13C and tree-ring width reflect different drought responses in Quercus ilex and Pinus halepensis

• Published in: Oecologia 2003-12, Vol.137 (4), p.512-518
• Main Authors: Ferrio, J. P., Florit, A., Vega, A., Serrano, L., Voltas, J.
• Format: Article
• Language: English
• Subjects: Carbon isotopes; Climate change; Drought resistance; Evapotranspiration; Flowers & plants; Herbivores; Water availability; Water stress; Water use; Water use efficiency
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-003-1372-7

Holm oak (Quercus ilex L.) and Aleppo pine (Pinus halepensis Mill) are representative of two different functional types of trees extensively found in the Mediterranean: evergreen sclerophyllous and drought-adapted conifers. The former is considered a partially drought-tolerant species, whereas the latter is a typically drought-avoiding, water-saving species. We postulated that contrasting strategies in response to water deficits in Q. ilex and P. halepensis would lead to a differential sensitivity to changes in water availability. To test this hypothesis, we compared the response of both species in growth rate (measured as radial increments) and intrinsic water use efficiency [WUE^sub i^, as inferred from carbon isotope discrimination (Δ^sup 13^C) in wood samples] among sites from different provenance regions in NE Spain. We found significant differences in Δ^sup 13^C and growth among provenance regions, partly explained by contrasting water availability. Wood Δ^sup 13^C was positively related with precipitation and the ratio between precipitation and potential evapotranspiration (P / E). However, these relationships were stronger in P. halepensis (for P / E, r^sup 2^=0.67, P