Drone footage shows an area where DoC has carried out more than 25 years of predator control. Photo / DoC
Drone footage shows an area where DoC has carried out more than 25 years of predator control. Photo / DoC
Newly released drone photography shows the impact of possums on a section of ancient forest in northern Coromandel, and also the value of predator control and restoring forest habitat.
The images were obtained by staff from the Department of Conservation's (DoC) Coromandel area when collecting seed to help stop the spread of the tree disease myrtle rust and safeguard genetic seed stock for the species.
Myrtle rust has the potential to weaken and eventually kill some native New Zealand tree species such as pōhutukawa, mānuka and rātā.
The drone images show sections of forest canopy in the Papakai block of the Coromandel Forest Park, which straddles the spine of the Coromandel ranges.
Nick Kelly, DoC's Coromandel operations manager, says the drone images show the stark contrast between an area where there has been more than 25 years of predator control effort, and an adjacent section of land where predator control has only been undertaken twice in the last decade.
"The tops of the rātā trees in the two images are where the difference is really evident," he says.
"In the area where we've had long-term predator control, you can see the distinctive red-brown colour of the rātā trees flowering — they're good healthy trees, with plenty of leaf coverage and no signs of the damage possums cause.
An area of the Coromandel Forest Park showing the damage when only two predator control operations were done. Photo / DOCHC Po
"But in the other image, several dead rātā are clearly visible — over time, they've been stripped of leaves by possums and that's led to the trees dying.
"Those dead specimens really stick out, and they're a trigger for what we term a 'top-down collapse' of the forest eco-system."
As larger trees die off due to the impact of possums, it compromises wider biodiversity and forest health, with birdlife, insects and other native wildlife affected.
Nick says the damage done by possums isn't always visible to visitors enjoying the forest.
"You can wander through the forest and not necessarily see the impact of these introduced pests. What the drone imagery shows us is what people do not see when they're out for a walk or a tramp."
DoC's predator control efforts are essential to protect New Zealand's native species, as introduced pests like possums, stoats and rats eat native plants, insects, birds and eggs.
The Coromandel forest is home to important native species such as Archey's frogs, Coromandel striped gecko and Coromandel brown kiwi.
Flowering Dactylanthus taylorii has been rediscovered on the Coromandel Peninsula.
It's also believed the area has woodrose/pua o te reinga (Dactylanthus taylorii), an extremely rare and threatened parasitic, fungi-like plant which is pollinated by long-tailed bats/pekapeka but destroyed by rats and possums.
The predator control operations target both rats and possums and the department says they will also decrease stoat numbers and reduce possum browsing, providing more food for birds.
Residents can help by joining community-driven predator control and replanting, and following advice about invasive tree diseases such as myrtle rust and kauri dieback.
DoC is currently consulting with iwi, landowners and stakeholders for a Tiakina Ngā Manu predator control operation recommended for later this year.
