Diachronic evolution of grasslands and open shrublands in pastoral landscapes of Greece

In recent years, studies of diachronic evolution have been carried out in several pastoral landscapes of Greece based on aerial photographs. These studies covered a total area of 69,372 ha and included the Kolchiko and Hortiatis watersheds of central Macedonia, the Kopatsari and Askio region of western Macedonia and the valley of Portaikos – Pertouli in Thessaly. This paper aims to review all these studies so that the trends in grassland and shrubland evolution are evaluated. The transformation of these landscapes was evaluated by means of Geographic Informational Systems (G.I.S.) and sequential sets of aerial photographs and orthophotos, covering a period from 1945 to 1998. Changes in grassland pattern were evaluated by the use of landscape metrics. From these studies it became evident that the pastoral landscapes have changed significantly over the last 65 years in terms of land use/ cover structure and landscape pattern. A major trend has been the reduction of the area covered by grasslands in favour of forests, dense shrublands and agricultural lands. Furthermore, a reduction of open shrublands in favour of dense ones was also recorded. Landscape metrics revealed that grassland patches are becoming more fragmented and disperse over the years. The reduction of grasslands and open shrublands represent a major obstacle to employing sustainable practices in livestock husbandry.