Influence of species and rain event characteristics on stemflow volume in a temperate mixed oak-beech stand

This study aimed at analysing the effects of biological and meterological factors on stemfolw generation in a temperature mixed oak (Quercus petraea Liebl.) and beech (Fagus sylvatica L.) stand. A statistical model was developed to predict single-event individual stemfolw volume from trunk circumference and rainfall depth allowing mechanistic stemflow parameters to be deduced from the model, namely stemflow rates (SFrate), storage of water on tree organs (S-t) and rainfall thresholds for stemflow (RFmin) was not significantly influenced by tree size, RFmin and, for a given tree size, S-t were higher for oak than for beech, and inversely for SFrate. For each species, RFmin was higher for the leaved season than for the leafless period, while the opposite was found for SFrate, and S-t was not significantly affected by the season. Increasing wind speed during rain increased SFrate, lowered RFmin and did not influence S-t. In contrast, S-t and RFmin tended, respectively, to decrease and to increase with increasing values of the ratio between the cumulated potential evaporation during the dry period preceding the rain event and the volume of the preceding rainfall (Evap(ADP)/R-previous). Stemfolw volume, which results from the combined effects of the previous parameters, was higher for beech than for oak and also higher during the leafless period than during the leaved period, these differences were large for the smallest events but decreased rapidly as rainfall depth increased. In addition, an enhancing and a depressing effect on stemflow volume were shown for the average wind speed during rain and for the ratio Evap(ADP)/R-previous, respectively. Copyright (c) 2008 John Wiley & Sons, Ltd.