Protestors are preparing to occupy trees to save them from being felled by Southampton Airport.
They claim a vital "green lung" in the city is to be destroyed if the felling takes place.
Southampton Airport says the trees are in the flight path and must be reduced in height by law.
It has promised campaigners it will protect wildlife and return the woodland to the community in a healthier condition.
Painted lines and numbers alerted Gareth Narbed to plans to fell 27 trees in the ancient woodland at Marlhill Copse, with dozens more drastically reduced in height.
Gareth has been walking in the copse for 30 years, and so upset by the plans that he spent £15,000 of his own money getting a legal injunction forbidding any tree work.
However that decision has been overturned, with the trees no longer protected by law but by environmental activists.
My fears are that there is nothing left to protect Marlhill Copse from the airport's unnecessary destruction of it. There are people braver than I am who are prepared to live in the trees to protect them if necessary. That in itself is a remarkably courageous activity."
WATCH: Dan Townsend from Southampton Airport says the work to the trees will be done as "sensitively as possible."
We have to comply with our certificate to operate. That's something that the European Union has set upon us to say 'in order to have an airport in Southampton you have to comply with these rules and regulations'. One thing we're doing at the moment is a full suite of expert led surveys, so that we can be full informed in terms of what's there and importantly what we have to do to be sure we do the work to the trees as sensitively as possible."
Southampton Airport, which bought the woods last year, has made a film in an effort to reassure residents of their plans.
For now the trees will remain untouched as it is bird nesting season and no felling can take place.
Watch Kerry Swain's report below