A 333-YEAR RECORD OF THE MEAN MINIMUM TEMPERATURE RECONSTRUCTION IN THE WESTERN TIANSHAN MOUNTAINS, CHINA

In this paper, a fragile ecological area in the Western Tianshan National Nature Reserve of China was selected as the research region, and Picea schrenkiana, which is sensitive to climate change, was selected as the research object. The mean minimum temperature in the growing season of the previous year (May to September) was the main limiting factor for tree radial growth based on an analysis of the relationship between chronological series and climatic factors during 1959-2012 (r = -0.792, p < 0.05). Moreover, the relationship was stable, which showed that tree rings can be used as alternative materials for climate reconstruction. Therefore, the mean minimum temperature of the previous year in 1680-2012 was reconstructed, and the explained variance of the reconstruction equation was 62.7% (R-adj(2) = 62.0%, F = 85.8). The 31 dramatically altered years were found via characteristic year analyses, and extreme changes occurred most often under relatively warm conditions. The mean minimum temperature in the reconstruction shows a clear warming trend by the 11-year moving average of the reconstructive series since the 1950s (the temperature increase: 0.341 degrees C/decade). The driving factors of the mean minimum temperature were influenced mainly by the interaction of solar activity and large-scale atmospheric-oceanic variability, especially the westerly circulations.