Living With the Bush

 IF THE relaxation of planning controls over removing vegetation goes too far in developed areas, this could lead to problems for fire protection.

In typical residential areas, most trees are within 10 metres of a dwelling - the zone proposed for relaxing controls. If a significant proportion of these trees were removed in places like the Dandenongs, there could be a significant increase in wind speed.

Wind is critical to fire behaviour, particularly in catastrophic conditions, when atmospheric conditions become more important than fuels.

Bushfire risk in developed areas is not high except in catastrophic conditions, so the benefits of removing trees is therefore not great. But the risk of increasing the wind speed, and hence fire intensity, in catastrophic conditions is higher than in rural areas (because a higher proportion of trees are within 10 metres of a dwelling).

Instead of a blanket exemption, a safeguard could be to allow trees to be removed where council officers give written approval based on fire protection. Otherwise, there may be excessive clearing out of fear, ignorance or the motivation to improve views.

Urban dwellers need to focus on measures such as preventing ember attack rather than a misplaced reliance on removing trees.

In rural areas, tree planting for windbreaks could even reduce fire intensity.

Dr Graeme Lorimer, environmental scientist, Bayswater North

The Age, Letter to the Editor, 24 August, 2009