Temporal And Spatial Variability Of Radial Growth Of Larix Gmelinii In Greater Khingan Mountains

Greater Khingan Mountains is one of the regions with the fastest temperature rise and the most sensitive tree growth to climate warming in China.In order to understand the differences of growth,the response of growth to climate and the impact of climate warming on the growthclimate response under different temperature conditions,this paper takes Larix gmelinii at different latitudes and altitudes in Greater Khingan Mountains as the research object,and uses principal component analysis,multivariate linear regression analysis,correlation and response function analysis to explore the temporal and spatial variability characteristics of growth difference and growth climate response of Larix gmelinii on individuals scale.The following results were obtained:(1)On the spatial scale,with the decrease of temperature,the common climate signal affecting tree growth decreases,the limitation of climate factors decreases,and the difference of individuals growth increases.(2)The growth "divergence problem" phenomenon appeared in the stand chronology at different latitudes and altitudes around 1984,which is consistent with the time of rapid climate warming.In addition,the continuous decline of stand chronology in Kudur area after 1992 is related to the "warm and dry" climate.The relationship between radial growth and climate is fluctuating,and the transformation of dominant climate factors is the main reason for growth "divergence problem ".The forest canopy density is larger,the tree height has a greater impact on the growth climate response,while the canopy density is smaller,the breast-height diameter and tree age have a greater impact.(3)After 1984(2004),Kudur and other sampling points showed asynchronous changes in the interpretation of variance of the first principal component,which may be due to the enhanced restrictive effect of climate factors caused by "warm and dry" in the later stage of kudur.In addition,while the variance interpretation of the first principal component in each location decreases,the growth climate relationship also weakens.Therefore,the growth climate relationship may reflect the change of tree growth consistency.The results show that during the study period,the tree growth difference and growth climate relationship have changed.When the climate limit is less,the consistency of tree growth will decline.After climate warming,the weakening of heat condition limit will strengthen the relationship between tree growth consistency and precipitation,and insufficient water will increase the growth consistency.