Cellulose δ18O of Tree Rings Reflects Vapour Pressure Variations in the Ordos Plateau

Abstract

In arid and semi-arid regions, a better understanding of the effect of climate change mechanisms on environmental evolution can be used to guide regional ecological conservation and to improve water resource availability. Increased aridity in arid and semi-arid regions considerably affects the physiological functions of plants and the exchange of carbon and water with the environment. We collected Pinus tabuliformis Carr. samples from Ordos, Inner Mongolia, and measured their δ18O variations. Vapour pressure (VP) was the main factor dominating δ18O variations from July to August, indicating the regulatory role of plant leaf stomata. Based on the δ18O series in the Ordos region, we reconstructed VP variations for July–August (VPJA) for the past 205 years. Spatial analysis showed the reconstruction as spatially highly representative. VP variations in the Ordos region mainly reflected precipitation variations and did not show a significant correlation with temperature. Since the late 1950s, VP has been decreasing, which is related to the weakening of the Asian monsoon. The results of reconstruction decomposed using ensemble empirical mode decomposition showed that El Niño–Southern Oscillation may affect VP in the study area, and the effect of sea surface temperature on the central and eastern Pacific Ocean in the Ordos region may lead to an increase in the drought.