Seed production of a masting dwarf shrub, Vaccinium myrtillus, in relation to previous reproduction and weather

Abstract

In an analysis of a 50-year time series of seed production in bilberry (Vaccinium myrtillus L.) from Aust-Agder, southern Norway, both previous reproduction and weather contributed to explain annual berry production. There was a relatively regular fluctuation in bilberry production, with intervals between peaks of 2-5 years. The bilberry-production index was negatively correlated with the average bilberry production index of the preceding 3 years. Regularity in the bilberry production was commonly interrupted by unfavourable weather conditions. Depressed bilberry reproduction was associated with high temperatures during flower-bud formation in autumn, high temperatures in winters with thin snow cover, low temperatures during flowering in spring, and low or high amounts of precipitation during berry ripening in summer. It was concluded that, in Fennoscandia, climatic conditions may be responsible for the temporal and spatial synchrony in seed production in bilberry.Key words: bilberry, climate, mast, reproduction, synchrony, weather.