From: Keith Briffa To: j.burgess@uea Subject: Re: report- edit this and send an email Date: Fri Jun 12 12:36:49 1998 >Return-path: >Envelope-to: f023@cpca11.uea.ac.uk >Delivery-date: Tue, 12 May 1998 17:42:11 +0100 >X-Sender: mbaillie@143.117.30.62 >Date: Tue, 12 May 1998 16:42:31 +0000 >To: Keith Briffa >From: Mike Baillie >Subject: Re: report- edit this and send an email > >Keith, here are some thoughts on belfast work. Come back to me on this. >Cheers Mike > >10K Belfast Report. > >All the remaining long chronology (prehistoric) oak data from Ireland, >England, north and south Germany (including the major Hohenhein holdings >(2827 tree series spanning 8239 BC to 841 AD) and the Netherlands (667 >series spanning 6025 BC with gaps to 1721 AD) has now been centralised and >screened. >Work has been progressing on calculating running statistics on and between >these data sets and their constituent ring patterns. Additional attention >has been paid to attempting to understand/interpret the data in various >ways. During the year, three principal work packages have been explored >with respect to assessing the oak data. > >work package i) >signatures >With such a wide grid of chronologies it is possible to review the >occurrence of years of common growth trend. Signatures are normally >defined as those years in which 80% or more of all trees in a 'region' >exhibit the same trend towards wider or narrower growth. All sub-regional >and overall European signatures have been isolated and the intention is to >re-do the 1985 analysis of Kelly et al. comparing rainfall, temperature and >drought index data with the ocurrence of widespread signatures. > >work package ii) >Stepped windows of correlation >With the availability of the raw data from each laboratory all regional >chronologies for Ireland, Britain, North Germany and South Germany have >been reconstructed by standard means (initially fitting a 30-year spline to >each individual tree-ring pattern). Using these standardised chronologies, >stepped windows of correlation have been run comparing all regions across >time back to 5000 BC. Notable changes are observed indicating periods of >consistent, north-European-wide similarity and dis-similarity. The >availability of the raw data then allows interrogation of anomalies. For >example, there is a notable fall-off in correlation between the >standardised Irish and English chronologies at AD 775 to 825. In the past >this would have been attributed to aspects such as a) poor replication or >b) narrow versus wide rings. In this case examination of these aspects >showed that neither was the cause of the poor correlation; it appears that >English and Irish trees were responding in completely opposite manner >during this period. Such findings have important implications for both >identifying and interrogating such episodes throughout the record. > >work package iii) >Widest and narrowest rings. >It had always been assumed that the widest (or narrowest) ring in any tree, >in any year, would be idiosyncratic. This assumption produced the >expectation that the information from such extremes would be largely >meaningless. With the availability of the raw data it is now possible to >create new chronologies of the 1st narrowest, and or the 2nd/3rd narrowest, >the widest, etc, rings in each year, for each region, or for the entire >regional dataset. The result of isolating these extremes turns out to be >surprising in that plots of the extremes show remarkable coherence. Figure >Z shows a section of the Irish chronology constructed from the widest (and >narrowest) raw ring widths (the narrowest values being converted to indices >for clarity). This presentation shows the 'maximum envelope of oak growth' >year by year through time. This is a remarkable way to demonstrate periods >when there are no narrow rings in any trees and others where there are no >wide rings in any trees. Extreme events such as that in AD 540 can be seen >as an overall downturn in the ring width envelope, not just a reduction in >mean ring width. > >Extreme events. >Work has continued documenting extreme events in the European oak, and >other, records, partly as a preliminary to the detailed comparison between >the oak and Fennoscandian and Finnish pine chronologies. Some of the >events appear to be of a sufficiently global character that their effects >should be apparent in the more temperature sensitive northern pine >chronologies. Recently preliminary work has documented declines in the >seventeenth century and twelfth century BC and in the later fifth century >BC. Notable declines in the 1620s and 1120s in Foxtail pine chronologies >from the Sierra Nevada (Scuderi 1993; Caprio and Baisan 1991) suggest >reduced temperatures around the time of spaced events in the floating >Fennoscandian record. With several exactly-spaced events available over >several millennia it should be possible to link the major oak and pine >holdings, with the additional possibility of using dated English and Irish >sub-fossil pine chronologies to confirm linkages. >Refs >Caprio, A.C. and Baisan, C.H. 1992. Multi-millennial tree-ring chronologies >from foxtail pine in the southern Sierras of California. Abstract in >Bulletin of the Ecological Society of America 73, 133. > >Scuderi, L.A. 1993, A 2000-Year Tree-Ring Record of Annual Temperatures in >the Sierra Nevada Mountains, Science 259, 1433-6 > > >Related applications: > >Interhemispheric Radiocarbon Calibration >In addition collaboration has continued on a range of topics including >interhemispheric radiocarbon calibration. Oak samples from Ireland and >exactly contemporaneous samples of cedar from New Zealand have been measued >in radiocarbon laboratories in Belfast and Waikato (samples from each >hemisphere being dated in both laboratories). This work is showing >interesting hemispheric changes through time with implications for carbon >cycle modellers (related paper accepted for publication). > >Global tree-ring responses to environmental change. >As part of our network of collaborators, it is possible to have access to >tree-ring patterns and related temperature reconstructions from a wide grid >of chronologies outside Europe. An example of the power of such grids is >provided by the observed changes during the fourteenth century AD. Here >chronologies from the EU oak group have been combined with those from Ed >Cook (Tasmanian Huon pine); Keith Briffa (Fennoscandian and Polar Urals >pine); Peter Kuniholm (Aegean oak and pine) and Xiong Limin (New Zealand >cedar). When permed (random groups of five from seven chronologies) to >show common responses, the overall pattern exhibits reduced growth in the >1340s, the decade of the arrival of the Black Death in Europe, see Figure. >Such a clear environmental context for the plague has never been available >before. > >Comparisons with other proxy data. >The strict annual character of tree-ring data is only truly comparable with >precisely dated human records. For the early fourteenth century >surprisingly complete records exist from England for crop yields and >prices. In an attempt to compare two different but parallel proxy records, >namely those for tree growth and for crop prices, collaboration with >economic historians (Prof. Bruce Campbell Econ. and Soc. Hist. QUB) has >been initiated. Preliminary plots of robust, screened European master >chronologies against grain prices reveals surprising levels of common trend. > >Innundated trees >As part of an effort to understand physiological response of oak to >waterlogging, 21 oaks were sampled at garryland Wood, County Galway. These >trees grow in a limestone area which is flooded in some winters to depths >of 10s of metres, for durations up to months. Some of the trees exhibit >scar damage almost certainly from bark burst during submersion. Scars >appear to to coincide with winters of higher than average rainfall. The >fact that the trees are not submerged during the growing season means that >they do not show the extreme dieback and micro-rings associated with trees >left standing in permanent water, such as examples from beside Loch Lomond, >Scotland. > >Publications with Grant number > >Baillie, M.G.L. 1996 Chronology of the Bronze Age 2354 BC to 401 BC. Acta >Archaeologica 67, 291-298 > >Baillie, M.G.L. 1998 Evidence for climatic deterioration in the 12th and >17th centuries BC. in Hänsel, B. Ed. Man and Environment in European Bronze >Age, Oetker-Voges, Kiel, 49-55 > >Baillie, M.G.L. and Brown, D.M. 1996 Dendrochronology of Irish Bog >Trackways. (in) Raftery, B. Trackway Excavations in the Mountdillon Bogs, >Co. Longford. Irish Archaeological Wetland Unit, Transactions Vol. 3, Dept. >of Archaeology, University College, Dublin, 395-402 > > >In Press (with Grant number) > >Baillie, M.G.L. 1998 Putting abrupt environmental change back into human >history, Environments and Historical Change; The Linacre Lectures, ed. Paul >Slack, Oxford University Press > >Baillie, M.G.L. 1998 Exodus to Arthur. Close encounters with comets and >the fiery dragons of myth. Batsford, London. > >Baillie, M.G.L. 1998 A View from Outside: Recognising the Big Picture. >Proceedings of the Joint AEA/QRA Conference, Sheffield January 1996. > >Baillie, M.G.L. 1998 Hints that cometary debris played some role in >several tree-ring dated environmental downturns in the Bronze Age. >Proceedings of the 2nd SIS Conference, Cambridge July 1997. > >Baillie, M.G.L. 1998 Dendrochronology. in Jones, T. and Rowe, N. Ed Fossil >Plants and Spores: Modern Techniques. Geology Society. > >Other >Baillie, M.G.L. 1998 Bronze Age myths expose archaeological shortcomings; >reply to Buckland et al. 1997 Antiquity, (forthcoming). > > >Mike Baillie >Palaeoecology Centre >School of Geosciences, Queen's University, Belfast >(01232) 335147 > > >