Tree rings of Cedrus libani at the northern boundary of its natural distribution

The present study was carried out taking a total of 41 increment cores from three sites located in the northern boundary of Cedrus libani and three site chronologies were constructed. Three response functions were computed and a higher correlation with climate was found in the trees on the steep slopes. The low precipitation was an important limiting factor for growth. At the valley bottom site, neither precipitation, except for December, nor temperature, except for February were a limiting factor. The radial diameters of tracheids were measured, and the tracheid numbers representing the last seven years, from 1994 to 2000, were counted. Although the radial diameters were almost similar in all sites, the numbers of tracheids were greatest at the valley bottom site and lowest at the steep slope site

Reconstruction (1689-1994 AD) of April-August precipitation in the southern part of central Turkey

A reconstruction of April-August precipitation (1689-1994) was developed for the region by using Pinus nigra tree rings. A linear regression was performed using the residual chronology, composed of at least nine trees (SSS > 0.85). Within this reconstructed period, dry years were distributed generally as I year (23 times), rarely 2 years (four times) and very rarely 3 years (one time). According to the results, dry events of 3 years' duration were seen only once (1745-47) in the reconstruction period, and wet events were seen twice (1727-29 and 1900-02). Events of 2 years' duration occurred during all three centuries: 1725-26, 1796-97, 1819-20, 1862-63 and 1927-28 (dry years), and 1770-71, 1901-02 (wet years). In accordance with other studies, the years 1693, 1725, 1819, 1868, 1878, 1887 and 1893, which were below two standard deviations, were determined as the driest years in the eastern Mediterranean basin. The distribution of dry and wet periods over time was irregular, and the time between two dry periods was not less than 6 years. There was a significant negative correlation between concurrent April-August North Atlantic oscillation and instrumental precipitation, but it was lower with reconstructed April-August precipitation and nonsignificant. The present results could be useful in the planning and management of water resources and agricultural activities in the region. Copyright (c) 2005 Royal Meteorological Society

Embryo anatomy in Quercus alnifolia Poech.

Seed germination characteristics of acorns of Quercus alnifolia Poech (Golden oak) were studied. Germination characteristics different from other oak species except Quercus aucheri Jaub.et Spach were identified as the radicle of the acorn elongated near the proximal end of the fruit, while the radicle protrudes from the distal end in the other oak species

A preliminary reconstruction (AD 1635-2000) of spring precipitation using oak tree rings in the western Black Sea region of Turkey

Tree-ring data for Turkey are crucial to the understanding of the climatological effect of drought and rainfall from one era to the next. To this end, the present study reconstructed precipitation patterns in the western Black Sea region of Turkey. Tree-ring widths of oak trees were used to reconstruct March - June precipitation patterns for the years A. D. 1635 - 2000. According to the findings, during the past four centuries drought events in this region persisted for no more than 2 years, and extreme dry and wet events occurred generally in 1-year intervals. Historical records of droughts in Anatolia and neighboring countries corroborate the data furnished by tree-ring widths to indicate that major droughts and famine events occurred in 1725, 1757, 1887, 1890 - 1891, 1893 - 1894 and 1927 - 1928

ASSESSING STREET-LEVEL DISTRIBUTION OF TREE OF HEAVEN (AILANTHUS ALTISSIMA) IN ISTANBUL (TURKEY)

Tree of heaven (Ailanthus altissima (Mill.) Swingle) from the Simaroubaceae family is recognized as an invasive species within urban, rural, and natural ecosystems in many parts of the world. There is no regional or national strategy for the management and control of A. altissima in Turkey, where it is also accepted as an invasive plant species and occurs in many cities. Google Street View images were used in the study for virtual inventory of street trees. This study has been conducted to reveal the presence of the tree of heaven in the streets of Istanbul, 8 very large, 45 large, 110 medium, 155 small, 80 very small single plants were detected in 7720 sample plots with a length of 50 meters. The average ratio of tree of heaven to the total street tree species composition was 2%, while this rate is 0.5% in some districts, it rises up to 6% in some others. This indicated that A. altissima was widespread even though it was not planted as a street tree on the roadsides of Istanbul

Reconstructions of spring/summer precipitation for the Eastern Mediterranean from tree-ring widths and its connection to large-scale atmospheric circulation

This study represents the first large-scale systematic dendroclimatic sampling focused on developing chronologies from different species in the eastern Mediterranean region. Six reconstructions were developed from chronologies ranging in length from 115 years to 600 years. The first reconstruction (1885-2000) was derived from principal components (PCs) of 36 combined chronologies. The remaining five, 1800-2000, 1700-2000, 1600-2000, 1500-2000 and 1400-2000 were developed from PCs of 32, 18, 14, 9, and 7 chronologies, respectively. Calibration and verification statistics for the period 1931-2000 show good levels of skill for all reconstructions. The longest period of consecutive dry years, defined as those with less than 90% of the mean of the observed May-August precipitation, was 5 years (1591-1595) and occurred only once during the last 600 years. The longest reconstructed wet period was 5 years (1601-1605 and 1751-1755). No long term trends were found in May-August precipitation during the last few centuries. Regression maps are used to identify the influence of large-scale atmospheric circulation on regional precipitation. In general, tree-ring indices are influenced by May-August precipitation, which is driven by anomalous below (above) normal pressure at all atmospheric levels and by convection (subsidence) and small pressure gradients at sea level. These atmospheric conditions also control the anomaly surface air temperature distribution which indicates below (above) normal values in the southern regions and warmer (cooler) conditions north of around 40 degrees N. A compositing technique is used to extract information on large-scale climate signals from extreme wet and dry summers for the second half of the twentieth century and an independent reconstruction over the last 237 years. Similar main modes of atmospheric patterns and surface air temperature distribution related to extreme dry and wet summers were identified both for the most recent 50 years and the last 237 years. Except for the last few decades, running correlation analyses between the major European-scale circulation patterns and eastern Mediteranean spring/summer precipitation over the last 237 years are non-stationary and insignificant, suggesting that local and/or sub-regional geographic factors and processes are important influences on tree-ring variability over the last few centuries