This study concentrates on the definition of the percentage of forest cover in forested pastureland, an essential element of the silvipastoral landscape. In the present forest, agricultural and of the environment and landscape preservation context, it aims to provide a reliable and cheap access to information which appears to be fundamental for each one of these domains, a true guide line to an integrated planning in forested pastureland. In the present federal forest legislation, the forested pastureland is incorporated, on the whole, in the forest with a peculiarity: its patchwork of forested populations and non covered surfaces, used for the animal production as well as for forest economy. The federal Council recognises its important function and its characteristics of local landscape, specifying that groups of trees can "move or undergo some modifications over the years, which prevents a final definition of forested and non forested areas" and that "what should remain constant is the ratio between forested and non forested area". The present study has the ambition of measuring the percentage of forest cover and showing its quite essential part for the foresed pastureland. We approach the zoning of forest cover and the perception of its dynamics over time with different methods, like the experimental sites in the cantons of Bern and Neuchâtel and on the basis of diachronic series of aerial photographs (traditional black and white photographs, the first of which date from 1936 and recent colour orthophotos). A high tech GPS system (Global Positioning System), with and without differential corrections (DGPS), has also been tested to give instantaneous lists of this particular environment, so heterogeneously forested. A simulation in time and space of the forest cover dynamics, realised with the AMAP software, developed in CIRAD, enables finally to visualise the future of the silvipastoral landscape according to different planning patterns, based on the observation of its past with the above mentined methods. A geographical information system (GIS) is used as main tool to supply and receive data.
