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Catchments

Following up on the condition of trees adjacent to the southern side of Cuttagee lake, it now appears that most if not all of the remaining Melaleucas have died. While a closer inspection is required, on this occasion some eucalyptus trees have also been affected.

As the factors leading to the death of these trees aren’t consistant with the known threat, overabundant and prolonged surface water. Another possibility is polluted groundwater.
Residents in the adjacent Murrah river catchment have known for many years that the groundwater is polluted. However, pollution that kills trees four years apart, in the same location is difficult to explain. Groundwater travels at a much slower rate that surface water. The Murray- Darling basin is a good example, where it takes some 2 million years for the groundwater to move from Queensland to South Australia.

Of course Cuttagee is quite different and a lot smaller than inland catchments. As indicated in the graphic from Council’s Rapid Catchment Assessment below, it is generally quite steep and short. The arrow is about 10 kilometers long and groundwater in these soils may travel only a ‘few centimeters a day, or even slower‘.

So rather than millions of years, a time frame of around 20 years is plausible, in the absence of other information.

As it turns out the first Melaleuca dieback, in May 2014, was exactly 16 years after rainfall that ended the first extensive dieback event in the Bio-region. The current tree deaths are 15 years after rainfall in February 2003, that punctuated the second extensive dieback event.

It is quite possible that groundwater was polluted with aluminium during these rainfall events, with subsequent negative impacts at the bottom of the catchment, in the longer term. It is also possible that the difference of one year reflects an increased ground water flow rate, due to ongoing soil dispersion and the associated reduction in soil Water Holding Capacity.

While it would be reassuring to know polluted groundwater isn’t and won’t be the cause of further environmental degradation. I expect the NSW government has no intention of restoring catchment management authorities.

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Following up my information request, back on December 22, the OE&H has actually provided a link  to a database (Access 2007-56Mb), with the most recent information from the koala surveys.  

I’m not sure if the link was just a one off thing, but if there’s anyone interested in looking at the data base and the link doesn’t work, drop me a line and I’ll pass on a copy.

While certainly no expert, the data base appears to have been put together from another larger database. So there is data, in the form of tables and queries, for the tablelands, Tantawanglo, Yurammie and Kooraban NP. Unfortunately the plots numbers have been changed since the first survey back in 2007-09. However, when the plot locations in the respective data sets are linked, they will provide the largest and probably only, data on tree growth on the far south coast.

In the interim, the chart below shows data from the two time periods including the number of plots, the active plots where koala fecal pellets were found and the percentage active plots. As indicated the percentage of active plots marginally increased during 2016-2017, although the total number of plots almost halved.

So one would have to be confident that an impression of increased habitat use, wasn’t due to an inappropriate interpretation of the data.  On the positive side it is possible that koala numbers haven’t reduced, within the 10,000 hectares allotted to them.

What may be reducing, again, are the Giant honey-myrtles, skirting the southern edge of Wapengo Lake in Cuttagee catchment. The first time this occurred was in 2014, when about half of the trees died. It will take a while to confirm or otherwise, but the remaining trees all looked decidely yellowish the other day. 

Dieback in this species is generally associated with prolonged periods of inundation, when the lake isn’t open to the ocean. While the lake wasn’t open during the first event or now, the water levels were quite low, as they are now. Perhaps there is another explanation.

As reported in the Bega District News, Wapengo lake oyster farmers Brian and Carol Orr were surprised to find a koala last week, hanging on to a oyster bag, in the lake. It seems likely that the young koala is the same animal sighted on the Bermagui- Tathra road back in September.

On this occasion Brian was going to let the koala loose, after it was brought back to shore. However, he rang WIRES and they suggested taking it to a vet for a check up. The vet found the animal was dehydrated and underweight and it was then taken to Potoroo Palace to recuperate.

The article quotes NPWS’s Chris Allen saying ” . . . It is probable that he had been pushed out by older males while trying to find his own territory.” Hence the animal is ” . . . to be released back to an area where he is less likely to be confronted with aggressive males. ”

Of course there is no evidence that the koala was confronted by any other koalas and a female koala is just as unlikely to welcome another koala in its home-range as male is.
The issue is whether the habitat in area proposed for the release is any better than the forest in Mimosa Rocks NP, where the koala has seemingly been for the past month.

The photo shows one of the views looking east from the Bermagui-Tathra road, into Mimosa Rocks NP, where the koala was first sighted. Along with a microwave oven, plastic bags etc, there are also broken bits asbestos cement sheeting and just next to this toxic rubbish a couple of dozen old truck tires. While these features may not reduce the quality of the habitat, it does say something about park management.

According to the results from the 2012-14 koala surveys, ” . . . it will be essential to ensure that the population does not experience any further loss and that provision is made for its expansion into apparently unoccupied but suitable habitat.”  The question is whether the NPWS, or anyone else, can tell what is suitable koala habitat, just by looking at it. This would seem to be an important consideration, because if all of the suitable habitat is occupied, releasing the koala could well be a death sentence.

While it isn’t ideal for the koala to remain at Potoroo Palace, a precautionary approach would be to radio track the animal, so it can be rescued again, should perceptions of suitable koala habitat prove incorrect.

Coupled with this uncertainty is the fact that local forests are starting to die due to a lack of rain. While 20mm has fallen this month, another 50-100mm is required to fully re hydrate the soils and avoid another extensive canopy die-back event.

Next Wednesday, 30 August, the Great Southern Forest steering group will present, to Bega Shire Council, its proposal to ending native forest logging. Coinciding with the end of the Regional Forest Agreements, ‘… The plan is to change management of public State Forests from timber extraction to climate stabilisation and carbon sequestration.”

The new management of State Forests is proposed to be based on adaptive management, in particular the approach outlined in ‘CLIMATE CHANGE AND FORESTS OF THE FUTURE: MANAGING IN THE FACE OF UNCERTAINTY’ (Millar et al, 2007)  

Of course public forest management under the RFA’s was intended to take an adaptive approach, ‘with an aim to reducing uncertainty over time via system monitoring.’ We can be fairly certain that such an approach is not consistent with the State government’s preferences.

Regrettably and like the proposed great koala national park on the north coast, there is no mention of die-back in the Great Southern Forest media brief. Nor is their reference to die-back in the groups document about carbon, perhaps due to a lack of system data.

On koalas the brief suggests ” . . . The unique Southern Koalas once roamed the region yet now only highly endangered small isolated colonies remain on the far south coast.19 The EPBC Act does not protect them in State Forests.20 Koalas prefer deep-rooted, tall specific eucalypts and logging compromises their ability to disperse and breed with other populations in the southern highlands, north-eastern Monaro and the far south coast.

Depending on one’s interpretation, the possibility that koalas have been translocated from Victoria to the Bega Shire, despite the expert advice, remains open.

Apart from the koala and a swamp wallaby passing by, an antechinus and the crimson rosellas in photo above, are the only creatures snapped drinking from the frying pan to date. The area, located at a higher elevation in the catchment, is arguably mostly devoid of life, apart from the trees.

Hearing news of the alleged illegal interstate waste dumping, aired on Four Corners last Monday, was a bit of a blast from the past. As it transpired the EPA’s director of waste management, Steve Beaman, was one of the first EPA employees I encountered back in the early 1990’s.

At the time the issue was logging in the Murrah catchment and concerns about the adequacy of what was then Forestry’s Environment Pollution Licence. One of the concerns was soil erosion and how the volume (tonnes) of soil lost after logging was being calculated.

Forestry relied on the broad map of geology, reproduced below, but a bit blurry. However the geology in the ellipse, where four compartments were being logged, wasn’t consistent with the map. After visiting the site and taking samples, Steve Beaman agreed the geology was not consistent with the leucogranite and sandstone indicated on the map.

However, Mr Beaman couldn’t say what sort of rocks they were because he had never seen them before. In one of these compartments, after the first large rainfall event, the majority of soil disappeared, leaving behind a course grained white quartz.

It was a couple of years after this that the EPA dropped the geology thing and allowed forestry to determine if soils were dispersible, rather than use the published soils data.
While one trusts the Independent Commission Against Corruption puts an end to the waste rort, the land degradation and pollution from logging is arguably just as corrupt. Two of the compartments, including the white one, were later put into Biamanga National Park.

Arguably the greatest advance in feral animal control over recent times has been the feral cat grooming trap or ‘felixer’. According the the information brochure “. . . Feral cats are the greatest threat to native wildlife in Australia. They have been implicated in at least 27 mammal extinctions across Australia and currently threaten more than 100 native species, including mammals, lizards and ground nesting birds. ”

To address this situation ” . . . The Ecological Horizons grooming trap uses sensors to detect the presence of a feral cat and sprays a lethal dose of toxic gel onto its fur from up to 4 metres away as it is walking past. The feral cat instinctively grooms the gel and in doing so ingests the lethal dose of the poison and dies.”

While looking forward to the deployment of these units at a bio-regional scale, the technology may have other useful applications. In particular closing a gate when a cat or fox is detected.
Such a device would enable one or more entrances in a fence to be kept open, for much of the time. Hence other species like kangaroos and wallabies could get into and out of fenced areas. The same applies to reintroduced species, should they breed up.

Coinciding with the National koala conference this weekend, the ABC has unearthed documents indicating logging prescriptions will be relaxed in NSW. So “… For koalas in north-east NSW, Forestry Corporation proposes a “reduced survey effort” and the dropping of a longstanding rule applying 20 metre buffers to “high-use” areas.” In reality this translates to – if we see a koala up a tree, we may not cut the tree down.

Several other constraints will also be relaxed to ensure unsustainable native forest logging can continue, until the trees run out. This outcome would not be so bad, if native forests and catchments weren’t declining across the state, but they are.

While forest decline is seemingly not directly on the agenda at the koala conference, there is one speaker talking about climate change. However, as Eleanor Stalenberg pointed out in her thesis ‘Nutritional ecology of the Mumbulla koala‘ – ” . . . human-induced climate change could have long-term negative effects on the suitability of leaves for koalas.”

In the short term, an increase in the number of very hot days is likely, along with a reduced availability of leaves with sufficient water and nutrient content. So it was interesting to read about research at Gunnedah, finding koalas are regularly coming down from the trees to drink water from artificial water stations.

According to the article, ” . . . Researchers think the koalas’ newfound thirst is because the leaves that used to keep them hydrated are drying out as Gunnedah gets hotter and drier. The leaves used to provide enough water for the koalas that they didn’t need to drink in addition. In fact, prior research suggests that koalas reject leaves with water contents less than 55 to 65 percent.”

The only issue is that the research was undertaken during winter. To me this suggests, if leaf water content is the main factor, other factors, rather than the weather, may be influencing its availability, as in these forests.

Tragically, getting NSW government agencies to acknowledge these issues is difficult, to say the least. So I was a little surprised to receive the flyer below, from Bega Valley Shire Council. I’m pretty confident that groups like the OE&H’s koala recovery team wouldn’t invite Professor Tim Flannery to attend one of its meetings.

Bega Valley Shire Council has recently released its ‘Understanding Our Place’ report, said to be “Phase 1 of Council’s adopted Community Engagement Strategy for the upcoming Bega Valley Community Strategic Plan 2040.” The report is based on a survey where 40.5% percent of respondents indicated the natural environment sets ‘our place’, apart from other places.

Closely following the report, Council called for the community’s feedback because ” . . New Coastal Management Programs (CMPs) are currently being developed for Wallaga Lake, Bermagui River, Merimbula and Back Lake, and Eden’s Lake Curalo.”

Although Council has previously requested feedback on the Bermagui catchment. On that occasion Council, its consultants and the OE&H were involved in the process  This time, consistent with previous recommendations, the UNSW Water Research Laboratory, part of the School of Civil and Environmental Engineering, is also involved and appears to be taking the lead role.

Among the project objectives is idea to “Identify all issues and pressures currently impacting, or with the potential to impact, Bermagui River and its catchment.” While there seems little doubt the major pressure in this and other catchments is eucalyptus die-back. Another objective is to “Describe all legislative instruments relevant to management of the Bermagui River study area.”

This is where things become uncertain as indicated in the OE&H map of the local area above. While the map purports to show ‘sensitive lands’, being predominantly endangered ecosystems, rainforests, river banks, lakes and wetlands.

Apart from the river banks, these areas are only identified on private land, rather than across tenures. Then there is the issue of the rainforest layer, given it remarkable similarity to the one employed for the Regional Forests Agreements, 20 years ago.

As I understand it, the latest round of federally funded koala surveys have been recording the presence of Bellminer colonies near plots.
Given current legislative instruments tend to exclude consideration of key threatening processes. I wonder whether the OE&H will be voluntarily passing on information about BMAD in the catchment/s.

It would be reassuring to know that all of the issues have been adequately identified.

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