2003 Seattle Annual Meeting (November 25, 2003)
Paper No. 106-9
Presentation Time: 3:45 PM-4:00 PM

DECIDUOUS AND EVERGREEN HABIT FOR CRETACEOUS POLAR CONIFERS?

FRANCIS, J.E.1, HARLAND, B.M.1, BEERLING, D.J.2, and BRENTNALL, S.2, (1) School of Earth Sciences, Univ of Leeds, Leeds, LS2 9JT, j.francis@earth.leeds.ac.uk, (2) Animal and Plant Sciences, Univ of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN

For most of the geological past high latitude regions were covered by dark dense forests. These forests would have significantly modified both the polar and global climate due to their low albedo and their effect on the land-surface heat budget and hydrological cycle. The leaf life span of conifers and their deciduous or evergreen habit would have played a significant part in this feedback. However, in the past this habit has been difficult to assess in fossil floras. A new technique that characterises the cell patterns within growth rings in fossil wood, developed by Falcon-Lang, can be used to determine whether fossil conifers were deciduous or retained their leaves for several years. This technique has now been applied to Early Cretaceous conifer wood from Svalbard. Analyses of tree taxa and growth rings indicate that the conifers, including for example Piceoxylon, Cedroxylon and Juniperoxylon, grew under strongly seasonal and often variable climates. The conifers had an evergreen habit, even though they lived at palaeolatitudes of ~70N. This would have primed them for photosynthetic activity as soon as ambient conditions, especially light, reached suitable levels and was likely to have been an important strategy for survival.

2003 Seattle Annual Meeting (November 25, 2003)
Session No. 106
Multi-Proxy Terrestrial Records and the Ocean-Climate System: Links and Perturbations in the Cretaceous
Washington State Convention and Trade Center: 609
1:30 PM-5:30 PM, Monday, November 3, 2003

Geological Society of America Abstracts with Programs, Vol. 35, No. 6, September 2003, p. 290

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