Differential response to soil drought among co-occurring broad-leaved tree species growing in a 15-to 25-year-old mixed stand
2013
Zapater, Marion | Breda, Nathalie | Bonal, Damien | Pardonnet, Sylvia | Granier, André
In the context of global environmental changes, better understanding of tree response to soil drought in young mixed species stands is needed to anticipate forest adaptation and management practices for the future. We investigated the functional response of five co-occurring broad-leaved tree species growing in a 15- to 25-year-old mixed stand in northeastern France during the 2006 summer drought. We measured functional traits related to water acquisition (phenology, rooting pattern and vulnerability of xylem to cavitation) and the ecophysiological response (sap flux density, leaf water potential) of these species to soil water shortage. Our study highlights contrasted drought response strategies among these species and a trade-off between leaf phenology, resistance of xylem to cavitation and root system depth. At this site, a deep root system seemed to be a key functional trait for the species to cope with drought. Quercus robur and Salix capreae can be characterised as drought-avoidance species as they possess a deep root system and therefore did not strongly experience soil drought. Despite deep rooting capacity, Betula pendula did not really avoid soil drought and strongly regulated transpiration during dry periods. Nevertheless, the earliness of budburst of this species contributes to high annual growth rate. In contrast, Carpinus betulus and Fagus sylvatica both displayed typical characteristics of drought-sensitive species.
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