Thursday, January 21, 2016

Canopy cover is only half the story

The accepted measure of urban forest in Australia (and most places) is percentage canopy cover. Councils in Australia have begun mapping their existing canopy cover to give themselves a baseline to measure future growth against.

But they need to go a step further. Because canopy increase alone isn't a sufficient measure of success.

Why not?

Because you also need to know if you're achieving the increase efficiently - ie getting the biggest percentage canopy increase for the lowest possible outlay.

In other words, getting the best bang for your buck.

There are two important ways Councils can make their urban forest spend more efficient:

1. Plant big trees instead of small ones
It costs the same to plant and maintain a large tree (eg Tuart, London Plane, Port Jackson Fig) as it does a small tree (eg Bottlebrush, Chinese Tallow, Ornamental Pear) yet the large tree provides much more canopy cover. Of course, sometimes you can't plant large trees because of overhead power lines or other constraints, but it's clearly a more efficient use of resources to do so where you can.

2. Improve tree mortality rates
There's not much hard data available in Perth but anecdotally it is suggested that mortality rates of young trees in Councils across the metropolitan area could be as high as 70 - 80%. This is clearly not efficient and represents an obvious area where gains can be made.


The first one takes courage. The courage to stand firm against the fearful who, to quote my old boss, "won't be happy unless we plant mosses and lichens".

The second one takes resources - more frequent watering and maintenance - but also LOVE. Yes, love. You've got to love trees, enjoy seeing them flourish and hate seeing them struggle. It has to keep you awake at night if you know they haven't been watered, if you know the lawnmower man is stripping the bark off them or a storm's coming and they haven't been staked and tied properly. This is us. If it's you too, email us. We want to work with you.

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