Forest reproduction processes and climate

2001

S. 86

Unselbständiges Werk

200073373

A long-term of the Federal Forest Research Centre Vienna aims to investigate progresses of forest tree reproduction: in seed orchards as well as in different forest standings, flowering and seed production processes are investigated since 1989. The study of intercorrelation between pollen production, female flower development and changes in climate and weather conditions shall allow a prediction of seed production in better time. By means of both volumetric and gravimetric pollen traps, start, peak, and duration of the pollination period has been determined in various altitudes from the lowland up to alpine regions. Subsequently, fruit production was compared to the flowering period conditions. Weather data, in particular winter maximum and minimum temperate divergences were compared with pollination periods in the 1980ies and 1990ies. The influence of temperature, precipitation and light (radiation) in connection with altitude becomes visible in the plant reproduction process: anomalies of weather, in particular late frost periods in March/April lead to a strong reduction or even loss of seed production in larch, elm and partially ash. On the other hand, hazel and alder are favoured by increasing temperature without relapses during December and January. Trees growing in high altitudes are less effected by the climatic changes during the past years than those in lower elevations. An abatement of hazel and alder on one hand, bad effects in low altitude stands of larch and elm on the other hand have been verified. Based on these results, we may assume a future increment of early flowering species (e.g. hazel), and a deterioration for species flowering approximately one month later (e.g. ash, elm, larch, birch, hornbeam).