Plant modulation on daytime ground surface temperature: An overlooked mechanism in climate warming regulation

Abstract

Despite the widely recognized greenhouse effect caused by greenhouse gases, atmospheric temperature is also directly driven by ground surface temperature. Tropical forests cover 7% of terrestrial land and likely play a noticeable and disproportionate role in regulating the temperature of the ground surface that emits infrared radiation available for the subsequent greenhouse effect. Here, we evaluated the role of plant leaves in modulating daytime ground surface temperature across tropical dry-rain forests in Puerto Rico. We found that leaf midday temperature decreased with altitude following a logistic function. In contrast, bare ground surface temperature linearly reduced with altitude. Canopy cooling effect ranged from 34.5°C to -10.2°C, with the strongest cooling observed in low-altitude forests and diminishing at higher elevations. Further, dicotyledons exhibited a stronger cooling effect on ground surface temperature than pteridophytes and monocotyledons. Dry forests showed the greatest cooling effect at high temperatures, whereas wet-rain forests exhibited the most effective cooling when temperatures were below 10°C. These findings highlight the critical yet often overlooked role of tropical forests in regulating daytime surface temperatures and call for greater attention to the biophysical impacts of deforestation on climate change beyond the carbon-centric discourse.