Invasive Species Invading Jerrabomberra Creek Territory

u7034198 by Christian Piton

In September, I spent two weekends removing some of the invasive willow species found within the Jerrabomberra Wetlands Nature Reserve. The ParkCare ranger, who is a member of the ACT Parks and Conservation Service, was unsure of the exact type of introduced species of willow, but that it was brought into Australia by European settlers. The work I completed benefited the ongoing Jerrabomberra Creek restoration project that began in 2012 as a way to enhance the quality of ACT’s rivers.

What’s the Issue with Weeds?

The type of willow I removed and crack willow (Salix fragilis) are two weeds that are considered of national significance. They have the potential to easily spread, absorb nutrients, and take up space that native plants and shrubs need to survive. Early detection of willow is crucial to increase the chance of eradicating the species, but in most cases it is impossible to complete get rid of an introduced species. In addition, willows do not provide a suitable habitat for mammals or birds found at Jerrabomberra, and do not provide any food resources to local species. Invasive species cause not only a tremendous amount of damage to the environment, but also harm the economy. In Australia, it has been estimated that introduced species can cost approximately $13.6 billion a year. Therefore, it is important that people take any role in protecting native species and volunteer just a small of time to help minimize the destruction of reserves.

Image 1. The introduced willow

The Removal Process

My partner Floriane and I took turns alternating jobs with this simple yet tedious task. One of us would use the large pair of shears to remove the willow, and the other would immediately dab poison on the roots of the tree to prevent it from growing back. The herbicide that we used was called glyphosate and is also used on other invasive plants within the wetlands such as the black alder (Alnus glutinosa). After removal, the next step is to plant native trees and shrubs to increase the amount of diversity within Jerrabomberra. Unfortunately, the two days that I volunteered were rainy and the ground was too wet to plant seeds. However, the ranger said the next session in October will most likely involve planting common reed (Phragmites australis) seedlings near the creek to create habitat and stabilize the shoreline. 

Image 2. The removal of the willow
Image 3. Applying the herbicide immediately after cutting the willow
Image 4. The glyphosate used to poison the willow

Reflection

My time spent at Jerrabomberra taught me how serious of a threat weeds are to Australia’s environment. There needs to be more education on how to effectively manage weeds because so many people do not know how to correctly identify invasive species. This leads to people accidentally planting exotic species instead of native, and can also lead to a failure to remove introduced weeds early on. I also recognized from my two days that there were not many volunteers, but plenty of work to be done. I think that if everyone put aside a couple hours of their time every few weeks to help plant native species then many of the problematic invasive species would not be as out of control as today.

References

Environment, Planning and Sustainable Development Directorate – Environment. (2019). Willow control in Jerrabomberra Creek. [online]

Environment.gov.au. (2019). Weeds in Australia. [online]

Plein, M. and Shine, R. (2019). Australia’s silent invaders. [online] Australian Academy of Science.

About Biodiversity Conservation Blog

I am an Associate Professor at The Australian National University and convene a (very awesome) course called Biodiversity Conservation. Myself and students in the course contribute to this blog.
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