Abstract:

【Objective】Because Scotch pine (Pinus sylvestris) plays an important ecological role in windbreak, sand fixation and farmland protection and so on in the north of China,we discussed the characteristics of the chronology of its tree rings in different age-classes and the relationship between its radial growth and climate factors and analyzed the differences in its responses to climate, to provide a theoretical basis for the dendroclimatology and forest management of Pinus sylvestris var. mongolica under different age-classes. 【Method】The COFECHA and ARSTAN programs were used to establish a standard chronology.Pinus sylvestris var. mongolica of 67 sample cores were obtained from two plots in Hulunbuir sandy land, China, and divided into three age-classes:young age trees-less than 55 years, 13 cores; middle age trees-more than 55 years and less than 100 years (A55-100),36 cores;old age trees-more than 100 years (A100), 18 cores. The standard chronology and climate factor responses were obtained using DendroClim 2002 analysis. 【Result】 Based on the statistical characteristic values of tree-ring-width chronologies under different age-classes, the results indicated that the mean sensitivity of the three age-classes was similar, responding to higher climate signals. The first-order autocorrelation (AC₁) gradually increased in the different age-classes. Signal-to-noise ratio (SNR) and expressed population signal (EPS) were the highest in middle-aged trees, whereas the lowest values were found in old-aged trees. Our results showed that the sensitivity of radial growth in young-aged trees to temperature was the highest, whereas the old-aged trees were the most sensitive to precipitation. The middle-aged trees were more affected by the precipitation and minimum temperature in June and July of the preceding year; however, radial growth of the middle-aged trees in the area was significantly negatively correlated with the mean temperature in June and the precipitation in December. 【Conclusion】 The radial growth ofPinus sylvestris var. mongolica in different age-classes in Hulunbuir sandy land was affected by the climatic response. The growth of trees in old age was most sensitive to the precipitation in December of the previous year, reaching the highest value of response coefficient. The growth of both the young- and middle-aged trees exhibited a negative response to the temperatures in June. Thus, further research is needed to determine whether the climatic factors are related to global warming and the resulting warm and dry climate in Daxing’ an Mountins,China.

Key words: Pinus sylvestris var. mongolica, tree-ring, tree age groups, climate response, Hulunbuir sandy land