Agriculture Reference
In-Depth Information
The leaf litter decomposition of
Q. ilex
was studied in the WWF Oasis “
Bosco di S.
Silvestro
” (BSS), where senescent leaves were collected at litterfall time, and in the Nature
Reserves of Castel Volturno (CV), Caserta (sea level) and Tirone-Alto Vesuvio, Mt Vesuvius
(VES), Naples (500 m a.s.l.).
The studied sites differed in soil characteristics, in such as the distribution of particle
sizes that, in turn, affects water holding capacity, pH, N content and C/N ratio (Table 7) as
well as by pluviometric regime that appeared different. Referring to the nearest
meteorological stations, the VES wood appeared to receive the greatest amount of
precipitations during the studied period (1999-2001), and BSS the smallest (with the only
exception of the 1999 year). It changed the soil moisture content (Papa et al., 2002).
In spite of these differences among the three oak woods chosen for the comparative
study, the leaf litter of
Quercus ilex
did not show significant differences in decomposition rate
and at the end of the incubation period (about 2 years) the remaining litter weight ranged from
about 50 to 60 % of the initial mass (Figure 4 a).
The degradation of the main recalcitrant material, holocellulose and lignin, however
some little differences among the sites. Cellulose was degraded from the first sampling and
continued at a constant rate in Castel Volturno holm-oak wood. Its initial mass was reduced to
50% after 2 years of incubation (Figure 4 b). In this stand, a significant increase of fungal
biomass occurred after about 300 days of exposure during the wet autumn season (Figure 5).
In the other two sites, cellulose degradation began after 6 months of exposure and continued
to the end of the study period. Lignin, on the contrary, did not show any significant
degradation during the decomposition period (Figure 4 c).
Table 7. Soil characteristics of the three oak woods located within the Natural Reserve
Tirone Alto-Vesuvio, WWF Oasis “Bosco di San Silvestro” and Natural Reserve of
Castel Volturno (Campania Region, South Italy)
Natural Reserve
of Tirone-Alto
Vesuvio
Natural Reserve
of Castel
Volturno
Oasis
WWF
Bosco di
S.Silvestro
Substrate
Volcanic
siliceous-
calcareous
Calcareous
Fraction*
Designation
Distribution of particle sizes (mass %)
1 cm- 2 mm
2 - 0.2 mm
0.2 - 0.02 mm
< 0.02 mm
Gravel
Coarse sand
Fine sand
Clay and silt
4.5
41.2
40.0
14.3
0
76.8
22.8
0.4
3.0
17.8
51.4
27.8
Water holding capacity (H
2
O g/100 g
d.wt)
71.7
62
156.7
pH
6.5
8.0
7.0
Potential pH
5.0
6.8
6.4
C org (%)
21.7
13.8
13.5
N (%)
1.47
0.51
0.50
C/N
14.8
27.1
26.0
* Gravel >1 cm was removed before fraction separation.
