Trees are an essential part of any healthy ecosystem, but in Australia a robust debate rages about whether to plant native or introduced species. With the assistance of Greening Australia, we planted thousands of trees at the original Rock Farm (see here). Our new property has a good mix of native and introduced deciduous trees, which provide an interesting comparison.
Whilst there is no question that some introduced species have become real problems, this doesn’t mean all introduced species are pests. Far from it.
The indigenous people of our area used fire to create grasslands and woodlands that attracted game. The landscape was managed, but the use of fire had created changes in the nature and types of trees that were abundant. The native deciduous trees died out, replaced by fire tolerant eucalyptus. Today it is only in Tasmania that the only native winter Deciduous Beech (Nothofagus gunnii) remains.
These woodlands provided tall straight trees such as the Red Box (eucalyptus polyanthemos) and Yellow Box (eucalyptus melliodora). These trees were highly valued by the early European settlers for their timber and the land was soon cleared, leaving small stands of less desirable timber such as Brittle Gum (eucalyptus mannifera) or Red Stringy Bark (eucalyptus macrorhuncha).
Our property was probably cleared not long after the first European settlers came through in the 1830’s. We have an old stone ruin that is well over 100 years old, and around it are some equally old English Elms (ulmus procera) and some fruit trees.
What is remarkable is looking at the ground around these Elms and comparing it to the open paddocks.
Within the leaf litter of the Elms trees, we see lush, green growing grass. As we move away from the trees, the soil dries out and the grass is dry and stunted. Lush grass like this is extremely unusual in our area this autumn which has been extremely dry.
This experience isn’t just our own. It is explained in an excellent book Broadscale Permaculture: The Mill Post Experience by David Watson. David explains that there is merit in planting both native species and introduced species. David’s property isn’t too far from the Rock Farm, and we found his book an inspirational study into how to employ permaculture principles on a larger scale.
Deciduous trees provide the following advantages over native eucalyptus:
- They help reduce the fire risk to a property
- They bring nutrients to the surface and make them accessible to the soil microbes
- They provide shade reducing evaporation
- They are delightfully cool to sit and work under on a hot day
The photos above show the green grass under the leaf fall of the Elm trees. They also show the double fenced tree lines between paddocks. We are extremely fortunate that the previous owners invested a lot of time and effort in establishing healthy wind-breaks of native and introduced deciduous trees along many of the fence-lines. This is an excellent foundation on which to build on.
The trees have now grown to form wonderful shelter breaks – as seen in this google-earth view below.
The only problem with the English Elm is that it produces suckers that can form impossibly dense thickets (mid right of google earth image above). Stock will keep the suckers in check, whilst they are little, but they can get out of hand. A better tree would be the Scotch Elm (ulmus glabra) which doesn’t grow from suckers.
We are fortunate that many trees on the Rock Farm are natives. These can be seen by the darker green colours in the lines of trees above. The native trees provide food and shelter for many native animals, and fill important roles in our environment. With many dozens of eastern rosellas living on the Rock Farm, I am confident we are providing a good balance of native trees for habitat for these beautiful birds. I also find natives such as wattles are particularly good at stabilising degraded or damaged soil, and I am actively encouraging their growth in gullies and other areas with bare soil.
The hard part is getting young trees established, and in my next post I will share some of the tree planting techniques we are trialing.
More information on David Watson’s experience can be found here: http://www.millpostmerino.com.au/product-page/millpost-a-broadscale-permaculture-farm-since-1979