We have monitored forest condition on a representative subset of the Swiss forest inventory network (level-I monitoring) since 1985. The main indicators we use in the Sanasilva Inventory are crown defoliation and mortality.
The size of the systematic sample grid has been progressively reduced over the years. Nowadays, we assess approximately 1,100 trees on a 16x16 km subgrid. This subgrid is part of the European "Level I" monitoring network that comprises 6,000 sample plots in 42 countries.
Comprehensive results of the Sanasilva inventory were published last in the 2015 Forest report. The main conclusions are that crown defoliation has significantly increased since 1985, whereas mortality has remained low.
We also summarize our results in the yearbook on forests and wood published in German and French by the Federal Office for the Environment FOEN and in the reports of the European network for Level-I Monitoring ICP-Forests.
The Sanasilva inventory was launched in the context of the forest decline debate. In the 1990s, however, it became obvious that this inventory would suffice neither to describe forest condition nor to explain the symptoms. This led to the creation in 1994 of the programme for long-term ecosystem research LWF (level-II monitoring), which now counts 19 sites all over Switzerland.