Tree use by koalas (Phascolarctos cinereus) after fire in remnant coastal forest
Matthews, A, Lunney, D, Gresser, S & Maitz, W 2007, Wildlife Research, vol. 34, pp. 84-93.
Resource depletion as a result of wildfire has a short-term impact on koala populations in remnant forests. The present study revealed that koala populations at Port Stephens in New South Wales returned to utilising burnt trees shortly after intense wildfires that occurred in 1994, and some koalas were even observed using burnt trees exclusively. Furthermore, the authors noticed differences in the preferences and uses of tree species between the sexes, breeding and non-breeding females, day time and night time, as well as between seasons.
Wildfire is listed as one of the key threatening processes for koala populations under the New South Wales Threatened Species Conservation Act 1995 and the National Koala Conservation Strategy; therefore, learning how koalas re-colonise forests after fire is an important step for koala conservation. In this study, koalas were found using burnt trees extensively for feeding and shelter from as little as three months after fire. This finding was attributed to the high nutritional values of post-fire epicormic growth compared to mature foliage. Moreover, patches of unburnt trees surrounding fire-affected areas offered refuges for the koalas during fire and allowed the populations to thrive until burnt areas had recovered and could be re-colonised. The study also revealed that preferences for tree species and tree sizes were different between different sexes, breeding statuses of females, the time of day and seasons. These differences were consistent with the behavioural ecology of koalas reported in other studies. For instance, koalas are known to utilise trees of bigger crown size during day time as well as during the hotter summer days for shelter, while at night time they are more commonly found foraging in their preferred food trees such as Eucalyptus robusta.
Currently, the New South Wales environmental planning process for koala habitat protection only covers the preservation of food trees. These results demonstrate the limitations of existing management strategies and the need to protect habitat patches with a variety of different tree species and sizes to ensure all important koala habitat is conserved.
Summarised by Cherie Chan
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