Quantifying landscape change with actual vs. potential natural vegetation

This paper deals with landscape change in central Italy. Landscape abandonment is analyzed integrating a transition matrix approach with a simphytosociological method. A transition matrix brings the complete description of the temporal dynamics of a particular landscape over a given time period. However, a well-known shortcoming of most of these analyses is that their results are going to depend non-linearly on the extent of the area analyzed. Therefore, a landscape classification scheme is needed that provides ecologically meaningful units for quantifying different aspects of landscape mosaics and correlate them to environmental processes. Plant sociology has formalized one possible approach for classifying plant communities that is widely used in most European countries for vegetation-based descriptions of landscapes. In this paper, we propose a landscape classification scheme based on Potential Natural Vegetation distribution as a reference framework for quantitative landscape change analysis in a grid-based GIS. A mountainous region of central Italy was selected. First, two 1:10.000 real vegetation maps (1954 and 1986) of the study area and a PNV map were produced. Next, a transition matrix for each PNV unit was calculated. Results show that, the use of PNV distribution as a baseline for a quantitative landscape change analysis may represent a first step towards a general model for the evaluation of the effects of disturbance on vegetation patterns.