Dynamic cloud regimes, incident sunlight, and leaf temperatures in espeletia grandiflora and Chusquea tessellata, two representative species of the Andean Páramo, Colombia

• Published in: Global Change Biology
• Main Authors: Sanchez, Adriana, Posada, Juan M., Smith, William K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Institute of Arctic and Alpine Research 2014
• Subjects: Air temperature; Climate change; Cloud cover; Dicotyledon; Ecophysiology; Solar radiation; Tundra; Andes; Chingaza national park; Colombia
• Online Access: https://repository.urosario.edu.co/handle/10336/22911; https://doi.org/10.1657/1938-4246-46.2.371

The alpine páramo of Chingaza National Park, Colombia, has a highly variable cloud regime typical of many tropical alpine areas. Yet, little information is available regarding the effects of such dynamic sunlight regimes on alpine temperatures. A close association between changes in incident sunlight and corresponding air (Ta) and leaf (Tl) temperatures occurred in two dominant species with strongly contrasting leaf form and whole-plant architecture. Spikes in sunlight incidence of and gt;3000 ?mol m-2 s-1 occurred during cloud cover and corresponded to increases in Tl of 4-5 °C in a 1-min-interval in both species. Although Tl was predominately above Ta, during the day, depressions below Ta of over 6 °C occurred during cloudy conditions when photosynthetic photon flux density (PFDs) was and lt;400 ?mol m-2 s-1. The greatest frequency (69%) of changes in incident sunlight (PFDs; over 2-min intervals) was less than 100 ?mol m-2 s-1, although changes and gt;1000 ?mol m-2 s-1 occurred for 2.4% of the day, including a maximum change of 1512 ?mol m-2 s-1. These data may be valuable for predicting the ecophysiological impact of climate warming and associated changes in future cloud regimes experienced by tropical alpine species.