Thursday, August 13, 2009

Hollow trees and Dropped Limbs

Rubbish - or Environmental Riches?
With the Cathedral Drive issue we are, once again, hearing the argument that hollow trees are “rubbish”, so might as well be cleared.
Wildlife - and those who value Australian fauna - don’t agree, of course. To them, trees only start to get valuable when they start forming hollows. The problem of tree removal is not one that can be simply solved by planting new ones. It will take them about 100 years to start forming hollows. Species can go extinct while they wait!
(Don’t let this put you off planting, of course.)
Big old Eucalyptus trees are often hollow. Despite this they have a lifespan of 300 to 500 years, and may stand for several hundred years more. There are still plenty of dead trees standing firm and tall in our paddocks, and showing a telltale ring around the trunk. They were probably killed by ringbarking around 1860.
As engineers explain to us, a pipe is almost as strong as a solid steel post.
Dropped limbs are part of the hollowing process. The stump of a dropped limb makes the best nest for all kinds of native birds and mammals.
As it drops, though, the limb isn’t so popular with humans! Most large species of Eucalypt are a dubious choice for suburbs, and have no place in any but the largest of gardens. And as plenty of drivers who use Cathedral Drive will verify, they can be dangerous when they hang over roads - especially roads where people want to drive at 100kph, so might not have time to avoid a dropped branch.
Not all Eucalypt species are widow-makers, however. If you want to plant a potentially big one near buildings or roads, you should choose one of the better-known timber species. The strength which makes them good for building also lets them keep their limbs on.
Many of Australia’s best-loved and most beautiful trees are Eucalypts of the limb-dropping kind. As the world grows ever more crowded, land use is needing to be more carefully planned. Let’s hope there’s space, in the planning, for lovely old gum trees.
(See the article posted 6 June last year for more on the value of hollows in trees.)

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