ECOLOGICAL BASES, SUSTAINABILITY, AND CURRENT TRENDS IN TRADITIONAL AGRICULTURE IN THE VENEZUELAN HIGH ANDES

The traditional land-use system in the agricultural belt of the Venezu elan High Andes (3,000-4,000 m) includes extended fallows (from 7 to m ore than 20 years) alternating with short cultivation periods (1-4 yea rs). This management produces a mosaic landscape where potato or cerea l fields coexist with recuperating fallows of various ages and with la nd remaining uncultivated because of limitations of slope or stoniness . This land-use strategy maintains a high natural diversity in a way t hat allows an acceptable productivity without the use of mineral ferti lizers. The ecological base underlying the functioning of the agricult ural system is analyzed, mainly in relation to the recuperation of nut rients during the fallow periods. The ecological sustainability is dis cussed in light of the negligible erosion rates and the maintenance of high levels of soil organic matter. The massive introduction of chemi cal fertilizers in recent years induced important changes that are exe mplified by the case study of the land-use strategy of a farmer.