by Ben Hope
Possums and rats may be a biological weapon against the spread of wilding pines in the high country by gobbling up the seeds.
Research led by Scion invasion ecologist Tom Carlin revealed that rodents and possums – classified by many as pests – are helping greatly to control the spread of wilding pines. The seed eating animals had strongly reduced conifer seed survival. And when the seeds were passed through the digestive system, they did not survive.
The research was carried out in the Arthurs Pass area and the results were a big surprise to the researchers.The study team did not expect possums to be eating pine seeds which are exceptionally small, about 2 to 4 mm on average. Rats and mice were the biggest consumers of seeds but possums per animal ate a greater quantity of seeds.
In dense forests – presumably pines – about 90 percent of the seed production was eaten. In tussock habitats only 50 percent of the seed was eaten.
The results led to the conclusion that pest control, seen by many as essential to protect native species, would result in greater pine seed survival and therefore increasing and denser spread by coinifers.
However, now knowing that mammals were strongly inhibiting the spread of wilding pines and that it was unlikely, indeed impossible to get rid of every possum and rat, gave greater optimism to stemming the spread of wilding pines.
What a revelation this was and must have been to the researchers. It should be to the Department of Conservation, Forest and Bird and groups like Predator Free NZ 2050 too. Candidly I have wondered about the alarmist calls about possums consuming foliage.
Yes they browse leaves since they are a herbivore but so do birds such as the kokako, pigeon (kereru), takahe and others and of course moas were herbivores.
It is well nigh time for the ignrant to stop calling them pests and realise they are a resource to be managed, i.e., fur and meat for pet food and even human consumption.
For every action there is a reaction and getting rid of rats and possums the reaction by the sounds of this could mean that wildling pines might spread quicker than they could be controlled. Many introduced plant species are also favoured by rats and possums will these plants explode into uncontrollable proportions?
I spoke with a pine man in Marlborough recently. He has vast knowledge and experience with them after a 40 year career in the pine industries.
He advised how scientists had come from the states to study our wilding problems
His conclusion was that after 2 to 5 hundred years pine will have completely eradicated our native fauna. Each tree I think he said can produce up to 50 thousand seeds a year that are spread and can lie dormant for many decades until the right conditions. Already it is too late to stop it.
Now with conclusive evidence that possums eat the fallen seeds I think it would be very wise but I doubt there are wise people in doc for the department to leave the possum alone. This will at least slow the spread
Don’t get me started on the 1080 and the plight of the likes of our kea That’s another reason why the Muppets in govt departments should cease it’s use immediately