基于不同树干高度树轮宽度的历史气候重建潜力研究

Based on tree-ring width historical climate reconstruction potential research from different stem height

本研究利用新疆伊犁地区雪岭云杉不同树干高度树轮样本建立树轮宽度年表,并尝试使用该年表进行历史气候重建。相关分析表明,10 m树干高度树轮年表与当年6—7月平均最低气温相关显著,相关系数可达0.585(P<0.001)。利用10 m树干高度树轮标准化年表建立了研究区1841—2014年当年6—7月平均最低气温,重建方程稳定可靠。分析表明,重建序列出现了5个偏冷阶段和4个偏暖阶段。其中,1938—1965年和1866—1912年分别是持续时间最长的偏冷和偏暖阶段。重建序列存在2.11 a、2.99—3.10 a、5.09 a、5.47 a、8.08 a、68.03 a的显著周期(P<0.05)。该重建序列的建立进一步证明了利用不同树干高度树轮年表开展气候重建的可能性。在野外采样环境允许的情况下,可以将树干更高处树轮样本纳入采样范围。

Background,aim,and scope Climate reconstruction using tree-ring data is based on the principle that the growth process of tree rings is influenced by climatic factors.However,previous climatology studies based on tree rings have generally used tree-ring samples taken at 1.3 m for follow-up studies.Less attention has been paid to climate reconstruction based on data from tree rings sampled at different stem heights.In this study,tree-ring width chronologies were established using Schrenk spruce(Picea schrenkiana)samples collected at different stem heights.The trees were growing in Ili,Xinjiang,China.The chronologies were used to reconstruct the historical climate.Materials and methods Tree-ring samples collected at stem heights of 1.3 m,5 m,10 m,15 m,and 20 m were evaluated to establish the chronologies.Correlation analyses were conducted between the tree-ring chronologies and the mean temperature,mean maximum temperature,mean minimum temperature,and precipitation.The tree stem height with the highest correlations with climate factors was used to build a model and carry out reconstruction analysis.Results The correlation analyses showed that the mean minimum temperature from Jun.to Jul.of the current year had the highest correlation with the chronological sequence at a stem height of 10 m.The reconstruction equation was able to reconstruct the historical climate.Discussion On the basis of the significant positive correlation between the tree-ring width chronology of Schrenk spruce at 10 m height and the mean minimum temperature in Jun.—Jul.,as well as the clear physiological significance of the trees,we reconstructed the mean minimum temperature series of Jun.—Jul.for the past 174 a in the study area.We found that there were 35 cold years and 29 warm years in the past 174 a,with the longest partial cold period lasting for 28 a and the longest partial warm period lasting for 47 a.When combined with historical disaster information,the reconstructed series could better capture the known climate disasters in the past.A cycle analysis revealed that climate change in the study area may be influenced by multiple climate mechanisms.Moreover,the extreme years in this reconstructed sequence corresponded to the extreme years in other reconstructed sequences,which further demonstrated the feasibility of climate reconstruction using the chronology of tree rings at different stem heights.Conclusions Correlation analyses showed that there were 5 cold and 4 warm phases in the reconstruction sequence.The longest-lasting cold stage was from 1938 to 1965,and the longest-lasting warm stage was from 1866 to 1912.There were significant cycles of 2.11 a,2.99—3.10 a,5.09 a,8.08 a,and 68.03 a in the reconstruction sequence.Recommendations and perspectives The establishment of the reconstruction sequence indicates that it is possible to carry out climate reconstruction using the chronology of tree rings at different stem heights.If the field sampling environment permits,tree-ring samples from higher up the trunk can be included in the sampling range.