Samples were prepared for pollen analysis as follows. A volume of 0.6 ml of each sample was prepared in seven steps following Moore et al. (1991): i) adding HCl, ii) sieving at 180 µm to ensure larger conifer pollen was included, iii) KOH digestion, iv) HF to remove silicates (Heusser and Stock, 1984), v) acetolysis, vi) alcohol dehydration, vii) and mounted in silicone oil. At least 300 terrestrial pollen grains were counted for each sample.