Sanasilva forest health ¶

Since 1985, we have been conducting a representative assessment of the health of trees in Swiss forests through the Sanasilva Inventory (Level I Monitoring) on a subnetwork of the Swiss National Forest Inventory (LFI). The most important characteristics assessed are crown thinning and mortality rate.

Crown thinning is described by the percentage of thinning in a crown compared to a tree of the same age with maximum foliage/needle cover at that site, the proportion of this thinning that cannot be explained by known causes, the location of the thinning, and the proportion and location of leafless/needle-less branches and twigs.

Crown discoloration is described by the deviation of a tree’s average color (hue, saturation, lightness) from the normal color (reference color) typical of that tree species, as well as by the presence, extent, and location of colors that deviate from the reference color.

A tree’s growth is described by the change over time in the measured tree dimensions (diameter at breast height, tree height, crown length, and crown width).