Abstract: Background，aim，and scope Lüliang Mountains, range in the west of Shanxi Province, China. Northeast striking, about 400 kilometers from north to south, located between the Yellow River and the Fenhe River. Due to the decrease of available water in recent years and the aggravation of drought, it is necessary to study the drought history of this area. In this paper, tree rings of pines from Lüliang Mountains were used to study the dry-wet change in the past and its influencing factors. Materials and methods 42 pine cores were collected from Lüliang Mountains, then they were dried, fixed and polished in the laboratory, the width was measured by LINTAB with an accuracy of 0.01 mm. The COFECHA program was then used for cross-dating quality control to ensure that each tree-ring had an accurate calendar year. Finally, three chronologies were generated with ARSTAN. Results Correlation analysis showed that the palmer drought index (PDSI) had the best correlation with the standard chronology (STD) from May to June, with a correlation coefficient 0.687 (n=50, p＜0.001). In addition, the STD chronology retained more low-frequency signals than the RES chronology. So the width standard chronology (STD) were selected to reconstruct the PDSI index changes from May to June during 1829—2003, the variance interpretation of the reconstructed equation was 47.16%. The reconstructed sequences including 9 wet sequences and 10 dry sequences. Discussion The reconstruction sequence reveals the drought in the 20th century and the intensification of drought in the end of the 20th century. Compared with the DWI index sequence in Yang et al (2013), the correlation coefficient is -0.235 (n=175, p < 0.002). After 10 years of low-pass filtering, the correlation coefficient is -0.4, indicating that the reconstruction sequence is reliable. Conclusions The east Asian summer monsoon has an important influence on the dry and wet changes in the study area. Multiwindow spectral analysis showed that the reconstructed sequences had periodic changes of 2—7 a, 12 a, 13.6 a, 19.2 a, 21.6 a and 26.1 a, which may be related to ENSO and solar activity. Recommendations and perspectives Further research into the factors affecting drought in the region is needed. At the same time, finding other sources of water available to alleviate water shortages is essential.
Keywords: northern Lüliang Mountains; tree ring width; PDSI reconstruction; the east Asian monsoon