While the likes of cane toads and feral pigs are commonly thought of as public enemy number one when it comes to endangering the ecosystems of national parks, a far more attractive threat is emerging in the west.
Pasiflora, or stinking passionflower, is a South American invader which is spreading aggressively through the north west’s most renowned national parks as existing control methods struggle to halt it.
The West Australian newspaper reports that it has already overrun the Jirndawarranha Pool’s surrounds in Millstream-Chichester National Park, and has been found in low densities near Karijini and in Murujuga National Park.
In the Kimberley, blankets up to one metre thick have reportedly been found in areas such as Geikie Gorge and it is overtaking freshwater crocodile nesting grounds.
CSIRO senior research scientist Bruce Webber told the newspaper that the threat was real.
“What we see in drier areas in the Pilbara and the Kimberley … is it gets up in the tree canopy and makes a huge load of dry, dead material,” he said. “It doesn’t break down as much as native flora might … so when fire comes through, it torches the canopy at an intensity far greater than what the fire itself might do otherwise.”
Mr Webber said use of existing control methods in Millstream was inefficient but necessary to maintain amenity of tourist and culturally significant areas.
Department of Biodiversity, Conservation and Attractions regional nature conservation leader Coral Rowston told the West Australian that under ideal conditions, pasiflora was blanketing areas and reaching the canopy within three months.
Ms Rowston said rangers were trialling management by fire as a control measure.
“Fire is thought to promote the stinking passionflower regrowth, but at the same time, fire takes it out and gives us an environment where it is easy to spray the regrowth,” she said. “We have a site set up where we are monitoring how long it takes to grow, how long it takes to hit the canopy, to flower, to seed, to give us an indication of how long we have after fire to control it.”
Ms Rowston said volunteer groups and rangers were brought into the park occasionally to help with control efforts.
“People are more than welcome to volunteer with us to keep it under control,” she said.
Ms Rowston said volunteers were also helping clear water lilies from Jirndawarranha Pool.
