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We developed six tree-ring width chronologies of Siberian spruce ( Picea obovata ) from the low elevation forest of the southern Altay Mountains in northern Xinjiang, China. Although the six chronologies come from different sampling sites, significant correlations existed among the chronologies ( r ≥ 0.477), and the first principal component (PC1) accounted for 72.2% of total variance over their common period 1825–2010. Correlation response analysis revealed that radial growth of Siberian spruce is mainly limited by a 12-month precipitation starting from July of the previous year to June of the current year. We therefore developed a July–June precipitation reconstruction spanning 1825–2009, which explained 65.5% of the instrumental variance for the period 1962–2009. The information of our precipitation reconstruction suggested that dry conditions existed for the periods 1829–1838, 1852–1855, 1876–1888, 1898–1911, 1919–1923, 1932–1936, 1943–1955, 1963–1968, 1973–1984 and 2007–2009, and wet conditions for the periods AD 1825–1828, 1839–1851, 1856–1875, 1889–1897, 1912–1918, 1924–1931, 1937–1942, 1956–1962, 1969–1972 and 1985–2006. Spatial climate correlation analyses with gridded land surface data revealed that our precipitation reconstruction contains a strong precipitation signal for the Altay Mountain ranges. Our reconstruction agreed with the moisture-sensitive tree ring width series of Siberian larch from the Altay Mountains of Mongolia on a decadal timescale. In addition, in contrast to a drying trend in north central China, a clear wetting trend has occurred in the southern Altay Mountains since 1980s. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we present the results of a dendroclimatological investigation of three coniferous tree species, Larix principis-rupprechtii, Picea meyeri and Pinus tabulaeformis, growing along an altitudinal gradient at the Lüliang Mountains in Northern China. Totally five tree-ring width chronologies were developed to explore the climate-growth responses of these tree species. No obviously regular trend associated with the increase of elevation was found by comparing the statistical characteristics of the chronologies. Correlation analysis indicated that the chronologies from lowerest to middle-high sites (SZ, BWD, BDGL and BDGP, respectively) were highly correlated, and different species from the same site showed the highest correlation. Growth–climate analysis indicated that the chronology of Larix principis-rupprechti at the uppermost site near the tree line (XWS) did not exhibit a significant response to the seasonal climatic factors, whereas the other four lower chronologies were consistently and significantly influenced by both the mean temperature from May to July and the total precipitation from March to June, regardless of tree species and elevation. The similarity of the tree growth–climate relationships of different species growing at different elevations (except that from the tree line) suggests that the trees in this region can provide common regional climate information, and combinations of multiple species (RC) are more successful in reconstructing the climate data than single species. The results of this research are very crucial for the future forest management and dendroclimatological sampling strategy in the arid to semi-arid area of northern China. [Copyright &y& Elsevier]

Abstract: While the forest-tundra zone in Siberia, Russia has been dendroclimatologically well-studied in recent decades, much less emphasis has been given to a wide belt of northern taiga larch forests located to the south. In this study, climate and local site conditions are explored to trace their influence on radial growth of Gmelin larch (Larix gmelinii (Rupr.) Rupr.) trees developed on permafrost soils in the northern taiga. Three dendrochronological sites characterized by great differences in thermo-hydrological regime of soils were established along a short (ca. 100m long) transect: on a river bank (RB), at riparian zone of a stream (RZ) and on a terrace (TER). Comparative analysis of the rate and year-to-year dynamics of tree radial growth among sites revealed considerable difference in both raw and standardized tree-ring width (TRW) chronologies obtained for the RZ site, characterized by shallow soil active layer depth and saturated soils. Results of dendroclimatic analysis indicated that tree-ring growth at all the sites is mostly defined by climatic conditions of a previous year and precipitation has stronger effect on TRW chronologies in comparison to the air temperatures. Remarkably, a great difference in the climatic response of TRW chronologies has been obtained for trees growing within a very short distance from each other. The positive relation of tree-ring growth with precipitation, and negative to temperature was observed in the dry site RB. In contrary, precipitation negatively and temperature positively influenced tree radial growth of larch at the water saturated RZ. Thus, a complicate response of northern Siberian larch forest productivity to the possible climate changes is expected due to great mosaic of site conditions and variability of environmental factors controlling tree-ring growth at different sites. Our study demonstrates the new possibilities for the future dendroclimatic research in the region, as various climatic parameters can be reconstructed from tree-ring chronologies obtained for different sites. [Copyright &y& Elsevier]

Abstract: In order to investigate climate–tree growth relationships at different elevations, tree-ring width chronologies of Qilian Juniper (Sabina przewalskii) were developed from four sampling sites at different elevations of a south-facing slope in the central Anyemaqen Mountains, northeastern Tibetan Plateau. Statistical characteristics of the chronologies indicated most tree-ring parameters decreased with the increase of elevations. Response analysis on the first principal component of all four chronologies indicated 76% of tree growth could be explained by climatic variations. Correlation analysis between chronologies and climate variables indicated there were significant differences in climate–tree growth relationships along the altitudinal gradients. The lower forest border chronology was negatively correlated with monthly mean temperature, except for previous October and current January–March, while the upper forest border chronology had positive correlations with monthly mean temperature, excluding previous September and current April–May. There was a decreasing trend from significantly negative to weakly negative correlations of tree growth with May–June temperature from low to high elevations, and an increasing trend from weakly negative to significantly positive correlations with July temperature. Meanwhile, there were significant positive correlations of prior August–October and current July precipitation with the two low-elevation chronologies. The correlations between tree growth and January–April precipitation varied from negative to positive with the increase of elevations, although there were no significant correlations between precipitation and high-elevation chronologies. Response analysis on all chronologies indicated tree growth was more limited by temperature along the entire slope, while precipitation tends to influence tree growth at some drier or lower-elevation sites. [Copyright &y& Elsevier]

Abstract: Dendroecological knowledge about non-dominant sub-canopy trees is scarce but needed to fully understand the tree-ring dynamics in temperate deciduous forests. Here I present a study on the effects of climate, habitat conditions and forest management on the radial growth in the rare tree species Sorbus torminalis. Increment cores were collected in 19 populations along a latitudinal gradient ranging from the regional distribution limit in Switzerland, through Germany, to the absolute northern limit in northeastern Germany and Denmark. The ring width measurements were crossdated and correlated with climate and habitat descriptors. The annual response of the chronologies showed a predominantly negative relation with monthly temperature, and both positive and negative relation with monthly precipitation. In some populations, high temperature together with low precipitation may thus cause water stress and thereby limit tree-ring growth. Mean tree-ring width correlated significantly with mean annual precipitation as well as with indicators for soil nutrient content, soil moisture, temperature and light, and cover of the vegetation layers. A third factor, which proved important for understanding the variation in tree-ring growth, was forest management history. The species responded with abrupt growth increase to clearing of the dominant canopy species. In addition, forest management in Europe has become more extensive during the past 50 years leading to reduced growth of S. torminalis due to competition with the dominant tree species. There was no latitudinal trend in radial growth, but chronologies showed a higher sensitivity and magnitude of growth changes towards the northern distribution limit. [Copyright &y& Elsevier]

Pinus brutia var. pityusa (Steven) Silba (Calabrian pine) is considered a vulnerable species because of reductions in its population sizes linked to habitat decline in recent decades. Global warming alongside the collateral modification of precipitation regimes may markedly affect the distribution ranges of this species. In this dendroecological study, we identified the most influential climatic factors affecting the radial growth of P. brutia on the northern and eastern coasts of the Black Sea among the northern refugia of this species. Chronologies from five sites located on the Crimea Peninsula and the Caucasian coast and exposed to varying climatic conditions were used in this analysis. The study of environmental factors controlling the growth of P. brutia trees in the coastal populations of Crimea and the Caucasus revealed that within the longitudinal transect, which encompasses a specific range of climatic conditions, correlations between climate and the growth of P. brutia under analogous orographic conditions are similar. Aridisation of the dry Crimean climate in 1981–2012 led to an increase in the tree growth response. In the same period, populations of P. brutia trees growing in the subtropical climate of the Black Sea coast exhibited a weakened growth response to the point of disappearance. The northern populations of P. brutia , which are at the climatic limit of the species' distribution, are exposed to a high risk of increasing climate aridisation. Our findings could provide useful information for further research on the effects of climate change on Black Sea coastal forest ecosystems. [ABSTRACT FROM AUTHOR]