The plantation and FACE facility is located in central Italy, near the city of Tuscania, province of Viterbo. The site is at 42°22'N , 11°48’E and is 150 m above the sea level. P.x euramericana (I-214) cuttings were planted during the spring of 1999 over 9 ha of former wheat field at a commercial spacing of 2 m x 1 m. Within this plantation, 6 experimental plots were equally spaced in order to avoid enrichment pollution of ‘control’ plots with air blown in from ‘FACE’ plots.
The whole of the plantation was drip irrigated at 6 to 10 mm of water per day during the growing season, starting approximately at the beginning of April until the beginning of November. The amount of water was sufficient to avoid water stress even during the hottest days of a growing season.
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In each
of the experimental plots cuttings of the following tree species
were planted at the
same time as the rest of the plantation: Populus alba (clone
2AS-11), Populus nigra (clone Jean Pourtet) and Populus
x euramericana (Populus deltoides x Populus
nigra,
clone I-214). The plots are 30 m x 30 m in size and the trees
are spaced at 1 m x1 m to facilitate early canopy closure.
Each of the plots is divided into 3 sections, every one of which
was planted out with trees of a single species. The plot is further
split into two halves with a 1m deep barrier to allow for high
and low fertilisation treatments. Image on the left illustrates
the planting scheme for plots 1 and
2.
In the
remaining
two pairs of plots, i.e. 3 – 4 and 5 – 6, the planting
scheme was rotated to avoid possible bias due to uneven growth
of different species. |
Each
of the FACE plots enclosing an area of circa 350 m2. The octagonaly
shaped ring was designed to provide an
internal area with equal distribution of CO2 with
a diameter of 22 metres. Each ring has eight telescopic masts
supporting layers
of horizontally positioned polyethylene pipes (diameter 25 mm)
releasing pure CO2. The pipes are suspended
at various heights to facilitate even vertical distribution of
CO2 within the canopy and the masts allow
for easy and rapid vertical movement of the pipes to account
for fast growth of the poplars. At the beginning of the experiment,
immediately after planting, an initial single layer of pipes
was
located at approximately 50 cm above ground. Later into the experiment
second and third layer of pipes were added, reaching a maximum
height of 12 m. |
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An aerial
view of the POPFACE rings taken in the spring 1999 at the beginning
of the first experimental season. The picture
shows the spatial arrangement of the structures and the control
unit located at the centre of the octagone is also clearly visible. |
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After more than
2 years of growth, canopy
movements did create some problems, as expected, to the CO2 control
that was affected by enhanced turbulence. Nevertheless, also
in the year 2001, system performances were adequate as figure
above shows for the top of the canopy. |
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In spring 2001 the whole plantation including the experimental
plots was coppiced. All biomass was chipped and used to generate
electricity in a newly constructed power plant. |