On the basis of mapped summary of pollen data by the present author,an attempt is made to reconstruct the positions of the foreststeppe ecotone in the Northeast China Plain for the different times of the Holocene.By correlating the modern tree pollen percentages with the present vegetation distribution,it seems reasonable to consider 40%isopoll for arboreal as an indicator for the position of the foreststeppe ecotone.This isopoll thus could be used to reconstruct the evolution history of the ecotone.On t...