US EPA

4307652 

Journal Article 

Tree stomata conductance estimates of a wax myrtle-tree heath (fayal-brezal) cloud forest as affected by fog 

Ritter, A; Regalado, CM 

2017 

Yes 

Agricultural and Forest Meteorology
ISSN: 0168-1923 

247 

116-130 

10.1016/j.agrformet.2017.07.021 

WOS:000416186700011 

Direct transpiration measurements of tree species obtained with Granier's heat dissipation probes, combined with micrometeorological data were used to derive tree conductance estimates in a cloud-immersed wax myrtle tree heath forest located in the Garajonay National Park (La Gomera, Canary Islands, Spain). The one-year period time series were analysed distinguishing between foggy and fog-free conditions in order to evaluate the vegetation response to fog. The presence of fog was found to reduce transpiration (7') in both species investigated (E arborea and M. faya), such that the yearly medians of the hourly T values were 6-15.6 times higher when no fog was present as compared to cloud immersed periods. By contrast the g(c) estimates exhibit larger values in the afternoon during foggy conditions when compared in terms of the hourly g(c) medians at each time of the day, and were clearly greater on a daily basis. During foggy conditions, g(c) followed a monotonically increasing trend. Large variability of conductance estimates was observed across the ranges of micrometeorological conditions explored. The largest conductance values were associated with low solar radiations, air temperatures between 8 and 15 degrees C, low VPD (< 0.5 kPa), and wind velocities of 2-4 m s(-1). Laurel forest trees, previously referred as following a profligate water use strategy, may thus profit from the foggy environment by maintaining the stomata opened during the day without significant water losses, while benefiting with the associated carbon gain. 

Cloud forest; Cloud immersion; Granier probes; Transpiration monitoring