introduction - Ecologia Mediterranea

PHENOLOGY AND GROWTH OF QUERCUS ILEX IN DIFFERENT ENVIRONMENTAL CONDITIONS IN SICILY u
phenological phases; the main differences just concern
the total duration of shoot elongation and flowering, that
at Castelporziano are almost twice than in the Sicilian
populations.This could be related to the less extreme climate
at Castelporziano, with regards as to temperature as
to the distribution of rainfalls throughout the year.
In all the Sicilian investigated, holm oak populations,
the mean annual shoot elongation is 20-30 % higher than
that reported for Castelporziano (Fioravanti, 1998). In
this respect, the different trends and values of temperatures
throughout the year, due to latitude differences, may
have a major role; but a lack of climatic data just give a
conjectural value to such an assumption. As a matter of
fact, it is to be pointed out that, like at Mt Pellegrino, a
second growth flush is observed also at Castelporziano
and Macchia Grande, but only in holm oaks with shrubby
habit (Gratani et al., 1989; De Lillis & Fontanella, 1992;
Gratani & Crescente, 1997).
ecologia mediterranea, tome 29, fascicule 1, 2003, p. 15-25
Figure 4. Shoot diameter growth in the investigated sites (mean of the four exposures).
In addition to shooting, the autumnal flowering recorded
only at Mt Pellegrino reinforces the hypothesis of
noteworthy potentiality of the species to polycyclism.
This behaviour often characterises other Mediterranean
evergreen oaks, as Quercus suber, and Quercus coccifera.
Also a population of the endemic Quercus soluntina, an
hybrid between Quercus ilex and Quercus coccifera, living
some 10 km afar from Mt Pellegrino in similar environment,
usually exhibits a second autumnal flowering and
a complete fruit ripening. Very seldom, even deciduous
oaks as Quercus pubescens, show autumnal flowering, as
observed by Bianco and Scaramuzzi (in Bianco &
Schirone, 1982) in 1978 in Apulia (S-E Italy). Such features
support the idea that holm oak is a species quite
well adapted to the seasonality of the mediterranean climate,
but its behavioural peculiarity seems to confirm
statements about its origin in a tropical-type climate
(Bernetti, 1995).
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