Forest and Bird says no amount of rehabilitation will replace the flora and fauna that would be lost if an open cast mine is built in part of the West Coast's Denniston Plateau.
The conservation group and the West Coast Environment Network are appealing against a resource consent granted in 2011 to Australian-owned mining company Buller Coal to mine 200 hectares of the plateau.
The Environment Court in Greymouth has previously heard from Buller Coal's experts that rehabilitating the area's plants to its present state would take more than 500 years.
Forest and Bird spokesperson Chris Toddsaid outside the court on Tuesday that no replanting or pest management would make up for the damage the mine would have on the land.
Mr Todd said the complex ecosystem on the Denniston Plateau could never be re-created.
However, a scientist specialising in wetland ecology told the court of ways rare plants could be restored to the Denniston Plateau if the mine went ahead.
Giving evidence for Buller Coal, ecologist Kerry Bodmin said rare plants existing on the site of the mine could be saved by a pre-mining survey that would allow a back-up population to be cultivated.
Bathurst chairman apologises
The chairman of Bathurst Resources, which owns Buller Coal, has apologised to the Environment Court for a comment at the company's general meeting last week.
On Monday, Judge Laurie Newhook raised concerns over Craig Munroe's comment that the company is facing a never-ending appeals process that allows minority groups to stifle development in New Zealand.
In a statement read out by the company's lawyer, Jo Appleyard, Mr Munroe said the company apologises for anything said during last week's meeting that might have been interpreted as criticism of the court or the hearing process.
He says it was not his intention to cause offence and is sorry for the discomfort it has caused.