Agriculture Reference
In-Depth Information
On pine needles the basidiomycetes, the most significant group of secondary saprophytes
able to carry out lignin degradation, became dominant about a year later, even if they were
detected already in the first month of incubation of the
P. pinea
litter, which had a high water
holding capacity (Virzo De Santo et al., 2002). Moreover, the occurrence of basidiomycetes
appeared to show a seasonal pattern. Basidiomycetes were absent in the N-rich silver fir
needle litter incubated at Monte Taburno, which was instead colonized by
Polyscitalum
fecundissimum
,
Chalara
, and
Endophragmia
.
In the later phase of pine litter decomposition (after about 2 years) the frequency of
ascomycetes with shield-like ascocarps (thyriothecia), became significant1y high.
Ascomycetes were also frequent on silver fir needles.
Microfungi succession was also studied during leaf litter decomposition of
Q. ilex
in the
WWF Oasis “San Silvestro” (Table 8) (Di Nardo, 2004).
Trichoderma
and
Penicillium
were
isolated at each sampling. They had cellulolytic and pectinolytic activity, respectively
(Kjøller and Struwe, 1990), and was important in controlling decomposition rate (Figure 10).
They, in fact, release low-molecular sugars for the accompanying Mucorales, whose
frequency was higher in the winter months. After 6 months of incubation, appeared in the
litter
Morteriella
spp., with chitinolytic activity. Nevertheless, their highest frequency was
observed when a significant decrease of litter pH occurred.
Microfungi of the genera
Alternaria
,
Cladosporium
and
Beltrania
were also found (Di
Nardo, 2004). The first two, as said before, are ubiquitous colonizers generally able to utilize
pectine.
Beltrania
, typical of Italian microflora, instead, has a unknown function. However
Beltrania
isolates from our
Q. ilex
litter did not evidenced cellulolytic activity when plated on
cellulose agar (Di Nardo, 2004). By considering the functional role of the isolated fungi, it
appears that about 40% were able to degrade pectin and occurred in the whole study period
(24 months) supporting the role of pectin degradation in making available other litter
compounds, like cellulose; about 30% were cellulolytic and occurred also during the whole
decomposition process.
60
45
30
15
pectinolytic
cellulolytic
chitinolytic
0
0
3
6
9
12
15
18
21
24
Jan
Oct
Jan
Apr
Jul
Oct
Apr
Jul
decomposition time (months)
Figure 10. The occurrence of the four most frequent fungi able to utilize pectin, cellulose and chitin
during
Quercus ilex
leaf litter decomposition in the holm-oak wood of WWF Oasis “Bosco di San
Silvestro”. Data from Di Nardo, 2004.
