Systematic review of heatwave experiments on plant health and survival

Background: Heatwaves, which are becoming more intense and more frequent due to global warming, are a major threat to the stability of plant populations and ecosystems. Safeguarding ecosystem function requires a clear understanding of vulnerability to these extreme events. Yet vulnerability cannot be reliably inferred from experiments that manipulate only mean temperatures or from standard thermal tolerance assays. These limitations have spurred a growing body of research specifically simulating heatwaves and studying their effect on plants. Method: Here, we present a systematic review of empirical studies on plant responses to heatwaves. Results: Regional biases are pronounced, reflecting the logistical and financial challenges of conducting these costly experiments. Likely for similar reasons, studies have largely been restricted to seedlings, with little attention to adult plants and wild species in the reproductive stage. Experimental approaches are also highly diverse, particularly in how heatwaves are simulated, creating major hurdles for cross-study comparison. More than half of the studies (53/84) incorporated at least one interacting factor—most commonly drought (23/84)—yet other ecologically important interactions, such as grazing and microbial associations, remain underexplored. Implications: This review offers a comprehensive resource to guide the next generation of heatwave experiments, highlighting underrepresented plant groups and geographic regions, and underscores the pressing need for greater standardisation in experimental approaches to facilitate a synthetic understanding of heatwave effects globally. Such coordination will improve our ability to identify heatwave-sensitive species and better predict ecological responses to climate extremes.