Environmental Engineering Reference
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in Sicily, site-specific technologies must be developed and validated to obtain the
maximum effect in term of quantity and stability of SOC sequestered.
10.3 Grassland Management and Carbon Balance
Grassland management is an important factor in C balance also because of its
impact on N availability. Meadows and pastures are among the ecosystems that
were subjected to the highest rate of change in the last decades for the reduction of
management intensity (e.g. livestock stock, fertilization, abandonment), hence the
analysis of these effects is important to understand and predict SOC stock dynam-
ics. Land management activities, such as haying, fertilisation and grazing affect
the assimilation and ecosystem respiration through changes in photosynthetic
activity and quality of respiratory substrate. The removal of aboveground bio-
mass modifies the soil microclimate (temperature and humidity), then influencing
the soil respiration. Moreover, mineral and organic fertilizations affect the nutri-
ent availability and thus leaf photosynthesis and ecosystem respiration compo-
nents. Among agronomic management techniques, conversion from cropland and
irrigation cause the largest increase in C sequestration rate (Conant et al. 2001 );
furthermore, well-managed pastures can have a positive impact on SOC level,
accumulating up to 7 % with respect to no grazed areas. Timing and frequency of
management practices in grasslands could affect the more labile C pools, leading
to short-term ecosystem response that can be detected by fast measurements, such
as Eddy Covariance (Wohlfahrt et al. 2008 ).
In the experimental area of Monte Bondone (see Sect. 2.2.13 ) an analysis of
the impact of climate on C balance of an alpine grassland was carried out using an
Eddy Covariance station. It is worth noting that the observation years (2003-2009)
were characterised by a high variability in precipitation, covering about 80 and
55 % of the historical range observed on a yearly basis and during the growing
season, respectively. The results showed that the portion of inter-annual variability
(IAV) generated by climate variability is considerably smaller than that induced
by changes of ecosystem responses, and the relative importance of climate related
IAV decreases from gross primary production-GPP (36 %) to total ecosystem res-
piration-TER (22 %) and to net ecosystem exchange-NEE (20 %), suggesting a
strong resistance of ecosystem carbon fluxes to the direct effect of climate driv-
ers. This analysis only marginally supports the hypothesis that temperature limited
ecosystems are highly sensitive and vulnerable to climate change though it rather
stresses the effectiveness of acclimation in limiting the impact of climate variabil-
ity on ecosystem productivity (Marcolla et al. 2011 ).
Considering that the inter-annual variability of the climate does not seem to
have a strong impact on the carbon balance of grasslands studied, an experimental
campaign was carried out on the Monte Bondone plateau (2 km 2 ) in which differ-
ent systems of grassland management are present (Fig. 10.4 ). Meadows represent
the principal land use on this plateau and they are traditionally managed with low
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