Author(s)

D. Emmanouloudis, I. Takos & I. Spanos

Abstract

Evolution of the erosive process after a watershed fire: An example: Prinos torrent, Thassos island, Greece. D. Emmanouloudis1, I. Takos1 & I. Spanos2 1 Department of Forestry, Technological Educational Institute of Drama, Greece. 2 N.AG.RE.F. Forestry Research Institute, Thessaloniki, Greece. Abstract North Mediterranean areas, like Spain, S. France, Italy and Greece are considered semi-arid regions and suffer from both extensive and intensive erosive phenomena, which are more obvious in areas that have been previously burned out. These phenomena cause serious floods and damages in areas close to torrent beds. The present paper focuses on such erosive phenomena, particularly in two burned mountainous watersheds in Thassos Island of northern Greece. The erosive process was initially monitored after the first heavy rainfall that followed the fire (15/8/1989) and then repeatedly during the next decade (1989-2000). The results show that during this period there was a decrease in erosion values probably due to two reasons: On the one hand, the soils that are exposed immediately after the fire in the runoff force present more intensive erosive phenomena. These soils are stirred and with low grade of compression due to the effect of the rooting system of the plants. This phenomenon is more obvious in shrublands. The soils pass in a relative equilibrium three or four hydrologic periods after the fire, the erosion values are decreased and the danger of floods is minimized. On the other hand, the existence of natural reforestation leads to the additional stabilization of the ex-bare soils. Finally, in this paper the very few cases in which there is no immediate decrease in erosion values are examined. In these cases, urgent actions are

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