.
But there is always good news as well, maybe give it a few years and it will regenerate. Anyway it made me look back at the old wood near us which is also managed by the National Trust, and which I photographically record each year for its marvellous show of bluebells. The NT also cleared a glade in this wood, BUT only kept the heavy machinery to the one track that went through, many of the cut trees stumps are left a couple of feet high with coppicing regenerating round the base. The great logs are stacked and brushwood is left in great heaps (proper conservation techniques surely).
As for trees left on longbarrows, I am going to be a heretic here, in 4000 years there must have been a lot of scrub and trees that have grown over this period, so it is not really a new issue. Compare EKLB with the Beckhampton long barrow which was shaved of its cover and looked like a great plucked goose last time I saw it. EKLB is, if anything, protected by the trees.
Edit.....
http://1.bp.blogspot.com/_yRv78EkvmOM/SgaHtPZYuUI/AAAAAAAAC1g/cGF4Kw50MVU/s1600-h/DSC04141.JPG