Dendrochronological Dating of Wooden Artefacts using Photography

Core sampling is normally used for dendrochronological age determination of both timber and living trees. As core sampling can seriously damage artefacts, a photographic method was tried on 29 wooden objects made of Scots pine (Pinus sylvestris L.). These were photographed and tree‐ring sequences for dendrochronological analysis were measured on the photographs in the laboratory. Nine objects could be dated. The undatable objects had few tree‐rings or a non‐matching tree‐ring pattern. The region in Norway where the material had grown could be determined by matching against various regional chronologies.     

The Potential of Tree Rings in Eucalyptus pauciflora for Climatological and Hydrological Reconstruction

We investigate the causes of variability in a tree‐ring chronology comprising data from Eucalyptus pauciflora Sieb. Ex. Spreng. at the alpine treeline on the Kosciuszko Plateau in New South Wales, Australia. Following verification of crossdating in a subset of the available data, we found that ring width correlates significantly with net radiation, precipitation and mean minimum and maximum air temperature during the preceding winter and spring of the growing season. Our results for spring are consistent with the impact of climate on tree growth in alpine woodlands reported in previous studies. Analyses of snow‐depth data revealed negative correlations with ring width throughout winter and spring. Our results indicate that low temperature and high precipitation during winter negatively affect the growth of E. pauciflora by prolonging spring snow cover. Ring width also correlates significantly with an index of soil dryness and flow in rivers with their headwaters in the Kosciuszko plateau. Given the apparent sensitivity of our chronology to climate and snow conditions, our results suggest that tree‐ring chronologies comprising data from E. pauciflora at the alpine treeline have potential for climatological and hydrological reconstruction in southeast Australia.     

A simple Bayesian approach to tree‐ring dating

Tree‐ring dating involves matching sequences of ring widths from undated timbers to dated sequences known as ‘master’ chronologies. Conventionally, the undated timbers (from a building or woodland) are sequentially matched against one another, using t‐tests to identify the relative offsets with the ‘best’ match, thus producing a ’site’ chronology. A date estimate is obtained when this is matched to a local master chronology of known calendar age. Many tree‐ring sequences in the UK produce rather low t‐values and are thus declared not to have a ‘best’ match to a master chronology. Motivated by this and the routine use of Bayesian statistical methods to provide a probabilistic approach to radiocarbon dating, this paper investigates the practicality of Bayesian dendrochronology. We explore a previously published model for the relationship between ring widths and the underlying climatic signal, implementing it within the Bayesian framework via a simulation‐based approach. Probabilities for a match at each offset are produced, removing the need to identify a single ‘best’ match. The Bayesian model proves successful at matching in both simulated and real examples.     

A 6000 Year‐old Fossil Dugong from Botany Bay: Inferences about Changes in Sydney's Climate,Sea Levels and Waterways

The excavation in the 1890s of a skeleton of the warm‐water marine mammal Dugong dugon, associated with Aboriginal artefacts, from a Botany Bay salt marsh, marked the beginning of speculation about climate and sea level change in Australia over the period of human occupation. The dugong bones have recently been dated, giving a conventional ¹⁴C age of 5520±70 years BP, which is consistent with three older ¹⁴C dates for a layer of buried trees that underlies much of the north Botany sediments. The carefully drawn cross‐sections of depositional strata produced by the original discoverers allow further interpretation of the pattern of Holocene sea‐level fluctuations in the Sydney region. Layers of estuarine sediment, such as the one containing the dugong skeleton, are inter‐bedded with peat layers containing in situ roots and stumps, suggesting that the site alternated between sub‐aerial exposure and submergence throughout the Holocene. The presence of the dugong is suggestive of warmer conditions, and its inland location indicates a more extensive Botany Bay in the recent past. This is in agreement with other work from southern New South Wales describing both warm‐water marine species and higher sea levels several thousand years ago.

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Dendrochronological dating of a wooden causeway in Finland

A mean ring‐width chronology for Scots pine in eastern Finland has been compiled based on living trees and dendrochronologically dated historical timber constructions. As an application of this master chronology, a young archaeological site near the town of Hämeenlinna, southern Finland, was dated. A previous assumption of the age of this site was that it could even be medieval. The construction was not older than 160 years, the road having been built after 1828, the year of growth of the outermost tree rings of the samples. A new pine chronology for southern Finland extending to the year AD 1539 is presented and it is now applicable for precise dating purposes in this area.     

Holocene Climatic Changes and Cultural Dynamics in the Libyan Sahara

Systematic surveys and excavations were carried out during the 1990–1996 field seasons in the Tadrart Acacus and surrounding areas, shedding new light on the climatic changes and cultural dynamics which occurred during the Holocene. In this paper, the geological, geomorphological, and archaeological evidence is assembled in order to provide a preliminary synthesis on the prehistory of the area. Pendant les saisons de terrain du 1990 au 1996, des récognitions et fouilles systématiques ont été conduites dans le Tadrart Acacus et dans les zones circonvoisines; ces études ont donne des nouvelles information en ce qui concerne les changements climatiques et les dynamiques culturelles de cette région pendant l'Holocène. Dans ce papier, les évidences géologiques, géomorphologiques, et archéologiques ont été intégrées afin d'obtenir une synthèse préliminaire sur la préhistoire de la région.     

Can tree-ring chemistry reveal absolute dates for past volcanic eruptions?

Discussion of the significance of volcanically induced impacts on human history, the natural environment, and climate through the Holocene, has frequently stalled because of controversy concerning certain key volcanic eruptions and their precise relationships with the archaeological/environmental record. A major stumbling block in such debates is a failure to obtain precise and accurate dates for many of these key volcanic events. Most existing dates currently float against archaeological, historical, environmental, and climate data. A potential means to resolution lies with tree rings: these can be dated precisely by dendrochronology, are available from a wide range of loci around the world, and can record global climatic influences. It has been suggested that certain growth anomalies in dendrochronological sequences could offer “proxy” absolutely dated records of major, climatically effective, volcanic eruptions. However, this assertion has been widely disputed given the lack of a direct, positive, causal connection. The hypothesis that the required connection may be chemically encoded in individual annual growth rings from dated sequences is explored here both via review of existing literature on dendrochemical techniques, and by LA-ICP-MS chemical analysis of two tree ring sequences. It is concluded that dendrochemistry provides a promising means by which absolute dates may one day be attributed to key volcanic eruptions of pre-modern times.     

Preservation of old‐growth forests: a case study of Big Timber Park,Whistler, BC

This paper explores the concepts of old‐growth forests, preservation and natural disturbance and demonstrates how contemporary biogeographic theory contributes to successful preservation of old‐growth forests. The case study analyzes the composition, structure, age and growth histories of trees in Big Timber Park, Whistler, British Columbia. Composition. The structure of the forest was diverse and tree ages ranged from 122 to 305 years. The densities of large old Douglas‐fir, shade‐tolerant trees and all snags are indicative of old‐growth forests; however, maximum tree diameters and densities of large snags and logs do not meet quantitative criteria for old‐growth forests. The abundance of tree regeneration and understory vegetation are relatively low. We conclude that some aspects of Big Timber Park are transitional between the mature and old‐growth stages of forest development. In the future, fine‐scale canopy gaps caused by tree senescence and interactions among insects, pathogens and wind are expected to dominate stand dynamics. Forest structure will become increasingly complex, exemplifying the dynamic nature of old‐growth forests. To successfully preserve Big Timber Park and La préservation des forêts other old‐growth forests in Canada requires understanding of natural disturbances. Preservation and the criteria and indicators used to measure successful preservation must explicitly include elements of natural change.     

The Effect of Climatic Fluctuation on the Physical Environment and Conditions of Economic Development of the Middle OB' District

Physical-geographic field work in the West Siberian plain has uncovered a peculiar stratification of peat bogs and other physical-geographic phenomena that are related to climatic fluctuation. These phenomena include local relief changes reported by old residents and evidence of differential tree growth based on study of annual rings. It is recommended that economic development of the Middle Ob' district, particularly the use of floodplain meadows, be sufficiently flexible to take account of the cyclical physical-geographic changes that appear to be typical of the area.     

On the similarity of tree‐ring patterns: Assessing the influence of semi‐synchronous growth changes on the Gleichläufigkeitskoeffizient for big tree‐ring data sets

The Gleichläufigkeitskoeffizient (GLK), or the percentage of parallel variation (%PV), is an often used non‐parametric similarity measure in dendrochronological research. However, when analysing big data sets using the GLK, this measure has some issues. The main problem is that it includes not only synchronous but also semi‐synchronous growth changes. These are years in which the growth in one of the compared series does not change in two subsequent years. This influences the GLK, often only slightly, but the larger the data set the stronger the effect. The similarity between tree‐ring series can be more objectively expressed by replacing the GLK with the synchronous (SGC) and semi‐synchronous growth changes (SSGC). The calculation is similar, since GLK = SGC + SSGC/2. Large values of the SSGC are indicative of possible anomalies or even errors. The SGC is much better suited than the GLK to describe similarity. The SGC should therefore be used to analyse big data sets, for clustering and/or dendroprovenance studies. It is recommended to combine the SGC with parametric measures.     

Climatic signal in tree-ring chronologies of Cedrus deodara from Chitral Hindukush Range of Pakistan

Tree-rings are an important tool for the investigation of paleoclimatic records for regions or periods of time with no instrumental climatic data. However, the responses of different species and sites to various climatic parameters are unusual. In the present study, we developed tree-ring-width chronologies of Cedrus deodara from three different sites of Chitral Hindukush range of Pakistan. The study was conducted to understand tree-growth climate relationship and its applicability in proxy climate investigations. The chronologies covered the past 469 to 595 years, with a mean segment length (MSL) ranging from 148 to 223 years. Climatic data obtained from the three weather stations showed strong correlation and was found useful for tree-ring climate relationships. Correlation Function (CF) and Response Function (RF) analysis showed that spring precipitation (March–May) is a critical limiting factor for tree-ring growth, and temperature prior to November may also play a major role in affecting tree ring-growth. The results exposed that the three sites have continuous relationship indicated that only single species from different locations are affected by the same environmental variables and hence can be used in climate reconstruction in combination. The Cedrus deodara chronologies developed at different locations had several corresponding narrow and wide marker rings indicating a large macroclimatic response to regional climatic conditions. The current study suggests that the tree-rings of Cedrus deodara from the Chitral Hindukush range could be used to develop chronologies for the reconstruction of seasonal climatic variables.     

Dendrochronological dating of wooden artifacts by measuring the tree rings using magnifying glass and photography-assisted method: an example of a Dutch panel painting

Dendrochronology, an analysis of tree rings, is a commonly used method for dating wooden structures in archaeological remains and historical objects. Fascinating subjects of examination are the historical oil paintings on oak panels. Here, we applied a tree ring analysis on three boards of a Dutch painting from the Sinebrychoff Art Museum (Helsinki). Tree rings were measured using the conventional lens-assisted method, in addition to the photography-based approach, where the widths of the rings were determined from digital enlargements of the photos. These two methods produced comparable tree ring series. The lens- and photography-based records of the measured panel exhibited higher agreement with each other than the conventional, lens-based, record against the different master chronologies. Dendrochronological cross-dating against the master chronology showed that the rings of the panel represent the period ad 1413–1620. Cross-dating was attained by comparing the tree ring series of the panel painting with the previously published chronologies obtained from timber transported from the historical ports of the Eastern Baltic Sea to Western Europe. Photography appears as a promising method to be used for dendrochronological investigations of archaeological and historical objects, alongside the conventional methods. We note that the importance of using photographs of tree ring cross sections was highlighted already in the 1930s. In the digital era, the photographic approach shows obvious benefits for archival purposes and remeasuring the rings, with additional future prospects of image processing and analyses.     

Depositional Context as the Foundation to Determining the Palaeolithic and Mesolithic Archaeological Potential of Offshore Wind Farm Areas in the Southern North Sea

Abstract

There is currently limited evidence on which to assess the submerged prehistoric potential in areas of renewable energy development. This paper presents a geomorphological approach to examine the Palaeolithic and Mesolithic archaeological potential in relation to the Round 3 offshore wind farm (OWF) areas of the southern North Sea. The depositional context and major stratigraphic correlations between the terrestrial sequence on east coast of Britain and offshore marine sequence of the southern North Sea are used to provide a first-order assessment for identifying horizons of archaeological interest in OWF zones. Using the examples Triton Knoll and East Anglia One OWF, the nature of renewable energy development on identified archaeological horizons is discussed, noting that any impact needs to be considered on a site-by-site basis. Studies are not only needed on the practical assessment of any development impact but also on the impacts of natural processes in OWF zones.     

Phenology of Six Ficus L., Moraceae,Species and its Effects on Pollinator Survival,in Brisbane,Queensland, Australia

The biogeography and historical distribution of various plants often depend as much on the environmental tolerance of their pollinators as they do on the tolerance of the plant. A four year, phenological study of 35 trees from six Ficus species was carried out in Brisbane's Central Business District. The presence of syconia (figs) and their sexual phases was recorded monthly for each tree. All six species bore ‘female’ phase syconia randomly in any month. The presence of ‘male’ phase syconia was seasonal for Ficus benjamina, Ficus microcarpa and Ficus virens. It was less seasonal for Ficus obliqua and Ficus rubiginosa. Ficus macrophylla exhibited aseasonal distribution of ‘male’ phase syconia. Symbiont pollinator wasp mortality was the cause of the skew in the seasonal distribution of ‘male’ phase syconia. Ficus benjamina, F. microcarpa and F. virens seldom had ‘male’ and ‘female’ phase syconia concurrently on an individual tree, while F. macrophylla and F. obliqua often did. Ficus rubiginosa was intermediate between the two groups. Intra‐tree overlap of syconia in both sexual phases permits short dispersal flights by pollinators and is advantageous to their survival during the cooler months. The pollinators of F. benjamina, F. microcarpa and F. virens, historically tropical and tropical/subtropical species, are unlikely to establish in temperate areas due to high winter mortality rates. The other three Ficus species historically occurred in temperate climates and the pollinators of two, F. macrophylla and F. rubiginosa, are extending their range into temperate Australia and New Zealand. The pollination biology of Ficus spp. will thus be a determining factor in whether a species is able to naturalise or become invasive in a location that experiences a particular climate, or if it is safe to use as a horticultural amenity species.     

TREES AS TOOLS,TREES AS TEXT: STRUGGLES OVER RESOURCES IN ZAMBRANA-CHACUEY,DOMINICAN REPUBLIC

The people of the Rural Federation of Zambrana-Chacuey, in the Dominican Republic, are engaged in complex and multivalent struggles over resources in a forest and farm landscape subject to rapid land use change. Acacia mangium, a fast growing tree recently introduced as a timber cash crop, has become an object, a site and a tool of struggle in conflicts between local and state interests, and between women and men. Until recently, tree cutting has been illegal, so the government-approved acacia has reversed the role of trees from liabilities to assets in land tenure. The acacia has also begun to alter the pattern of land use, land cover, and the species composition of the region's forests, gardens, and fields, and could replace women's diverse gardens with single species blocks of timber.     

Sapwood estimates in the interpretation of tree-ring dates

Many timber finds lack some or all of the outer, sapwood rings formed in the years just before felling. In order to estimate felling date once the outermost remaining ring has been dated, it is necessary to estimate the number of sapwood rings originally present. Methods doing this for oak are reviewed in the light of an intensive study of living trees at one site and an extensive study of 175 samples from living trees in North Wales and northwest England. Some methods reported in the literature are found to be invalid. A method reported by Hollstein (1965) is most reliable, with modifications for known variations in sapwood number with position in the tree. At present the best available estimate is that a value of 30 sapwood rings be used (95% confidence limits: 19–50).     

THE EFFECT OF LAND‐USE CONTROLS ON THE SPATIAL SIZE OF U.S. URBANIZED AREAS*

ABSTRACT On a sample of U.S. urbanized areas in 2000, we test theoretical hypotheses of the effect of land‐use controls on the spatial size of urban areas. We find that minimum lot‐size zoning and maximum FAR restrictions expand the urban area, while maximum lot‐size zoning, urban growth boundaries, minimum square footage limits, maximum building permit restrictions, minimum person per room controls, and impact fees contract the urban area. All of these findings are consistent with theoretical predictions although the effect of urban growth boundaries and minimum square footage limits are not statistically significant.     

Practical surveying in schools

Analysis of detailed geomorphological mapping enables a sequence of glacial events to be established. An ice sheet whose source was to the west of the area of study is shown, by the suites of fluvioglacial landforms produced, to have down‐wasted in situ; meltwaters escaped beneath or through the ice, moving uphill across certain areas. Finally, a sub‐aerial drainage system was established and outwash terraces were spread down valley.     

An exploration of Hul’qumi’num Coast Salish peoples’ attitudes towards the establishment of no‐take zones within marine protected areas in the Salish Sea,Canada

The Canadian Government has committed to establishing a national network of Marine Protected Areas. Progress in the Salish Sea (Strait of Georgia) of British Columbia has been slow. Opposition by First Nations is a factor as these protected areas have the potential to impact on Aboriginal rights. This case study with the Hul’qumi’num First Nations examines their approaches to marine conservation and their perspectives on “no‐take zones” as a component of marine conservation. The study used a variety of community engagement procedures including relationship building, hiring of a Hul’qumi’num research assistant, conducting individual interviews, focus groups, and field surveys. Interviews were conducted with 41 participants contacted because of their knowledge and interest in marine resource use. The views reported provide a rich understanding of Hul’qumi’num attitudes, but cannot be generalised to the whole population. There was widespread support for efforts to involve local First Nations communities in the development of management plans for marine resources, and also for recognition of First Nation reliance on marine resources for food, social, and ceremonial needs and for economic development opportunities. The establishment of permanent no‐take zones was met with both opposition and support. The most highly endorsed statement about no‐take zones is one of principle—that they are a violation of Aboriginal rights. However, there was also strong agreement that permanent no‐take zones would help reduce over‐fishing. The National Marine Conservation Area program is in its infancy and it remains to be seen how the “strictly protected” zone of the legislation will be interpreted in relationship to Aboriginal harvesting practices. However it is clear that successful conservation will only occur with Aboriginal consent in many areas and there needs to be greater investment in understanding Aboriginal perspectives on marine conservation.     

MULTIVARIATE MIXTURE OF NORMALS WITH UNKNOWN NUMBER OF COMPONENTS: AN APPLICATION TO CLUSTER NEOLITHIC CERAMICS FROM AEGEAN AND ASIA MINOR USING PORTABLE XRF*

Multivariate techniques and especially cluster analysis have been commonly used in archaeometry. Exploratory and model‐based techniques of clustering have been applied to geochemical (continuous) data of archaeological artefacts for provenance studies. Model‐based clustering techniques such as classification maximum likelihood and mixture maximum likelihood have been used to a lesser extent in this context and, although they seem to be suitable for such data, they either present practical difficulties—such as high dimensionality of the data—or their performance gives no evidence that they are superior to standard methods. In this paper standard statistical methods (hierarchical clustering, principal components analysis) and the recently developed model‐based multivariate mixture of normals with an unknown number of components, are applied and compared. The data set provides chemical compositions of 188 ceramic samples derived from the Aegean islands and surrounding areas.