Tree-ring based precipitation reconstruction for the forest–steppe ecotone in northern Inner Mongolia, China and its linkages to the Pacific Ocean variability

Abstract

We present a precipitation reconstruction for the ecotone of Hulunbei'er steppe and Great Xing'an Mountain forest region, Inner Mongolia, based on tree rings of Mongolian pine (Pinus sylvestiris Linnaeus var. mongolica Litvinov) scattered in regional sandy dune forests. The ring-width chronology shows most significant correlation with precipitation from prior August to current June. Based on this relationship, a precipitation reconstruction (1806–2007A.D.) was developed. The reconstruction was verified with independent data, and accounts for 39.7% of the actual precipitation variance during their common period (1953–2007). The reconstruction shows a relatively wet early half of the 19th century, a reversal from generally dry conditions during the late-19th century to generally wet conditions during the early 20th century, and a drying trend in general since the mid-20th century. The driest decades are found in 1856–1865 and 1889–1898, and the wettest decades occurred in 1944–1953 and 1826–1835, respectively. Multi-decadal (≥56.8year) and inter-annual (2.3, 4.6, 4.8, 4.9, 5.7–6.0, 9.0 and 9.1year) cycles are also detected in our reconstruction. Our precipitation reconstruction is significantly correlated with the East Asian Monsoon and Pacific Ocean signals, such as the El Niño-Southern Oscillation and Pacific Decadal Oscillation.