Resum:
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• Quercus ilex L., the dominant species in Mediterranean forests and one with a great capacity for
resprouting after disturbances, is threatened by the expected increase in fire frequency and drought
associated with climate change.
• The aim of this study was to determine the contribution of photosynthesis limitants, especially mesophyll
conductance (gmes ) during this species’ resprouting and under summer drought.
• Resprouts showed 5.3-fold increased gmes and 3.8-fold increased stomatal conductance (gs) atmidday
with respect to leaves of undisturbed individuals. With increased drought, structural changes
(decreased density and increased thickness) in resprouts contributed to the observed higher photosynthesis
and increased gmes. However, gmes only partially depended on leaf structure, and was also under
physiological control. Resprouts also showed lower non-stomatal limitations (around 50% higher carboxylation
velocity (Vc,max) and capacity for ribulose-1,5-bisphosphate regeneration (Jmax)). A significant
contribution of gmes to leaf carbon isotope discrimination values was observed.
• gmes exhibits a dominant role in photosynthesis limitation in Q. ilex and is regulated by factors
other than morphology. During resprouting after disturbances, greater capacity to withstand drought,
as evidenced by higher gmes , gs and lower non-stomatal limitants, enables increased photosynthesis
and rapid growth. |