A BETULA PLATYPHYLLA TREE-RING BASED PRECIPITATION RECORDS IN ERGUNA DURING LATEST HUNDRED YEARS
Tree ring has a high potential for detecting changes in climate factors during historical periods.In this study,we reconstructed the June-July precipitation in the study area(51°46′12″～52°00′36″N,121°55′48″～122°00′36″E;706.3 m a.s.l.)over 118 years based on a total of 94 cores from 47 Betula platyphylla trees at two sampling sites in Erguna in northwestern Greater Khingan Mountains area for the first time.All cores were standardized using negative exponential curves to remove the influences of itself and the surrounding environment,and the standard chronologies for 1902～2019 A.D.were obtained.We correlated the climate data of Erguna meteorological station and the standardized chronologies,and found the highest correlation between the regional chronology and June-July precipitation(r=0.56,p＜0.01)during 1957～2019.And then,we reconstructed June-July precipitation with 30.4％total variance explanation of actual precipitation records by the reconstruction model.At the same time,the reconstruction has a good correspondence with the historical data from neighboring areas,further verifying the reliability of the reconstruction sequence.The reconstruction shows that precipitation was relatively stable since 1902 in the study area,with eight dry periods(1903～1916,1924～1929,1937～1941,1949～1954,1965～1972,1979～1983,1990～1993,and 2001～2007)and eight wet periods(1917～1923,1930～1936,1942～1948,1955～1964,1973～1978,1984～1989,1994～2000,and 2008～2019),and there is no obvious trend with the longest dry period 1903～1916(14 years in total).The reconstruction exhibits enhanced temporal and spatial representativeness,with 1967,1968,and 2003 representing three extreme drought years within the period,while 1920 stands out as one extreme wet year.The results of wavelet and multi-taper spectrum analysis show that the precipitation in this area has a quasi-period of 2.2 year,7～7.7 year and 8～15 year at the 95％confidence level.In addition,precipitation change in the study area is related to Sea Surface Temperature(SST)fluctuations in the tropical Pacific(such as El Nino-Southern Oscillation(ENSO),Pacific Decadal Oscillation(PDO))and polar ocean oscillation(such as Arctic Oscillation(AO)),and is affected by solar activities.This study not only fills the regional gap about dendrochronology and extends the precipitation record in this area,but also proves that the broad-leaved tree species Betula platyphylla is a reliable proxy for dendroclimatic data in the study area.
Betula platyphyllatree-ringprecipitation reconstructionErguna area
NETL
NSTL
万方数据
