Open AccessNo altitude‐dependent effects of climatic signals are recorded in S mith fir tree‐ring δ 18 O on the southeastern T ibetan P lateau, despite a shift in tree growth
Author(s) -
Zeng Xiaomin,
Liu Xiaohong,
Wang Wenzhi,
Xu Guobao,
An Wenling,
Wu Guoju
Publication year - 2014
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/bor.12053
Subject(s) - latitude , relative humidity , altitude (triangle) , atmospheric sciences , precipitation , climatology , geology , physical geography , geography , meteorology , geometry , mathematics , geodesy
To reveal the influence of current warming on tree growth and δ 18 O in a sensitive high‐latitude region that is undergoing rapid climate change, we examined tree width and the earlywood and latewood δ 18 O at two sites with a 400‐m elevation difference in the S ygera M ountains of the southeastern T ibetan P lateau. The study period was from 1950 to 2011. The mean tree‐ring index at the low site was higher than that at the high site during the study period. The climatic responses of earlywood and latewood δ 18 O at both sites were similar. Earlywood δ 18 O was mainly influenced by the J une to A ugust temperature and total cloud cover, whereas latewood δ 18 O was mainly controlled by relative humidity from J uly to A ugust. Spatial correlations with CRU TS 3.1 regional data suggest that our δ 18 O chronologies can represent climatic changes over large regions. The high offset between earlywood δ 18 O at the two sites (2.3‰ higher at the low site) was mainly influenced by the high temperature lapse rate as a function of altitude during the earlywood growing season. Furthermore, meltwater with lower δ 18 O values might have affected earlywood δ 18 O at the high site, and thereby increased the earlywood δ 18 O offset between two sites. The low latewood δ 18 O offset between the two sites (0.4‰ higher at the low site) was not significant, but appears to have been primarily influenced by the low precipitation δ 18 O lapse rate as a function of altitude during the latewood growing season. Earlywood δ 18 O of S mith fir suitable for reconstructing past temperatures and latewood δ 18 O suitable for reconstructing past relative humidity on the southeastern T ibetan P lateau were identified.