Leaf phenology correlates with fruit production in European beech (Fagus sylvatica) and in temperate oaks (Quercus robur and Quercus petraea)

Abstract

Phenology and fruit production are sensitive to climate. Variation of leaf phenology alters canopy duration (an indicator of growing season length), which in turn affects forest ecosystem functioning and tree productivity. However, the influence of canopy duration on tree reproduction is poorly explored. In this study, we investigated if and to what extent the canopy duration influences fruit production in three major European deciduous trees: European beech (Fagus sylvatica) and two temperate oaks (Quercus robur and Quercus petraea). We used a long-term (11 years) monitoring dataset from 50 populations. In addition to the widely reported main effect of previous summer temperature on fruit production in European beech, we detected a nonlinear relationship between current canopy duration and fruit production. For beech, intermediate canopy duration is associated with highest fruit production. In oaks, fruit production was positively correlated with spring temperature and current canopy duration. Total variance explained by our models is 45% and 13%, for beech and oaks, respectively. These results suggest contrasting effects of expected increase in canopy duration on fruit production: nonlinear in European beech and positive linear in oaks.