Xiaoyuan Li, Weiwei Jia, Hongda Wan
Forest resilience is commonly inferred from stem growth alone, yet this trunk-centered perspective may overlook how resource allocation and climate responses differ between stems and branches and reorganize across tree ontogeny. We used paired stem and branch tree-ring records from juvenile and near-mature Larix olgensis plantations in Northeast China to examine ontogenetic shifts in allometric growth, environmental controls, and organ-specific resilience to climate extremes. Juvenile trees showed crown-prioritization allometry, with a branch-stem scaling slope of 1.10, whereas near-mature trees approached isometry (slope = 0.90), indicating a shift toward more balanced allocation. Growth of juvenile trees was primarily constrained by neighborhood competition, with little detectable organ-specific response to climatic moisture deficit or growing-season temperature. In contrast, branches of near-mature trees were more responsive than stems to both climate variables, indicating greater organ-specific plasticity. During climate-defined pointer years, near-mature stems displayed higher resistance and resilience than branches. Resistance and recovery were positively coupled in stems but negatively related in branches, revealing contrasting organ-level strategies within the same trees. These patterns are consistent with functional hydraulic segmentation, in which distal organs incur greater growth costs while central stem function is comparatively buffered. Overall, Larix olgensis shifts from competition-driven canopy expansion in juvenile stands to more coordinated hydraulic preservation near maturity. These findings show that trunk-centered metrics can overlook persistent branch-level impacts and support stage-specific management that reduces competition in juvenile stands while maintaining canopy integrity and hydraulic safety in near-mature stands.