Tree-ring based December–February precipitation reconstruction in the southern Zagros Mountains,Iran

We developed the first tree-ring width chronology from Quercus brantii Lindel for the period 1796–2015 in the southern Zagros Mountains, Iran, using standard dendrochronological procedures. Climate-growth relationships revealed that DecemberöFebruary precipitation has strong positive effects (r = 0.66; P < 0.01) on the species’ growth while mean temperature during the growing season has strong negative effects. Spatial correlations with Palmer Drought Severity Index (PDSI) and gridded precipitation data revealed that the chronology contains regional climate signals and tree growth variations may represent precipitation fluctuations over large areas of the Middle East. The linear regression model accounts for 44% of the actual DecemberöFebruary precipitation variance. The reconstructed precipitation revealed that over the period 1850–2015 extreme dry years occurred in 1870-71, 1898, 1960 and 1963-64, and extreme wet years occurred in 1851, 1885, 1916 and 1921 in the southern Zagros region. The longest dry period lasted 16 years and occurred from 1958 to 1973. Two-year consecutive wet and dry events showed the highest frequencies and the average length of dry and wet events were 2.9 and 3.6 years over the reconstructed period. Correlations between the long-term reconstructed precipitation and the North Atlantic Oscillation (NAO), Southern Oscillation Index (SOI), and Pacific Decadal Oscillation (PDO) confirmed the effects of teleconnection patterns on precipitation in the southern Zagros region.     

The Suceava oak chronology: A new 804 years long tree-ring chronology bridging the gap between central and south Europe

Although the importance of centuries-long tree ring width oak chronologies in dating wood, eastern European regions are still lacking a reference chronology. To fill this geographical gap, we combined living and historical chronologies from the Moldova region, including part of Romania and the Republic of Moldova. Here we present the “Suceava oak chronology” as the first 804 years long chronology continuously covering the 1216–2019 period. Our analyses further revealed the strong teleconnection of the Suceava oak chronology with south European ones. The link between Romania and northern Turkey chronologies is of particular importance in the context of the high abundance of undated subfossil and archaeological/historical oak wood in eastern Europe and intense wood trades with central Europe in XV-XVII centuries. The availability of the Suceava oak chronology will provide a good base for precise dating and climatic reconstructions.     

Using large-scale climate indices in climate change ecology studies

Recently, climate change research in ecology has embraced the use of large-scale climate indices in long-term, retrospective studies. In most instances, these indices are related to large-scale teleconnection and atmospheric patterns of which over a dozen have been identified. Although most of these relate to different geographical areas, many are related and interact. Consequently, even the simple task of selecting one to use in ecological research has become complicated, despite our ability to disentangle the results from analyses involving large-scale climate indices. Leaning upon recent reviews of the definition and functioning of large-scale climate indices, as well as reviews on the relationship between these and concomitant changes in ecological variables, we focus here on the usefulness of large-scale climate indices in different aspects of climate change ecology. By providing a general framework for using climate indices, we illustrate the potential advantages of their utility by integrating three case histories focusing on two groups of evolutionarily distinct organisms: birds and mammals.     

Atmospheric forcing on chlorophyll concentration in the Mediterranean

Recent research suggests the coupling of climatic fluctuations and changes in biological indices that describe species richness, abundance and spatiotemporal distribution. In this study, large-scale modes of atmospheric variability over the northern hemisphere are associated with chlorophyll-a concentration in the Mediterranean. Sea level atmospheric pressure, air temperature, wind speed and precipitation are used to account for climatic and local weather effects, whereas sea surface temperature, sea surface height and salinity are employed to describe oceanic variation. Canonical Correlation Analysis was applied to relate chlorophyll concentration to the above-mentioned environmental variables, while correlation maps were also built to distinguish between localized and distant effects. Spectral analysis was used to identify common temporal cycles between chlorophyll concentration and each environmental variable. These cycles could be interpreted as mechanistic links between chlorophyll and large-scale atmospheric variability. Known teleconnection patterns such as the East Atlantic/Western Russian pattern, the North Atlantic Oscillation, the Polar/Eurasian pattern, the East Pacific/North Pacific, the East Atlantic jet and the Mediterranean Oscillation are found to be the most important modes of atmospheric variability related to chlorophyll-a concentration and distribution. The areas that are mostly affected are near the coasts and areas of upwelling and gyre formation. The results also suggest that this influence may arise either through local effects of teleconnection patterns on oceanic features or large-scale changes superimposed onto the general circulation in the Mediterranean. Guest editor: V. D. Valavanis Essential Fish Habitat Mapping in the Mediterranean