KEY POINTS:
Puriri trees nearly a century old are gradually being replaced along their namesake, Puriri Drive in Cornwall Park.
The stately trees, which can live for hundreds of years in the bush, are not doing so well in the landscaped grounds of the park.
Park director Michael Ayrton said the trees were planted in 1927, effectively on the side of a volcano and the scoria pan saw the drought susceptible trees suffer from dry feet.
About 300 of the evergreen trees formed a leafy avenue about one kilometre long between Greenlane West Rd and Campbell Cres, near St Cuthbert's College.
Mr Ayrton said in summer the red flowers and berries attracted bird life including wood pigeons. He accepted puriri were not ideally suited to city living but they would continue to be planted due to their historic and iconic association with the area.
The puriri were being mulched to improve their health and young specimens were being planted at the rate of about a dozen a year.
Plant ecologist Graeme Platt said puriri trees represented the final stage in forest development and therefore did best when they had shelter and plenty of leaf litter around their base and roots.
Mr Platt has monitored the Cornwall Park puriri for 60 years and never thought they looked that well.
Dr Ross Beaver, of Landcare Research, said there had been a concern about the health of puriri generally but it had not been thoroughly investigated. There had been some concern they were falling prey to the sort of organism which had been killing off cabbage trees yet there was no substantial evidence to support that theory.
A decline in the health of oak trees was also proving a concern around the Auckland region.
Simon Cook, an Auckland City Council arborist, said their health had been failing over the past four years and 50 oaks had died in that time. "It has been happening in the Domain, Cornwall Park and throughout Auckland. It is a bit of mystery."
Mr Cook said some of the trees had really bad powdery mildew over them and others had been harmed by insect pests or an oak anthracnose fungus. It was possible climate change could be a factor, he said.
