The dates of Easter Island are currently in flux in that the traditional dates have been challenged, so two different sets of dates must be given.
In the meantime Bahn and Flenley have been fighting back with the new edition of their book, now published in Easter Island itself, with splendid illustrations, in which they restate and refine their original position, suggesting that the earliest partial decline of the tree pollen may occur as early as AD 690 or even AD 100, and that it took many centuries for the decline to spread from the original settlement in the south east to the rest of the island.
They propose a dramatic lowering of the dates so that the first colonisation comes as late as AD 1200.
They argue that the trouble with the radiocarbon dating of peat samples is that you never know whether the peat in fact incorporates older material, decaying vegetable matter that has been floating around for centuries and will therefore give a radiocarbon date that is too old.
When, walking beside the lake, I picture the heathery birch forest that grew there in post-glacial times, the warm forest of pine and bracken that followed it, the saltmarsh that formed when swings in climate brought the ocean flooding in, there are facts to frame the pictures in my mind.
The clearances and fires of Neolithic farmers, the "weeds" that took root among their crops - all this is on record in cores of peat extracted from the nearby bog.