Tree Ring Density-based Summer Temperature Reconstruction For The Central Hengduan Mountains In Southern China

摘要

Variations in ring width and wood density of Picea brachytyla were used to develop high-resolution climate proxy data to extend the existing climate record in the central Hengduan Mountains, north-western Yunnan Province, China. Growth-climate response analyses showed that the total ring width (TRW) and maximum latewood density (MXD) in the sub-alpine zone are mainly influenced by summer temperature variability. Based on a MXD regional chronology derived from two high elevation sites, we developed a warm season (April-September) temperature reconstruction for the period A.D. 1750-2006. The climate/tree-growth model accounts for 41% of the instrumental temperature variance during the period 1958-2004. Warm summers occurred during 1750s, 1820-50S, 1880-1890s, 1930-1950s and 1990-present; while the periods of 1790-1810S, 1860-1870S, 1900-1920S, and 1960-1985 were relatively cold. Spatial climate correlation analyses with gridded land surface data revealed that our warm season temperature reconstruction contains a strong regional temperature signal for the Hengduan Mountain ranges. Our reconstruction successfully captured recent abrupt climatic changes and agreed in general with other tree ring-based temperature reconstructions from nearby regions on a decadal timescale. In addition, reconstructed summer temperature variations were consistent with recorded glacier fluctuations in the surrounding high mountains.