Changes in forest understorey vegetation over 25 years at LWF sites

The understorey vegetation is a major component of the biodiversity in forest ecosystems. Its species composition has been recorded since the mid-1990s at intervals of two to ten years within the long-term forest ecosystem research program (LWF). The number of vascular plant species and the cover of the herb layer have significantly decreased since the start of the surveys, likely due to the closure of stands in the absence of silvicultural management. Temporal variations in average Landolt indicator values indicate a slight decrease in nutrient availability (N value) when bryophytes are included in the calculation of site averages, and a slight increase in temperature (T value) when they are not.