Reconstruction of the regional summer ground surface temperature in the permafrost region of Northeast China from 1587 to 2008

To extend the historical temperature record in the permafrost region of northeast China, we reconstructed the regional ground surface temperature (GST) for the past four centuries based on a network of Dahurian larch (Larix gmelinii Rupr.) tree ring width chronologies. Seven standard tree ring chronologies, which correlated well with each other, were averaged to create a regional mean chronology. The GST was the major limiting factor for tree growth in this region. The optimum range of GSTs was from 30 May to 26 August (summer GST), identified by combining the days on which tree growth was strongly influenced by the daily GST data. The summer GST was significantly correlated with the regional mean chronology (r=0.704, p<0.001) over the common period 1971–2008 and was reconstructed for the period 1587–2008. The reconstructed GST accounted for 49.4% of the actual variance in the GST over the period 1971–2008 and captured four warm periods (1597–1603, 1716–1723, 1781–1788, and 1925–1929...