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Quaternary environments and N. hemisphere temperate forests

Quaternary environments and N. hemisphere temperate forests. Distribution Holocene dynamics The interglacial cycle “Long core” records Last Glacial Maximum refuges Migrations (rates and agents) Genetic divergence Quaternary extinctions. Global distribution of temperate forests. 60°N.

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Quaternary environments and N. hemisphere temperate forests

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  1. Quaternary environments and N. hemisphere temperate forests • Distribution • Holocene dynamics • The interglacial cycle • “Long core” records • Last Glacial Maximum refuges • Migrations (rates and agents) • Genetic divergence • Quaternary extinctions

  2. Global distribution of temperate forests 60°N 45°N 30°N 15°N Eq. 15°S 30°S 45°S Temperate forest 60°S

  3. Pollen sites,easternNorth America

  4. Pollen diagram, Kirchner Marsh, Minnesota. from: Webb (1980) J. Interdisciplinary History, 10, 749-772.

  5. Reconstructing post-glacial climate change (Kirchner Marsh, MINN)

  6. Reconstructing post-glacial vegetation change at a site

  7. The post-glacial (Blytt-Sernander) sequence

  8. Interglacial cycle of vegetation and soils(based on Iversen, 1948)

  9. Interglacial vegetation succession, Japan Climate PhaseDominantsTemperature Moisture UpperCryptomeria, SciadopitysTemperate Wet MiddleCyclobalanopsis, Warm Wet Castanopsis LowerFagus, LepidobalanusCool Wet from: Miyoshi et al., (1999) Rev. Palaeobot. Palynol, 104, 267-283.

  10. Is there a repetitive interglacial cycle? e.g. vegetation succession in mid to late Quaternary interglacials in Britain

  11. Does an increase in Pinus signal the end of an interglacial? Kirchner Marsh, MINN.

  12. Long cores from temperate forest areas 60°N 45°N 30°N 15°N Eq. 15°S 30°S 45°S > 50 ka >100 ka 60°S

  13. Pollen record, Lago di Monticchio (Italy) from: PAGES website

  14. Pollen record, Grande Pile (France) From: Guiot (1998) Nature 388, 25-27.

  15. Pollen record, Lake Biwa (Japan) Pinus = cool indicator; Cryptomeria = warm Indicator; Artemisia -grass-herb (not shown) “steppe/tundra” in full-glacial phases

  16. Pollen record, Carp Lake, WA. from: Whitlock and Bartlein (1997) Nature, 388, 57-61.

  17. from: Whitlock and Grigg, in: Webb et al., (1999) Mechanisms of Global Change at Millenial Time Scales, AGU Monograph, p 227-241.

  18. Heinrich events recorded at Lake Tulane, FLA.

  19. Present (potential)vegetation of North America Biome maps from: www.esd.ornl.gov/projects/qen

  20. LGM vegetation(18 ka 14C yrs BP):North America

  21. Present (potential)vegetation of Europe

  22. LGM vegetation(22-14 ka 14C yrs BP):Europe

  23. LGM (a) and present (b) pollen and vegetation (c,d) patterns in East Asia from: Harrison et al. (2001) Nature 413, 129-130. NB continental shelf extent

  24. Reconstructing LGM refuges and post-glacial migrations: isopoll data from: Davis and Shaw (2001) Science 292, 673-679.

  25. LGM refuges (R) and post-glacial isochrons in eastern North America. Where there separate Atlantic and Gulf refuges? R? R? White pine Oaks R? R? E. hemlock Elms

  26. How quickly did trees migrate in eastern North America in the post-glacial? Jack/Red pine White pine Spruce Larch Elm Hemlock Balsam fir Maple Beech Oak Hickory Chestnut 0 100 200 300 400 500 m / yr Data: Davis; in West et al. (1980) “Forest Succession: Concepts and Applications”. Springer-Verlag p. 153; and Delcourt and Delcourt (1987) “Quaternary Ecology” (after Webb, 1986)

  27. (a) (b) (c) (=a x b) (=a x c)

  28. 500 400 300 200 100 0 Was the rate of post-glacial migration controlled by rates of climatic change or seed size? jack pine m / year red pine white pine larch spruce elm maple fir hemlock hickory beech oaks chestnut Data: see previous slide and USDA (1974) “Seeds of Woody Plants in the United States” Agric. Handbook No. 450. 1 10 100 1 000 10 000 seed wt. (mg)

  29. blue jay passenger pigeon Are seed-caching birds the main agents of dispersal in post-glacial time for ‘nut trees’? Quercus macrocarpa see: Webb (1986) Quat. Res. 26, 367-375 for discussion Fagus grandiflora

  30. Postglacial fossil finds:passenger pigeon (dots) and blue jay (triangles ) from: Delcourt and Delcourt (1987) “Quaternary Ecology”

  31. Were some endochorous temperate trees marooned? (i.e. refugial relicts?) e.g. Maclura pomifera (osage orange) fruit weighs up to 1 kg Range Source: USDA Handbook - Silvics of Forest Trees

  32. Was this a product of the extinction of potential megafaunal vectors? e.g. Megalonyx jeffersoni (Jefferson’s ground-sloth) extinct by 10ka BP

  33. Did post-glacial migration result in reduced genetic diversity in northern populations? Allelic diversity Colonization date in ka BPfrom pollen data low high from: Cwynar and MacDonald (1988) Amer. Nat. 129, 463-469.

  34. Which refugial populations supply the migrants?e.g.Fagus crenata(a montane species during interglacials) recolonized northern Honshu and Hokkaido from northern coastal refuges after LGM LGM coastal refuges from: Davis and Shaw (2001) Science 292, 673-679.

  35. Hypothetical refugia and migration paths of Alnus rubra since the LGM based on genetic variation from: Hamann et al., (1998) Can. J. Forest Res., 28, 1557-1565.

  36. Post-glacial colonization routes of tree species based on DNA variation Fagus sylvatica Quercus sp. Taberlet et al., (1998) Molecular Ecology 7, 453-464

  37. Post-glacial colonization routes of tree species based on DNA variation Abies alba Picea abies Taberlet et al., (1998) Mol. Ecol. 7, 453-464; Scottii et al. (2000) Mol. Ecol. 9, 699-708.

  38. Post-glacial colonization routes of animals based on DNA variation from: Hewitt (2000) Nature, 405, 907-913.

  39. Post-glacial colonization routes of animals and subsequenthybrid contact zones from: Hewitt (2000) Nature, 405, 907-913.

  40. Extinction: Picea critchfeldii wasa dominant tree in eastern North America in LGM; it died outabout 15 000 cal. yrs BP Above: cross-sections of needles (E-G are P. critchfeldii). Left: cones of P. critchfeldii From: Jackson and Weng (1999) Proc. Nat. Acad. Sci. US, 96, 13847-13852.

  41. Why is the European forest depauperate? E N Am Europe E Asia X X X X X X X X X X X X X F X X X X X X X X X X X F X X F X Quercus (oak)Acer (maple)Fagus (beech)Castanea (chestnut)Carya (hickory) Ulmus (elm) Tilia (basswood) Juglans (walnut) Liquidambar (sweet gum) Nyssa (sour gum) X = extant; F = fossil

  42. Quaternary extinctions of trees in the Netherlands loss of sub-tropical genera

  43. Causes of Quaternary plant extinctions 1. Abrupt climate change? 2. Barriers to migration (e.g. E-W mountain ranges)? 3. Loss of seed dispersal agents?

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