Dissimilarity coefficients for fossil pollen spectra from Iowa and western illinois during the last 30,000 years

Abstract

Abstract Fossil pollen counts from Iowa and western Illinois ranging in age from 30,000 yr B.P. to the present were compared with the modern pollen rain of eastern North America using dissimilarity coefficients (squared chord distances). The fossil samples came from several sites to give a general representation to the major vegetational changes in the region. The best analogs were for the period from 28,000 to 25,000 yr B.P., when Picea‐Pinus forests existed that were apparently comparable to the modern boreal forest. Some acceptable analogs also exist for samples dating from full‐glacial time (about 25,000 to about 15,000 yr B.P.), when open spruce forests and parklands similar to the northern edge of the present boreal forest were present, and from late Holocene time (the last 6000 yrs), when the modern prairie and oak savanna were developing. Many samples from late‐glacial (about 15,000 to 10,000 yr B.P.) and early Holocene (10,000 to 6,000 yr B.P.) time have no acceptable analogs. Reconstructions fro...