Vegetatio

, Volume 67, Issue 2, pp 93–103

Dispersal versus climate: Expansion of Fagus and Tsuga into the Upper Great Lakes region

  • M. B. Davis
  • K. D. Woods
  • S. L. Webb
  • R. P. Futyma
Article

DOI: 10.1007/BF00037360

Cite this article as:
Davis, M.B., Woods, K.D., Webb, S.L. et al. Vegetatio (1986) 67: 93. doi:10.1007/BF00037360

Abstract

Pollen records for American beech (Fagus grandifolia) and eastern hemlock (Tsuga canadensis) compiled from 50 sites in Michigan and Wisconsin, USA, show that both species entered the Upper Great Lakes region about 7000 yr B.P., reaching their western and southwestern boundaries between 2000 and 1000 yr B.P. Fagus advanced northward into lower Michigan as a continuous front, except where Lake Michigan posed a geographic barrier. Colonies were established on the far side of the lake after a 1000 year lag, implying that longdistance dispersal across a 100-km wide barrier can occur. The Fagus range may not have been in equilibrium with climate for one or two thousand years before this time, when seeds were dispersed across the lake to Wisconsin. Tsuga seeds may have been dispersed 150 km or more from Ontario to reach Upper Michigan. Scattered colonies were established 6000–7000 yr B.P. on either side of Lake Michigan, which did not pose a significant barrier to this wind-dispersed species, Tsuga spread rapidly over a large region prior to 5000 yr B.P. Subsequent expansion to the west occurred more slowly, and may reflect gradual climatic changes in northern Wisconsin during the second half of the Holocene. Tsuga's range may have been limited by dispersal, rather than climate, for an unknown length of time prior to 5000 yr B.P. During this period Tsuga was expanding its range rapidly. The study shows, however, that it is difficult to devise rigorous tests to distinguish between dispersal limitations and climate as factors limiting range limits in the past.

Keywords

Climatic change Fagus grandifolia Great Lakes region Holocene Palynology Range extension Range limits Seed dispersal Tsuga canadensis 

Copyright information

© Dr W. Junk Publishers 1986

Authors and Affiliations

  • M. B. Davis
    • 1
  • K. D. Woods
    • 1
  • S. L. Webb
    • 1
  • R. P. Futyma
    • 1
  1. 1.Department of Ecology and Behavioral BiologyUniversity of MinnesotaMinneapolisUSA
  2. 2.Department of BiologyUniversity of CaliforniaSanta BarbaraUSA
  3. 3.Division of Biological SciencesUniversity of MichiganAnn ArborUSA

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