Environmental Engineering Reference
In-Depth Information
farmers' income through high quality wood production in the plain, to support
agricultural products' prices by reducing cropland area; to diversify the landscape
by restoring some natural elements; to mitigate climate change by increasing
carbon storage in the biosphere. With reference to the latter aspect, the net car-
bon exchange in terrestrial ecosystems is the result of a delicate balance between
uptake and emissions which show a diurnal, seasonal and annual variability.
Consequently, small changes in the relative rates of carbon uptake through photo-
synthesis and/or carbon loss through respiration can have profound effects on the
accumulation of CO 2 in the atmosphere. The Kyoto protocol suggests that man-
agement of natural terrestrial carbon sinks, primarily afforestation and reforesta-
tion at a global scale, can increase the sink strength and reduce atmospheric CO 2
concentration.
The terms used in this chapter refer to those adopted by the IPCC Guidelines
( 2000 ) which define afforestation as the “planting of new forests on lands which,
historically, have not contained forests” and reforestation as “the establishment of
trees on land that has been cleared of forest within the relatively recent past”. The
distribution of sources and sinks of carbon over the land surface is dominated by
changes in land use: in the tropics current rates of deforestation are responsible for
a large loss of carbon; in the north mid-latitudes past changes in land use (i.e. nat-
ural forest recovery, forest plantations) can explain much of the observed carbon
sink (Houghton and Hackler 2000 ; Pacala et al. 2001 ; Houghton 2003 ).
In Italy, recent estimates report that forest plantations cover a total area of
122,252 ha (54 % poplar plantations; 34 % mixed broadleaf plantations; 12 %
coniferous plantations) (Gasparini and Tabacchi 2011 ). This area is only 1.4 %
of total Italian forest area and covers only 0.4 % of country surface, but it has
been increasing year by year in the last decades following new European Union
regulations and incentives. Thus, the role of these plantations for carbon seques-
tration has become quite relevant (Magnani et al. 2005 ) as afforestation and refor-
estation do not only increase above-ground carbon stocks, but also restore and
increase carbon into soil. At steady state, each soil has a theoretical equilibrium
carbon content depending on the nature of vegetation, precipitation and tempera-
ture (Paul et al. 2002 ; Guo and Gifford 2002 ). This equilibrium is the result of the
balance between inflows and outflows of the pool and can be disturbed by land
use change until a new equilibrium is reached in the new ecosystem. During land
use changes, soil can act as a source or a sink of carbon according to the ratio
between inflows and outflows. Rodeghiero ( 2006 ) reports a carbon accumulation
of 0.33 Mg C ha 1 y 1 following conversion of a cropland into a forest plantation.
Guo and Gifford ( 2002 ), in their comprehensive meta-analysis, report an increase
of 18 % in soil carbon stocks after cropland afforestation.
The Friuli Venezia Giulia Region, following the application of the measure 06
of the EU 2080/92 Regulation and the application the Rural Development Plan
Rural 2000-2006 (measure h and i.1), encouraged the conversion of agricultural
and non-agricultural lands into forest plantations.
The aim of the present study can be described as follows (i) to quantify
total carbon stock and its partitioning among different ecosystem pools (i.e.
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