Resumen
Aim of the study: To investigate the secondary forest succession in the study area and the pathways of its spread and the existing environmental, autecological factors and possible inter-specific competition relationships.Area of study: The study area is a Site of Natura 2000 network in northern Greece dominated by two pioneer forest species, Betula pendula and Pinus sylvestris. Study area is the southern limit of Silver birch in Europe and genotypes of these forests may be important due to the anticipated global increase of temperature and the forthcoming climate change.Materials and methods: The main forest types studied were: pure forests of B. pendula and P. sylvestris and mixed forests of these two main species. To study the expansion of forests in the area, a spatial analysis was performed based on geographical data. To detect forest changes, the rate thereof and their specific spatial distribution and preferences, a statistical analysis was performed.Main results: Approximately 60% of the studied area in 1945 was transformed from grasslands/barelands to forests. The composition of new forests was found to be different from the old ones. The rate of forest establishment in the first years was lower than in the latter years. All factors examined played an important role to the expansion of forest exept slope.Research highlights: Distance from the old stands played the most determining role to new forest structure and composition. Inter-specific competition results to the formation of pure stands, as indicated by the older stands.Keywords: secondary forest succession; Betula pendula; GIS; spatial analysis; forest species competition; forest species distribution.