Despite numerous reports of old trees protected by Tree Preservation Orders (TPOs) being cut down – often because they stand in the way of developers' building proposals – the DoE has admitted that its policy is to "negotiate" with the perpetrators, rather than take them to court.

And, in what environmentalists and politicians have said is an example of the "farcical" protection given to old trees, the sole prosecution the department could point to saw the perpetrator fined £200 for cutting down several trees – just 0.6 per cent of the £30,000 total fine that could have been imposed for each tree.

Northern Ireland has less tree cover than any other European country, with just six per cent of the land area covered by woodland.

Responding to a written Assembly question from North Down UUP MLA Alan McFarland, Environment Minister Arlene Foster said that the only prosecution brought was against City of Derry Golf Club in 2003 for "wilfully destroying trees".

In response to the revelation, Green Party MLA Brian Wilson attacked the DoE's record of protecting trees and said some developers had been "laughing at the system for years".

"To only prosecute one case of violating a TPO makes a farce of the whole thing," he said.

"The current system is totally ineffective and unenforceable – it's laughable that the only fine was £200 which will obviously not deter anyone."

Fellow North Down MLA Alan McFarland, who raised the issue in the Assembly, said the problem of trees being cut down illegally was widespread: "Clearly the whole thing is a nonsense.

"There is no point putting protection orders on trees, then letting people cut them down and not enforcing them.

"People are raising this right across the constituency but to only prosecute one case, and have a £200 fine, makes a mockery of the whole thing when there are so many examples of trees being cut down illegally.

"The time has come for us to take these issues seriously if we care at all about our countryside and the sensible development of our towns."

However, the DoE insisted that it took its enforcement responsibilities "very seriously".

A spokesman said: "The department's approach to enforcement generally is to attempt to reach a resolution through negotiation without the need for formal court action, with each case being treated on its merits."

And, despite Mrs Foster's answer seeming to state that there had been one prosecution since TPOs were introduced, the spokesman appeared to contradict the minister and said the department kept no "formal record" of how many prosecutions it had taken.

But Friends of the Earth campaigner Declan Allison said the current system needed to be looked at urgently as there were clear cases of developers acting with impunity to remove protected trees because they knew they were not going to be prosecuted.