Annal report 2018

In this exceptionally dry and warm year, seed production was high for the four main tree species beech, oak, spruce and silver fir, with half or full mast. Spruce produced particularly many cones at altitudes below 1400 m a.s.l. (half or full mast); above this altitude, production was more heterogeneous and lower overall. Beech also developed a half or full mast at lower altitudes (< 1000 m), while at the highest altitudes it produced mostly few fruits (partial mast). 

The progressive drought from mid-June to autumn led in many places to fruit without seeds, a so-called abortion. Despite a full crop of fruit, the seed yield was low. The white fir showed a large seed production (half or full mast) in all regions and altitudes. In the case of oaks, most regions showed seed masting, with the exception of the regions in which the trees already produced many seeds in 2016 and 2017.

Fig. 1: Map of observed and modelled seed production of Norway spruce (Picea abies) in 2018 (left). Observations of seed production along the altitudinal gradient (right).
Fig. 2: Map of observed and modelled seed production of silver fir (Abies alba) in 2018 (left). Observations of seed production along the altitudinal gradient (right).
Fig. 3: Map of observed and modelled seed production of European beech (Fagus sylvatica) in 2018 (left). Observations of seed production along the altitudinal gradient (right).
Fig. 4: Map of observed and modelled seed production of oaks (Quercus petraea, Quercus robur, Quercus pubescens) in 2018 (left). Observations of seed production along the altitudinal gradient (right).