Landscape metrics and topographical determinants of large-scale forest dynamics in a Mediterranean landscape

The analysis of land-use and land-cover change has long been a key topic in Landscape Ecology. In particular, forest fragmentation is known to affect species composition and diversity, thus threatening the integrity of forest habitats. This paper examines the forest cover dynamics in a Mediterranean area (the Province of Siena, central Italy), by comparing historical (1933) and recent forest maps (2000). The historical map has been geo-referenced, digitised in a GIS environment, and classified in three forest classes: broad-leaved, conifer and mixed forests. The same classification was used for the recent forest map. Image processing techniques and landscape pattern metrics were applied to quantify the changes in forest cover patterns, while appropriate statistical descriptors were adopted to investigate the relationship between land-cover changes and topographical factors. A general afforestation process was detected in the investigated area over the period 1933-2000, resulting in a high landscape transformation overall considering zones with higher elevation and slope. The forest landscape structure changed in terms of decreased fragmentation and patchiness. The general trend observed in this area was in line with previous results achieved in similar ecological situations, thus reinforcing the need to link landscape change patterns with appropriate management decisions.