DOCSLIB.ORG

Physiological Influences on Carbon Isotope Discrimination in Huon Pine (Lagarostrobos Franklinii)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physiological Influences on Carbon Isotope Discrimination in Huon Pine (Lagarostrobos Franklinii) Oecologia (Berlin) (1985) 66 :211-218 Physiological influenceson carbon isotope discrimination in huon pine (Lagarostrobos franklinii) R.J. Franceyl, R.M. Gifford2, T.D. Sharkey3*, and B. Weir3 I CSIRO Division of AtmosphericResearch, Private Bag No. 1, Mordialloc, Victoria, 3195,Australia 2 CSIRO Division of Plant Industry, P.O. Box 1600, Canberra City, A.C.T. 2601, Australia 3 Department of EnvironmentalBiology RSBS,Australian National University,P.O. Box 475, CanberraCity, A.C.T. 2601,Australia Summary. Measurements of the light environment and sto- plants were accurately predictable, then the d13C value of matal and photosynthetic behaviour are reported for Huon tree-rings from long tree ring records would provide infor- Pine (Lagarostrobos franklinii, family Podocarpaceae) in mation on past atmosphericdi3C values. western Tasmanian rainforest. For a variety of microenvi- Penget al. (1983)give an excellentsummary of the con- ronments, these are used in an analysis of stable carbon troversy surrounding the global carbon budget (and in par- isotope measurements in the air, and in branch and leaf ticular the CO, arising from fossil fuel combustion versus material, using a model for carbon isotope fractionation forest removal), and of the attempts to seeka solution using in leaves(Farquhar etal.1982). tree ring d13Crecords. The major features of d13C variations with respectto A serious diffrculty with the deconvolution of tree ring branch position can be explained in terms of the direct d13C variations to give atmosphericvariations is evident, influence of light level acting via the rate of CO, assimila- for example,in a comparison of the tree ring d13C results tion. In addition a relatively constant d13C gradient of of Freyer (1979)and Francey (1981).Each describescoher- aboat 2.61o between leaf tip and branch wood is observed. ent d13Ctrends over the last 1-2 centuriesusing many trees Alternative explanations are advanced for the tip-to- from their respective regions. Freyer's trees from Europe wood gradient in d13C. If the d13C of leaf tips is taken and USA indicate a large consistentd13C decline of almost to represent the value for photosynthate, maintenance res- 2/oobetween 1850 and 7975 A.D., while Francey's results piration is proposed as a mechanism for the further frac- from Tasmania indicate a practically constant d13C over tionation; a significant 13C depletion in respired CO, is the same period (a decline of more than about 0.21, is implied which is not supported by indirect measurements excluded). of atmospheric isotope ratio. Furthermore, an assumption Inherent in most published deconvolutions of atmo- of significant sampling errors (e.g. related to humidity ef- sphericCO, from tree rings (e.g.Stuiver 7978,Freyer7979, fects on assimilation) is required to obtain good quantita- Peng et al. 1983)is an assumption that on average,fraction- tive prediction of the light influence. ation by plant processesis constant.Tans and Mook (1980) If the branch wood d13C is taken to representthat of and Leavitt and Long (1983) empirically allow for "local the photosynthate, the tip-to-wood gradient may hnd an influences" by removing variance associatedwith tempera- explanation, via the model, in terms of tip tissue comprising ture and precipitation records (generally available over re- carbon from immature cells. Translocation of photosyri- cent decadesonly, and even then, typically accounting for thate from exposed to shaded branches is then proposed a small proportion of the variance). In addition, there is as a means of obtaining quantitative agreement with the a consistentbias towards selectionof isolated trees based predicted light infl uence. on unsupported assumptions concerning build up of re- The support provided for the applicability of the Farqu- spiredCO, around photo-synthesizingtrees in a forest. har et al. (1982)model in the field is discussedin the context Following a suggestion(Francey 1981) that variations of the problem of obtaining past global atmospheric CO, in the carbon isotope fractionation by the tree might explain levelsfrom d13Cin tree-rinss. the differences in tree-ring isotopic trends, the purpose of this work is to examinethe physiologicalaspects of carbon isotope fractionation in Huon Pine (Lagarostrobosfrank- linii; Quitn 1982).Huon Pine is a long-lived speciescon- The d13C value of a tree-ring reflects the carbon isotope f,rnedmainly to river margins in southwest Tasmania. The ratio of CO, in the atmosphereat the time the carbon longevity ofindividual trees, the ability to cross date annual was fixed, and the fractionation of CO, by plant processes rings, the frequent dominance of individual specimensin which occur between the time carbon is f,rrstfixed and when the rainforest community and the abundance of fallen and it is eventually laid down in the tree ring (Farquhar etal buried logs (which are particularly resistant to decay) con- 1982; Francey and Farquhar 1982). If fractionation by tribute to the value of Huon Pine for isotope studies over recent millenia. Offprint requestsro.' R.J. Francey The gas exchange characteristics of Huon Pine leaves * Present address: Desert Research Institute, P.O. Box 60220 were measured for different light intensities, age of shoot, Reno, Nevada 89506-0200,USA and position within the canopy and are comparedto dl3C 212 values of leavesand wood from correspondinsmicroenvi- Table 1. Average dayJong(14.2 h) photosynthetic photon flux den- ronments. The comparison is basedon the Faiquhar et al. sities (PPFD) and daily fluxes at an exposed site overlooking the (1982)model of carbon isotope discrimination during pho- StanleyRiver Valley in 1981 tosynthesis,in which dl3C of the photosynthateis relrated primarily to CrfCo, the ratio of internal to external CO, Date Average photon flux density Flux (pmol concentrations for a leaf. The measurementsform part ol m-2 s-1) (mol m-2) a major study of isotopes in tree rings, focussed on Huon 4 February 121 o 5 February 820 ia 6 February 930 49 7 February 885 40 Thus the highest hour-long PPFD which the seedling Methodology and measurements was ever likely to experiencewas about 60 pmol m-, s-1 which in plant physiologicalterms is very low indeed (com- This section briefly summarizesrelevant technical informa- 'full pared to >2,000 pmol m-2 s-1 in sun'). An average tion from Francey et al. (1984),and includesmeasurement hour-long PPFD during daylight of between i and 20 pm-ol resultsto be discussed. m-2 s-t is more likely during the summer months. Occa- sional sunfleckswere observedat both sub-canopy sites, Expedition details with the highest instantaneous PPFD neat the seedlins ob- servedat approximately 150 pmol Several expeditions have been mounted to a small area of m-2 s-1. rainforest on the Stanley River. The site is 19 km from the Tasmanian west coast in an atea largely free of human Leauesand stomata of huonpine influenceprior to 1970.Prevailing winds are south westerly The "needles" of Huon Pine and the composition of the troposphere representsthat of are thin stems completely ensheathedby overlapping air over the vast southern oceansto a large extent. Rainfall bractJike leaves.The leavesare arranged in a spiral with three is high, typically around 1,900 mm per yeat, with 190 adjacent leaves forming ap- proximately one whorl of the spiral cloudy days (> 75o/ocloud cover) and annual averagedaily around the stem. On sunshineduration of 4.8 h. each bractlike leaf, stomata were found to occur on an adaxial surface (with poor Atmospheric composition, light level and stomatal con- exposure to the open atmo- . sphere), and on the ductance measurementswere first made during February abaxial surface in two frelds divided by a ridge running length-wise 1981. Full gas exchangecharacteristics of attached shoots down the leaf. The epidermis was covered with a thick were measuredin the field in February 1982.Leaf atd wood waxJike layer, in some places completely obscuring samplesfor d13C analyseswere collected on both expedi- stomata, elsewhere only partially blocking holes over stomata. tions, as were seedlingsfor propagation and further mea- We have not been able to look at guard cellsof Huon Pine. surementsunder controlled conditions. Atmospheric com- position measurementswere continued in September1982. Slomatal conductance measurements ( February 19 8 1 ) Characteristicsof the light enuironment(February 1981) Stomatal conductance was estimated using a ventilated dif- Quantum flux density in the photosynthetically active wave- fusion porometer.Leaves were selectedfrom both seedlings band 400-700 nm, was measured on a treelessridge over- and mature trees, from low in the forest to high in the looking the StanleyRiver, and 10 minute integralsrecorded canopy, and from various degreesof shadingranging from continuously over four days. Resulting photosynthetic pho- permanently well-illuminated to permanently shady. With ton average fluxes, and flux densities (PPFD), are summa- Huon Pine it was necessaryto obtain a successionof esti- rized inTable 1. mates over 5-10 min and to exttapolate back to insertion It was raining on February 4 until mid-morning and time as the readings began to decline immediately after in- overcast all day. On February 5 7 it was sunny with scat- sertion of individual needlesinto the porometer; first read- tered cloud. This is atypical for the region which averages ings were taken within 30 s of insertion. Measured needles only 3 clear days(<25o/o cloud cover)per month over sum- were subsequentlyharvested and a micrometer used to esti- mer. mate projected leaf area. At each location light intensity Concurrent measurements were made at two forest- was determined using a pocket light meter, calibrated in floor locations,one having very little, and the other moder- sunlight againstthe quantum sensors. ate understory vegetation.At the frrst of thesesites 1.40% No clear pattern of conductances could be discerned of the (diffuse) incident photons reached the forest floor with respectto leaf position in the canopy. The entire data on the overcastday. On February 5 under bright conditions set are plotted against light intensity in Fig.
Load more

Recommended publications
  • Evolution of the Female Conifer Cone Fossils, Morphology and Phylogenetics
    DEPARTMENT OF BIOLOGICAL AND ENVIRONMENTAL SCIENCES EVOLUTION OF THE FEMALE CONIFER CONE FOSSILS, MORPHOLOGY AND PHYLOGENETICS Daniel Bäck Degree project for Bachelor of Science with a major in Biology BIO602, Biologi: Examensarbete – kandidatexamen, 15 hp First cycle Semester/year: Spring 2020 Supervisor: Åslög Dahl, Department of Biological and Environmental Sciences Examiner: Claes Persson, Department of Biological and Environmental Sciences Front page: Abies koreana (immature seed cones), Gothenburg Botanical Garden, Sweden Table of contents 1 Abstract ............................................................................................................................... 2 2 Introduction ......................................................................................................................... 3 2.1 Brief history of Florin’s research ............................................................................... 3 2.2 Progress in conifer phylogenetics .............................................................................. 4 3 Aims .................................................................................................................................... 4 4 Materials and Methods ........................................................................................................ 4 4.1 Literature: ................................................................................................................... 4 4.2 RStudio: .....................................................................................................................
    [Show full text]
  • Pollination Drop in Relation to Cone Morphology in Podocarpaceae: a Novel Reproductive Mechanism Author(S): P
    Pollination Drop in Relation to Cone Morphology in Podocarpaceae: A Novel Reproductive Mechanism Author(s): P. B. Tomlinson, J. E. Braggins, J. A. Rattenbury Source: American Journal of Botany, Vol. 78, No. 9 (Sep., 1991), pp. 1289-1303 Published by: Botanical Society of America Stable URL: http://www.jstor.org/stable/2444932 . Accessed: 23/08/2011 15:47 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Botanical Society of America is collaborating with JSTOR to digitize, preserve and extend access to American Journal of Botany. http://www.jstor.org AmericanJournal of Botany 78(9): 1289-1303. 1991. POLLINATION DROP IN RELATION TO CONE MORPHOLOGY IN PODOCARPACEAE: A NOVEL REPRODUCTIVE MECHANISM' P. B. TOMLINSON,2'4 J. E. BRAGGINS,3 AND J. A. RATTENBURY3 2HarvardForest, Petersham, Massachusetts 01366; and 3Departmentof Botany, University of Auckland, Auckland, New Zealand Observationof ovulatecones at thetime of pollinationin the southernconiferous family Podocarpaceaedemonstrates a distinctivemethod of pollencapture, involving an extended pollinationdrop. Ovules in all generaof the family are orthotropousand singlewithin the axil of each fertilebract. In Microstrobusand Phyllocladusovules are-erect (i.e., the micropyle directedaway from the cone axis) and are notassociated with an ovule-supportingstructure (epimatium).Pollen in thesetwo genera must land directly on thepollination drop in theway usualfor gymnosperms, as observed in Phyllocladus.In all othergenera, the ovule is inverted (i.e., the micropyleis directedtoward the cone axis) and supportedby a specializedovule- supportingstructure (epimatium).
    [Show full text]
  • Methods for Measuring Frost Tolerance of Conifers: a Systematic Map
    Review Methods for Measuring Frost Tolerance of Conifers: A Systematic Map Anastasia-Ainhoa Atucha Zamkova *, Katherine A. Steele and Andrew R. Smith School of Natural Sciences, Bangor University, Bangor LL57 2UW, Gwynedd, UK; [email protected] (K.A.S.); [email protected] (A.R.S.) * Correspondence: [email protected] Abstract: Frost tolerance is the ability of plants to withstand freezing temperatures without unrecov- erable damage. Measuring frost tolerance involves various steps, each of which will vary depending on the objectives of the study. This systematic map takes an overall view of the literature that uses frost tolerance measuring techniques in gymnosperms, focusing mainly on conifers. Many different techniques have been used for testing, and there has been little change in methodology since 2000. The gold standard remains the field observation study, which, due to its cost, is frequently substituted by other techniques. Closed enclosure freezing tests (all non-field freezing tests) are done using various types of equipment for inducing artificial freezing. An examination of the literature indicates that several factors have to be controlled in order to measure frost tolerance in a manner similar to observation in a field study. Equipment that allows controlling the freezing rate, frost exposure time and thawing rate would obtain results closer to field studies. Other important factors in study design are the number of test temperatures used, the range of temperatures selected and the decrements between the temperatures, which should be selected based on expected frost tolerance of the tissue and species. Citation: Atucha Zamkova, A.-A.; Steele, K.A.; Smith, A.R.
    [Show full text]
  • Podocarpus Has a fleshy Enlarged Stem with the Seed Capsule Attached
    Some members of the Podocarpaceae It now seems as if the general lock down is being eased across the country and I am looking to do other things than write these notes which seemed helpful eleven weeks ago but hopefully soon will not be so. Not quite a bakers dozen but one more than a S.I. preferred unit. Also I must get on with the June FACTT Newsletter which I like to think is as eagerly awaited as these notes. This note is about a family, members of which are found in fossils of Gondwana times and now in those countries which formed the original landmass and some other countries. Podocarpus has a fleshy enlarged stem with the seed capsule attached. It is easy to see the possibility of birds spreading the seeds, unlike Nothofagus where the seed is less likely to be spread widely one would think. Regarding the movement of continents it needs to be mentioned that a million is a very large number. If, as Australia is presently doing, a landmass moves 70mm a year in just 1 million years; a short period of time in geological terms; the distance traveled is 70km. Australia is moving so fast in fact that GPS can’t keep up. Some people think that taxonomists fall into two broad categories - Lumpers and Splinters. Lumpers tend to say -Well the species are so similar they are in fact one. Splitters on the other hand tend to the view that the fine details represent sufficient differences to recognise they are different species.
    [Show full text]
  • Abstract Clark, Catherine Margaret
    ABSTRACT CLARK, CATHERINE MARGARET. Genetic diversity and phylogeography in a Tasmanian rainforest conifer (Lagarostrobos franklinii (Hook f.) Quinn Podocarpaceae. (Under the direction of Dr. Ronald Sederoff and Dr. Thomas Wentworth). Genetic variation in Huon pine (Lagarostrobos franklinii), a Tasmanian rainforest conifer, was estimated using several marker systems and two spatial scales. Genealogy based methods were used to infer population history of eight Huon pine stands based on chloroplast DNA variation. Chloroplast nucleotide diversity (π) was low (0.00093± 0.00006) in a multilocus haplotype generated by three universal chloroplast primers (trnS-trnT, trnD-trnT, psbC-trnS). Five haplotypes were identified; two were€ widely distributed but the most frequently occurring haplotype was found only in trees in the western portion of the range. Genetic differentiation among populations was significant and showed a high degree of structure (GST = 0.26077 p ≤ 0.00001). Pairwise comparisons between populations revealed significant structure between the southeastern and northwestern watersheds and significant isolation€ by distance€ ( p ≤ 0.0220). Nucleotide variation was also assessed in segments of three nuclear genes, 4Cl (4- € coumarate: coenzyme A ligase), ITS2 (intergenic spacer region of ribosomal DNA) and G3pdh (glyceraldehyde 3-phosphate dehydrogenase). A total of 1,154 base pairs were sequenced from 79 individuals (158 alleles) representing seven geographic locations. Estimates of nucleotide diversity (π = 0.00089 ± 0.00007) and theta (θ) (0.00061 ± 0.00031) were low for the combined loci and similar to chloroplast estimates. There was a higher level of variation at the 4Cl locus (π = 0.00167 ± 0.00014) associated with recombination. Nucleotide diversity for nuclear loci was highest in the subalpine Mt.
    [Show full text]
  • Tassie's Trees Black Peppermint - Eucalyptus Gum-Top Stringy Bark - Eucalyptus Amygdalina Delegatensis
    Tassie's Trees Black peppermint - Eucalyptus Gum-top stringy bark - Eucalyptus amygdalina delegatensis Black peppermint is a tree of the more open This impressive gum tree is one of the giants of forests that can grow up to 30 metres tall. It can Tasmanian forests and can reach heights of up to be found mostly in the drier areas of Tasmania, 90 metres. This tree is the dominant forest species often in association with white gum and silver that grow in the cooler, higher altitude areas. It is wattle. This species is only found in Tasmania. one of the ash group of eucalypts which include swamp gum and stringy bark. White gum - Eucalyptus viminalis Silver wattle - Acacia dealbata White gum is a tree with many forms. It can grow Silver wattle is a distinctive tree or large shrub of to over 90 metres tall in the Evercreech forests the wattle family. It is widely distributed near Fingal in the north east, but it is usually throughout eucalypt forests and woodlands in found growing among black peppermint in drier eastern Australia. The tree can easily be identified eucalypt forests. White gum is a major species in by its blue-green feathery foliage and yellow the open woodlands of Tasmania. flowers during spring. It is more valued for horticultural uses than for its timber. Tassie's Trees Native Laurel - Anopterus King Billy pine - Athrotaxis glandulosus selaginoides More an understorey shrub rather than a canopy Although related to the famous redwoods of tree, this endemic species is wide-spread in wet California, the King Billy pine is only a medium eucalypt forests and rainforest up to 1200m above sized tree, usually between 25 and 30 metres sea level.
    [Show full text]
  • The Ecology and Conservation of Bryophytes in Tasmanian Wet Eucalypt Forest
    The ecology and conservation of bryophytes in Tasmanian wet eucalypt forest Perpetua A. M. Turner B.Sc. (Hons) Submitted in fulfilment of the requirements of the degree of Doctor of Philosophy School of Geography and Environmental Studies University of Tasmania Hobart July 2003 Declaration This thesis contains no material that has been accepted for the award of any other degree or diploma in any tertiary institution and, to the best of my knowledge and belief, the thesis contains no material previously published or written by another person, except where due reference is made in the text. Perpetua A.M. Turner (nee Blanks) 11th July 2003 Authority of Access This thesis may be made available forloan. Copying of any part of this thesis is prohibited fortwo years fromthe date this statement was signed; after that time limited copying is permitted in accordance with the Copyright Act 1968. Perpetua A.M. Turner (nee Blanks) 11 th July 2003 11 Abstract The aim of this study was to determine the factors that affect bryophyte richness and species composition in wet eucalypt forest, including old growth and forest disturbed by wildfire or silvicultural practice. Approximately one third of the total bryophyte flora for Tasmania was recorded in old growth mixed forest, with more liverwort than moss species found. Bryophyte species composition was significantly different between groups of sites of forest from the northwest, central and southern areas of the state. Mean annual temperature, altitude, rainfall of the driest month and aspect were most significant in predicting variation in bryophyte species composition. The use of vascular plants as surrogates for the conservation ofbryophyte species was examined.
    [Show full text]
  • Document Title 1
    Document title 1 Contents CHAPTER 1. Context.................................................................................................................................. 2 1.1 Purpose ...................................................................................................................................................................................... 3 1.2 Scope .......................................................................................................................................................................................... 3 1.3 Policy and legislative framework .......................................................................................................................................... 3 1.4 Development and custodianship of this document ......................................................................................................... 4 CHAPTER 2. Rainforest Ecology ................................................................................................................ 5 2.1 Definition and classification ................................................................................................................................................... 6 2.1.1 Rainforest types ............................................................................................................................................................... 6 2.1.2 Further classification ......................................................................................................................................................
    [Show full text]
  • Forest to Fjaeldmark: Rainforest and Related Scrub
    Edition 2 From Forest to Fjaeldmark The Vegetation Communities Rainforest and related scrub Eucryphia lucida Edition 2 From Forest to Fjaeldmark (revised – May 2018) 1 Rainforest and related scrub Community (Code) Page Athrotaxis cupressoides-Nothofagus gunnii short rainforest (RPF) 10 Athrotaxis cupressoides open woodland (RPW) 12 Athrotaxis cupressoides rainforest (RPP) 15 Athrotaxis selaginoides-Nothofagus gunnii short rainforest (RKF) 17 Athrotaxis selaginoides rainforest (RKP) 19 Athrotaxis selaginoides subalpine scrub (RKS) 21 Coastal rainforest (RCO) 23 Highland low rainforest and scrub (RSH) 25 Highland rainforest scrub with dead Athrotaxis selaginoides (RKX) 27 Lagarostrobos franklinii rainforest and scrub (RHP) 29 Nothofagus-Atherosperma rainforest (RMT) 31 Nothofagus-Leptospermum short rainforest (RML) 34 Nothofagus-Phyllocladus short rainforest (RMS) 36 Nothofagus gunnii rainforest scrub (RFS) 39 Nothofagus rainforest (undifferentiated) (RMU) 41 Rainforest fernland (RFE) 42 General description Diselma archeri and/or Pherosphaera hookeriana. These are mapped within the unit Highland This group comprises most Tasmanian vegetation coniferous shrubland (HCS), which is included within dominated by Tasmanian rainforest species (sensu the Highland treeless vegetation section. Jarman and Brown 1983) regardless of whether the dominant species are trees, shrubs or ferns. Rainforests and related scrub vegetation generally Tasmanian cool temperate rainforest has been occur in high rainfall areas of Tasmania that exceed defined floristically
    [Show full text]
  • Ethnobotany, Phytochemistry and Pharmacology of Podocarpus Sensu Latissimo (S.L.) ⁎ H.S
    Available online at www.sciencedirect.com South African Journal of Botany 76 (2010) 1–24 www.elsevier.com/locate/sajb Review Ethnobotany, phytochemistry and pharmacology of Podocarpus sensu latissimo (s.l.) ⁎ H.S. Abdillahi, G.I. Stafford, J.F. Finnie, J. Van Staden Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa Received 26 August 2009; accepted 2 September 2009 Abstract The genus Podocarpus sensu latissimo (s.l.) was initially subdivided into eight sections. However, based on new information from different morphological and anatomical studies, these sections were recognised as new genera. This change in nomenclature sometimes is problematic when consulting ethnobotanical data especially when selecting plants for pharmacological screening, thus there is a need to clear any ambiguity with the nomenclature. Species of Podocarpus s.l. are important timber trees in their native areas. They have been used by many communities in traditional medicine and as a source of income. Podocarpus s.l. is used in the treatment of fevers, asthma, coughs, cholera, distemper, chest complaints and venereal diseases. Other uses include timber, food, wax, tannin and as ornamental trees. Although extensive research has been carried out on species of Podocarpus s.l over the last decade, relatively little is known about the African species compared to those of New Zealand, Australia, China and Japan. Phytochemical studies have led to the isolation and elucidation of various terpenoids and nor- and bis- norditerpenoid dilactones. Biflavonoids of the amentoflavone and hinokiflavone types have also been isolated.
    [Show full text]
  • Radiocarbon Variations from Tasmanian Conifers: Results from Three Early Holocene Logs
    Radiocarbon Variations from Tasmanian Conifers: Results from Three Early Holocene Logs Item Type Article; text Authors Barbetti, Mike; Bird, Trevor; Dolezal, George; Taylor, Gillian; Francey, Roger; Cook, Edward; Peterson, Mike Citation Barbetti, M., Bird, T., Dolezal, G., Taylor, G., Francey, R., Cook, E., & Peterson, M. (1995). Radiocarbon variations from Tasmanian conifers: Results from three early Holocene logs. Radiocarbon, 37(2), 361-369. DOI 10.1017/S0033822200030836 Publisher Department of Geosciences, The University of Arizona Journal Radiocarbon Rights Copyright © by the Arizona Board of Regents on behalf of the University of Arizona. All rights reserved. Download date 27/09/2021 14:54:22 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/653427 RADIOCARBON VARIATIONS FROM TASMANIAN CONIFERS: RESULTS FROM THREE EARLY HOLOCENE LOGS 2 MIKE BARBETTI,1 TREVOR BIRD, GEORGE DOLEZAL,1 GILLIAN TAYL OR1 ROGER FRANCEY,3 EDWARD COOK4 and MIKE PETERSON5 ABSTRACT. Dendrochronological studies are being carried out on two conifer species in the Stanley River area of western Tasmania. The chronology for Huon pine (Lagarostrobos franklinic), with living trees up to 1400 yr old, extends back to 571 BC. Living celery-top pine (Phyllocladus aspleniifolios) trees are up to 500 yr old. Apart from living or recently felled trees, sections have been taken from 350 subfossil logs preserved in floodplain sediments. They range in age from >38 ka to mod- ern, with good coverage for the periods 9-3.5 ka and from 2.5 ka to the present. We report here on 14C measurements of dec- adal samples from three early Holocene logs, between 10 and 9 ka BP, providing short (ca.
    [Show full text]
  • Podocarp Evolution: a Molecular Phylogenetic Perspective Edward Biffin, John G
    1 Podocarp Evolution: A Molecular Phylogenetic Perspective Edward Biffin, John G. Conran, and Andrew J. Lowe ABSTRACT. Phylogenetic reconstructions of the relationships among extant taxa can be used to infer the nature of the processes that have generated contemporary patterns of biotic diversity. In this study, we present a molecular phylogenetic hypothesis for the conifer family Podocarpaceae based upon three DNA fragments that have been sampled for approximately 90 taxa. We use Bayesian relaxed- clock methods and four fossil con- straints to estimate divergence times among the lineages of Podocarpaceae. Our dating analyses suggest that although the family is old (Triassic–Jurassic), the extant species groups are of recent evolutionary origin (mid- to late Cenozoic), a pattern that could reflect a temporal increase in the rate lineage accumulation or, alternatively, a high and constant rate of extinction. Our data do not support the hypothesis that Podocarpaceae have diversified at a homogeneous rate, instead providing strong evidence for a three- to eightfold increase in diversification associated with the Podocarpoid– Dacrydioid clade, which radiated in the mid- to late Cretaceous to the earliest Cenozoic, around 60–94 mya. This group includes a predominance of taxa that develop broad leaves and/or leaf- like shoots and are distributed predominantly throughout the tropics. Tropical podocarps with broad leaves may have experienced reduced extinction and/or increased speciation coincident with the radiation of the angiosperms, the expansion of megathermal forests, and relatively stable tropical climates that were widespread through the Tertiary. Edward Biffin, John G. Conran, and Andrew J. INTRODUCTION Lowe, Australian Centre for Evolutionary Biol- ogy and Biodiversity, School of Earth and Envi- Patterns of species diversity reflect the balance of speciation and extinction ronmental Science, The University of Adelaide, Adelaide, South Australia 5005, Australia.
    [Show full text]