Navigation mit Access Keys

MastwebHow to recognise seed mast?

How to recognise seed mast?

Main menu


Seed masting is the mass production of fruits and seeds by all or most individuals in a stand of trees. The term 'fattening' comes from the formerly common practice of fattening pigs under oak trees. In forestry, different degrees of seed mast are distinguished:

Classification of seed quantities in forest trees, according to Rohmeder (1972)
DescriptionCodeStand levelFruits/seed on indivudal trees
No mast00 < 10% of all trees in the standNone or few
Partial mast110‒50% of all trees in the standLittle to abundant
Half mast250‒80% of all trees in the standAbundant to lush
Full mast3> 80% of all trees in the standLush to expansive

Foresters and hunters refer to the years of massive fruit and seed production by all or most of the individuals in a forest stand as full mast. 

A particular form of grazing is the acorn crop, which refers both to an exceptional acorn year and to the practice of letting pigs feed on oak and beech acorns in the forest.




Information on the most important forest tree species in Switzerland


European beech – Fagus sylvatica

The European beech is the second most common tree species in Switzerland. It occurs in almost all parts of the country, but is absent in the Alpine...


Ash – Fraxinus excelsior

The ash is widespread and forms extensive forests in the northern Alpine foothills together with the sycamore maple.


Pedunculate oak – Quercus robur

The pedunculate oak needs a lot of light and a long, warm growing season. That is why it is most common on the Central Plateau and in the eastern...


Sessile oak – Quercus petraea

The drought-resistant sessile oak is more common in Switzerland than the pedunculant oak, but is more susceptible to late frosts.


Norway spruce – Picea abies

The Norway spruce is the most common and widespread tree species in Switzerland. Its main natural distribution area is the Alps, the Pre-Alps and the...


Silver fir – Abies alba

The third most common tree species in Switzerland, the silver fir, occurs mainly in the western Jura, the central Swiss Plateau and the Pre-Alps.