Vegetation and climate history of montane Costa Rica since the last glacial

Abstract

New palynological evidence from the Cordillera de Talamanca (Costa Rica) is presented. The La Chonta-1 core (2310 m a.s.l) shows the development of montane vegetation during the late Quaternary. A shorter core (La Trinidad-III) shows the Lateglacial-Holocene transition, including the La Chonta stadial based on earlier published evidence. A soil section from the paramó belt at 3100 m shows vegetation recovery after fire. Modern pollen rain was studied along an altitudinal transect from 2100 m to 3800 m at Mt Chirripó. A comparison with other palaeoecological data of the region is given to elucidate climatic and vegetational changes throughout the Central American region. Data show a cooling of 7–8°C during the Last Glacial Maximum (LGM) for montane Costa Rica, which is in accordance with data from lowland Guatemala. A 1.5° to 2.5°C temperature drop is recorded during the Younger Dryas Chron in both Costa Rica and Guatemala, but apparently not in Panama. The Lateglacial-Holocene transition in montane Costa Rica is established at 10,400 BP. Between 9000 and 8500 BP moist forest developed in mountainous Costa Rica as well as in lowland Guatemala and Panama. Environmental change during the mid-Holocene seems more affected by changes in humidity than temperature change throughout Central America. Distribution maps of paramó and montane vegetation in Costa Rica are reconstructed for 10 ka, 14 ka and 18 ka based on currently available palynological data. These data indicate that during the LGM a paramó vegetation corridor existed between northern Costa Rica and probably northern Panama.