Una nueva hipótesis acerca del origen y edad del bosque de Fray Jorge (Coquimbo, Chile)

Abstract

The aim of this paper is to formulate a hypothesis concerning the age and origin of the relict forest of Fray Jorge (30° 30' S; 71° 35' W), on the basis of an analysis of the distribution and systematic relationships of the relict taxa and floristic comparisons with other relict forest of central Chile. Paleobotanic, paleoclimatic and geomorphologic data are also reviewed. The systematic relations, the present distribution of the taxa and paleobotanic evidences show that the Fray Jorge's floristic element has a mixed origin from boreal, austral and southern and central Chile diversified ancestors. These ancestors would have arrived into Chile during the Cretaceous Eocene period. According to phytosociological comparisons, the Fray Jorge-type community would have occupied in the past a more extense area. In central Chile, such community type would have been floristically disorganizated due to the mixture with sclerophyllous elements. Palynological and paleoclimatic data suggests that such event began in the early Holocene. In the Pleistocene, however, a wetter climate would have favoured the developmnt of the Fray Jorge community type in central Chile. Geomorphological studies in the area of Altos de Talinay indicate the early and middle Quaternary as the oldest possible age for the forest in Fray Jorge. In conclusion, the relict forest of Fray Jorge and Talinay are proposed to be conservative remnants from a vegetation type continuosly extended along the coastal range of central Chile during the Pleistocene.