A 42 year inference of cloud base height trends in the Luquillo Mountains of northeastern Puerto Rico
The Luquillo Mountains of eastern Puerto Rico are home to the only tropical rainforest managed by the United States Forest Service, with cloud-immersed forests historically occupying the highest elevations. However, within the past 50 years, studies of the Luquillo cloud forest have suggested an increase in cloud base altitudes, although the cloud base altitudes in the area were not quantified until recently. We compared long-term weather balloon observations of cloud-forming condensation altitudes from the nearly city of San Juan to more recent observations of cloud base altitudes from instruments measuring over the Luquillo mountains. The weather balloon data agrees with the recent and geographically closer data, and thus could be used to complete a 42 year (1975?2016) proxy record of cloud base altitude to determine if there is evidence for rising cloud base. Cloud base altitude was found to be increasing with strong statistical evidence in the late rainfall season, and possibly increasing in the other seasons of the year. This result is important for foresters, biologists, and ecologists studying the rainforest ecosystem. Future research will need to investigate the potential ecological impact of the cloud lifting documented here, especially during the hydrologically important rain season, as it may lead to reduced rainfall in the rainforest.
Forest Service Partners