A battle to save a 4.2ha native bush block in the path of a new $472 million highway parallel to the Southern Motorway is going to the Environment Court.

The Tree Council has lodged an appeal against a decision by commissioners to allow Auckland Transport to slice the new four-lane highway, from Manukau to Drury, through Graham's Bush.

Tree Council chairman Sean Freeman was disappointed the commissioners accepted the proposals without any modifications and a strong case made to protect the bush.

"This nationally important ecological fragment of a broadleaf podocarp forest that once covered the Manukau lowlands is almost all we have left and it is in a pristine state and weed and pest free. It should not be destroyed when there are alternative solutions that can enable the road to cross the area without killing the trees."


Landowner Graham Cheesman died before the commissioners' decision was released. He spent 18 years working to preserve and protect the 4.2 hectare forest fragment in a gully on his land, Mr Freeman said.

He said Auckland Transport's proposal is to span the gully using embankments to support the road bed which will result in removal of 1500sq m of vegetation, topping and felling of emergent trees in the 500m below the bridge structure and loss of vegetation in close proximity to the two embankments due to rain shadow and shading.

It is estimated that six or seven large trees plus smaller canopy trees will be removed. The bush fragment will be cut in half by the road, severely affecting its ecological value, Mr Freeman said.

He said Auckland Transport has proposed compensation planting for the loss of bush areas affected by the proposed route through the bush remnants at 38 and 146 Mill Rd, but The Tree Council does not consider that this can compensate for the loss of a significant remnant of such a severely threatened forest habitat.

At the hearing before commissioners in September last year, Forest and Bird member Graham Falla called Graham's Bush a natural treasure demanding preservation as other cultures protected monuments.

"One may ask what sort of culture treats its ancient monuments, dead or alive, with contempt," he told five commissioners considering applications by Auckland Transport to protect an 8.9km route from Manukau to Alfriston for the first stage of a four-lane highway to Drury.

"Can we imagine cutting off the head of a Greek sculpture of Venus de Milo to force it through a doorway, or putting a road through one end of a medieval cathedral because it's perceived to be in the way?"

Auckland Transport wants to build a 17m-high bridge across the narrowest part of the block at 146 Mill Rd. It told the hearing the bridge, 30m long and of the same width, will require clearing 1500sq m of bush amounting to just 3.6 per cent of the block.

Auckland Transport told the hearing that skirting the Cheesman property will add up to $43 million to the project cost, and a higher bridge will have large impact on the surrounding landscape as well as being more expensive.

Forest and Bird board member Lindsey Britton said Mr Cheesman intended bequesting his property to integrate it with a nearby 8ha bush block which her organisation had owned since 1975 and hoped to form part of a green corridor between the Hunua and Waitakere ranges.