Another Reason Privet Has to Go – Increased Fire Risk

Congratulations to local “passionate” resident Pauline Collins and her efforts to remove the invasive privet tree within Thames town and the surrounding hills.  She deserves all the help we can give her, for the well-known reasons that privet crowds out native trees and also because of the significant adverse health impacts.


But there is another great reason to remove privet which has been overlooked.  Privet increases fire risk compared to many other tree and shrub species. 

We only need to look to the disastrous events unfolding near Nelson to appreciate the serious fire hazard dry highly flammable vegetation poses to communities.  And it was only a few years back that a fire in the Moanataiari Valley threatened nearby houses.  Back in early 2017, I wrote about the need to remove privet and other invasive species.

With climate change and more intense droughts already turbocharging wildfires in California, Australia, and most recently in Nelson, the planting of “green” firebreaks near houses and communities is being studied seriously.

Unfortunately, the invasive spread of privet has been documented as posing a much higher fire risk, especially in drought conditions.  A recent study in Alabama and Mississippi in the USA suggests that as privet spreads throughout forest lands the annual frequency of wildfires will approximately double within the next two decades.

Other studies have looked at the flammability of various New Zealand native species using a “plant barbecue”.


A more in-depth study looked at 60 native and exotic species ranking them for flammability.  Exotic gorse ranked highest followed by eucalyptus, rimu and silver beech.

Fire risk must be an additional weighting factor when Waikato Regional Council and Thames Coromandel Council ( and Civil Defence ) consider privet removal plans for Thames and other places where it is invading landscapes close to settlements. As we are learning from the Port Hills and Nelson fires, climate change and hotter drier drought seasons are a potent recipe for more intense dangerous fires.  Thames has large tracts of invasive gorse, privet, and pine close to the town and is highly vulnerable to this threat.

We would be crazy to ignore this threat to the town.