Seven centuries long spurce ring width chronology in the area of Engilchek glacier, Tien Shan mountains, Kyrgyzstan Republic


O.E.Maximova
Russian Federation, 109017, Moscow, Staromonetny-29, Institute of Geography RAS
olgamasha@yandex.ru


We have presented here a new ring width chronology of spruce (Picea Schrenkiana Fish. et May.) - the longest spruce chronology at the moment in Kyrgyzia (1360-2005). The samples were collected at the timberline in the Engilchek valley at the elevation of 2726-3120 m.a.s.l. (42 09 N, 79 27 E) (fig. 1). We cross-dated 44 radii and combined them in the ENG chronology extending from AD 1360 to 2005 (table 1). We used ARSTAN to build the standard chronology. The chronology is quite well replicated especially since the mid 16th century. According to the EPS test the chronology is reliable for 1425-1495 and 1645-2005. The ENG ring-width site chronology positively correlates with the regional Tien Shan ring width chronology at the upper tree limit (R^2=0.5).
We found positive correlations with January and September temperature as well as with precipitation in November and December preceding the growth and September of the current year measured at the Tien Shan meteorological station (fig. 2). The precipitation in the early winter is important for the spruce growth because the snow protects the trees from the ground frost and creates future resources of water when it melts in spring.
The comparison with glaciers parameters from Karabatkak and Sarytor glacier shows that the ENG chronology smoothed by 11 years running mean positively correlates with the accumulation, mass balance and ELA elevation and negatively – with ablation. The ENG chronology positively correlates with the reconstruction of drought index based at the spruce ring width regional chronology from the lower tree limit in Tien Shan (Solomina et al., 2007) (fig. 3). The general coherence of the two curves shows that they may have a common signal most probably related to the humidity.


Table 1. Statistics of the ENG chronology

Number of dated series

47

Master series

1360-2005, 646 yrs

Total rings in all series

10347

Total dated rings checked

10347

Series intercorrelation

0.666

Average mean sensitivity

0.259


 

Fig. 1. Map of tree-ring sites, glaciers and meteostations.

Fig. 2. Comparison of mean monthly temperature (A) and precipitation (B) for instrumental period at Tien Shan and Koylu Meteorological Stations for the years of maximal (1930, 1999) and minimal (1938, 1984) ring width in the ENG chronology.
A,B - comparison of mean monthly temperature (A) and precipitation (B) for instrumental period at Tien Shan and Koylu Meteorological Stations.
C,D - comparison of mean monthly temperature (C) and precipitation (D) at Tien Shan Meteorological Station for the years of maximal (1930, 1999) and minimal (1938, 1984) ring width in the ENG chronology.
E,F - comparison of mean monthly temperature (E) and precipitation (F) at Koylu Meteorological Station for the year of minimal (1984) ring width in the ENG chronology.
 

 

Fig. 3. Comparison of the standard ring width spruce local ENG (1) chronology and TSH UP 09 (2) regional spruce regional chronology at the upper tree limit in Tien Shan.

 


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