A dendroclimatic reconstruction of May-June mean temperature variation in the Heng Mounatins, north China, since 1767 AD

High-resolution tree-ring records covering the last hundreds years in north China are very scarce, yet essential for understanding the process and pattern of climate change and designing climate model. In this paper, a Chinese pine (Pinus tabulaformis Carr.) ring-width chronology spanning 1767-2008 AD was developed using standard dendroclimatological methods in the Heng Mountains, Shanxi province of north China. Strongly negative relationships were detected between the ring-width chronology and the monthly mean temperatures (minimum, mean, and maximum) from April to September during the growing season. Based on correlation analysis, the mean temperature from May to June was reconstructed back to 1767 AD. Both spatial correlation analysis with CRU grid dataset and comparisons with other tree-ring based temperature reconstructions from surrounding areas revealed that this reconstruction represented a larger-scale regional temperature variation for north-central China. Significant spectral peaks were found at 2.04-, 2.05-, 2.22-, 7.69-, 75- and 100-year, implying the possible influence of ENSO and solar activity on the local climate. Considering the strong and negative relationship between tree growth and temperature, the future warming will possibly bring increasing drought stress for the tree growth, as shown by the recent warming since the 1950s. However, due to the limit of tree age, this reconstruction did not capture the multi-century scale variations which presents the necessity for developing more and longer tree-ring chronologies in the future in north-central China.</p

Tree-ring-based annual precipitation reconstruction in Kalaqin, Inner Mongolia for the last 238 years

A tree-ring-width chronology of Pinus tabulaeformis from Kalaqin, Inner Mongolia was developed using modern dendrochronological techniques. Based on the results of correlation function analysis, the total precipitation from the previous August to current July was reconstructed for 1771-2008 AD with an explained variance of 49.3%. The reconstruction correlated well with the dryness/wetness series derived from historical documents, as well as the precipitation reconstruction of the Chifeng-Weichang region. There were eight intervals with greater precipitation than the average (associated with the strong East Asian summer monsoon) and seven intervals lower than the average (weak monsoon). A power spectrum analysis showed that there were 120 a, 80 a, 8 a and 2 a periodicities.</p