Forest expansion in the Swiss Alps - a quantitative analysis with an emphasis on structural change in agriculture

In Switzerland, the closing down of farms is widely seen as the dominant reason for land abandonment and forest expansion in the Alps. Also agricultural policy, which aims to pre-serve open land and to ensure cultivation of marginal lands, relies on this conclusion.

Based on contemporary concepts of agricultural economics and empirical indications, it is suggested that the relationships between forest expansion and structural change in agriculture are more complex because in Switzerland, forest expansion is a phenomenon typical for mountain areas, whereas the rate of farm exits in the mountain areas between 1955 and 1990 was not higher, but lower compared to the plain.

The general research question of the PhD thesis is: How can the pattern of land abandonment and forest expansion during the last decades be explained with the help of newly available large quantitative datasets? Hypothesis and variables will be derived from economic theory. Spatial statistical modelling approaches will be used to determine the relevant biophysical and socioeconomic causes of land abandonment and forest expansion and to quantify their relative impact. The analyses are carried out on different spatial and temporal scales, both with the help of extensive, recently completed data of nationwide landuse statistics and with aerial photograph time series.

Two complementary methodical approaches will be used to study forest expansion in the Swiss Alps (i) the Total Area Analysis (TAA) and (ii) the Repeated Aerial Photograph Approach in Selected Areas (RAPAS). The TAA aims to investigate forest expansion in the Swiss moun-tain area defined by the Swiss federal law of investment assistance for mountain areas (Bundesgesetz über Investitionshilfe für Berggebiete - IHG). With RAPAS findings in TAA will be extended using datasets with higher spatial and temporal resolution in few selected case study areas. While the main advantage of the TAA lies in the large representative data-sets covering the whole Alps, with RAPAS allows forest expansion will be investigated in case study areas (ca. 4 mountain communities) with higher spatial resolution and over a long time period.

The expected findings will be significant for the understanding of land-use changes in the Alps and may have important implications for policy design: As bio-physical and socio-economic conditions vary widely within the Alps, centrally planned policy measures hardly correspond with local biophysical and socioeconomic characteristics. The necessary knowl-edge for designing target-oriented and efficient measures to avoid land abandonment and natural regrowth of forest might therefore rather be found at the local level.