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VEGETATION
Forest classification
The vegetation in the Luquillo Mountains is influenced by evolution, climate, natural disturbances, land use history, and the steep elevational gradient, which rises abruptly to over 1000 m in elevation in a short distance of 8 km (5 miles) from the coast. 7, 32, 33 Forest types in El Yunque are not homogenous or static, and boundaries are not always clear between vegetation associations.32 Recurrent natural events such as hurricanes and landslides also affect forest structure and species composition, keeping the forest in flux.33 However, spatial patterns formed by the tree canopy of vegetation communities in El Yunque are observed in air photos and satellite images, which facilitate the mapping of forest types. 7, 33 The map shown here simplifies the vegetation associations found in El Yunque and serves as an important tool for describing and managing the forest. 7 Forest types are identified by cloud cover and life zone with a brief description in the following pages.
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Forest types Riparian forest Secondary forest Mature tabonuco forest
Developed land
Mature palo colorado forest
Nonforest (grasslands, shrubland, and natural barrens)
0
4 km
Mature sierra palm forest Mature Tabebuia/Eugenia forest
CLIMATE CHANGE AND THE FOREST The effects of climate change on a tropical forest ecosystem such as El Yunque are complex and are still being studied. 7, 34 Records show decreasing rainfall totals and increasing temperatures over the last century in the Luquillo Mountains. 34 Furthermore, statistical models of future climate for Puerto Rico predict an increase in temperatures of 4° to 9° Celsius, declines in rainfall, and an increase in drought intensity and extremes by the end of this century. 35 In general, climate change has the potential to transform El Yunque’s forest structure and function, altering its species composition and distribution along the elevational gradient. 34
Photo by Jerry Bauer