"Despite being portrayed as a villain, timber harvesting in the form of thinning can substantially counteract the impact of fire regrowth on water yield. The benefits of regrowth thinning have been widely studied throughout Australia. In Melbourne's catchments, strip-thinning trials have shown that up to 2.5 million litres a year of additional run-off can be generated from each hectare of thinned regrowth. A program of thinning the 1939 regrowth could add billions of litres of water to our storages.
Western Australia has been quicker to take advantage of thinning as a water management tool. Earlier this year, a $20 million, 12-year thinning program was initiated in a substantial segment of Perth's catchment following four years of exhaustive public and stakeholder consultation. Every 1,000 hectares thinned is expected to deliver an additional one billion litres of run-off into the Wungong Dam a year."
This is an extract from an opinion piece by Mark Poynter first published in The Age and just republished by On Line Opinion, entitled 'Fired-up Forests, Have More Impact Than the Loggers'. Read the full article here: http://www.onlineopinion.com.au/view.asp?article=5213
The Archers et al of this world have long criticised the supposed "fragmentation" of private native forest and the implications for biodiversity. But this view has always been based on an intellectually sloppy use of native vegetation as a surrogate for habitat.
In the real world, most species derive habitat services from a whole range of landscape attributes that do not get mapped as native vegetation. How many orchards, for example, are mapped as habitat for flying foxes? The answer, none, but we know that orchards have played a critical role in the expansion of flying foxes into areas well beyond their historical range with resulting population increases.
The recent large scale wild fires, with numerous examples of localised "extinctions" in the continguous national parks estate is now making it very clear that the supposed fragmentation of the private native forest estate is actually the key to the long term viability of many forest dependent species.
In short, nothing stops a forest fire like an absence of forest. And the numerous gaps in native vegetation that have been assumed by many to be impacting on lifecycles and colony viability have actually been critical in excluding habitat destroying fire.
And far from being cooped up in small, unviable habitat clusters, the resident species have never been reluctant to include crops, orchards, barns and widely spaced paddock trees in their home ranges.
It seems the best thing one could do to maximise the ecological value and durability of a large forest area would be to put a golf course smack in the middle of it.
Centralised production has never worked. So why would anyone believe that centralised ecology would be any better?
Dear Jennifer, I have enjoyed reading Mark's articles at On Line Opinion and agree with much of what he says but he must check his facts re thinning in Perth water supply catchments. The Wungong catchment is only 3.8% (THREE POINT EIGHT PERCENT) of the area of Perth catchments. So it is incorrect to say, "Western Australia has been quick to take advantage.."
This thinning is only a tiny TRIAL, just a PR effort so the WA Govt water orgs can trumpet that they are doing something and most of what they say has to have spin "fine tooth combed" out before truth emerges.
The reality of what is happening in Perth water supply catchments can be seen in my graphic at http://au.geocities.com/perth_water/ scroll down to, "Graphic of Catchment Efficiency 1980-2005 showing disastrous falloff 1996-2005 after ceasing catchment management." Click on thumbnail for a larger graphic.
It is perfectly clear from my graphic that the WA Govt is de facto decommissioning Perth catchments. If catchments had been managed post 1996 as they were before that date so as to keep yields steady, Perth would have enjoyed about 90 GL extra water per year on average. Equal to production from two Kwinana sized seawater desalination plants, which require an investment of ~$500 million each now. That puts on scale the cost of catchment neglect.
This colossal bungling extends into other areas of water resources.
North of Perth a pine plantation at Gnangara suppresses the potential of the
groundwater there by about 100 GL per year. With incremental water valued by investment required in seawater desalination, Govt claims that the pines are needed to support a proposed plywood industry is simply ludicrous. Timber can easily be sourced on the open market if anyone is of a mind to make plywood and the pines must have a negative net present value now in view of their manifest Billion dollar damage to groundwater potential.
The Avon, Murray and Collie Rivers pass about TWICE Perth's total water
consumption each year but in a weakly saline state. Surely desalination of a
small part of these flows would be cheaper and lower impact than seawater desal and could take place away from the fragile and crowded coast. In fact a private company, Agritech has been valiantly trying to interest the Govt. in a proposal to desalinate water currently wasted to sea each year from the Wellington dam near Collie. This proposal would be at no capital cost to Govt and would produce water at half Govt desal costs and would I am told use gravity in the process thus cutting back greatly on electricity.
Perth is not running out of water, the water is running out of Perth.
The Ancient Romans were vastly better water managers than the WA Govt.
“And when you can find an entire region that has undergone a simultaneous thinning event on a scale that is capable of influencing rainfall patterns then by all means give us a call” is a key statement from Ian.
It’s my guess we can’t find any sizable area on crown land today where managed thinning is occurring at a scale that will prevent major bushfires either. The most significant threat to our native forest ecology is the extent of severe bushfire damage today. Obtaining the maximum biomass again in our remaining bush reserves will be a tricky business from here on.
I proposed that we look first at forest management of our remote water catchments for major city supply infrastructure as a stepping stone to finding timber again in other reserves including national parks. The idea came after the acute case in the ACT (2003 bushfires) where we lost most of our pine plantations and much of our water supply.
From the subsequent McLeod inquiry we gained the concept of a Bushfire Abatement Zone (BAZ) and that all but eliminated our commercial forestry east of the Murrumbidgee River. Further studies revealed a conflict of interest in our recovery upstream from the old Cotter Dam. After that came the Namadgi National Park Draft Management Plan.
I’ve been saying; hey, what about access to our natural resources ever since. The irony is I only wanted to eliminate volatile pine tree crops right under our noses. Returning the bush to some form of hardwood forests it seems is the most difficult option in this parched country. Regarding our reaction to climate change; transition is difficult. Various principles get in the way as we blunder on.
But guess what happened, pines where they were hastily replanted after a previous bushfire and pines as wildlings are now doing better than anything else in this drought.
Eliminating pine has become another issue for the purists however I keep reminding them, our long term sustainability as a community has more to do with developing some resource independence and cunning.
In selecting the next dominant species we must go with the flow. By eliminating ground cover in the garden I’m making a good start to the current fire season.