Tree Growth and Temperature

Photosynthesis, or the process through which plants use the Sun’s energy to convert carbon dioxide and water into sugar, is most efficient at a certain optimal temperature. Although plants throughout the World have adapted to conditions unique to their locations, the warm and wet conditions in the equatorial tropical rain forests support what are by far the most productive and diverse ecosystems on the Planet. It appears, however, that the optimal temperature for photosynthesis is being surpassed. Since the early 1980’s, the average temperature in Costa Rica’s tropical rainforest has risen, and this trend has corresponded to a steady decline in annual tree growth. Conditions are the warmest and driest during El Niño years, and the coolest and wettest during La Niña years. On average, trees in Costa Rica’s rainforest grow over 80 percent more during cool and wet La Niña years than they do during hot and dry El Niño years.

(Source: Clark, DA. “Tropical rain forest tree growth and atmospheric carbon dynamics linked to interannual temperature variation during 1984-2000.” Proceedings of the National Academy of Sciences (2003), vol.100, pp. 5852-5857)