Using drones to spot weeds

Eyes in the sky - using drones to spot weeds

Article by Ben Green, natural areas technical officer, Sunshine Coast Council

In this ever changing world, new technologies are continuously emerging that prove useful in conservation and ecological restoration. Sunshine Coast Council has adopted the use of UAV (unmanned aerial vehicles), or drones, as useful tools to view and record the world from above.

Drone technology has recently been used to find infestations of madeira vine (Anredera cordifolia) at Tuan environmental reserve near Kenilworth. The reserve is named after the ‘Tuan’ or brush-tailed phascogale (Phascogale tapoatafa), a small, arboreal (tree-dwelling) and nocturnal marsupial of the family Dasyuridae. This reserve was purchased through the environment levy in September 2013 and was extended through the acquisition of a neighbouring lot in 2017. The total reserve size is in excess of 100 hectares.

Tuan environmental reserve is characterised by steep hillsides and ridges containing eucalypt forest and rainforest communities in protected gullies and along Chinaman Creek in the valley. This reserve is home to rare flora and fauna, listed under legislation, including the Maroochy nut (Macadamia ternifolia) and yellow satinheart (Bosistoa transversa), glossy black-cockatoo (Calyptorhynchus lathami) and black-breasted button-quail (Turnix melanogaster).

Council is currently establishing this reserve by using contractors to manage weeds and employ ecological restoration practices. During this establishment phase, surveys are carried out to determine the values and constraints of the reserve which will ultimately influence how the reserve is managed.

During ground surveys, the madeira vine was detected in a small number of locations within the reserve. Madeira vine is a highly invasive environmental weed from South America. It is a restricted invasive plant under the Biosecurity Act 2014 known as a ‘transformer’ species. It has the ability to cause irreversible damage to ecosystems by destroying the canopy layer of a forest and smothering the understorey so recruitment of natives is halted. It was imperative that all madeira vine locations within the reserve were identified so infestations can be treated and ultimately eradicated from the reserve. This is where the drones came into use.

Much of the reserve is densely vegetated and rugged, making vine infestations difficult to discover on foot. During the peak flowering period of the madeira vine, council officers carried out a drone aerial survey to help locate infestations. More than one hundred photos of drone footage were searched, successfully identifying the madeira vine’s white flowers against a sea of green images.

Ground-truthing confirmed that there was a serious infestation along a ridgeline that was almost 1 acre in size (4500m2). The understorey was carpeted in dense vine which also smothered the canopy of mature brush box (Lophostemon confertus) trees. Madeira vine was also located within a gully where vine tubers were able to be transported into other parts of the reserve.

Contractors are now working to contain this huge infestation with an aim to eventually eradicate it from the reserve.

Following the success of this work, additional drone surveys are expected to be carried out in the future at this reserve to monitor the success of vine treatment and to search for additional infestations.