Maori are describing the Emissions Trading Scheme as the biggest attack on their wealth since the 19th century land confiscations.
The comments have been made to the select committee hearing submissions on the Government's amendments to the scheme.
By the time all Treaty settlements are finished, iwi will own about 750,000ha of forestry land, most of it forests planted before 1990.
Federation of Maori Authorities chief executive Rino Tirikatene says under the scheme it would cost iwi about $5.6 billion in deforestation liabilities to convert the land to another use.
Mr Tirikatene says this will stop future generations of iwi getting any economic benefit from their land.
He says the scheme should be suspended for a year while a new framework respecting Maori ownership is worked out.