Extreme climate events (e.g., extended drought, extreme temperatures) have increased in frequency and severity across numerous ecosystems raising concern over possible climate-induced state transitions in vegetation communities and ecosystem functioning. To date, such transitions have not yet strongly manifest in natural settings—a situation some have interpreted as indicating widespread resilience of vegetation communities to extreme climate events. However, this interpretation is plagued by a dearth of long-term data regarding vegetation community responses to extreme climate events, particularly within experimental studies subjecting vegetation communities to climate change scenarios. To address this issue, we examined the responses of dryland vegetation, subjected to 11 years of experimental warming (+2 or +4°C over ambient temperatures across experiments) implemented via infrared lamps, to extreme climate events on the Colorado Plateau, Utah, USA.
We found that while the cover, phenology, and physiology of plant species were significantly affected by experimental warming, interannual variation in climatic extremes had stronger overall effects on the vegetation community than warming treatments alone. At the same time, climate extremes had larger effects on vegetation communities subjected to higher levels of warming. Our results suggest that background rates and magnitudes of climate change will interact with extreme climate events to shape future vegetation community structures and ecology.