Agriculture Reference
In-Depth Information
Chapter 1
L
EAF
L
ITTER
D
ECOMPOSITION
D
YNAMICS IN
M
EDITERRANEAN
A
REA
A. Fioretto, S. Papa, A. Pellegrino and A. Fuggi
Dipartimento di Scienze della Vita, Seconda Università di Napoli. Via Vivaldi n 43,
81100 Caserta ,Italy
A
BSTRACT
The Mediterranean area is characterized by high temperature and low moisture in
summer seasons. The aim of this study was to summarize and compare the decomposition
dynamics of eight litter types (
Pinus laricio
,
P. pinea,
Quercus ilex,
Cistus incanus
,
Myrtus communis, Phillyrea angustifolia, Abies alba
and
Fagus sylvatica
) in their natural
sites followed for about 2 years. The effect of litter quality was evaluated by comparing
lignin, cellulose and nitrogen content. The effect of site characteristics and microclimatic
conditions on decomposition was also evaluated by exposing the same litter
simultaneously in different stands.
The dominant effect on litter decomposition in Mediterranean area was summer
aridity because it highly reduces the activity and growth of microorganisms, affecting
also the interactions with litter quality and soil organisms. The decomposition rate was
positively related to the Lang aridity index for all the studied litter even if no statistical
significance was evidenced. Microbial activity, that was high in autumn and spring, was
strongly reduced in summer as evidenced by the high decrease of soil respiration and the
activity of cellulases and xylanases. Seasonal fluctuations also occurred for lignin
degrading peroxidases, in agreement with the view that the overall microbial community
was affected. The overall activity of lignin degrading laccases did not show significant
seasonal changes even if its isoenzymes forms were seasonally expressed. N- content on
decomposition rate was in line with that reported for temperate areas even if the influence
of climatic conditions makes less evident the correlation.
The effect of nutrient, like nitrogen, on decomposition rate was in line with that
reported for temperate areas even if the influence of climatic conditions makes less
evident the correlations.
The positive relation between lignin decay rate and the initial Mn content support the
role of Mn dependent enzymes in such a process. However, the Mn poor
P. pinea
litter
was not affected by its low Mn initial content when incubated in the original native stand.
