In the last 100 years, the Earth’s climate has warmed by approximately 1 0C, causing extreme climatic events (ECEs) to increase in frequency, intensity, and severity worldwide. ECEs can change nutrient flows, alter organismal development, and modify population and community dynamics. As a result, ECEs have major ecological consequences that can last years after the event. Contrary to increases in mean climatic averages, ECEs are discrete events that occur at specific times during the life cycle of organisms or a community assembly. Because ECEs are characterized by extreme weather such as extreme heat or intense rain, ECEs have the potential to behave as a disturbance for many organisms and species interactions. Many studies have focused on the consequences of ECEs on phenology, ontogeny and some on population and community dynamics. Although the consequences of ECEs might be sensitive to when they occur, their timing has mostly been ignored in previous studies. In my first chapter, I explored how ECEs timing alters biological processes at the individual, population, and community scales. In my second chapter, I investigated how the timing of heat waves alters community composition and plant growth. In my third chapter, I investigated how the timing of heat waves can change plant physiology and have consequences for ecosystem services. During 2019, 2020, and 2021 I found that early- and late-season heat waves have the most potential to alter plant community compositions, stomatal conductance, and plant growth. These effect can be positive or negative depending on the plant species. Beyond these, I show that the consequences of heat waves can occur even a year after the event. Finally, certain heat waves have the potential to cascade to lower trophic levels, decreasing decomposition rates. My research provides information on the timing of ECEs and indicates that changes in community composition, plant growth, physiology, and decomposition respond to heat waves depending on when they happen.
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