Koala comments, suggestions and the catchment research priority

As the Forestry Corporation now takes second place with regard to koala management. My comments on the OE&H’s koala strategy focused mostly on its ideas about koalas. In particular the paper titled “Extinction in Eden, identifying the role of climate change in the decline of the koala in south-eastern NSW” (Lunney et al, 2014).

While not doubting climate change has recently had a major negative impact on koala habitat. I do doubt the notion that climate change has played the major role in koala decline, particularly in this bio-region.

The research Lunney et al quote in support of the climate change theory, Lawler et al ( 1996), found either increased CO2 levels or reduced nutrient availability led to ” . . . lower leaf nitrogen concentrations, higher leaf specific weights and higher levels of both total phenolics and condensed tannins” in Forest red gum leaves

Hence, changes to soils that lead to a permanent decrease in nutrient and/or water availability, will have a negative impact on koalas. The problem within the OE&H is a belief that soils have not changed and are fairly consistent throughout NSW. So Lunney et al infer, because trees grow well in paddocks around Gunnadah, there’s no reason why they won’t do the same in the Bega Valley.

So it was interesting to read, in the Bega District news, that koalas around Gunnadah, where the population has dropped 50% since 2008, have taken to ” . . . drinking extensively from custom-made watering stations, even in autumn and winter.” According to Valentina Mella, from Sydney University’s school of life and environmental sciences. “My thought is that the leaves they’re eating are not providing enough moisture … because with climate change the chemical composition of the leaf changes. The leaves become tougher, they become drier, they have less nutrients and they even have more toxins. In the past decade there have been a lot of heatwaves and prolonged droughts, which have killed a lot of koalas. They literally drop out of trees.”

What Lunney et al neglect to mention is that fact that all the koalas on former primary habitat in this bio-region dropped dead over 110 years ago. Linking this decline with climate change seems to be drawing a long bow.

cuttagee-pe

Bega Shire Council has released the final Rapid Catchment Assessment reports for the Cuttagee, Middle and Nelson lake catchments. They are comprehensive documents that make many sensible and practical recommendations to address degraded areas, mostly on private land.

On public land, as indicated in the map a Cuttagee catchment above, many locations, in this case around 200, where found to be potential sources of water pollution. In addition, significant areas of ‘head-cut’ and gully erosion were identified. The sediment yield from ‘head-cut’ erosion areas alone is estimated to be more than 1000 cubic metres in all three catchments. Many of these locations have never been subject to integrated logging, but were trashed before woodchipping began.

The consultants Elgin Associates Pty Ltd, provide the following description and recommended action for the Nelson catchment :

” Multiple examples of active head-cut that have formed deep incised gullies. Natural erosion process that shows examples of undercutting, lateral bank erosion and slumping due to highly erodible, sodic soils. These may have been exacerbated by historical logging operations and past fire events in the forest. Difficult to treat due to scale of problem and site access. Majority of the sediment fractions eroded from the head-cut and gullies have been re-deposited downstream and may not reach the estuary. However, a proportion of dispersible fraction of sediment fines has and will continue to be delivered to the estuary back lagoon under high flow events. Recommend a collaborative research project with a university to further investigate the significance of the process – spatially and temporally, and identify factors that may be exacerbating the process, and what potential actions could be undertaken to halt or slow down process.”

While I did some include some management suggestions with my comments on the koala strategy. The starting point requires the NPWS/OE&H to firstly acknowledge the issues and learn more about the land they manage, so they can do something positive, for a change.

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