In numerous forests worldwide, there is a growing prevalence of insect disturbances that impact the composition of plant communities and the overall structure of forests. Despite this, the degree to which these alterations in community composition and structure affect the annual storage of carbon in plant biomass, also known as net primary production (NPP), remains poorly understood. Our study investigates whether changes in plant community composition, structural adjustments, and NPP exhibit similar responses to increasing severity of disturbances and two specific disturbance orientations that selectively impact large (top-down) and small (bottom-up) diameter trees. Understanding these responses is crucial for effective management and modeling, particularly when making inferences about how forested ecosystems structurally and functionally respond to varying levels of disturbance caused by insects. The Forest Resilience Threshold Experiment (FoRTE) is a replicated study focused on disturbance orientation and severity, using stem-girdling to induce four levels of gross defoliation ranging from 0% (control) to 85%. Through the analysis of five years of data on leaf litter, seedlings and canopy composition, and portable canopy LiDAR, we explored the relationships between community composition, structure, and NPP across different levels of disturbance severity. Our findings, observed five years after the initiation of the girdling disturbance, indicate that mid-successional Fagus and Acer species consistently dominate the composition of seedlings and saplings, regardless of disturbance severity. In contrast, the canopy is predominantly occupied by Acer and Populus species, surpassing Quercus and Fagus. Despite expectations that high canopy mortality would create conditions favorable to early successional species, their anticipated dominance did not manifest in any of the plots. Surprisingly, NPP demonstrated significant resistance to disturbance across the gradient of severity, irrespective of compositional changes and the level of tree mortality for mid-successional species, but not for early successional species. This suggests a decoupling between composition and production following altered functional responses to disturbance for early successional species. Our analysis implies that, as we strive to manage forests for greater stability in the face of increasing disturbance and intensifying climate change, stability in carbon cycling may be achievable even in the presence of substantial changes in community composition. References: [1]Nave, L.E., et al (2011) Journal of Geophysical Research, 116, G04016. [2] Johnstone, J., et al (2016) Frontiers in Ecology, 14(7), 369-378. [3] Gough, C.M., et al (2021) Ecosystems, 24(10). [4]Gough, C.M., et al (2013) Ecological Applications, 23(5),1205-1215. [5]Stuart-Haentjens, E.J. (2015) Ecology, 96(9), 2478-2487. [6] McDowell et al. (2020) Science, 368(6494). [7] Fahey et al. (2018) Forest Ecology and Management, 421, 59-71.