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Bushfire 2016

To Rake or not to Rake? – study into the effectiveness of prescribed burn preparation around trees

To Rake or not to Rake? – study into the effectiveness of prescribed burn preparation around trees. 
As part of her honours project, Victoria Crepin of Griffith University, is investigating if the raking of leaf litter away from large trees protects them from increased temperatures and burning during controlled burns in dry sclerophyll forests in southeast Queensland. It is also investigating how different distances of raking effects the amount of heat the trunks are subject to during the burns.
For prescribed burn practitioners across Queensland this will have relevance as to the effectiveness of an already well-established industry practice of raking around trees to protect trees for different management purposes. This study may help verify industry standards to rake around trees and potentially specify specific conditions that do and do not require raking to different distances. Managers of prescribed burns can then use this information to help prepare controlled burns to meet different outcomes.

Image: Left An unraked tree that has caught alight during a controlled burn., Right A tree that was not raked far enough and caught alight during a controlled burn. Images by V Creplin 2018

The target trees are defined as above 40cm DBH, in dry sclerophyll forests across southeast Queensland. Victoria has been working with many prescribed burn practitioners across SE Queensland since January 2018 and will conclude her studies in October this year. 
So far we have observed that there has been a clear temperature and scorch mark difference between raked and unraked trees. Raked trees often do not even reach 50°C at the base of their trunks, where unraked trees have reached temperatures of 500°C. There has not been a significant difference in temperatures at trunks between 1 metre and 2 metre raking distances from trees.
If you have any questions about this research, please contact Victoria directly via email v.crepin27@gmail.com 

Image: One of the study sites during a prescribed burn. image by V Creplin 2018

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