Weeds could ‘take over’ maunga
If sheep and cattle are banished from Auckland’s volcanic cones weeds could flourish, an ecologist says.
The days of livestock grazing on Auckland’s volcanoes are numbered as Auckland’s Maunga Authority plans to remove livestock to protect and restore biodiversity.
Bruce Burns, an ecologist at the University of Auckland, said he did not think it was a bad idea to remove livestock from the cones, but he was concerned about how the Maunga Authority will go about taking care of the cones once the livestock has gone.
‘‘There’s going to be longer grass, and one thing they’re going to have a lot more of is weeds,’’ Burns said.
‘‘Auckland’s one of the most weedy cities and if they remove the cattle there’s an army of weeds just waiting to take over.’’
Slightly more dramatic is the heightened fire risk on the dormant cones.
In June three totara and six pohutukawa were planted on One Tree Hill’s summit as a step to restore some of the cone’s history. Three maunga are grazed by cattle including Mt Wellington/ Maungarei, Mt Richmond/ Otahuhu and Mangere Mountain and two by sheep including One Tree Hill/Maungakiekie and Mt St John/Te Kopuke.
Grazing cattle have already been been cleared from Mt Hobson/Ohinerau in Remuera.
With cattle gone, kikuyu -a type of tropical grass - can grow to a significant hight, which dries out in summer and becomes a fire hazard, Burns said.
‘‘There have been a number of fires on cones throughout history, only a few years ago Mt Welling- ton had a fire because of long grass.’’
Even if weeds and fire hazards were well managed the cones themselves would look very different.
The cones will go from highly grazed, manicured areas of grassland to become far more wild with much more diverse vegetation, Burns said.
Federated Farmers’ Auckland president Andrew Maclean said the cones were not significant from a production point of view, so banning livestock would not be a loss for farming.