses, upwards of 20 beautiful trees that provided shade, and sheltered bird life. The soil is shallow and was saturated to the point of liquification after intense rainfall. The area had already been flooded several times this year before Alfred! The strength of the roots could not withstand the lateral (side to side) stress caused by the wind. Those that blew over had been planted during the development of the estate and were all planted as advanced trees. No trees that grew naturally on the estate blew over, although there were branch losses. Nearby street trees in confined spaces also blew over and it is likely these were also planted in advanced form. (Following Cyclone Winifred a notable difference was shown between cultivated and naturally grown trees. Oliver and Wilson 1986). Gardening The Yasi Research paper indicated compromised root systems were often the cause in those planted as advanced plants, as well as differing soil types. It advises the emphasis should be on several factors including planting small trees, loosening surrounding soil, and with no added backfilling. Our estate also had several snapped trunks on semi-mature trees. The Yasi report cites this failure occurs when wind loading exceeds the mechanical strength of the wood. Another factor that may contribute to branch loss is branch lopping that is not compliant with Australian Arborist Standards. This may result in regrowth with poor connections and attachments. I hope everyone remains safe as they go about the recovery. One thing is certain to me after the losses across the whole City of Gold Coast – we will always need trees. Please choose wisely and re-plant carefully. FOOTNOTE – The Botanic Gardens has sustained major damage and flooding and will be closed until all works are completed. by Kate Heffernan Honorary Life Member Friends of GCRBG Botanic Garden Consultant
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