AGRICULTURAL-DEVELOPMENT VS BIODIVERSITY CONSERVATION - THE MEDITERRANEAN SEMIARID VEGETATION IN EL EJIDO (ALMERIA, SOUTHEASTERN SPAIN)

The development of a greenhouse agriculture in the traditionally impov erished region of Poniente de Almeria, on the Mediterranean coast of S pain, has caused an enormous rise in living standards. However, the en vironmental impact of this badly-planned growth threatens the very dyn amics of the exploitation system. A special examination must be made o f the use of the three major resources responsible for the functioning of greenhouse production and its impact on the ecosystems and particu larly on the vegetation. These resources are: clayey soils, sand from fossil dunes and ground water. While the use of the clayey soils and s and have negative effects on the conservation of ecologically valuable communities found nowhere else in Europe, ground water overexploitati on has produced an increase in salinity in most of the aquifers. Of th ese, sand has been by far the best monitored resource and restoration programmes have been implemented in the extraction zones. This survey deals with the recent evolution of areas where the arte (Maytenus sene galensis subsp. europaeus) and the sabina (Juniperus phoenicea subsp. turbinata) have long been the dominant species, although the presence of the former is nowadays notoriously diminished. The study is based o n aerial photographs taken in 1957, 1977 and 1985, together with our o wn field work. Curiously enough, all this man-made process of degradat ion has stimulated ornithological diversity. Finally, we propose here some measures which aim to preserve the most important enclaves of the se Mediterranean shrub formations, specially those of the arte, since sabina-dominated communities already belong to existing conservation a reas.