Assessment of coastal mediterranean landscapes in the Andalién river basin, Chile

This study analyzes the Andalien River Basin in the western side of the Coastal Range (36o 42’ S and 36o 56’ S. 72o 36’ W and 73o 04’ W), Biobio Region, Chile. This basin drains an area of 775 Km 2 (Jaque, 1996) and is situated near the Concepcion-Talcahuano conurbanization, which is the second most populous nucleus in Chile and is important in demographic, industrial, business and cultural aspects (466,409 hab. INE, 2002). Its Mediterranean climate favoured early occupation of the territory and intensive use of its natural resources during economic cycles, developed in Chile and the Region (Cunill, 1971; Guerrero, 1971). In the 16th and 17th centuries it was a cattle-raising area; in the 18th and 19th centuries, its principal activity was agriculture (Carmagianni, 1973); and since mid-20th century its principal activity is exotic forest plantations (CONAF, 2005). The two most recent economic cycles have been clearly speculative, determined by an intense exploitation of its resources for external and internal markets in short time periods. Beginning in the 18 th Century, these speculative economies resulted in the overload of the basin’s soils with the early populations concentrated in the upper Basin. In 1885, its population was 8% of the province’s total (INE, 1975); at present, it only represents 1% (INE, 2002). Close to 100,000 persons live in the Basin, corresponding to 6% of the regional population; only 10% presently live in the upper and mid Basin, in the coastal mountains, while the remaining 90% are concentrated in the lower Basin (4% of the Basin’s territory). Additionally, the urban sector contrasts with the rest of the Basin, where there are important problems of poverty and ecological degradation. From a socio-economic point of view, a large percentage of the poor population is concentrated in this territory with rates slightly higher than the regional average of 20.7%: there is 20.8% poverty in the county of Florida, while the counties of Concepcion and Talcahuano located in the lower Basin have poverty levels of 14.7% and 17.6% respectively (MIDEPLAN, 2006). From the environmental perspective, the Andalien Basin is one of the