Free a Tree
What is the 'Free a Tree' project?
The Campaign ran in June until 9 August 2019, and raised $7545.00 from 68 donors.
Check this page for updates on how the money is being spent and how the trees are progressing.
BackgroundThe Free a Tree project started in 2017 when volunteers realised that significant eucalyptus trees in the Black Hill Conservation Park's Ambers Gully grassy woodland site were dying due to the extra pressure put on them when weedy wild olive trees grew up around their base.
The project has two main aims:
- To protect the existing significant trees by killing the olives which surround the trees showing the greatest signs of stress. Literally, it is freeing a tree today so it is still alive tomorrow!
- To remove the olives scattered throughout the site which will reduce the seed source causing the problem and protect the biodiversity of the grassy woodland in the long term.
Tree health comparison.
How do the olives affect significant trees?
Significant trees at this site are a victim of their own success. As they grow in a grassy woodland environment they have the space to produce long horizontal branches which woodland birds love to perch on. The trees spread much further and wider in a grassy woodland than they do in a more closed forest environment where the trees grow tall and close together, with no room or light for branches to spread out. This is problematic as the same birds may have visited the nearby olive trees and eaten the fruit, sitting along the full length of the extra wide branches they then deposit beautifully fertilised olive seeds all around the base of the tree.
Over time the small olive seedlings become larger olive trees, which then compete with each other and the eucalyptus tree they are growing under for both water and nutrients. Soon the eucalypts become visibly stressed, losing leaf cover. Ultimately the olive trees win the battle for survival as they have no local natural predators.
Why is this a concern?
If the number of stressed and dying trees was small and the number of olives manageable then we would not be so concerned, however we are noticing that a large number of significant trees in the area are affected and there is a very real concern that a particularly dry summer could tip a large number of trees over the edge all at once. This would lead to too many large trees dying, too much loss of habitat and could possibly lead to complete collapse of this grassy woodland ecosystem.
Why are grassy woodland sites important?
Remaining native grassy woodlands are important here in South Australian as many original woodlands were utilised for grazing purposes by settlers and have now been lost. As well as large imposing trees in the overstory they have a minimal mid-layer of vegetation and a significant diversity of species in the understory. This includes all manner of plants such as lilies, ferns, daisies, orchids and many other different species of herbaceous plant. As the name suggests they also contain a vast array of native grasses.
The greater the variety of the flora, the greater the variety of insects the woodland can support. Butterflies, bees, bristleflies and bugs all help to make up a wide and varied diet for our native fauna. This vast array of insect life is vital for the survival of our woodland birds. We know from the Biodiversity report submitted to SA parliament 2017 that many woodland bird species regarded as common thirty years ago have now disappeared altogether from a number of areas in the Mount Lofty Ranges and are in serious decline all over the state.
Small woodland birds need large trees with spreading horizontal branches to perch on when searching for food on the ground. Grassy woodland site provide this.
Grassy woodlands are in decline generally across South Australia and this particular grassy woodland site contains a number of regionally threatened ecological communities including Drooping Sheoak, Black Mallee Box, Blue Gum and Red Gums.
Meadow Argus butterfly
What is a significant tree?
For us a significant tree is any tree which has reached an age where it has viable nesting hollows. . In the case of blue gums and red gums a small hollow with narrow entrances suitable for small mammals (such as antechinus) to inhabit take about 100 years to form. Hollows of a medium size which would be suitable for parrots to nest in take around 200 years to form, and the larger and deeper hollows occupied by bigger birds such as cockatoos and owls can take much longer.
Yellow-tailed Black Cockatoo.
Why are significant trees important?
Significant trees are important as they contain nesting hollows. Every single Australian parrot species requires a nesting hollow to breed. So every single parrot pair needs a two hundred year old tree in order to nest naturally in Ambers Gully, for larger species like the vulnerable yellow tailed black cockatoo which nests in the area that age is even greater as they are a much larger bird.
Many other native bird species like the white-throated tree creeper, the owlet nightjar and the nankeen kestral all use hollows for nesting as do a number of mammals, in particular bats, antechinus and possums.
Is Ambers Gully that important?
As well as providing habitat for a huge variety of native plants which in turn support insects, woodland birds and small mammals the Ambers Gully site is an important nesting site for a number of raptors. Tawny Frog mouths, Collared sparrowhawk and Brown goshawk were all photographed nesting and successfully fledging young in the project site in the summer of 2017/18.
Wedge Tailed eagles have also been observed roosting in the larger trees and Square tailed kites have been observed flying over the site.
The site is also home to koalas, kangaroos, possums, echidnas, frogs and reptiles which are all precious native animals.
What has been done so far?
Once we had an understanding of the underlying issue we mapped the site to determine where the areas which most needed our attention were. We also determined which trees were showing the worst signs of stress. We have held Fund Raising BBQs and utilised donations to employ contractors on the steeper, less accessible areas of the site not suitable for volunteers. Yes, we have already freed a number of trees! Volunteers have removed scattered olive in some higher quality bush areas with help from the 4WD Adventures club who provided transport and workers.
Olives around a stressed gum tree.
How can I help?
Spread the word about this campaign! The more people who help out in any way they can the greater impact we can have.
Volunteer your time. The Friends of Black Hill & Morialta in conjunction with the 4WD Adventurers club hold working bees at the site each year. There will be a working bee on Sunday the 23rd June 2019 followed by another on Sunday 25th August 2019. See our Dairy Dates page for more details. Join the Friends group and become a long term supporter of our conservation parks. Many of our supporters are not volunteers on the ground, but we value each and every membership as every one helps support the work we do in parks.
What will my money buy?
- $50 will reduce the area that olives are spreading into by 400m2. As the olives are thinly spread across vast areas of the site removing these will help prevent the problem from re-occuring. 400m2 is the area of a small housing block!
- $100 will "Free a Tree" which is surrounded by olives so that it can continue to grow for many more years. This is our highest priority right now.
- $215 will equip a new volunteer with a spray pack, respirator and elbow length gloves, all essential safety equipment needed when spraying olives using the basal technique. This technique has been found to be the most cost efficient way of treating wild olive.
- $300 will purchase the chemical, oil and dye a volunteer needs to spray olives using the basal technique.
- $900 will reduce the area that olives are spreading into by the size of a World Cup sized Football field.
11 August 2019 - Page Updated - Landcare campaign has ended.
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