Annual Growth Rings in a Sample of Hymenaea Courbaril
2006
Westbrook, Jessica A. | Guilderson, Thomas P. | Colinvaux, Paul A.
Several tropical tree species form regular growth rings that may be annual and thus be useful in paleoclimate reconstructions. Regular growth rings were observed in one stem disk of the tropical legume Hymenaea courbaril harvested near the city of David, Panama. By comparison to annual reference Δ₁₄C values from temperate tree wood and air, Δ₁₄C values from the growth rings in this H. courbaril sample indicated the rings were annual. During this study, H. courbaril was also observed to translocate recently produced photosynthate into older growth rings as sapwood is converted to heartwood. This process alters the overall Δ₁₄C values of these transitional growth rings as organic carbon with a higher Δ₁₄C content is translocated into growth rings with relatively lower Δ₁₄C content. Proper chemical pretreatment can recover the original cellulose Δ₁₄C content.
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