The pre-disturbance vegetation characteristics that predict carbon (C) cycling responses to disturbance are not well known. To address this gap, we initiated the Forest Resilience Threshold Experiment, a manipulative study in which more than 3600 trees were stem girdled to achieve replicated factorial combinations of four levels (control, 45, 65, and 85% gross defoliation) of disturbance severity and two disturbance types (targeting upper or lower canopy strata). Applying a standardized stability framework in which initial C cycling resistance to disturbance was calculated as the first-year natural log response ratio of disturbance and control treatments, we investigated to what extent pre-disturbance levels of species diversity, aboveground woody biomass, leaf area index, and canopy rugosity—a measure of structural complexity—predict the initial responses of subcanopy light-saturated leaf CO₂ assimilation (A_sat), aboveground wood NPP (ANPP_w), and soil respiration (R_s) to phloem-disrupting disturbance. In the year following stem girdling, we found that above-ground C cycling processes, A_sat and ANPP_w, were highly resistant to increases in disturbance severity, while R_s resistance declined as severity increased. Disturbance type had no effect on first-year resistance. Pre-disturbance aboveground woody biomass, and canopy rugosity were positive predictors of ANPP_w resistance and, conversely, negatively related to R_s resistance. Subcanopy A_sat resistance was not related to pre-disturbance vegetation characteristics. Stability of C uptake processes along with R_s declines suggest the net C sink was sustained in the initial months following disturbance. We conclude that biomass and complexity are significant, but not universal, predictors of initial C cycling resistance to disturbance. Moreover, our findings highlight the utility of standardized stability measures when comparing functional responses to disturbance.

预测碳（C）对扰动的循环响应的扰动前植被特征尚不清楚。为了弥补这一差距，我们启动了森林抗御力阈值实验，该实验是对超过3600棵树进行茎环剥除，以实现干扰严重度和干扰的四个级别（对照，45、65和85％的总落叶）的重复因子分解组合。两种干扰类型（针对上部或下部冠层）。应用标准化的稳定性框架，计算干扰的初始碳循环抗性作为干扰和防治措施的第一年自然对数响应比，我们调查了物种多样性，地上木质生物量，叶面积指数的干扰前水平，₂同化（A _sat），地上木材NPP（ANPP _w）和土壤呼吸（R _s）对韧皮部造成干扰。在茎环环绕的第二年，我们发现地上C循环过程A _sat和ANPP _w对干扰严重性的增加具有高度抵抗力，而R _s抵抗力随着严重性的增加而降低。干扰类型对第一年的抵抗力没有影响。地上扰动前的木质生物量和冠层皱纹度是ANPP _w抗性的正向预测因子，反之与R _s抗性呈负相关。子冠层一个_SAT性是不相关的预干扰植被特征。碳吸收过程的稳定性以及R _s的下降表明，扰动后的最初几个月中净C汇一直维持。我们得出的结论是，生物量和复杂性是重要的，但不是通用的初始C循环抗扰性预测因子。此外，我们的发现突出了当比较对干扰的功能响应时标准化稳定性测度的效用。