Success in the demographic expansion of Fraxinus excelsior L.

Abstract

This review examines the ecological traits and ecophysiological characteristics of the common ash (Fraxinus excelsior L.) that help to explain the current spread of ash communities in Europe. As a consequence of anthropogenic disturbance, the common ash has experienced new environmental conditions and the frequency of the species has fluctuated over space and time. Owing to its ubiquity, over the last few decades the common ash has been greatly favoured in areas abandoned by agriculture and also along impounded rivers. F. excelsior is a mesophilic species that usually thrives on alluvial soils and can also survive the strong water deficit on hillslopes. Drought tolerance in ash trees is related to stomatal regulation, a decrease in osmotic potential and also an increase in the elastic modulus ε. Malic acid plays a central role in drought tolerance, first as one of the major solutes involved in osmotic adjustment, and second as an effector for stomatal regulation through a drought-induced increase in its xylem concentration.

New insights in the recognition of the European ash speciesFraxinus excelsiorL. andFraxinus angustifoliaVahl as useful tools for forest management

“…The present set of markers allows us to distinguish the two species adequately and this discrimination improves with increasing sample sizes, which was not the case for earlier studies. Moreover, the present study points out possibly different ecological strategies of the two species that can be linked with their colonizing abilities (see [9] for F. excelsior). This can be useful for studies of hybridization in zones of sympatry and/or of putative replacement of common ash by narrowleaved ash, for example in the context of global change.…”

“…The embryo made up a larger proportion of the seed in F. angustifolia and this species produces more vigorous seedlings during the first years of growth (Dufour, unpublished results). This could represent a better ability for colonizing newly open forest gaps or open habitats, and thus explain the replacement of common ash by narrowleaved ash in some regions [9]. Embryo size also affects germination and dormancy.…”

Leaf water status and stem xylem flux in relation to soil drought in five temperate broad-leaved tree species with contrasting water use strategies

“…Much lower and highly variable Ψ L have been reported by Carlier et al (1992), with minima ranging between -5.54 MPa on shallow soils and -1.94 MPa on alluvial deposits. F. excelsior has an ample plasticity range of adaptation to wet and dry environments (Marigo et al, 2000).…”

“…The species can develop very low Ψ L (up to -6 MPa, Marigo et al (2000)), and is able to maintain sufficient leaf conductance and CO 2 assimilation during drought (Carlier et al, 1992;Guicherd et al, 1997;Korn, 2004;Marigo et al, 2000). A high maximum g L and a low sensitivity of sap flow to water shortage are elements of a drought-tolerating strategy.…”

“…Sycamore (Acer pseudoplatanus L.), European beech (Fagus sylvatica L.), European ash (Fraxinus excelsior L.), hornbeam (Carpinus betulus L.) and little-leaf linden (Tilia cordata Mill.) represent species with a contrasting distribution range in Europe and, thus, putatively differing in drought avoidance and tolerance strategies (Marigo et al, 2000;Bolte et al, 2007;Ellenberg and Leuschner, 2009). Except for beech, data on the drought response of the important Central European tree species is scarce (Aranda et al, 2005;Bréda et al, 2006;Cochard et al, 1996;Leuzinger et al, 2005;Magnani and Borguetti, 1995;Marek et al, 1989;Nardini and Salleo, 2000).…”