Long exposure to extreme heat magnifies the decoupling between bacterial resistance and recovery

Climate change is intensifying the duration of heat waves and threatening community stability. Using soil Pseudomonas communities, we investigated how different heat pulse durations impact resistance (immediate response) and recovery (post-stress response). We first assessed thermal performance traits across six species (16 strains) and found no trade-off between growth rate and heat resistance. We then assembled synthetic communities and exposed them to single heat pulses of 6, 12, 24, or 48 hours. We expected the fastest and most heat resistant species, P. putida, to dominate where present, but an intermediate grower, P. protegens, dominated all communities due to diffusible toxins and unexpected heat tolerance due to density-dependent growth. On average, each additional hour of heat increased extinction risk by 21.5% but fast growing communities were protected from extinction. The longest heat pulse duration led to sharp losses in diversity and productivity. We found that longer heat exposure magnified the decoupling between resistance and recovery phases, reducing community stability. These results reveal that growth rate and species interactions — not heat resistance alone — shape community fate during extreme events. Our findings highlight the need to consider nonlinear dynamics and trait-based interactions in predicting microbial responses to climate extremes.