Abstract:

Using information from historical records, previously published studies bythe authors and the results of more than a decade of empirical earth and soil science research, an integrated account of landscape evolution during the Late Pleistocene and Holocene is presented for the Algarve region, southern Portugal. Whereas in the Late Pleistocene and Early Holocene, landscape change was under the influence of factors of the physical environment - particularly those of climate and sea-level, the period from c. 3000 BP has seen two episodes of rapid erosion punctuated by a period of relative stability. These episodes of erosion are dated at c. 3000 PB to c. 300 BP and from c. 1914 to the present. Whilst the role of physical causal mechanisms cannot be ruled out and may have been contributory factors, it is argued that these phases equate to three differing styles of human impact on the Algarve landscape. The period from c. 3000 BP to c. 300 BP was associated with pre-Roman, Roman, Moorish and early Portuguese phases of settlement, exploitation of the region for timber and other agricultural products, widespread erosion of hillslopes, extensive deposition of sediment within inland valleys and situation of coastal estuaries. From c. 1700 to c. 1914, a reduction of human pressure on the most erosion-susceptible land and the spread of more environmentally sustainable agriculture led to a stabilization of slopes, a reduction in sediment movement, and the incision of valley and estuarine sediments. The 20th century has witnessed renewed 'pressure' on the landscape, due, first, to a campaign to foster agricultural self-sufficiency through the development of what cultivation on easily eroded soils, and, secondly, subsequent widespread ploughing and afforestation using Eucalyptus globulus. At the present time, signs of erosion and sediment movement may be observed as the landscape continues to evolve under human pressure. Finally, the authors assess some of the pressures currently being placed on the landscape as a consequence of mass tourism in the region.

Author: David K. Chester, Peter A. James