Environmental Engineering Reference
In-Depth Information
Fig. 11.2
Yearly course of decadal and cumulated NEE at the Negresia site, related to pheno-
logical stages
development was monitored regularly both by direct, destructive measurements on
a sample of shoots, and by indirect, optical method, using a LiCor LAI-2000 can-
opy analyzer. Extensive biometrical sampling of leaves, shoots, trunks and roots
has been carried out to provide independent measurements of vine growth dynam-
ics and biomass partitioning.
The Eddy Covariance equipment is based on a 3-dimensional ultrasonic ane-
mometer (Metek USA-1) and an open-path IR gas analyzer (LiCor LI-7500),
both logged at 20 Hz by a low-power industrial PC. Ancillary measurements of
net radiation (CNR-1, Kipp and Zonen) and basic meteorological parameters
(air temperature and humidity, barometric pressure, rainfall, etc.) are measured
every second and averaged every 30 min by a CR23X Campbell datalogger. Eddy
Covariance data were processed according to the standard EUROFLUX methodol-
ogy (Aubinet et al.
2000
). Data quality check has been performed according to
Foken and Wichura (
1996
) and gap-filling following Desai et al. (
2005
).
Following the set up of the station, the Negrisia vineyard proved to be a strong
carbon sink. Data for 2009 (Fig.
11.2
) showed a rapid increase of NEE already
before budbreak, due to the increased activity of the grass cover, as soon as the
temperature turned milder (Fig.
11.3
). The quick development of the vine can-
opy further increased carbon absorption up to a maximum decadal NEE of
50 g C m
−
2
, which occurred around veraison. Leaf senescence and fall brought a
steep decrease of NEE by the end of October. However, the system never showed a
net release of carbon, because of the residual activity of the grass cover even dur-
ing wintertime. Obviously, this behaviour strongly reflects both the adequate water
availability (the vineyard never experienced significant stress, because of the gen-
erally high water table of the area) and the mild temperature (seldom below 0 °C).
The annual total NEE (814 g C m
−
2
) suitably matched the biometrical measure-
ments. Yield represented roughly 20 % of NEE and therefore Negrisia vineyard
