Botswana und Südafrika: Baobabs und das Königreich Botswana

The aim of this project is to find a valid source of high-resolution palaeoclimatic information as a means for predicting the climate change impact on the African continent. The baobab is a common tree in semi-arid Africa that can reach ages of up to 2000 years. The way its tree rings develop has not been fully understood yet. Therefore, by using radius and circumference dendrometers on trees as well as special drilling to obtain wood samples, primary questions concerning dormant and growth periods shall be answered. In a second step, it will be scrutinized how climate signals and stable isotopes are transferred into the tree rings. The first results show a correlation between tree ring growth and the precipitation amount of the same year as well as significant correlations between the δ 13 C and δ 18 O values with climate data

First Dendrochronological Datings of Historical Timber in Albania

Die dendrochronologischen Untersuchungen wurden hauptsächlich an Hölzern aus der Region Korça im Südosten Albaniens vorgenommen. Die Proben stammen von rezenten Bäumen, aus Kirchen, Profangebäuden, von Ikonen sowie von Pfählen prähistorischer Seeufersiedlungen vom Großen Prespasee und von der makedonischen Seite des Ohridsees. Die Mehrheit der insgesamt 564 Proben stammt von Nadelbäumen, insbesondere Schwarzkiefern (Pinus nigra), Bergkiefern (Pinus heldreichii), Tannen (Abies sp.) und in prähistorischer Zeit auch Wacholder (Juniperus sp.). Laubhölzer wie Buchen (Fagus sp.) und Eichen (Quercus sp.) konnten bislang nur in weitaus geringerem Umfang beprobt werden. Die Proben ermöglichten den Aufbau von Jahrringmittelwertserien aus dem Neolithikum (6. Jt.), der Mittelbronzezeit (3. Jt.) sowie aus Mittelalter und Neuzeit. Absolute Datierungen gelangen vorerst nur für Holzfunde der letzten 1000 Jahre. Bisher konnten 219 Jahrringserien von 36 Ikonen und sieben Gebäuden datiert werden. Außerdem werden Aspekte von Klimageschichte, Bau- und Kunstgeschichte sowie historische Waldnutzungsformen angesprochen. Die Weiterführung dieser Untersuchungen trägt wesentlich zum Aufbau absolutchronologischer Zeitgerüste im Raum südlich und südöstlich der Alpen bei.The dendrochronological investigations were conducted primarily on timber from the region of Korça in the south-east of Albania. The samples come from recent trees, from churches, secular buildings, icons and from the piles of prehistoric settlements on the shore of the Great Prespa Lake and on the Macedonian side of Lake Ohrid. The majority of the 564 samples come from conifers, in particular European Black Pine (Pinus nigra), Bosnian Pine (Pinus heldreichii), fir (Abies sp.) and in prehistoric times also juniper ( Juniperus sp.). So far it has only been possible to sample wood from deciduous trees like beech (Fagus sp.) and oak (Quercus sp.) on a much smaller scale. The samples enable us to establish median series of annual growth rings from the Neolithic (6th millennium), middle Bronze Age (3rd millennium), the Middle Ages and the modern era. Absolute datings are at the moment sufficient only for timber finds from the last 1000 years. So far, 219 annual growth ring series from 36 icons and seven buildings have been dated. The contribution also discusses aspects of climate history, the history of building and art, and historical forms of forest utilization. The continuation of these investigations is contributing significantly to the development of an absolute chronological framework for the region south and south-east of the Alps

High-resolution 14C bomb peak dating and climate response analyses of subseasonal stable isotope signals in wood of the African baobab – a case study from Oman

The African baobab, Adansonia digitata L., has great paleoclimatological potential because of its wide distributional range and millennial length life span. However, dendroclimatological approaches are hampered by dating uncertainties due to its unique, parenchyma-dominated stem anatomy. Here, securely dated time series of annual wood increment growth and intra-ring stable isotopes of carbon and oxygen of cellulose for a baobab tree from Oman covering 1941 to 2005 were established and tested for relationships to hydroclimate variability. Precise dating with the atomic bomb peak (ABP) using highly resolved 14C measurements confirmed the annual character of the baobab's growth rings. F14C values of tree-ring cellulose were found up to 8.8 % lower than in the corresponding atmospheric CO2 for the period around the ABP, which in conjunction with a considerable autocorrelation of the δ13C series points to the incorporation of previous year's carbon contributing to the average age of intra-ring wood samples. F14C of terminal parenchyma bands, marking the tree-ring boundaries, were found to be considerably younger than their corresponding tree ring, indicating that parenchyma tissue is alive for many years, probably undergoing cell division and structural reorganization and contributing to secondary growth. In contrast to the δ13C time series, no significant autocorrelation was found in the δ18O series of tree-ring cellulose despite the enormous water storage potential of this stem-succulent tree species. Year-to-year variability in tree-ring width and stable isotope ratios revealed radial stem growth and the geochemistry of wood cellulose are influenced by fluctuations in the hydroclimate. In particular, δ18O was found to be a good climate proxy, followed by tree-ring width and δ13C. Tree-ring width and intra-ring δ18Omin correlated well with each other and with precipitation amount for the period from pre-monsoon May to the end of the monsoon season in September/October. Intra-annual stable isotope courses were found to be rather similar for both δ13C and δ18O. Years with particularly low monsoon rain were reflected by increased stable isotope values in the mid-section of intra-annual courses. Distinct patterns with low subseasonal isotope values seem indicative for years with heavy rainfall events from pre-monsoonal cyclones. Rain events from post-monsoonal cyclones may also be recorded; however, only 2 years of observation prevented a more conclusive evaluation.ISSN:1726-4170ISSN:1726-417

Traditionelles Bauen und Wohnen der Salar in Nordwest-China

This report concerns research on the architectural history of Salar households conducted between 2004 and 2006. The Salars are an Oghuz-Turkic people who in the 13th century migrated with Gengis Khan's troops from the Samarkand area to northern Tibet. The present project compared house construction styles and the use of living space in two Salar communities: a larger community in northern Tibet (today Qinghai province) and a smaller community in Yil/Ghulja (today the Xinjiang Uygur Autonomous Region)

Removing the no-analogue bias in modern accelerated tree growth leads to stronger medieval drought

Abstract In many parts of the world, especially in the temperate regions of Europe and North-America, accelerated tree growth rates have been observed over the last decades. This widespread phenomenon is presumably caused by a combination of factors like atmospheric fertilization or changes in forest structure and/or management. If not properly acknowledged in the calibration of tree-ring based climate reconstructions, considerable bias concerning amplitudes and trends of reconstructed climatic parameters might emerge or low frequency information is lost. Here we present a simple but effective, data-driven approach to remove the recent non-climatic growth increase in tree-ring data. Accounting for the no-analogue calibration problem, a new hydroclimatic reconstruction for northern-central Europe revealed considerably drier conditions during the medieval climate anomaly (MCA) compared with standard reconstruction methods and other existing reconstructions. This demonstrates the necessity to account for fertilization effects in modern tree-ring data from affected regions before calibrating reconstruction models, to avoid biased results

Traditionelles Bauen und Wohnen der Salar in Nordwest-China

This is the published version, © 2009 by Deutsches Archäologisches Institut. Made available in KU Scholarworks with permission of the copyright holder.This report concerns research on the architectural history of Salar households conducted between 2004 and 2006. The Salars are an Oghuz-Turkic people who in the 13th century migrated with Gengis Khan's troops from the Samarkand area to northern Tibet. The present project compared house construction styles and the use of living space in two Salar communities: a larger community in northern Tibet (today Qinghai province) and a smaller community in Yil/Ghulja (today the Xinjiang Uygur Autonomous Region)

Removing the no-analogue bias in modern accelerated tree growth leads to stronger medieval drought

In many parts of the world, especially in the temperate regions of Europe and North-America, accelerated tree growth rates have been observed over the last decades. This widespread phenomenon is presumably caused by a combination of factors like atmospheric fertilization or changes in forest structure and/or management. If not properly acknowledged in the calibration of tree-ring based climate reconstructions, considerable bias concerning amplitudes and trends of reconstructed climatic parameters might emerge or low frequency information is lost. Here we present a simple but effective, data-driven approach to remove the recent non-climatic growth increase in tree-ring data. Accounting for the no-analogue calibration problem, a new hydroclimatic reconstruction for northern-central Europe revealed considerably drier conditions during the medieval climate anomaly (MCA) compared with standard reconstruction methods and other existing reconstructions. This demonstrates the necessity to account for fertilization effects in modern tree-ring data from affected regions before calibrating reconstruction models, to avoid biased results.</p

Interdisciplinary Geo-ecological Research across Time Scales in the Northeast German Lowland Observatory (TERENO-NE)

The Northeast German Lowland Observatory (TERENO-NE) was established to investigate the regional impact of climate and land use change. TERENO-NE focuses on the Northeast German lowlands, for which a high vulnerability has been determined due to increasing temperatures and decreasing amounts of precipitation projected for the coming decades. To facilitate in-depth evaluations of the effects of climate and land use changes and to separate the effects of natural and anthropogenic drivers in the region, six sites were chosen for comprehensive monitoring. In addition, at selected sites, geoarchives were used to substantially extend the instrumental records back in time. It is this combination of diverse disciplines working across different time scales that makes the observatory TERENO-NE a unique observation platform. We provide information about the general characteristics of the observatory and its six monitoring sites and present examples of interdisciplinary research activities at some of these sites. We also illustrate how monitoring improves process understanding, how remote sensing techniques are fine-tuned by the most comprehensive ground-truthing site DEMMIN, how soil erosion dynamics have evolved, how greenhouse gas monitoring of rewetted peatlands can reveal unexpected mechanisms, and how proxy data provides a long-term perspective of current ongoing changes