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Zusammenfassung:
Erica arborea (L) is a widespread Mediterranean species, able
to cope with water stress and colonize semiarid environments.
The eco-physiological plasticity of this species was evaluated
by studying plants growing at two sites with different soil
moistures on the island of Elba (Italy), through dendrochronological,
wood-anatomical analyses and stable isotopes
measurements. Intra-annual density fluctuations (IADFs)
were abundant in tree rings, and were identified as the key
parameter to understand site-specific plant responses to water
stress. Our findings showed that the formation of IADFs is
mainly related to the high temperature, precipitation patterns
and probably to soil water availability, which differs at the
selected study sites. The recorded increase in the 13C-derived
intrinsic water use efficiency at the IADFs level was linked to
reduced water loss rather than to increasing C assimilation.
The variation in vessel size and the different absolute values of
δ18O among trees growing at the two study sites underlined
possible differences in stomatal control of water loss and possible
differences in sources of water uptake. This approach not
only helped monitor seasonal environmental differences
through tree-ring width, but also added valuable information on E. arborea responses to drought and their ecological implications for Mediterranean vegetation dynamics.
