色季拉山急尖长苞冷杉种群径向生长对气候的分异响应OA

[Objective]The study aimed to analyze the response of Abies georgei var.smithii(Smith fir)communities in the Sygera Mountains to climate change and to explore the similarities and differences in their adaptation strategies to global warming at different altitudes.[Method]Dendrochronological me-thods were applied to A.georgei var.smithii communities across four altitudinal gradients(3 700,3 900,4 100,and 4 300 m)in the Sygera Mountains.Standardized tree-ring width chronologies for the four altitu-dinal gradients were developed through the integrated application of TASP-Win and ARSTAN software.Regression analysis and Pearson correlation analysis were adopted to investigate the trends in tree radial growth before and after the abrupt temperature change,and assess the correlations of the tree-ring width index with temperature and precipitation.[Result]The abrupt temperature change in Sygera Mountain was identified with a threshold year of 1985.The radial growth response of A.georgei var.smithii to this cli-matic shift exhibited significant altitudinal divergence,reflecting altered temperature-growth relationships across altitudes.Before the abrupt temperature change,the radial growth across all elevations exhibited pri-mary constraints from minimum temperatures:the 3 700 m site displayed a highly significant negative cor-relation with July minimum temperatures of the current year,while the 4 100 m site showed a significant negative correlation with August minimum temperatures of the preceding year.After the abrupt tempera-ture change,radial growth of A.georgei var.smithii was enhanced by maximum temperatures.At lower elevations(3 700 m and 3 900 m),radial growth demonstrated significant positive correlations with maxi-mum temperatures during July-August of both the current and the preceding years.The higher elevation site(4 300 m)exhibited highly significant positive correlations with October and December maximum tem-peratures of the preceding year.Notably,the 4 100 m site transitioned to a significant negative correlation with May maximum temperatures of the current year,no longer showing minimum temperature limita-tions.Prior to the abrupt temperature change,radial growth at 3 700 m and 3 900 m was not enhanced by precipitation,whereas the 4 100 m and 4 300 m sites correlated positively with April and July precipitation of the current year,respectively.After the abrupt temperature change,the 3 700 m area was negatively cor-related with August precipitation of the current year and August and October precipitation of the previous year,while the 4 100 m area was not correlated with the precipitation.[Conclusion]Climate warming en-hances radial growth of A.georgei var.smithii at higher elevations,driving an upward shift in its growth acclimatization zone.Concurrently,climate change has induced elevational divergence in the radial growth of A.georgei var.smithii.