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Save our verge trees!
Trees in gardens, parks and on verges play a vital role in a number of ways:
- shade and temperature reduction
- pollution filters
- natural air conditioning
- protect buildings & structures
- reduce winds
- increase property values
- provide fauna habitats
- stabilise soils
- calming ambience
- carbon sequestration
- healthier people
- safer streets (safer drivers)
And one of the biggest advantages of well managed trees in gardens is they reduce summer water use by lowering both air and soil temperatures, thus reducing the stress on the lower-level garden plants.
But with shrinking property sizes, larger buildings (and therefore more heat sinks), and a disgraceful reduction in Public Open Space area requirements in new developments, the problems are increasing. And not just in Perth - it's happening in most regional cities and some towns as well.
I am witnessing an increasing amount of conflict on our verges. There is no doubt that verge lawns waste a disproportionately huge amount of precious water, and there are rarely any sensible reasons for having one.
So while it is absolutely terrific that many people are converting their verge lawns to other uses (native ground-covers, etc), unfortunately this may be to the detriment of the verge trees. The photo above shows two Jacaranda trees that are suffering very badly after the verge lawn was no longer watered.
Why? The root system of any tree will develop and operate according to the conditions around it, particularly soil and water. So if that area is lawn that had previously been watered regularly, the root plate and feeder-root system would be quite shallow, and somewhat dependent on the management regime of the lawn.
Stop watering that lawn and trees may well go into decline, due to mass feeder-root death caused by moisture stress as well as nutritional deficiencies. Quite often, this decline can be mortal, especially considering the other climate change stresses trees are trying to put up with - higher temperatures, less winter rain, dryer subsoils and falling shallow water tables.
So good on you if you are killing off your verge lawn, but please consider the health and well-being of the street trees. There are two main actions you can take to ensure their healthy survival:
1. Arrange for a suitably qualified arborist to carry out a canopy thinning or even a canopy reduction. This will greatly reduce the tree's water requirements and take a lot of the work load off its root system.
2. Consider an alternative watering system to alleviate this stress. Even a good watering as little every five to ten weeks has been proven to make a huge difference in the health status of both street and park trees.
And it's even better if you can do both.
So let's all be 'treesonable' and actually value our trees as tremendous living assets, and be prepared to spend both time and some money to preserve them.
Cheers, Peter
You can check out more on his website:
http://www.petercoppin.com