Old poplars may get the chop

An arborist has recommended felling four 100-year-old trees in a lakeside park in Queenstown and the staged removal of the remaining 30-metre-high poplars.

A mature Lombardy poplar was felled by high winds on January 17, crushing a car parked in Lake Esplanade, damaging other vehicles and destroying a corner of the Lakeside Motel.

Auckland arborist Samuel Earp, of GreensceneNZ, carried out a risk assessment on all the heritage poplars in St Omer Park.

"The potential risk to persons and/or property from part or whole Lombardy poplar tree failure is of concern due to the frequent use of St Omer Park, Lake Esplanade and adjoining buildings and structures," his report says.

"Problems associated with old age are beginning to manifest themselves in the form of cavities and heartwood decay."

The fallen poplar snapped at the base and parts of the tree were hollow and subject to white rot.

There were few outwardly visible signs of rot before it fell, the report said.

Twenty-six poplars remain in the park and Mr Earp's assessment used a visual tree analysis and a resistograph, a device that drives a fine drill into wood and measures resistance to detect structural integrity.

Visually, all trees were in good health but the resistograph detected pockets of decay and hollows in almost all specimens.

Four black poplars in the western end of the park were in generally good health.

However, four Lombardy trees should be removed and the remaining trees' crowns chopped back by one-third. The report recommends a staged removal of the remaining trees and replanting.

Annual inspections and a replacement planting programme using more robust, longer-lived species were recommended.

The Queenstown Lakes District Council is expected to use the report to manage the future of St Omer Park.

The Southland Times