Drivers of canopy temperature dynamics across diverse ecosystems

Temperature of leaves and canopies is critically important for many physiological processes, including photosynthesis, respiration, and transpiration. But the variation of canopy temperature and its relationship with air temperature across a range of ecosystems and environmental conditions is understudied, challenging our ability to predict canopy temperature responses in a rapidly warming climate. Therefore, to better understand how environmental drivers and site characteristics interact with vegetation types to influence these temperature dynamics, we analyzed canopy temperature estimates derived from upwelling longwave radiation measurements across seven years and 36 NEON (National Ecological Observatory Network) sites in the USA. Canopy temperature consistently exceeded or closely tracked air temperature, with the strength and magnitude of this relationship varying by vegetation type. Multiple linear regression analysis confirmed incoming shortwave radiation as the dominant driver of ΔT (canopy temperature—air temperature). While this driver was consistently important across all sites, sites within the same vegetation type tended to respond similarly to the full set of environmental drivers. Vegetation height was associated with variation in the magnitude of ΔT. These findings support the use of vegetation type groupings to capture generalizable patterns in canopy temperature dynamics, patterns that are critical for understanding ecosystem responses under future climate scenarios.