Riparian zones are prone to both water and land degradation – so what effect does Cat’s Claw Creeper have on riparian zones? In this episode, you will learn about the string of destructive impacts that Cat’s Claw is having on the health of the Upper Clarence River catchment riparian zone. The weed is strangling large native trees to death resulting in increases in erosion causing multiple side effects.
WARNING – Aboriginal and Torres Strait Islander viewers are warned that the following video may contain images and voices of deceased persons.
[Screen reads – Focus question: How has the invasive pest species Cat’s claw creeper impacted on the riparian zone of the Upper Clarence river?]
Melissa – Riparian zones are land alongside creeks, streams, gullies, rivers and wetlands. They can support diverse vegetation, help maintain bank stability and increase ecological and economic productivity. These conditions support cleaner water, reduce disease and pests and retain important nutrients and soil. Cat's Claw Creeper causes severe damage to riparian zones. The plant has the ability to completely smother native vegetation. It can grow as a ground cover forming a thick carpet of stems and leaves which choke out all small existing plants and prevents the germination of all other species, some of which may be essential to the health of the local ecosystem.
In the Upper Clarence River, Cat's Claw vines have been observed completely smothering large native trees. Eventually these collapse under the weight of the vine. There are a lot of negative implications for a catchment when large trees are removed.
As the Cat's Claw Creeper causes large trees to die and collapse, the soil is no longer held stable by the large and complex root systems. This process leaves the soil more prone to water erosion. The increased erosion and loss of vegetation caused by environmental weeds in the riparian zone can have several interrelated effects, including increased water temperature, increased erosion, changing hydrological cycles, modified channel form, loss of native species habitat, decreased water clarity and increase of pollutants and unnatural levels of nutrients in the rivers.
Several of these effects have been observed in the Clarence River catchment. Due to damage to the riparian zone, increases in upstream erosion have led to changes in deposition further downstream. As a result, in some parts of the Clarence River the river depth has been decreasing. This leads to reducing the numbers of deep pond fish, reptile and mammal’s species as they lose the food and habitat needed for survival.
In this way, the invasion of Cat's Claw Creeper can have a devastating impact on the natural ecosystem. Local tourism operator, Steve Ross, outlined his concerns about the impact of Cat's Claw Creeper.
Melissa – As a tourism provider, are you concerned about this weed as an issue?
Steve Ross [Tourism provider, owner of Clarence River wilderness lodge] – I am yes. The long-term impacts of the river with the trees falling in and changing the riparian area so that will have an impact on the quality of the river.
Melissa – Local boy Bell recalls the river having a series of large, deep pools as a child. Now it's all shallow and he voices his concern that this is changing the habitats for culturally significant turtles in the Jubullum area. Other significant cultural sites are under threat due to the spread of Cat's Claw Creeper.
Considering how prolific and impacting this weed is, there is a need to assess the extent and impact of the Cat's Claw Creeper along the Upper Clarence River.
List of sources and acknowledgements:
- Video – Drone footage of The Everlasting Swamp. We would like to thank The Everlasting Swamp National Park and Jessica Robertson Photography and Design for contributing their beautiful drone footage
- Narration. Voice over by Melissa Ellis, Southern Cross School of Distance Education
- Acknowledgment – We wish to thank Father Pop Harry Walker, Annabelle Walker, Roy Bell, Jubullum Local Aboriginal Land Council, Steve Walker, Marty Walker, David Foley, Upper Clarence River Landcare, Terry Moody, Steven Ross, Frederick Ellis
End of transcript