Competitive Advantages of Metasequoia in Warm High Latitudes

Abstract

Although the fossil remains of several conifer species have been found from numerous lowland Eocene sites throughout the very high latitudes (above 75° N), many were rarities, and only Metasequoia Miki appeared to have thrived under the warm and unique lighting conditions of the High Arctic regions of the Northern Hemisphere. To estimate the relative competitiveness of the fossil conifers, mechanical/hydraulic stem attributes, photosynthetic water-use-efficiency and photobiology were compared among extant nearest-living-relatives: Metasequoia glyptostroboides Hu et Cheng, Sequoia sempervirens (D. Don) Endlicher, Taxodium distichum (L.) Richard, Glyptostrobus pensilis (Staunton ex D. Don) K. Koch and Larix laricina (Du Roi) K. Koch. Based on these physiological comparisons we conclude that Taxodium Richard would have been limited primarily by a significant decrease in photosynthetic efficiency when growing under continuous light. Sequoia Endlicher should have been highly competitive, but was likely limited by its evergreen habit. Glyptostrobus Endlicher would have been restricted to minor component status by its slow growth rate and short stature. Finally, although Larix Miller demonstrated improved water-use-efficiency under continuous light, it had a less-competitive photobiology than Metasequoia, and sequestered more resources into stem biomass.