Linking aboveground and belowground drought responses of European beech
2 Ökophysiologie der Pflanzen, TU München
P 1.3 in Ecosystem Function
European beech is assumed to play a crucial role in forest conversion from coniferous towards deciduous forests. As especially young beech trees in state of establishment are vulnerable to water limitation, rising frequency and intensity of summer droughts predicted by climate models may threaten beech afforestation. Aim of this study is to investigate responses of young beech trees to experimentally induced drought stress and to determine threshold values for beech plantations by means of climatic and soil hydrological parameters. The study site is a thinned Norway spruce plantation in the Fichtelgebirge with planted 4-year-old beech trees. Responses of the young trees to drought will be characterized by assessing above- and belowground plant parameters (leaf water potential, transpiration rate, photosynthesis rate, stem diameter increment, root shoot ratio, water use efficiency, fine root morphology and biomass, mycorrhization, nutrient uptake, accumulation of carbohydrates, etc.) as well as soil hydrological and meteorological conditions during the growing season. An accompanying rhizotron experiment combined with CO2 flux measurements will allow insights in fine root dynamics linked to respiration and photosynthetic traits at adjusted soil water potentials. Preliminary results after one year point to a beginning adaptation of the beech trees to summer drought. By means of fine root parameters (fine root biomass, average fine root diameter, root tip density) a trend to a more efficient soil exploitation has been observed. Drought also affected shoot growth as a smaller radial and height increment has been observed.