One significant source of annual temperature and precipitation data arises from the regular annual secondary growth rings of trees. Several tropical tree species are observed to form regular growth bands that may or may not form annually. Such growth was observed in one stem disk of the tropical legume Hymenaea courbaril near the area of David, Panama. In comparison to annual reference {Delta}{sup 14}C values from wood and air, the {Delta}{sup 14}C values from the secondary growth rings formed by H. courbaril were determined to be annual in nature in this one stem disk specimen. 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 {Delta}{sup 14}C values of these transitional growth rings as cellulose with a higher {Delta}{sup 14}C content is translocated into growth rings with a relatively lower {Delta}{sup 14}C content. Once the annual nature of these growth rings is established, further stable isotope analyses on H. courbaril material in other studies may help to complete gaps in the understanding of short and of long term global climate patterns

Colinvaux, P. A.

Guilderson, T. P.

Westbrook, J. A.

UNT Digital Library

UCRL-JRNL-202325Annual Growth Bands inHymenaea courbarilJ. A. Westbrook, T. P. Guilderson, P. A. ColinvauxFebruary 12, 2004International Association of Wood Anatomists BulletinDisclaimer   This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.  Annual Growth Bands in Hymenaea courbarilJessica A. WestbrookDepartment of Plant BiologyUniversity of California, DavisThomas P. GuildersonCenter for Accelerator Mass Spectrometry, LLNL& Department of Ocean Sciences, University of California, Santa CruzPaul A. ColinvauxMarine Biological LaboratoriesWoods Hole MASummaryOne significant source of annual temperature and precipitation data arises fromthe regular annual secondary growth rings of trees.  Several tropical tree species areobserved to form regular growth bands that may or may not form annually.  Such growthwas observed in one stem disk of the tropical legume Hymenaea courbaril near the areaof David, Panama.  In comparison to annual reference D14C values from wood and air, the∆14C values from the secondary growth rings formed by H. courbaril were determined tobe annual in nature in this one stem disk specimen.  During this study, H. courbaril wasalso observed to translocate recently produced photosynthate into older growth rings assapwood is converted to heartwood.  This process alters the overall ∆14C values of thesetransitional growth rings as cellulose with a higher ∆14C content is translocated intogrowth rings with a relatively lower ∆14C content.  Once the annual nature of thesegrowth rings is established, further stable isotope analyses on H. courbaril material inother studies may help to complete gaps in the understanding of short and of long termglobal climate patterns.IntroductionThe intimate coupling of the tropical surface ocean and the overlying atmosphericboundary layer implicitly links variations in atmospheric characteristics to the underlyingsea surface temperature (SST) field and local heating.  Warm ocean waters provide latentand sensible heat to the atmosphere, which localizes convection and drives surfaceconvergent winds.  Convection exports moisture, which eventually precipitates outproviding a freshwater source to the surface and a warming and drying of the atmosphere.The Amazon basin, southeast Africa, and Indonesia and the western tropical Pacific playimportant roles in the localization of deep atmospheric convective activity.  The tropicsas a whole are a major exporter of latent and sensible heat to both hemispheres.  Oninterannual (e. g. El Nino-Southern Oscillation, Atlantic dipole) and longer-timescales,the export of sensible and latent heat out of the convective regions is linked to globalclimate through atmospheric teleconnections.  Thus, variations in tropical ocean-atmosphere interactions have the capability to orchestrate worldwide climate variabilityover a range of timescales.Instrumental records of key environmental variables such as temperature andprecipitation are necessary to understand climate patterns and variability.  In general,such observations from the tropics do not exist prior to the late 19th century, and existingrecords contain large special and temporal gaps and are sparsely distributed.  Animportant source of annual temperature and precipitation data comes from the regularannual growth rings of wood formed by trees.  Tree growth rings occur in response toperiodic seasonal changes in the environment (eg Jacoby, 1989).  Although expansiveand diverse in numbers and ecology, a vast majority of tropical trees do not producedistinct annual growth rings.  Because of this, tropical dendrochronology andpaleoclimate reconstructions have lagged behind their temperate and higher latitudecousins.  However, some tropical tree species form growth bands, which couldpotentially be sources of data for climate studies if these growth bands form annually.For example, teak (Tectona grandis) and mountain pine (Pinus kesiya and Pinusmerkusii) found in areas of Indonesia and Thailand have been shown to produce annualrings that relate to monsoonal climate and ENSO variations (e. g. Buckley et al. 1995,D’Arrigo et al. 1994 & 1997, Stahle et al. 1998).Hymenaea courbaril is a large hardwood tree within the legume family Fabaceae.This species is widespread in Central and South America, with related species inMadagascar and Africa (Lewis, 1987).  These trees display some form of lateral bandedgrowth.  The Panama area experiences a yearly dry season that may induce annualgrowth rings in H. courbaril.  One stem disk from one H. courbaril tree harvested fromthis country in 1997 was observed to form regular lateral growth bands (Fig. 1).  In orderto determine the annual nature of these lateral bands, radiocarbon (14C) analyses wereperformed on each lateral increment zone of this stem disk and compared to atmospheric14C data to determine if the growth bands formed by this tropical species were annual innature.  If the bands in this tree species are confirmed to be annual, it may be possible touse it along with related species in multi-proxy climate reconstructions.Materials and MethodsA stem disk Hymenaea courbaril felled in September 1997 was obtained fromcolleagues Paul Colinvaux and Eduardo Montenegro.  This single specimen was fellednear the city of David, Panama (8º 26’ N, 82º 26’W).  Initial visual inspection indicatedthat this stem disk of H. courbaril consisted of 51 increment zones.  Bands thatmaintained circuitry were assumed to be true annual growth bands and were given a yearrelative to when the tree was felled following the 1997 growing season.  Samples ofwood were taken from each increment zone and treated with a modified deVriestreatment of alternate acid and base treatments of 1N HCl and 1N NaOH at 90°C,followed by repeated rinsing with deionized (Milli-Q) water to remove wood lignins(Hoper et al. 1998).  Approximately 2.5mg of pretreated wood for each sample wascombusted with CuO and Ag to form CO2 gas in an evacuated and sealed quartz test tube.CO2 from each combusted sample was reduced to elemental carbon in the form ofgraphite with H2 gas in the presence of Fe catalyst (Vogel 1989). D14C values weredetermined for each graphite target at the Center for AMS, LLNL (Davis et al. 1990) andwere reported in accordance with Stuiver and Polach (1977).  The D14C reported valuesinclude a background subtraction determined from 14C free coal and a d13C correction.To present a more representative comparison with atmospheric D14C data, the tree ringdata are presented as age corrected described in Stuiver and Polach (1977).  In order toassess chemical pretreatments, a small subset of samples were processed to holocellulosewith an additional acid-bleach pretreatment prior to  graphitization and were thencompared to D14C data of the same increment zones receiving only the standard acid andbase pretreatment.ResultsD14C values were determined for each wood increment zone of H. courbaril, witheach increment zone assumed to represent the growth during one year (Fig. 2).  The D14Cvalues form a distinct curve with an amplitude of ~550‰.  The maximum D14C value is~650‰ at the increment zone representing the 1967 growing season.  The minimum D14Cvalue is 106‰ which occurred in the last growth increment zone representing the 1997growing season.  A small and distinct peak in the D14C values occurs in the incrementzones that represent growth in years in the late 1950s.DiscussionsThe D14C values of H. courbaril were compared to D14C values of atmosphericCO2 samples from Wellington New Zealand (Manning and Melhuish, 1994),Vermunt/Schaunisland Germany (Levin et al., 1994), and tree-ring based measurementsfrom Olympic Peninsula firs (Stuiver and Quay, 1981).  Aboveground nuclear bombtesting in the Northern Hemisphere in the late 1950s and early 1960s created a spike inatmospheric 14C.  14C in the atmosphere in the form of CO2 is taken up and incorporatedinto wood cellulose in plants through photosynthesis.  The elevated D14C values observedin wood increment zones were a result of the incorporation of elevated 14C levels inatmospheric CO2 during this time.  It is expected that the tree ring based record will bearmore of a resemblance to the southern hemisphere atmospheric record due to themigration of the intertropical convergence zone (ITCZ) and the intense recycling of airmasses associated with convection.  In comparing wood samples of H. courbaril to thereference data, the similarity of D14C values of the two data sets suggest that H. courbarilforms lateral growth rings that are annual in nature.H. courbaril D14C values form a small and distinct elevated spike in the late 1950sthat does not correspond to the D14C values of some of the reference data.  This variationis most likely due to the translocation of photosynthate from younger wood having ahigher D14C content into older growth rings as sapwood is converted to heartwood.  Asimilar observation was made by Worbes and Junk regarding the D14C values of woodfrom trees in Costa Rica and Venezuela (1989).  Many trees translocate photosynthatefrom the cambial region to interior growth bands where it is stored for later use asresinous compounds.  Incomplete removal of these compounds during wood pretreatmentleads to a compromised carbon isotopic record when there is a large D14C differencebetween the respective years.  This trend has been extensively observed in d13C studies ofoak (Quercus) and cedar (Librocedrus) (Hoper et al., 1998 and references therein), aswell as in the study of Worbes and Junk (1989).  Chemical pretreatments can be used toremove these compounds, resulting in a reliable tree ring a-cellulose based 14C recordcomparable to representative air flask samples (e. g. Stuiver and Quay, 1981).  In thisstudy, samples from the late 1950s that were converted to holocellulose had lower D14Cvalues that were more representative of the atmosphere reference records.ConclusionsIn comparison with the D14C values of wood increment zones in H. courbaril withD14C reference values of known annual nature, this stem disk of H. courbaril appears toform annual lateral growth rings.  The formation of this annual growth is likely due toannual wood dormancy induced by a seasonal yearly dry season in the Panama area.Only one stem disk of H. courbaril was examined in this study.  In order to confirm aconsistent annual growth ring pattern within this tropical hardwood species, similaranalyses of additional H. courbaril specimens must be completed.  Once the annualnature of H. courbaril lateral growth bands is confirmed, its D14C record may be crossreferenced with similar H. courbaril wood samples from different tropical regions inorder to assess any D14C value differences that are induced by environmental differences.H. courbaril trees and other related plant species are widespread throughoutvarious tropical regions of the world.  If H. courbaril and related species of the genusHymenaea are proved to form annual growth rings in multiple tropical environments,increment wood samples may be analyzed for various stable isotopes to be used in otherclimate and paleoclimate studies.  These data help to fill spatial and temporal gaps in theclimate record that is necessary in understanding short and long term global climatepatterns and variability.AcknowledgementsFunding for this research was provided by the University of California’s DirectedResearch and Development Program.  Radiocarbon analyses were performed under theauspices of the U.S. Department of Energy by the University of California LawrenceLivermore National Laboratory (contract W-7405-Eng-48).ReferencesBuckley, B., M. Barbetti, M. Watanasak, R. D’Arrigo, S. Boonchirdchoo, & S.Sarutanon. 1995. Preliminary dendrochronological investigations in Thailand. IAWABull. 16: 393--409.D’Arrigo, R., G.C. Jacoby, & P.J. Krusic. 1994. Progress in dendroclimatic studies inIndonesia. TAO. 5: 349--363.D’Arrigo, R., M. Barbetti, M. Watanasak, B. Buckley, P. Krusic, S. Boonchirdchoo, & S.Sarutanon. 1997. Progress in dendroclimatic studies of mountain pine in northernThailand. IAWA Bull. 18: 433--444.Davis, J. C., et al.., 1990.  LLNL/UC AMS facility and research program.  NuclearInstruments and Methods in Physics Research, Sect. B, 52: 269--272.Hoper, S.T.,  F. G. McCormac, A. G. Hogg, T. F. G. Higham & M. J. Head 1998.Evaluation of wood pretreatments on Oak and Cedar, Radiocarbon, 40: 45--50.Jacoby, G.C. 1989. Overview of tree-ring analysis in tropical regions. IAWA Bull. 10:99--108.Levin, I., B. Kromer, H. Schoch-Fischer, M. Bruns, M. Münnich, D. Berdau, J.C. Vogel& K.O. Münnich, 1994  14CO2 observstions from Schauinsland, Germany and Vermunt,Austria.  In: Trends ‘93: A Compendium of Data on Global Change, ORNL/CDIAC-65T. A. Boden  (ed)., Carbon Dioxide Inf. Anal. Cent., Oak Ridge National Laboratory,Oak Ridge, TN.Lewis, G.P. 1987. Legumes of Bahia. Royal Botanical Gardens, Kew, London.Manning, M. R., & Melhuish, W.H., 1994.  Atmospheric D14CO2 record fromWellington. In: Trends ‘93: A Compendium of Data on Global Change, Pub.ORNL/CDIAC-65. T. A. Boden  (ed)., Carbon Dioxide Inf. Anal. Cent., Oak RidgeNational Laboratory, Oak Ridge, TNStahle, D.W., R.D. D’Arrigo, P.J. Krusic, M.K. Cleaveland, E.R. Cook, R.J. Allan, J.E.Cole, R.B. Dunbar, M.D. Therrell, D.A. Gay, M.D. Moore, M.A. Stokes, B.T. Burns, &L.G. Thompson. 1998.  Experimental reconstruction of the Southern Oscillation. Bull.Amer. Met. Soc. 79: 2137--2152.Stuiver, M., & H.A. Polach. 1977. Discussion: reporting of 14C data. Radiocarbon. 19:355--363.Stuiver, M., & P.D. Quay. 1981. Atmospheric 14C changes resulting from fossil fuel CO2release and cosmic ray flux variability. Earth and Planetary Science Letts. 53: 349--362.Vogel, J. S., Southon, J. R., and Nelson, D. E., 1987.  Catalyst and binder effects in theuse of filamentous graphite for AMS. Nuclear Instruments and Methods in PhysicsResearch, Sect.B, 29, 50-56.Worbes, M. & W.J. Junk. 1989. Dating tropical trees by means of 14C from bomb tests.Ecology. 70: 503- -507.Figure CaptionsFig. 1.  Cross section of a specimen of H. courbaril felled in the fall of 1997 near David,Panama (43.2 x 35.6 cm nominal elliptical axis dimensions).  The visible densityvariations are consistent with the bands being delimited by parenchyma tissue.Fig. 2.  ∆14C data of H. courbaril increment zones compared to the reference ∆14C data ofwood and air samples of known annual origin.  Closed circles represent data from H.courbaril material pretreated with the deVries method, and open circles represent datafrom H. courbaril material pretreated with an additional acid-bleach treatment toholocellulose. Air flask data are from Europe (Levin et al., 1994), and Wellington(Manning and Mellhuish, 1994).  Pre-bomb tree-ring data are from Stuiver and Quay(1981).Fig. 1.Fig. 2

Annual Growth Bands in Hymenaea courbaril

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Annual Growth Bands in Hymenaea courbaril

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