Saturday, January 27, 2007

De-stocking trees to save forests in drought

The best thing one can do to a forest in drought is to conduct a partial harvest.

It is not widely understood that, unless the forest owner actually enjoys being ripped off blind, native forest harvesting is always a partial harvest. Most native forests are multi-aged and no farmer willingly sells a small tree for peanuts when it will be worth ten times more in 15 years.
So once the metropolitan brain can allocate sufficient attention to hold on to the fact that native forest harvesting is partial (selective) harvesting with healthy trees left evenly distributed over the site, it can then begin to grasp the ecological impact of this activity, especially in a drought.

There is nothing that does more to maintain the health and volume of stream flows in a drought than the removal of every second tree in part of the catchment. It means that the remaining stems get a much larger share of the remaining soil moisture and groundwater supplies. When this groundwater is moving slowly down a gentle slope it means that a much greater proportion of it makes it into the creek to maintain the quality of the waterholes.

The remaining trees capture a slightly higher portion of ground water due to lack of competition but it will take 10 to 15 years before they have grown sufficiently to capture the entire preharvest volume. And by then there will be more trees ready for harvest. In the mean time, soil moisture remains available for longer which enables the remaining trees to maintain leaf moisture content above the critical 65% digestibility threshhold for longer.

Below the 65% moisture level the trees switch to survival mode. They discard much of their leaf mass to the forest floor while releasing polyphenyls to make the remaining leaves both indigestible and nutritionally negative. Maintaining the leaf, sap, bud and seed based food chains is a luxury the trees cannot afford in drought.

And that means that not only the possum, koala and glider populations survive longer in a partially harvested forest but also the bugs, grubs etc that birds and other animals also feed on. Without this thinning, these species undergo a population collapse in the order of 90 to 95%. But as they die off, slowly and cruelly, they also gather in the few trees that have access to water and often completely defoliate them.

The beneficial effect of partial harvesting in drought is so significant that there is a strong case, continuity of supply issues aside, for scheduling most harvest operations to coincide with dry periods. This is especially so when the partial removal of canopy also increases ground cover and fodder reserves to both protect the soil and maintain minimal herd numbers and grassland species.

It is doubly important when one realises that the overwhelming number of adverse impacts that are normally associated with forestry operations, and which form the major part of Code of Practice prescriptions, are only present when operations are undertaken in wet conditions or at times when heavy downpours are likely soon after harvesting. And while it may take a torrential downpour to break a drought, they are nearly always preceded by smaller, less intense falls that restore ground cover and counteract the effects of harvest activities.

But don't hold your breath for the bimboscenti to grasp the notion that, just as the reduction of grazing stock is the best way to protect grassland ecosystems in drought, the reduction in tree stocks is the best way to protect forest and woodland ecosystems in the same conditions.

This summer a million hectares of Victorian forest has already been subject to broadscale clearfiring that has decimated habitat and wildlife populations on a charcter, scale, intensity and frequency that has never been matched by the most intensive land clearing. Yet, the urban public is still, apparently, capable of being persuaded that 10,000 hectares of partial harvesting, dispersed over more than 30 different sub-catchments, is an ecological impact that our forests cannot sustain.

That is the nature of the management contract the green movement has tricked Australians into signing. Instead of 1% harvesting disturbance on a 100 year rotation to cover the wages of those who look after the forests, the Greens have given us entirely preventable 100% wildfire disturbance for the second time since 2003. These wildfires can only cause the damage they have done because the people who actually know how to look after a forest are prevented from doing so. Instead of numerous small "cold" burns that help the forest and it's animal and human residents, the Greens have given us one big "hot" fire that destroys forest long before it has even recovered from the previous one.

When the Greens were given control of the forests they obtained a benefit by deception. They now want us to ignore the fact that these "stolen goods" are being destroyed and even seek the advice of the former custodians on how to protect their "ill-gotten gains". And it is time for the communities that looked after these forests so well for so many years to stop providing the critical help that enables the greens to avoid responsibility for their negligence. The greens can only maintain the facade of forest protection because rural communities protect the public form even worse harm.

There are no green volunteer bushfire brigades. It is all left to the farmers and forest workers who were, and still are, treated with contempt, to deal with the products of green neglect. And it is time to stop. It is time to restrict their contribution to protecting their own communities and let the arrogant greens reap what they have so liberally sown.

We need to send one simple but powerful message to the urban public.

If they really want to protect the forests then all they have to do is to give them back to the people who know how to.

Ian Mott



At May 02, 2010 11:21 am, Blogger Dixie said...

Right on the money!

See the Greens duck meaningful, engagement and the opportunity to fine tune environmental management on the smaller scales it needs....yet again, in the Report on the Senate Inquiry into the Native Vegetation and greenhouse abatement legislation released on Ap 30th.


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