The response of three Fagus sylvatica L. provenances to water availability at different soil depths

Abstract

Current climate change scenarios predict changes in precipitation patterns resulting in a longer and more intensive droughts. These changes pose a challenge for Fagus sylvatica as the most common European deciduous tree species. We asked how different genotypes respond to drought conditions and paid particular attention to how soil moisture availability can be manipulated. We established a tube technique that allowed to add water horizontally at different rooting depths, which allowed to measure water contents and to observe root growth along the full length of 1-m deep tubes. Three F. sylvatica provenances were compared in their response to different depth of water supply with respect to growth, leaf stomatal conductance as well as root and leaf traits. There were short-lasting differences between the watering regimes in soil water content and depth of soil moisture maxima. Adding water to depths of 30–60 cm resulted in reduced leaf stomatal conductance and lower survival but increased root tip growth rates compared to watering the tubes at 10–20 cm. There were differences between the three provenances for specific leaf area and stem dry mass, which however, were independent of the watering regime and did not support the idea of local adaptation to drought of populations from dry or moist origins. The findings indicate that differences between provenances might have been caused by environmental factors other than drought. Technically, we demonstrated the high potential of using the tube technique for a fine-tuned manipulation of soil moisture in the rooting space.