Measurement of European beech transpiration rate under drought stress

Abstract

The paper presents results of a pilot measurement of transpiration rate in European beech plants under drought stress. The measurement was carried out with “Baby EMS 62 modular sap flow systems for small stems or branches”. The plants used for measuring the transpiration rate were 4-year-old, the measurements was carried out in the summer 2010. The trees were divided into two groups: a drought-stressed group and a regularly irrigated (control) group. The simulation of drought started on July 9 2010, the measurement of sap flow on August 20 2010. In order to find out the possibility for the transpiration recovery, irrigation was applied after a severe drought exposure on the drought-stressed plants on August 24 2010. Despite expectations, the irrigation did not influence transpiration of the drought-stressed plants, although the absolute value of the soil water potential dropped to a minimum. The drought-stressed individuals achieved substantially lower values of transpiration rate, both before and after irrigation, in comparison with the control group. Further, dependence between transpiration and meteorological factors was investigated. The meteorological factors in concern are continually recorded at the mesoclimatic station situated in the “Borová hora” Arboretum. The values of transpiration rate for the drought-stressed individuals were less dependent on meteorological factors (relation fitted with a polynomial regression function of the second order) than for the control plants.