Assessing Vegetation Recovery and Carbon Dynamics in Eucalyptus regnans Forests Following the 2009 Black Saturday Wildfire: Implications for Disaster Risk Reduction

ABSTRACT The escalating frequency and intensity of wildfires globally necessitate a deeper understanding of ecosystem carbon dynamics post‐disturbance. This study utilizes a valuable pre‐ and postfire eddy‐covariance dataset from the AU‐Wac site to quantify the recovery of net ecosystem CO 2 exchange (NEE) in a carbon‐dense Eucalyptus regnans forest following the catastrophic 2009 Black Saturday wildfire. Our findings, derived from Bayesian additive regression trees (BART) modeling of no‐fire scenarios and locally estimated scatterplot smoothing (LOESS)‐smoothed recovery indices (Div and Sub), indicate that the forest returned to an initial net carbon uptake 16 months postfire, exhibited its peak recovery rate at 44 months, and regained prefire NEE levels by 48 months, with a total carbon loss of 44.34 t C/ha. Our analysis, employing random forest (RF) regression, SHapley Additive exPlanations (SHAP), and Spearman correlation for key factor analysis, considering both lagged and cumulative effects, further reveals a fundamental shift in NEE drivers. From prefire air temperature and soil water content control, postfire NEE became predominantly governed by soil temperature and water content along with atmospheric humidity, exhibiting stronger multifactor couplings. These results emphasize the crucial role of postfire hydrological conditions for recovery and provide critical science‐based information for proactive forest management, including prescribed burning and enhanced biodiversity, to mitigate degradation and maintain carbon sequestration in fire‐prone regions.