Increasing rainfall, decreasing winds, and historical changes in Santa Catarina dunefields, southern Brazil

摘要

Morphological and vegetation changes on the Mo?ambique barrier dunefield system are examined for the period 1938-2002 from aerial photography, and a variety of factors are investigated as possible driving factors. Human factors include a decrease in grazing pressure and tree felling from the early 1960s onwards after 200years of these activities, and fires. In the 1960s tree planting also took place. During the period 1963 to 1970 there was a marked decline in drift potential (DP - potential sand transport), and then a period of very low DPs (1970-1974). This period falls within the time interval when vegetation cover significantly increased by ~70% along the Mo?ambique barrier (from 1956 to 1978). During the 1960s to present, the rainfall increased. Analyses of other transgressive dunefields in Santa Catarina and Rio Grande do Sul states show similar trends so it is likely that climatic factors such as increasing rainfall and decreasing DPs are responsible for driving dunefield changes and vegetation colonization of the barriers.