FIDO has been involved in weed eradication at Happy Valley since the early 2000s. An intensive program commenced in March 2004, involving four, week-long weeding excursions per year. These trips usually involve from 5 to 12 volunteers.
Despite the long-term efforts of FIDO weeders and others, the Happy Valley township and surrounds was heavily weed infested with a cocktail of weeds when this intensive program began. Most of these weeds were either garden escapees or accidental introductions arising from human settlement and visitation to the village.
Five years and 21 weeding trips later, the situation is much better, but it is an everlasting ongoing task.
FIDO operates under a Deed of Agreement with DNRM on 245ha of Unallocated State Land (USL) surrounding the village. The program aims to destroy invasive exotic plant species to prevent their spread into the National Park.
Considerable effort has been put into removing the usual culprits, Easter cassia, lantana, broad-leafed pepper, basket asparagus, mother in law’s tongue, mile a minute, corky passion fruit, mother of millions, North Queensland umbrella trees and several others. These are all common and well-known weed species that landcare workers have been battling with throughout South East Queensland for many years.
A new invasive weed has arrived in Happy Valley and has been the focus of our efforts since 2014. It is a creeper, Abrus precarious subspecies africanus, commonly known as crabs eye. As the subspecies name indicates, it is out of Africa.
The plant has attractive bright green compound leaves, relatively insignificant mauve flowers and spectacular persistent bright red seeds with a black spot. It was most probably brought to the village as an ornamental.
The Genus Abrus has about 20 species, spread throughout tropical Africa, Asia and through to Australia. Australia has only one native species, Abrus precatorius subspecies precatorius. Its range is from Gladstone North, across Northern Australia to New Guinea.
The introduced subspecies africanus that has turned up in Happy Valley has a recorded range from Shoalwater Bay South. It is now widespread throughout South East Queensland. The two subspecies are all but identical in appearance. The distinguishing feature is the seed pod which, when immature, is smooth in the Australian subspecies and hairy in the African subspecies.
Volunteer weeder Trevor Armstrong collected the first K’gari record of the species held by the Queensland Herbarium in Happy Valley in 2007. In the early days of the infestation at Happy Valley, it was thought to be to the Australian subspecies and did not cause much concern. The Australian subspecies is not highly invasive.
However, by 2014, it had been identified as subspecies africanus and had infested at least 40ha around Happy Valley, and was seen to be extending into the canopy of vegetation with resultant smothering effect. Clearly, we had a problem.
Since the infestation on K’gari was restricted to Happy Valley, FIDO prioritised its destruction in an endeavour to contain it and hopefully eliminate it.
Early trials indicated that hand removal was not effective. The plant is very deep-rooted and regrows vigorously when hand weeded/dug out. It regenerates from root parts remaining in the ground. Given the magnitude of the problem, the only option was foliage spray. We have been using 1.5% roundup. It is extremely effective.
Where the plants have extended into the canopy, as much as possible we hand pull them down and spray them on the ground. Where this is not possible, we cut the stems off to prevent future flowering and seed set in the canopy, and spray the plant material on the ground.
The spectacular bright red seeds have a hard seed coat, and like many plants of the Fabaceae Family can be expected to persist in the ground for some time.
We established a germination trial under field conditions in March 2016. One thousand seeds were planted. 14.6% germinated in the first month. This slowly increased to 19.8% by September 2016, and since then only one has germinated. That was in February 2019.
It remains to be seen if the remainder are no longer viable or are lying dormant in the soil waiting for the required conditions. We have evidence that seeds stored in dry condition remain viable for several years.
Seeds persist on the plant for long periods, often well more than a year. Seed collection has been an important element of the control program, to prevent the build-up of the seed bank in the soil. Follow up destruction of emergent seedlings is now very important to prevent regenerating plants reaching maturity, flowering, and setting seed.
In most of the infested areas that we have been working, there are now very few mature plants, and hence very low seed set. The population in these areas is down to less than 1% of the level of infestation when we began. However, we continue to locate new outbreaks further afield, particularly to the North of the village. More extensive surveying is necessary to determine the extent of the range of the plant.
This is a program that must continue for some years to be effective. It requires extensive site examination and follow up. Elimination of Abrus will remain the main focus of the Happy Valley Weed Eradication team, while also dealing with all the other species above.
Senna pendula var glabrata (Easter Cassia) has been heavily targeted. We have significantly decreased the population in the areas in which we operate. We pull the plants where possible, and where not possible we cut low to the ground and apply roundup to the stump. We also use this method to destroy lantana.
In April 2018 and 2019, we conducted a “Cassia Blitz” around the village. We pick this time because the plants are in flower, and their spectacular yellow flowers make them easy to locate. Both week-long events involved more than 12 FIDO volunteers, as well as Fraser Island Association members. In 2019, we were joined by four Butchulla Sea and Land Rangers. The April Cassia Blitz will be an ongoing event.
The area where our efforts are most pleasing is to the ocean side of Yidney Rocks Bypass Road to the South of the village. Much of this area was so heavily infested with Easter cassia and lantana that it was all but impenetrable. Years of work has completely changed the structure of the forest, making it a delight to walk through.
We seek to play an ongoing part in the maintenance of the natural integrity of the magnificent World Heritage island, K’gari.
Contributed by Peter Shooter, FIDO