Climatic Impact of Tropical Lowland Deforestation on Nearby Montane Cloud Forests 

Centro Científico Tropical (CCT), Costa Rica

National Aeronautic Space Agency (NASA)

Remote Sensing Imagery: Geostationary Operational Environmental Satellite visible wavelength imagery, Landsat

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Cloud Forest

To use Geostationary Operational Environmental Satellite visible wavelength imagery to monitor cloud occurrence over Nicaragua and Costa Rica throughout the year, with a focus on the dry season. To examine the impact of regional deforestation on cloud formation in this region by applying the Colorado State University Regional Atmospheric Modeling System. To collect remotely sensed and locally acquired data on surface temperature, heat and moisture fluxes, and cloud base height, generated at 15-minute to hourly and daily intervals.

Tropical montane cloud forests (TMCFs) depend on predictable, frequent, and prolonged immersion in cloud cover. Clearing upwind lowland forest alters surface energy budgets in ways that influence dry season cloud fields and thus the TMCF environment. The Landsat and Geostationary Operational Environmental Satellite imagery found that deforested areas of Costa Rica's Caribbean lowlands remain relatively cloud-free when forested regions have well-developed dry season cumulus cloud fields. Further, regional atmospheric simulations show that cloud base heights are higher over pasture than over tropical forest areas under reasonable dry season conditions. These results suggest that land use in tropical lowlands have a serious impact on ecosystems in adjacent mountains - deforestation in the lowland tropics of the trade wind zone tends to shift the cloud forest environment upward in adjacent downwind mountains.

This shows that when entities make decisions about development projects, any cost-benefits analyses need to extend off-site. Ecological consequences need to be considered not just in the immediately affected area but also in other regions that may be hundreds of kilometres distant.

For our follow-up study, we will be working with Dutch, U.S. and Costa Rican scientists in Monteverde to see if deforestation has an impact on cloud forest water yield. We will conduct a flora and fauna inventory in both the cloud forests on the windward side of the country’s central mountain range and in small areas on the leeward side that routinely receive moisture from clouds rolling over the hilltops. We will also investigate whether deforestation on the Pacific slope of Costa Rica creates updrafts that force clouds upward as they crest the mountain tops, and what impacts this may have on local weather patterns.

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