Environmental Engineering Reference
In-Depth Information
−
1
) in the various stages of secondary succession and in the affor-
ested sites and in three bioclimates (0-30 cm soil depth). Abbreviations:
CU
cultivated areas,
HE
herb-dominated plant communities,
PG
perennial grasslands,
GS
garrigues and low shrublands,
MA
maquis,
NF
natural forests,
AF
artificial afforestations;
Thermo
thermo-mediterranean,
Meso
meso-mediterranean,
Supra
supra-mediterranean bioclimate
Fig. 12.2
SOC stock (Mg ha
In the meso-mediterranean bioclimate, relative SOC stock increase with cul-
tivation abandonment, i.e. from cultivated soils to herb-dominated soils, is only
half as much as in the thermo-mediterranean belt. On the other hand, there was a
higher increase from herb communities to perennial grasslands. SOC gain in the
older succession stages was similar to the thermo-mediterranean belt.
Finally, in the supra-mediterranean belt SOC stock increase was very high with
cultivation abandonment: SOC stock doubles from cultivated soils to herb-domi-
nated soils. In contrast, SOC gain in the older succession stages was lower in com-
parison to the other two bioclimates.
12.3.2 SOC Variation in Artificial Afforestation
Results showed a lower SOC stock in artificially afforested soil in comparison
with natural afforested soil (Fig.
12.2
). More in detail, in the thermo-mediterra-
nean belt, artificial afforestations showed higher SOC contents with respect to nat-
ural afforestations up to the succession stage of garrigues and low shrublands, and
