立地条件对长白落叶松人工林单木径向生长-干旱关系的调节效应OA

[Objective]This study aims to quantify the regulatory effects of site conditions on the tree-ring radial growth-drought relationship in Larix olgensis plantations,providing scientific support for sustainable forest management under climate change.[Method]We investigated 36 L.olgensis plantation plots in Shengli Forest Farm,Bin County,Harbin City,Heilongjiang Province.The plots were classified into three site quality grades using the site index(SI):good site conditions(SI≥20.0 m,7 plots),medium site conditions(17.0 m≤SI＜20.0 m,14 plots),and poor site conditions(SI＜17.0 m,15 plots).Dendrochronological methods combined with three drought response indices(resistance,recovery,and resilience)were employed to evaluate how site conditions modulate the growth-drought relationship.[Result]The standardized precipitation evapotranspiration index(SPEI)identified four moderate drought events with an average duration of 1.25 years.Growth-limiting climatic factors varied across site condition grades:for overall group,non-growing season precipitation and SPEI were the primary limiting factors;poor site condition was constrained by monthly minimum temperature,precipitation and SPEI during the non-growing season;medium site condition by non-growing season precipitation and SPEI;while good site condition was mainly affected by monthly maximum temperature,precipitation and SPEI in the non-growing season.The differences in resistance,recovery of L.olgensis under different site conditions were different,and the resistance and resilience showed a comparative pattern:good site condition＞medium site condition＞poor site condition,while the recovery and resilience showed an opposite trend.With the continuation of drought years,the resistance of L.olgensis in different site conditions increased significantly,the trend of recovery increased first and then decreased,the overall trend showed a significant decrease,and the resilience showed an overall upward trend,which was consistent with the results of resistance and contrary to the results of recovery.[Conclusion]Non-growing season precipitation and SPEI were identified as the primary limiting factors for L.olgensis growth.However,site conditions showed no significant moderating effect on the relationship between radial growth and moderate drought events.Further research is needed to determine whether site conditions significantly regulate radial growth-drought relationships under different drought severity levels and durations.