Environmental Engineering Reference
In-Depth Information
Fig. 12.1
Location of the study sites (
black circles
) within the three most widespread biocli-
matic belts (sensu Rivas-Mart￭nez) of Sicily:
light grey
thermo-mediterranean,
medium grey
meso-mediterranean,
dark grey
supra-mediterranean.
Dashed
other bioclimates; climatic data
issue from Drago et al. (
2002
)
areas (Alberti et al.
2011
; La Mantia et al.
2013
) are influenced by climate, the
dataset has been subdivided into three bioclimatic groups of sites (1. thermo-med-
iterranean, 2. meso-mediterranean, 3. supra-mediterranean), which represent the
most widespread bioclimatic belts of Sicily (Fig.
12.1
). Thermotype classification
follows Rivas-Mart￭nez and Loidi Arregui (
1999
). The thermotype (
It
) is a biocli-
matic index based on the temperature regime of a site, and it is calculated as fol-
lows:
It
=
(
T
+
M
+
m
) 10, where
T
is the average annual temperature,
M
is the
average of the maximum temperatures of the coldest month, and
m
is the average
of the minimum temperatures of the coldest month. In total, 16 thermo-, 22 meso-,
and 10 supra-mediterranean sites have been analyzed.
12.2.1 Original Sampling Data
Soil sampling was carried out in sites where series of secondary succession, i.e. dif-
ferent progressive successional stages, were present. Throughout all bioclimates,
we defined as successional stages the following six land use classes: (1) CU
=
cul-
tivated areas (orchards, cereal crops); (2) HE
=
herb-dominated plant communi-
ties without presence of woody species (grazed pastures, old fields abandoned by
