Contrasting foliar responses to drought in Quercus ilex and Phillyrea latifolia
2006
Ogaya, R.(Universitat Autonoma de Barcelona (Spain). Unitat d'Ecofisiologia CSIC-CEAB-CREAF) E-mail:[email protected] | Penuelas, J.(Universitat Autonoma de Barcelona (Spain). Unitat d'Ecofisiologia CSIC-CEAB-CREAF)
Leaf morphology, longevity, and demography were examined in Quercus ilex and Phillyrea latifolia growing in a holm oak forest in Prades mountains (northeast Spain). Four plots were submitted to an experimental drought during three years (soil moisture was reduced about 15%). Leaf mass per area ratio (LMA) and leaf thickness increased since leaf unfolding except in summer periods, when stomatal closure imposed low photosynthetic rates and leaves consumed their reserves. LMA, leaf area, and leaf thickness were higher in Q. ilex than in P. latifolia, but leaf density was higher in the latter species. Drought reduced the leaf thickness and the LMA of both species by about 2.5%. It also increased leaf shedding up to about 20% in P. latifolia and decreased it up to about 20% in Q. ilex. In the latter species, the mean number of current-year shoots produced per previous year shoots decreased by 32%, the mean number of current-year leaves per previous-year shoot by 41%, percentage of previous-year shoots that developed new ones by 26%, and leaf area by 17%. Thus, the decrease of leaf number and area was stronger in the less drought-resistant Q. ilex.
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