Forest and Bird wants to stop a tenure review in South Canterbury's Mackenzie Basin because of the rate of vegetation loss in the region.

It  follows the release of a 2009 report by Landcare Research saying agricultural intensification, especially on the Canterbury Plains, has caused the highest rate of loss of native vegetation since European colonisation.

The Government is assessing five high-country farms in the Mackenzie Basin and  may potentially freehold more than 30,000 hectares of Crown land.

Forest and Bird conservation advocates say that would lead to intensive land use and the loss of more native plants and animals.

Jacqueline Rowarth, Professor of Pastoral Agriculture at Massey University, says farmers need to make the environment a higher priority.

But Landcare Research’s chief executive Warren Parker says the report is based on 10-year-old data, and farming practices are much less destructive now.

Meantime,  Federated Farmers High Country chairperson Graham Reed,  says large tracts of the McKenzie Basin are already protected by the government – and under tenure review, more land has been taken out of agricultural production than transferred to freehold.