LAND OCCUPATION PATTERNS AND VEGETATION STRUCTURE IN THE ANTHROPOGENIC SAVANNAS (ESPINALES) OF CENTRAL CHILE

Land occupation patterns and the ecological structure and diversity of woody and herbaceous strata were studied al two scales in the anthrop ogenic savannas (espinales) occupying unirrigated portions of the subh umid and semiarid regions of central Chile (ca. 30 degrees to 36 degre es S), This anthropogenic formation is dominated by the spiny legume t ree Acacia caven (Mol.) Mol, and a wide variety of Eurasian annual gra sses and forbs, and is the basis for rainfed farming and agroforestry systems that appear outmoded and increasingly unproductive, The curren t study forms part of a larger effort to determine causes for this tre nd and to ascertain ways and means for reversing it, Vegetation mappin g was carried out along a representative transect of espinales coverin g 22 970 ha, in the subhumid region. The botanical composition and pri mary productivity of each stratum was studied for seven vegetation typ es, in both the occasionally inundated plains (llanos) and the well-dr ained hillsides (lomas). Complementary data were obtained on community structure, total cover, and tree shape and size in relation to coppic e age since last cutting. Degradation patterns in the lomas and llanos , and the various alternatives to ongoing degradation that could repla ce current land and resource use practices are discussed.