Dieback science

In an article printed in the Narooma News last year (24 August) the OE&H’s koala recovery officer made the following claim about Kooraban NP in the Dignam’s Creek catchment –  “ . . . Conditions for these animals in the park have undoubtedly improved over the past 10 years, most likely as a result of improved wild dog control and careful management of fire. Mr Allen said the survey results would be a great guide for focussing the management of fire in and around the identified koala areas and also reminded everyone of the importance and the fragility of this population.”

Like their final  ‘Management Plan’  for Kooraban, Mr Allen neglects to mention Dieback Associated with Dry weather and Drought (DADD). The OE&H do this because acknowledging their failure to maintain and improve biodiversity would require changing their management and the licences they give Forests NSW, especially the so-called Environment Protection Licence.They would also have to challange FNSW’s bizarre ideas about DADD which they won’t do, because they want to co-operate and they have convinced themselves that forests ‘recover’.

As a consequence and because die-back is an issue in many forests around the world it is necessary to seek credible science on the issue. In western North America there is a similar problem in Aspen forests called Sudden Aspen Death (SAD).

Recent research on SAD titled “The roles of hydraulic and carbon stress in a widespread climate-induced forest die-back”  has found that rather than a previous theory about depletion of carbohydrate reserves, hydraulic failure in tree roots and branches is the major problem.

The long-term outcome is that forests subject to SAD do not really ‘recover’ because tree roots are subject to ‘cavitation’ that makes them more susceptible to future hydraulic failure. While SAD with DADD are both associated with low rainfall we can’t be certain if Eucalyptus are affected in the same way, but if they are conditions for koalas in Kooraban NP can only get worse.

Skull of an 'island koala' that the NSW Government translocated to unsuitable habitat around Numerella where it died, probably from starvation. Some of these koalas have survived by eating tree bark but, eventually they ringbark the trees and they die too.

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