The 2025 seed year in Switzerland showed an overall heterogeneous pattern. While beech and Norway spruce clearly did not exhibit pronounced mast production across the country, oaks showed regionally distinct mast tendencies. Silver fir reached moderate seed production levels in many stands, although without widespread full mast. Overall, 2025 was therefore not an exceptional mast year across all tree species.
Beech (Fagus sylvatica)
As in the previous year, beech showed predominantly a mast failure in 2025. In most regions, only very small quantities of fruits were observed.
Consequently, the contribution of beech to natural regeneration through seed production was likely limited in many areas in 2025.
Oak (Quercus spp.)
For oaks, 2025 was overall rather a mast year, although without exceptionally strong or widespread full mast events. In many regions, stands with moderate to full mast were observed, indicating an overall good fructification year.
However, spatial differences were pronounced. Particularly in northeastern Switzerland, numerous stands with mast production occurred alongside areas showing mast failure or only sparse mast. Locally, fruit production was therefore highly variable. Overall, seed availability in oak species was clearly higher than in beech, Norway spruce or silver fir.
Spruce (Picea abies)
For Norway spruce, 2025 was clearly a mast failure year throughout Switzerland. Across all regions and elevation zones, only very small quantities of cones were observed. There was little evidence of regional mast hotspots or larger seed production events.
This continues the strong temporal variability in seed production observed in Norway spruce, with 2025 clearly belonging to the weak seed years.
Fir (Abies alba)
Silver fir showed an overall moderate seed year in 2025, but without pronounced mast production. In most stands, sparse to moderate mast levels were observed. Many trees carried small to moderate numbers of cones, whereas larger or particularly dense fructification events remained rare.
This pattern was relatively consistent across different regions and elevation zones. Seed availability is likely sufficient in many areas to allow a certain degree of natural regeneration, although it did not reach the level of strong mast years.
