Timing of bud burst and tree-leaf development in a multispecies temperate forest

Abstract

Timing of bud burst and leaf unfolding in trees growing in a mixed species stand was recorded during nine years (1997–2005) in primeval old-growth forests preserved in the Białowieża National Park (E Poland). Performance of five main woody species (producing over 98% of foliage) growing in the most diversified oak–lime–hornbeam Tilio-Carpinetum habitat were observed. Despite 2–3-week, interyear shifts in dates of bud burst onset, the order of bud burst by different species remained constant (from Coryllus avellana L., through Carpinus betulus L., Acer platanoides L., Quercus robur L., to Tilia cordata Mill.) among years. Depending on the year, the median bud burst dates of Coryllus and Tilia differed by 13–26 days. These differences tended to be smaller in the late (13–17 days) than in the early (20–26 days) springs, though the relationship was not significant. Leaf spread dates were much more synchronous than bud burst dates (span of 9 and 24 days, respectively), as the earliest commencing species – Coryllus and Carpinus – developed leaves at slower rates. Within a species, individual trees were developing leaves consistently early or late. The high repeatability across years, despite strong environmental variation, suggests existence of genetic differences. Leaves appeared earlier and grew faster in warmer springs. This variation was strongest influenced by weather variation in March and April, the temperature sums accumulated from March 1 were the best predictors of the actual burst dates. This appears to be the first multi-year study of timing of tree-leaf development in a multispecies deciduous forest in Europe.