Vegetation patterns in the succession from wood fringes towards woodlands

A fragmented landscape, once belonging to a larger woodland complex named «Ancient Circaei and Terracinae Forest», has been investigated to find floristic and ecological relationships between wood fringes and woodlands in three forest patches. The linear transect method was adopted to follow the variations of species composition and micro-habitats: parallele transects from the border to the core of the woodlands were carried out to observe succession stages occurring into the woodlands, while perpendicular transects were done to observe the variation from wood fringes towards the internal zones of the study areas. All individuals occurring along a 20 meter long line at the ground level were identified and counted from the wood fringes into the woodlands. Two matrices (species frequencies/transects), respectively for woodlands and wood fringes, were obtained and treated with multivariate analysis. Results were interpreted basing on ecological indicators, chorotypes and life forms. Two main results were obtained: 1) application of Ellenberg's indicator values to PCA gradients gives information on the trends along the principal components, allowing a direct interpretation of gradients, based on range variations of environmental factors; 2) the transects method applied to an environmental net at microscale level detected a mosaic of variations across the habitats found from the wood fringes into the woodlands. Four units in the woodland vegetation were identified and their links with wood fringes were discussed. Discriminant species for both of them were selected and proposed as «Keystone species» (Wilcox and Murphy, 1985).