VEGETATION AND CLIMATE HISTORY OF MONTANE COSTA-RICA SINCE THE LAST GLACIAL

New palynological evidence from the Cordillera de Talamanca (Costa Ric a) is presented. The La Chonta-1 core (2310 m a.s.l) shows the develop ment of montane vegetation during the late Quaternary. A shorter core (La Trinidad-III) shows the Lateslacial-Holocene transition, including the La Chonta stadial based on earlier published evidence, A soil sec tion from the paramo belt at 3100 m shows vegetation recovery after fi re. Modern pollen rain was studied along an altitudinal transect from 2100 m to 3800 m at Mt Chirripo. A comparison with other palaeoecologi cal data of the region is given to elucidate climatic and vegetational changes throughout the Central American region. Data show a cooling o f 7-8 degrees C during the Last Glacial Maximum (LGM) for montane Cost a Pica, which is in accordance with data from lowland Guatemala. A 1.5 degrees to 2.5 degrees C temperature drop is recorded during the Youn ger Dryas Chron in both Costa Pica and Guatemala, but apparently not i n Panama. The Lateglacial-Holocene transition in montane Costa Rica is established at 10,400 BP. Between 9000 and 8500 BP moist forest devel oped in mountainous Costa Pica as well as in lowland Guatemala and Pan ama. Environmental change during the mid-Holocene seems more affected by changes in humidity than temperature change throughout Central Amer ica. Distribution maps of paramo and montane vegetation in Costa Rica are reconstructed for 10 ka, 14 ka and 18 ka based on currently availa ble palynological data. These data indicate that during the LGM a para mo vegetation corridor existed between northern Costa Pica and probabl y northern Panama. (C) 1997 Elsevier Science Ltd.