Environmental Engineering Reference
In-Depth Information
were considered (3, 6 and 9 years). Moreover, adjacent cropland (i.e. maize and
wheat for mixed broadleaf and poplar plantations, respectively) were also included
in the analysis. Within each forest stand or agricultural crop, five points were ran-
domly selected. Then eight soil cores around each point were collected at two
depths (0-15 and 15-30 cm) after litter removal. Prior to processing, samples
were kept at 4 °C. Each sample was mixed and sieved through a 2-mm sieve and
then dried at 102 °C for 48 h. Dried material was ground to a fine powder, treated
with HCl 2:1 to remove carbonates and then analyzed for organic C and N using a
CHN Elemental Analyzer. Soil bulk density for each depth was estimated at each
selected point following the excavation method (Elliott et al.
1999
). Measured val-
ues were then plotted against aboveground carbon stocks and linear regressions
were used to quantify soil carbon stocks and soil carbon stock changes at different
stand ages.
13.3 Results for the Friuli Venezia Giulia Case Study
By using the data provided by the Regional Forest Administration, it was possi-
ble to determine the annual cropland surface converted to mixed broadleaf and
poplar plantations (Fig.
13.1
). In this last case, only plantations realized after
2002 were considered as at the end of the rotation period (8-10 years) the stand
is usually clear-cut. Thus, our carbon budget considered the normal rotation
period length for both plantation types. The annual conversion rate was between
3 and 532 ha
−
1
y
−
1
and between 238 and 606 ha y
−
1
for mixed broadleaf and
poplar plantations, respectively. Overall 2,592 ha of mixed broadleaf plantation
Fig. 13.1
Annual area converted into mixed broadleaf (
black
) and poplar plantations (
grey
) in
Friuli Venezia Giulia (Italy)
