The National Trust said people were being invited to choose their own tree from Hindhead Commons in Surrey on the Saturday before Christmas.
The trees that are being cut down are non-native and quickly become dominant.
Felling them will help the local ecology, rangers said.
Matt Cusack, head ranger for Hindhead Commons and the Devil's Punch Bowl, said the area of high hills topped with pine trees had its own micro-climate and often saw the first scattering of snow in winter.
He said the Scots Pines being harvested grew rapidly and left fewer nutrients and less light for slower-growing, native species, so felling them would be "a win-win all round".
The pines are being cut down as saplings before they grow into mature woodland that would overshadow the heathland.
Rangers expect all the trees to be taken at the Hindhead Commons event, because a similar event held at Leith Hill in 2012 was so busy that the trees ran out.
It takes about four or five years for enough saplings to grow back so that another Christmas tree harvest can be held.
The charity said it was part of its ongoing conservation work.
There are no set price for the trees, but the National Trust has said donations will be gladly accepted.
Christmas trees are to be harvested at a beauty spot known as "Little Switzerland" because of its pine trees, hills and early snowfall.