As a result of free market forces in the agricultural and silvicultural sector, mountain regions in Western Europe are at great risk of experiencing increasing land abandonment, particularly of land with low production potential. In order to mitigate undesirable negative effects on landscape qualities or to initiate incentives for remedial actions, the importance of understanding natural succession in these abandoned systems increased considerably within the last two decades.
The Swiss National Park (SNP) is one of the few areas in Western Europe that was not influenced directly by humans during most of the 20^th century. Therefore, the Park provides a unique opportunity to study how mountain forests may develop in the absence of human intervention. Fortunately, long-term data on forest development in the SNP is available for a 44-year period. This study is based on a comparison of historic (1957) and present data (2001) from subalpine forest stands.
Our results showed that the SNP's forests are developing from an earlysuccessional stage dominated by mountain pine (Pinus montana Mill.) through a mid-successional mixed-species stage into a late successional stage dominated by Swiss stone pine (Pinus cembra L.) and European larch (Larix decidua Mill.).
With the present study we were able to empirically elucidate major successional pathways. In addition, we found that current natural disturbances, such as fungal diseases, parasitic insects, ungulate browsing, small-scale wind-throw or snow pressure, do not prevent succession from mountain pine to Swiss stone pine-European larch communities.