Wood Anatomy of Metasequoia - Separation from Glyptostrobus and Function/Structure Considerations

• Main Author: Visscher, George E.
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2002
• Subjects: Metasequoia; Paleo-forest dynamics; Forest Sciences; Plant Sciences; Arctic; Axel Heiberg Island; Canada; Heiberg; Nunavut
• Online Access: https://digitalcommons.library.umaine.edu/etd/471; https://digitalcommons.library.umaine.edu/context/etd/article/1467/viewcontent/VisscherGH2002.pdf

This thesis is part of a broader cooperative study aimed at understanding Paleo-forest dynamics -- namely those of the Eocene period in the Canadian High Arctic. Wood of the dominant tree species -- Metasequoia -- that grew on Axel Heiberg Island, Nunavut, Canada is the focus of this research. The text is divided into two chapters written as articles to be submitted to the International Association of Wood Anatomists Journal (IAWA). The first chapter of this text is a direct result of classifying the fossil wood of Axel Heiberg. The wood of Glyptostrobus is similar to that of Metasequoia. Because both trees grew on the same sites, it was vital to be able to separate the wood of these species. We obtained extant wood samples of these relatively rare woods from herbaria around the world, tested previously published descriptions, and report observations that more consistently separate these species. The second chapter of this text discusses the xylem strategies of Metasequoia. Because Metasequoia is a tall tree with a high water demand, its wood must be sufficiently strong, and provide the canopy with enough water to meet its needs. A microscopic analysis of tracheid parameters provides evidence for postulating strength and hydraulic conductance functions. The results indicate that Metasequoia possesses unique specific gravity and microfibril angle trends that may be adaptive strategies for this species at its unique high latitude sites. We have shown that as Metasequoia trees increase in diameter and height, they produce tracheids that concomitantly strengthen and potentially improve hydraulic efficiency. This finding provides a new perspective on the strengthhydraulic conductance compromise proposed by other researchers, and demonstrates a strategy of strength enhancement that does not involve significant latewood production.