New South Wales Natural Resources Commission and Australian National University recently held a talkfest on so-called dieback. Unfortunately, the scientists mostly don’t understand that dieback is a natural response of healthy trees to acute stress. For example, healthy eucalypts may suffer drought scorch and regain full healthy crowns after drought-break. Source: Vic Jurskis
Chronically declining trees deteriorate further after drought-breaking rains because their roots are sick as a result of physical and chemical soil changes in the absence of frequent mild burning to recycle nutrients and maintain airy and sunny conditions. Traditional burning expert Victor Steffensen talks of upside-down country – thin on top and thick underneath, as well as sick trees with lazy roots on damp soils.
NRC has published the ‘short talks’ from their symposium:
https://vimeo.com/701461224?ref=em-share
Short Talks Part 2 on Vimeo
Here’s a brief summary of the ‘highlights’:
Talk 1. Professor Brack says we don’t know why ‘Monaro Dieback’ started. This is the third generation of chronic decline in Eucalyptus viminalis woodlands. Howitt (1891) identified that the first recorded mass death of E. viminalis (near Omeo) was a direct result of disruption of Aboriginal burning. Norton (1887) incorrectly attributed the same problem on the New England to introduction of cattle. The second and third waves on both the New England and Monaro Tablelands were primarily results of pasture improvement programs (Jurskis 2016).
Brack says we don’t know why it supposedly ended. Each wave ‘ended’ when most of the old trees in mismanaged stands died. Young trees generally aren’t affected by soil changes until vigorous root extension slows down (Jurskis 2005). Brack repeatedly drove through nearly 150 km of mostly chronically declining woodlands of other species between Canberra and Berridale, apparently without noticing, to study ‘Monaro Dieback’.
Talk 2. Leah Moore studied hydrogeological patterns instead of the obvious differences according to land management. There are fenceline contrasts across Australia, including the Monaro, showing that chronic decline is not caused by environmental or biotic factors.
Talk 3. Vanessa Tonet gave a different perspective of the same problem in Tasmania. The Midlands are littered with examples of dead and dying stands of E. viminalis where owners have excluded grazing to protect them and exacerbated the problem.
Talk 4. Jasmyn Lynch studied the same problem in different species at Canberra. She identified that wet seasons exacerbated the problem. This is happening right now in coastal forests because sick roots are unable to cope with waterlogging just as much as they’re unable to cope with drought.
Talk 5. Hannah Windley identified that lack of fire and high nitrate levels in soils are associated with chronic decline. This has been evident for half a century. I don’t think she made the connection with sick roots.
Talk 6. Nigel England’s provenance trials have little relevance to reversing chronic eucalypt decline.
Talk 7. Justin Black from NSW Forestry Corp made most of the salient points, evident from scientific observations, in a way that was apparently too subtle to get thru to the academic scientists. His project seems to be the only one testing a scientific and pragmatic solution to chronic eucalypt decline including so-called Bell Miner Associated Dieback.
Talk 8. I skipped Paul Rymer’s presentation on ‘assisted migration’ of trees.
Talk 9. If Victoria Perez-Martinez had started with careful “field observations” of “patterns of mortality”, her experimental approaches could surely have confirmed the connections between land management, soil conditions, tree health and contributing biotic factors such as weevils and wood grubs.
Talk 10. Cal Bryant’s presentation on ‘Borer Mediated Dieback’ in snow gum didn’t mention that it’s the same genus of woodgrub that was equally wrongly fingered for tuart decline in WA.
Talk 11. I skipped the bit about managing risk of dead trees in alpine resorts.
Talk 12. Professor Adrienne Nicotra’s wrap-up, beautifully, if unintentionally, highlighted the real problems with the unscientific newsearch of so-called eucalypt dieback. It ignores all the historic scientific observations and research that have indicated the solution to chronic eucalypt decline, pestilence, megafires and loss of biodiversity.
Nicotra correctly identified that dieback is an episodic natural phenomenon and incorrectly stated that climate change is accelerating the cycle. Even if climate change were accelerating the dieback cycle, it wouldn’t matter because healthy trees recover from acute drought stress as soon as flooding rains break the drought.
I think it ironic that Nicotra thanked an Aboriginal elder for his welcome to country and simultaneously endorsed the cop-outs that are being used to cover up the failures of Lock It Up and Let It Burn mismanagement under a wilderness mindset.
Professor Nicotra also embraced the cop-out that everything’s changed: “I think the takehome is these are all novel ecosystems always, they’re constantly changing”. She said it’s complicated and “it’s not just about the trees. It’s about the communities, it’s about the vegetation, it’s about all the interacting species and so the values aren’t just the trees and those values are really tightly tied to cultural heritage as well.”
I think it’s scary that our green bureaucracies and academia are wasting millions of taxpayers’ dollars on newsearch of problems that have long been solved by genuine scientific research which supports traditional Aboriginal and European Australian knowledge of the big picture.
Howitt, A.W. 1891 The eucalypts of Gippsland. Transactions of the Royal Society of Victoria II, 81-120.
Jurskis, V. 2005 Eucalypt decline in Australia, and a general concept of tree decline and dieback. Forest Ecology and Management 215, 1-20.
Jurskis, V. 2016 ‘Dieback’ (chronic decline) of Eucalyptus viminalis on the Monaro is not new, unique or difficult to explain. Australian Forestry 79, 1-4.
Norton, A. 1887 On the decadence of Australian forests”. Proceedings of the Royal Society of Queensland 1886 III, 15-22.
