YAKUTAT — “There they are,” Ben Gaglioti said, after a short hike off a gravel road leading away from this small fishing town. Gaglioti walked in rubber boots on a green, squishy carpet of muskeg — a wild garden of water-loving plants growing on acidic soil that has for centuries prevented the encroachment of giant rainforest trees. He spotted the lime-green shade of a few lodgepole pine trees here, at their farthest-north location in Alaska.