KEY POINTS:
Inner-city bush reserves are important homes for insect populations that would be otherwise unable to get a foothold in urban areas, says an Auckland scientist.
Dr Nicholas Martin, from Crop & Food Research, has been studying the biodiversity of the Dingle Dell native bush reserve in St Heliers.
In 1933 about 8ha were put aside for the reserve, which was planted out with natives including pohutukawa, tree ferns, rimu, totara, nikau, tanekaha and kohekohe.
Dr Martin said a "BioBlitz" in 2000 had shown a wide range of insects in the reserve, sparking his interest in assessing which were successfully habitating the bush.
Through analysing plant damage, he found that the stem miner moth, for example, had established itself in abundance, living off a Pseudopanax lessonii shrub better known as Houpara.
Dr Martin said while the moth was a widespread species it was not usually common in such shrublands.
It could be evidence that parasitoids of the moth were less common in Dingle Dell than in the Waitakere Ranges, where findings of the moth were relatively rare.
Dr Martin said the insects and the damage they left behind might not sound that attractive but were an important part of biodiversity.
While growing native plants in gardens and parks supported some species, most needed the conditions provided by the native habitat found only in a reserve based on their original ecosystem.
Landcare Research is holding another BioBlitz at 3pm on Friday at Smiths Bush on the North Shore. Members of the public are invited to help students and scientists count as many species as possible in a 24-hour survey of the reserve, to record the total number of species.
Organiser Peter Buchanan said the BioBlitz aimed to allow the public to engage with scientists and for people to learn more about different life forms that occur in a city and more specifically in reserves or remnants of native bush.
"We set up a public laboratory and go into the reserve to try and find and record every life form that we can, from the smallest bacteria and insects right up to the large birds and plants," he said.
Dr Buchanan said BioBlitz assisted land managers in their work to protect biodiversity within large urban centres.
"Without reserves like Smiths Bush, cities will lack a huge amount of biodiversity, so from the point of view of city and regional councils they will probably understand a great deal more about just how special these sites are once they get an idea of the huge number of species that are present."
