Grazing Swamp Wallabies are a huge hurdle to successfully growing new trees in sections of Tarra-Bulga National Park. Hard lessons have been learnt, 1000’s of trees have been planted, but experience has shown that even if they are hidden or planted among unpalatable species the Wallabies will eventually find them and eat them. Regular tree-guards have proven to be of little use, they may protect the plant for a short while but Wallabies will chew any growth at the top of the guards that they can reach, the plant will remain stunted and eventually die. A commercially available Wallaby repellent mixture can be sprayed on new growth to protect it, but that is labor intensive and requires regular follow up to have any chance of success, not a viable task in our situation with limited time and rough terrain to encounter . The only strategy that does seem to work for us is to use large wire mesh tree-guards which are expensive and very labor intensive to install and eventually remove once the trees have grown big enough..
Why do we think direct seeding might be a solution? Nursery grown tube-stock are generally grown in ideal conditions, with fertiliser, controlled sunlight and regular watering, as a result the leaves are highly palatable. Plants that germinate from seed on sites should be tougher, slower growing and as a result have less tasty foliage. Mountain Ash along with other species of Eucalyptus seeds are very small, one gram of Mountain Ash seed contains nearly 200 viable seeds. For our trial we have 390 grams of Mt Ash seed, if all of them germinate we would have almost 80,000 seedlings scattered over the site. That is clearly an optimistic outcome but hopefully we can get a good germination strike rate and some of those tiny little seedlings can overcome the Wallabies and other forces of nature to successfully grow into mature trees. We will keep you posted.