Biggest change in land ownership for more than 80 years described as 'watershed moment in the history of the nation'

The National Trust is poised to offer to take over or buy much of the state-owned English woodland which the government is planning to sell off.

The initiative, says the trust's director, Dame Fiona Reynolds, could protect in perpetuity not just large areas of "heritage" areas such as the Forest of Dean and the New Forest, but other woodland expected to be offered for sale to communities and commercial enterprises in the biggest change in land ownership for more than 80 years.

"This is a watershed moment in the history of the nation. These much-cherished places have been in public hands for centuries, enjoyed by everyone for generation after generation. The future of these important national assets will be decided in a matter of weeks," Reynolds told the Guardian.

"For 116 years, the National Trust has helped to save the places the people of this country most value when their existence, or access to them, has been threatened. If the government is determined to pursue the course of action it has outlined and the public wish us to, we are ready to play our part in giving them a secure future. We are ready to step in."

The government has met fierce resistance to its plans to dispose of 258,000 hectares. It plans to hand roughly 25% of the most treasured woodland over to new or existing trusts, offer communities and charities the right to buy a further 25%, with the rest being put on the open market over a period of years. However, strong objections have been raised over whether access and ecological quality will be guaranteed. By today, 288,000 people had signed a petition to halt the disposal.

Reynolds said that the trust, which has 3 million members, was looking at all the options and would consult conservation groups, local organisations, other forest users and individuals to gauge how important the English woods are for people and to see how their future can be preserved for future generations. It expects to make proposals to its board of trustees within three months, when the government's consultation exercise ends.

"Our board will decide how to respond," she said. "We stand ready to help in a variety of ways. It could be ownership or to help others play a role."

The Department for Environment, Food and Rural Affairs said: "We're interested to hear ideas from all interested parties as part of this consultation process and welcome all contributions."