Negligible local-factor influences on tree ring cellulose δ¹⁸O of Qilian juniper in the Animaqing Mountains of the eastern Tibetan Plateau

Figures & data

Fig. 1. Map of the study area. Red spots and black triangles indicate ring width and cellulose oxygen isotope data (>1000 yr), respectively. Stars and rectangles indicate sampling locations and meteorological stations, respectively.

Fig. 2. Regional monthly mean temperature (black circles), precipitation (grey bars) and relative humidity (triangles) from 1960 to 2014.

Fig. 3. Tree ring δ¹⁸O values from young trees (red lines) and old trees (black lines). The dashed line indicates the pith year.

Fig. 4. Tree ring δ¹⁸O chronology based on all trees (black) and non-young trees (red).

Fig. 5. Tree ring δ¹⁸O values from different sampling heights (a) and directions (b).

Table 1. Statistical analysis of data for each tree in this study.

Sampling altitude	4250 m
Sample ID	YK177	YK178	YK179	YK180	Mean
Average (‰)	29.43	30.42	30.23	30.34	30.10
STD	1.36	1.40	1.50	1.56	1.34
1st autocorrelation	0.17	0.14	0.01	0.07	0.04
Sampling altitude	4150 m
Sample ID	YK181	YK182	YK183	YK184	Mean
Average (‰)	31.09	30.74	31.39	31.35	31.13
STD	1.61	1.67	1.74	1.47	1.55
1st autocorrelation	0.12	0.03	0.04	0.01	0.00
Sampling altitude	4000 m
Sample ID	YK123	YK168	YK171	YK173	Mean
Average (‰)	31.27	29.35	31.78	32.04	31.42
STD	1.65	1.36	1.51	1.40	1.40
1st autocorrelation	0.15	N/A	0.01	0.04	0.01
Sampling altitude	3900 m
Sample ID	YK115	YK114	YK105	YK109	Mean
Average (‰)	30.07	30.18	28.82	30.85	29.98
STD	1.47	1.93	1.25	1.95	1.50
1st autocorrelation	0.00	0.39	0.08	0.53	0.13
Sampling altitude	3800 m
Sample ID	YK162	YK134	YK133	YK137	Mean
Average (‰)	30.23	30.69	31.87	30.72	30.78
STD	1.55	1.36	1.77	1.10	1.33
1st autocorrelation	0.19	N/A	N/A	N/A	0.12
Sampling location	ND
Sample height	15 cm	70 cm	70 cm	70 cm	70 cm
Sample direction	North	North	South	West	East
Average (‰)	32.64	32.63	32.49	32.98	32.60
STD	1.69	1.59	1.61	1.78	1.66
1st autocorrelation	0.18	N/A	N/A	0.25	0.16

Table 2. Correlation coefficients among tree ring δ¹⁸O time series from different directions.

r	North	South	West
South	0.952
West	0.928	0.928
East	0.891	0.926	0.887

Fig. 6. Tree ring δ¹⁸O time series from different altitudes. Coloured lines in Figure 6a–e indicate oxygen isotope time series from different trees in each altitude, and coloured lines in Figure 6f indicate tree ring oxygen isotope time series from different altitudes.

Fig. 7. Average and standard deviation of tree ring δ¹⁸O data from different altitudes.

Table 3. Correlation coefficient among tree ring δ¹⁸O time series from different altitudes.

r	4250 m	4150 m	4000 m	3900 m
4150 m	0.970
4000 m	0.959	0.971
3900 m	0.894	0.900	0.901
3800 m	0.886	0.884	0.909	0.895

Fig. 8. Correlations between tree ring δ¹⁸O from different altitudes and regional temperature (a), precipitation (b) and relative humidity (c) obtained from eight instrumental stations during 1960–2014.

Fig. 9. Spatial correlations between tree ring δ¹⁸O and May–July precipitation from meteorological stations on the Tibetan Plateau from 1960 to 2014.