The NPP is allocated to the production of biomass (wood, leaves, roots, fruits, seeds etc.) and respired back to the atmosphere mainly due to decomposition by microbial activities. The quantity of carbon lost by respiration for heterotrophic organisms is defined heterotrophic respiration (Rh) and the difference between NPP and Rh is the Net Ecosystem Production
The NEP represents the net ecosystem carbon sink or source due to physiological processes and it is also named Net Ecosystem Exchange (NEE) when it is quantified using measurements of CO2 exchanges between ecosystem and atmosphere (while it is called NEP when measured using inventory approaches). The two terms are somehow interchangeable but in general with opposite signs: a flux of carbon from the atmosphere to the ecosystem is positive in NEP and negative in NEE. The sum of the two respiration components (Rh and Ra) represents the total ecosystem respiration (TER).
The NEP is however different from the long term carbon balance of the ecosystem because there can be changes in the carbon stocks due to episodic losses by natural or anthropogenic disturbances and management practices. For this reason the Net Biome Production (NBP) is defined as (Schulze et al. 2000):
There are different possible approaches and methods to measure the fluxes of energy and greenhouse gases (GHGs) in terrestrial ecosystems, ranging from inventory approaches to chambers measurements and ecosystem scale techniques such as the Eddy Covariance method (Aubinet et al. 2012).
The Eddy Covariance methodology has been developed in the early ’90s and has been widely applied at global level. It is based on high frequency (10 Hz) measurements of wind speed, temperature and gas concentration using a three-axis sonic anemometer (which measures the wind speed along the three axis) and a fast response gas analyzer, typically an Infra Red Gas Analyzer (IRGA) for CO2 and H2O, even if new systems have been recently developed and commercialized to measure high frequency concentrations of other gases such CH4, N2O and O3.
With the Eddy Covariance technique it is possible to measure the Net Ecosystem Exchange (NEE) of a GHG of a given surface extended around the monitoring tower (the footprint). The extension and shape of the footprint is function of the wind speed, wind direction and the difference between the measurement and canopy heights and it has generally a radius between few hundred meters and one kilometer around the measurement point. The Eddy Covariance technique is the only method available today to continuously measure the net ecosystem exchanges at ecosystem level and in a not-destructive way.
In addition, for CO2 NEE measurements, there is the possibility to statistically partition the net carbon fluxes measured into its major components as the gross primary production (GPP) and the ecosystem respiration (Reichstein et al. 2005; Lasslop et al. 2010) allowing a better interpretation of the fluxes in terms of ecosystem processes.
Nowadays, more than 500 sites exist globally, organized in regional networks contributing to the global network FLUXNET (fluxnet.ornl.gov/) with the aim to create global standardized datasets of Eddy Covariance measurements available to the scientific community (Papale et al. 2012). The usefulness of these measurements has been proved by the large range of applications published in the last years, ranging from empirical up scaling (Jung et al. 2010; Beer et al. 2010) to climate-ecosystem interactions (Reichstein et al. 2007), ecosystem functioning (Mahecha et al. 2010; Williams et al. 2012) and model and remote sensing products parameterization and validation (Maselli et al. 2009; Chiti et al. 2010; Migliavacca et al. 2011; Wang et al. 2012).
2.2 The Italian Network
In Italy the first sites measuring CO2 and H2O fluxes continuously using the Eddy Covariance technique were started in 1996–1997 (IT-Cpz, IT-Col and IT-Ren) within the context of the EUROFLUX European project (ENVCT 0095-0078), but the number increased rapidly in the following years thanks to other European research projects supporting the continental network of sites.
The CarboItaly FISR Italian project offered the opportunity to consolidate, enlarge and standardize the Italian network of sites which amounted to 29 sites in the 2007–2010 period. These sites, representing different Plant Functional Types (PFTs) and distributed along the Italian peninsula (Fig. 2.1), are briefly described in the following subsections. The network has been coordinated by the University of Tuscia, also hosting the database where all the data have been processed, stored and are today available to its users.
Map of the Italian Eddy Covariance sites contributing to the CarboItaly project. Colors represent the different PFTs: CRO cropland, GRA grassland, DBF deciduous broadleaf forest, ENF evergreen needleleaf forest, EBF evergreen broadleaf forest, SHB shrubland. The Roccarespampani cluster includes two DBF and two CRO sites
The data measured with the Eddy Covariance technique need a multiple-steps processing that, in particular for CO2 and H2O, has been standardized and consolidated also during the CarboItaly project. The developed processing chain is applicable to all those sites minimizing potential differences due to the data Quality assurance/Quality control (QA/QC) used in particular when synthesis activities involving multiple sites are performed. The measurements acquired by the Italian sites have all been centrally processed according to the international standards described in Papale et al. (2006), Moffat et al. (2007) and Reichstein et al. (2005).
2.2.1 Amplero (IT-Amp)
The Amplero Mediterranean mountainous grassland is located in central Italy in the Abruzzo region (41.90409° N; 13.60516° E) on a flat to gently south sloping (2–3 %) area, at 884 m.a.s.l. The experimental area is a homogenous mixed grassland, mainly composed by few dominant graminoids (genus Poa 10 %), forbs (genus Trifolium 30 %, genus Medicago 20 %) and composites (genus Geranium 20 %, genus Cerastium 20 %). The growing season ranges from April to the end of May (roughly 60 days long) with the maximum of production at the end of May, while the senescence occurs in June. At the end of June there is a clip and after that the animal grazing (cows, horses and donkeys) until the end of November. The estimated stoking rate is around 0.5–1 animals per hectare each year and we can therefore assume that the grazing is extensively managed. The climate of this area is mountainous Mediterranean (Petriccione et al. 1993), typical climate of the Italian Apennines region. Average annual precipitation is 1,365 mm (ARSSA local database) with two precipitation peaks: one in autumn (October to December) and the other one in spring (March to April). The precipitation minimum occurs in July. The soil is Haplic Phaeozems (FAO 2008) with a depth of more than 1 m and drainage from poorly to imperfectly. The percentage of clays is 56 % and pH is 6.5. Roots reach down to 30 cm and more than 90 % of roots is placed in the first 15 cm. Starting from the last 50 years the area has been managed by a combination of clipping/harvesting and cattle grazing. The Eddy Covariance flux tower has been installed in June 2002 and the measurements have been carried out until July 2008 (Gilmanov et al. 2007; Wohlfahrt et al. 2008).
2.2.2 Beano (IT-Be1 and IT-Be2)
An agricultural field of 13.3 ha was selected in the north-eastern part of Italy in the late autumn of 2006. In this field, irrigated maize (Zea mays L.) was cultivated during the last 30 years and the soil was tilled using a winter plow to a depth of 0.35 m and a spring soil preparation (5 cm) prior to sowing. A quite constant high yield (10–11 Mg ha−1 dry matter) was achieved using a sprinkler irrigation system and adding chemical fertilizers used in accordance with standard practices. The average annual temperature at the site was 13.7 °C and annual precipitation was around 1,200 mm (2000–2007). Soil can be classified as a Chromi-Endoskeletic Cambisol (FAO 2008) with the following characteristics in the 0–30 cm horizon: total SOC = 48.4 ± 8.5 Mg C ha−1, total N = 4.2 ± 1.1 MgN ha−1, soil bulk density = 1.25 ± 0.15 g cm−3, soil field capacity = 23 % v/v, wilting point = 12 % v/v and pH = 7.1 ± 0.02 (Alberti et al. 2010). The study area was divided into two sections obtaining an eastern area of 8.6 ha and a western area of 4.7 ha. Maize was cultivated in the East field (IT-Be1, 46.00361° N; 13.0256° E) using similar management practices described above. After harvest, grain was removed from the field while residues were left there (harvest index: 50 %). Instead, the West field (IT-Be2, 46.00431° N; 13.02776° E) was converted to fodder alfalfa (Medicago sativa L.), with a late winter plowing at 0.35 m (February 2007). At sowing, 39 kg ha−1 of seeds were used. No N fertilization was performed in IT-Be2. Alfalfa was maintained from 2007 to 2009 with an average of four harvests during summer. In 2010, IT-Be2 was converted again to maize with a minimum tillage (0–5 cm) before sowing and following the same management practices used in IT-Be1.
2.2.3 Bonis (IT-Bon)
The experimental site is located in Southern Italy, in the Sila Greca mountain range, in the region of Calabria (39.47778° N; 16.53472° E). The watershed area is 140 ha, ranging from 975 to 1,300 m.a.s.l. and has been reforested between 40 and 50 years ago with conifers (Pinus nigra J.F. Arnold subsp. laricio, 80 %) and broad-leaves (Castanea sativa L., 6 %). The remaining surface is covered by pastures, crops, creeks and bare soil. The area is characterized by a Mountain Mediterranean climate with variable but generally sufficient rainfall (1,170 mm) and an average temperature of 8.7 °C. Since 1986, the watershed has been equipped with meteorological stations and instrumentation in order to monitor hydrometrical heights and river discharge. Components of the hydrological balance are studied since 1994 in forest structures characterized by different thinning regimes. Since 1999, the effect of different fire types on soil erosion and hydrology is also studied. The flux stations have been established in 2003 over 35 years-old pine plantation (1,175 m.a.s.l.) with 637 trees ha−1. Mean diameter and height are 29.3 cm and 20 m, respectively, with a basal area of 45.4 m2 ha−1. In 2006, all sided Leaf Area Index (LAI) was 6.55 ± 0.18. Substrate is granite and soils are Ultic Haploxeralfs.
2.2.4 Borgo Cioffi (IT-BCi)
The Borgo Cioffi monitoring site has been running since July 2002 on a arable field located on Gaetano Iemma’s farm (Eboli, Salerno, 40.52375° N; 14.95744° E), covering a total area of 150 ha in the centre of the Sele river Plain, an alluvial plain featuring an intensive and high income agricultural activity. The station is located about 20 m.a.s.l., which can be found south-west at a distance of about 5 km. The 16 ha field, in which all the experimental activities are carried out, is surrounded by irrigated land, has no aerodynamic obstacles in the vicinity of the boundaries able to influence the vertical profiles of atmospheric properties and it is irrigated by means of an automatic central pivot system.
The farm hosts a water buffalo operation with over 800 adult cattle, and the fields have been cultivated for decades to forage crops (alfalfa, winter and spring grass, corn silage) and winter vegetables (fennel, cauliflower). Solid and liquid manure are frequently applied at high rates.
The station is located approximately in the centre of the field, featuring an approximately rectangular shape with sides of 270 and 600 m. The fetch in the prevailing wind directions, south-west and north-east, is about 200 m. The slope is almost flat with a 2 % downward gradient towards the south.
The soil, classified as a Calcic Kastanozem Skeletic (FAO 2008) and derived from calcium carbonate parent rock, boasts an alluvial origin and features a silt-clay texture.
2.2.5 Castellaro (IT-Cas)
The site is located in Lomellina, a typical rural area of the Po Valley in Northern Italy, in the municipality of Torre Beretti and Castellaro (Pavia) (45.07005° N; 8.71752° E, 88 m.a.s.l.). The field extends for 400 × 700 m and it has been cultivated with hybrid corn (Zea mais L., variety pioneer for silage production) in 2006 and with rice from 2007 to 2010. The rice cultivar was Balilla (japonica rice short grain), a typical management cycle starts with 25 cm deep ploughing in January, laser soil leveling in February, in March sugar beet industrial slops (2,250 kg ha−1) and urea (75 kg ha−1) are incorporated and compacted before sowing in April into water with 210 kg ha−1 of seed. Weed control in May, top dressing with Urea (90 kg ha−1) in June. The average depth of standing water was maintained at about 5 cm in 2007 and 10 cm in 2008. The standing water level fluctuates during the flooded periods due to the continuous water flow through the rice field, a typical management practice for this crop. At the beginning of September the water is removed from the field and the harvest takes place in October. The final rice production was about 9 tree ha−1. The soil originating from fluvial deposits is poorly drained and characterized by a ground water table very close to the surface. In most parts of the field it is a Calcic Gleysol (FAO 2008), with a loam to clay-loam texture, in other parts of the field we find Haplic and Mollic Gleysols. The A-horizon shows pH (H2O) values ranging at 6.4–7.1, the organic carbon content is between 1.6 and 2.4 %. The gleyic color pattern of soil materials indicates dominant water saturation for most of the year in combination with poor drainage due to cultivation tillage and agricultural practices. During the observation period the average annual rainfall was 704 mm while the average annual temperature was 13.0 °C.
2.2.6 Castelvetrano (IT-Ctv)
The site is an olive orchard (cv. Nocellara del Belice) located in western Sicily at Castelvetrano (37.64416° N; 12.84638° E). The orchard has an extension of about 11 ha and has four different plots characterized by trees of different age (75 % 12–16 years old, 25 % 150 years old) but similar LAI (2.6–3.4) and trees height (3.4–3.7 m).
The soil texture is clay-loam with a volumetric water content at a field capacity of 36.1 and 17.4 % at −1.5 MPa soil water potential.
All of the plots were equipped with an irrigation system characterized by two micro sprinklers (8 liters hour-1) per tree. During the vegetative season, the total volume of water varied between 1,500 and 2,000 m3 ha depending on summer weather conditions. In accordance with the cultural practice adopted in this traditional olive-growing area, soil is clean cultivated during the vegetative season, whereas no weed control is undertaken during the rain season (autumn and winter).
The adopted tillage in the soil during the year allowed the growth of spontaneous annual herbaceous crops, characterized by the prevailing presence of grass (Graminaceae spp).
2.2.7 Castelporziano (IT-Cpz)
The experimental site was a 60 years-old coppice under conversion to high forest, inside the Presidential Reserve of Castelporziano (41.70525° N; 12.37611° E), 2.8 m.a.s.l., 25 km West of Rome. The natural Reserve covers about 4,800 ha, of which 85.6 % are forests. The climate is Mediterranean Type humid sub humid with an average yearly rainfall of 780 mm and an air temperature of 15.6 °C.
The forest structure is characterized by two layers: a dominant layer of Quercus ilex L. 12–15 m high and a shrub layer, 2–4 m high, with Phillirea latifolia L. Pistacia lentiscus L., Erica arborea L., Cistus salvifolius L.,Cistus incanus L., Cytisus scoparius L., and some vines (Clematis flammula L., Hedera helix L., Rubia peregrina L., Smilax aspera L.). Large trees over 100 years old, and up to 17 m high and 170 cm in diameter, represent only 1 % of the stand. LAI is in between 3.2 and 3.8. The herbaceous layers are represented by Brachipodium sylvaticum (Hudson) Beav., Cyclamen repandum Sibth et Sm., Carex distachya Desf., Asperula laevigata L., and Alliaria petiolata Bieb. The current Q. ilex forest represent a secondary succession after a fire destroyed the area in 1944. In 1985 the stand was converted from coppice into high forest.
The morphology of the reserve is mostly flat with altitudes ranging between 0 and 85 m.a.s.l. The soil is 40–60 cm deep with a pH 5.8 and the profile of the experiment is type A–C, with a fairly deep, well draining A horizon, rich in humus and calcium carbonate. The soil is sandy (75.2 % coarse sand, 11.2 % fine sand, 3.7 % coarse silt, 2.2 % fine silt, and 6.7 % clay). The soil organic matter is 3.4 % between 0 and 20 cm and 1.1 % between 20 and 40 cm. Organic carbon is 1.9 % in the organic horizon with a C/N ratio of 66 and is 0.65 % with a C/N ratio of 100 in other mineral Horizons.
The climate is characterized by a dry season extending for 4 months, from the beginning of May to the end of August. Water deficit during the dry seasons is 406 mm, while excess rainfall in other seasons is 410 mm. The scattered low summer rains are offset by high night humidity, which over a period of 10–15 days can contribute to 0.2–0.8 mm of precipitation.
2.2.8 Collelongo (IT-Col)
The experimental site is located near the village of Collelongo, Abruzzo region, in central Italy, close to the external belt of the Abruzzo, Lazio and Molise National Park. The Selva Piana forest stand (41.84936° N; 13.58814° E, 1,560 m.a.s.l.) belongs to a 3,000 ha forest community which is part of a wider forest area. The environmental and structural conditions of the stand are representative of central Apennines beech forests. The site was established in 1991 to study ecology and silviculture of Apenninian beech (Fagus sylvatica L.) forest. In 1993, the site was the first European forest to be instrumented to measure ecosystem level fluxes with Eddy Covariance (Valentini et al. 1996). In 1995–1996, the area became an ICP-Forests level II and an ICP-IM monitoring plot (icp-forests.net/). Since 2006, the site has become one of the main stations of the Long-Term Ecological Research site “Forests of the Apennine”. Over the years, the site was included in several EU and national research, monitoring and environmental projects. It is a pure beech forest with 830 trees ha−1, with an average diameter of 22 cm and an average height of 21.5 m. The average tree age is approximately 120 years (2011). LAI ranges between 4.5 and 6.2 (1992–2011). Aboveground and belowground biomass is 171 Mg C ha−1. The 40–100 cm deep soil is developed on calcareous bedrocks and is classified as humic alisol. Mineral soil carbon stock (0–80 cm) is 223 Mg C ha−1, with 4.4 Mg C ha−1 stocked as litter (OL layer). The climate at the site is Mountain-Mediterranean with an average annual temperature of 6.9 °C and an average annual precipitation of 1,230 mm. Snow cover can last from mid December to mid March–early April.
2.2.9 La Mandria (IT-LMa)
The tower site (45.15258° N; 7.58259° E) is included into La Mandria regional park which has an extension of 3,000 ha and is located in the suburbs of Turin, near Venaria Reale, at about 350 m.a.s.l. The area is typical for peculiar geomorphic features originated by the presence of old terraces, residual of the ancient level of the main plain, which forms a hilly landscape with highlands and valleys, connected by steep slopes and characterized by regressive erosion of small rivers.
Vegetation is mainly constituted by the oak-hornbeam (Quercus robur L. and Carpinus betulus L.) of the high plains, which is considered an important forest-type to be studied and conserved. In the park there are also some plantations of red oaks (Quercus rubra L.), which cover around 20 % of the woods, some Robinia psuedoacacia formation on the slopes, some grasslands and poplar formations on the plains. Age of the oak-trees is about 80 years in average but an increase of trees mortality is registered along with wildlife high pressure which stops plant regeneration.
The soil on the top of the terraces is mainly ‘paleosols’, which according to the USDA classification are called Typic Fragiudalf, fine-silty, mixed, acid, mesic. One of the main features of the soil profile is connected to a temporary groundwater, placed at 60–70 cm below the ground level and a top-layer rich of silt, above a sub-layer called ‘fragipan’ which is very hard to root penetration. Therefore trees tend to stay with their root-apparatus within the upper part of the soil profile, often increasing the chances of tipping. Moreover, the greatest percentage of biological activity is detected in the topsoil, due to the difficulties of organic matter to deepen below the ground water zone.
Climate is classified as humid (second mesothermic with a low summer efficiency) with an annual rainfall of 1,030 mm and an annual temperature of 11.6 °C. The stand in the surrounding area of the flux tower has a measured biomass of 14 kg m-2, a leaf litter of 1.4 kg m-2 and a tree density of 311 ha.
2.2.10 Lavarone (IT-Lav)
The Lavarone station is situated in the south east of the Trento province (45.95620° N; 11.28132° E; 1,300 m.a.s.l., average annual temperature 7.2 °C, total annual precipitation 1,150 mm) on a mountain plateau ranging from 1,000 to 2,000 m.a.s.l. The whole study area covers nearly 80 km2. This composite landscape is still widespread in the southern Alps, although it is undergoing a rapid transformation because of the combined effect of land use intensification in some more productive areas and the abandonment of more marginal ones. The landscape is characterized by the spatial succession of the three typical mountain management systems: grasslands (Arrenatheretum), pastures (Festucaetum) and mixed coniferous and broadleaf forests (Abietis-fagetum). The area analysed is characterized by an uneven-aged mixed forest dominated by Abies alba Mill. (70 %), Fagus sylvatica L. (15 %) and Picea abies (L.) H.Karst (15 %), with an average of 1,300 stems ha−1 (dbh > 7.5 cm) and a LAI of 9.6. The canopy has a dominant layer reaching 33–38 m and crown lower limits at about 12 m. In the understorey suppressed beeches form a discontinuous second layer from 0 to 4 m. The site is located on a gently rolling karst plateau and has a homogeneous vegetated fetch larger than 1 km in all directions, except for a 45° sector (300 m fetch in the SSW direction). Soils are generally well developed brown earth lying on a calcareous bedrock with the following characteristics in the 0–30 cm horizon: total SOC = 11.8 ± 1.8 kg C m−2, total N = 0.61 ± 0.05 kg N m−2, CN ratio = 15.9 ± 1.0.
2.2.11 Lecceto (IT-Lec)
Lecceto forest (43.30359° N; 11.26975° E) is a Holm oak coppice with a shift of 18–20 years located South-East of Siena, near the centre of the region of Tuscany, at about 300 m.a.s.l. It is the residual part of a broader forest named Selva del Lago for its proximity, during the Middle Ages, to a marshy area, subsequently drained in the XVIII century. That forest covered a surface of 10 km from north to south and 7 km from east to west. Because of the large use of wood during the Middle Ages, the Selva del Lago forest was subjected to specific rules of management and became a crucial crossroad between surrounding rural communities. In the XI century the most important Augustinian hermitage of Siena territory was founded in the middle of the forest. Since 1972 the hermitage was turned into a monastery of Augustinian cloistered nuns.
The forest covers an area of 900 ha and Holm oak represents 81 % of the total tree canopy; others species are represented by Arbutus unedo L., Juniperus communis L., Quercus pubescens L., Phillyrea latifolia L., Fraxinus ornus L.
The soil of the site is rocky and shallow, characterized by metamorphic schists and anagenite, and secondarily by cavernous limestone and carsism phenomena. The climate of Lecceto is a Mediterranean one, characterized by a strong seasonality with rainfall concentrated in autumn-winter, high inter-annual variability and frequent extreme events, such as summer drought and heatwaves. The average cumulated annual precipitation (1961–1990) at the nearest rain gauge is 780 mm, with a minimum in July (29 mm) and a maximum in November (108.7 mm); average annual temperature is 13.5 °C; July is the hottest month and January the coldest.
The stand in the surrounding area of the flux tower was coppiced about 15 years ago; its average stand height is around 9 m and the density of the stumps is about 1,200 ha−1.
2.2.12 Malga Arpaco (IT-Mal)
Tesino Upland is located in the eastern part of Valsugana, in the southern part of external Dolomites; its Northern border is marked by the Lagorai mountains (2,700 m). The study site is located on a farm (Malga Arpaco) at 1,730 m.a.s.l. (46.11402° N; 11.70334° E), near Passo Brocon, it is a seasonality pasture (alpeggio) with pasture times from the beginnings of June to the end of August (around 100 days). The climate in the southern part of Dolomites is influenced by the Adriatic sea, while in the northen part it is more continental; the annual rainfall is about 1,100–1,550 mm concentrated in spring (May–June) and in autumn (October–November); the average temperature is lower than 0 °C from December to March.
The examined pasture is in the inferior alpine horizon. This vegetation layer is the upper limit of the microtherrmal Fagus forest and it may be constituted by Picea in the lower part and by Larix in the higher part. In this area, human activity changed the original vegetation to pastures and grasslands by cutting the forests, while in other sites the alpine pastures are typically above the upper tree vegetation line. The soil is an alfisol, sandy-loam and a Typic Hapludalfs (FAO 2008).
The Malga Arpaco pasture results to be sufficiently used, without bushes, pasturing paths, erosion; yet, the negative effects of understocking begin to appear, as evidenced by the existence of some limited overpastured areas surrounded by Deschampsia spp. and Cirsium spp.
From the floristic survey the grassland resulted to be composed predominantly by good fodder Poaceae (genera Festuca, Poa, Phleum), reduced by pasturing in summer; yet, the area shows, at least in some parts, the specific composition of a mid-damp and degraded grassland, with nitrophilous species, and the signs of a strong use, in transition from a grassland to an unrationally grazed pasture.
2.2.13 Monte Bondone (IT-MBo)
The study site was located at 1,550 m.a.s.l. on a mountain plateau in the Italian Alps (Viote del Monte Bondone, 46.01468° N; 11.04583° E). The average annual air temperature is 5.5 °C with monthly averages ranging from −2.7 °C in January to 14.4 °C in July. The average annual rainfall is 1,189 mm, with peaks in June (132 mm) and October (142 mm); snow cover occurs between November and April. The area is managed as an extensive meadow dominated by Festuca rubra L. (basal cover of 25 %), Nardus stricta L. (basal cover of 13 %) and Trifolium sp. (basal cover of 14.5 %), which represents a typical low productivity meadow of the alpine region. The maximum canopy height at the peak of the growing season (mid June to early July) can reach up to 30 cm. Meadows represent the main land use on this plateau (2 km2) and are traditionally managed for hay production with low mineral fertilization and one cut per year in mid-July. Soil can be classified as a Typic Hapludalfs, lyme loamy, mixed, mesic with the following characteristics in the 0–30 cm horizon: total SOC = 9.4 ± 0.4 kg C m−2, total N = 0.29 ± 0.02 kg N m−2, soil bulk density = 0.79 ± 0.29 g cm−3.
2.2.14 Negrisia (IT-Neg)
The site is located in North-Eastern Italy in a commercial vineyard located in Negrisia di Ponte di Piave (45.74756° N; 12.44673° E, 11 m.a.s.l.). The climate is mediterranean, with average annual precipitations of 833 mm and an average annual temperature of 13.1 °C. The station, set up in July 2005, is in the center of a one single 25 ha plot. The terrain is quite flat and both soil and canopy are very homogeneous and thus suitable for both micrometeorological and remote-sensing approaches. The vineyard is mainly composed of Vitis vinifera L. cv.‘Carmenère N.’ grafted on SO4 rootstock. The vines were planted in 1992 in north–south oriented rows (500–600 m long) 2.50 m apart. Plant spacing on the rows is 1.30 m, resulting in a density of 3,076 vines per hectare. Vines were grown with a single trunk trained to spur-pruned cordon, at about 1.7 m aboveground, for vertical shaker harvesting. The floor is grass covered and a 1 m wide strip on the rows is chemically treated. The silty-clay loam soil (International textural classes), classified as Vertic Eutrudent (FAO 2008), is >1 m deep and highly homogeneous within the study site, rich in organic matter (about 18.2 g kg−1) and with an average pH of 7.7. The vineyard receives standard management. Maximum canopy height was kept at 2.70 m, and no foliage could be found below the cordon. Maximum LAI, monitored both by direct and by indirect methods, ranges from 2.2 to 2.5.
2.2.15 Noè (IT-Noe)
The Noè site is located within a nature reserve called “Le Prigionette” (40.60613° N; 8.15146° E, 27 m.a.s.l.). The area is part of the Capo Caccia peninsula, in North-Western Sardinia, near the town of Alghero. The nature reserve, with a surface area of approximately 1,200 ha, is delimited by a cliff dropping to the sea on the north-western and western boundaries.
The climate is Mediterranean, semiarid with a warm summer, mild winter, and a prolonged water shortage from May through September. The averages for annual, minimum and maximum temperatures are respectively 15.9, 7.0, and 28.0 °C. The average annual thermal excursion is about 14 °C (10 °C in January and 24 °C in August). The average annual precipitation is 588 mm, mainly concentrated during the spring season. In the course of the autumn intense rainstorms often occur with high runoff and low water storage.
The main species are juniper (Juniperus phoenicea L.), lentisk (Pistacia lentiscus L.), tree phyllirea (Phyllirea angustifolia L.), and dwarf fan palm (Chamaerops humilis L.). These species form a sparsely vegetated shrub land, where juniper and lentisk, which respectively cover 53 and 22 % of the vegetated surface, are aggregated into variably-sized patches with bare ground in between. Phillyrea and palm can only be found as isolated elements inside the main patches. Other species typical of Mediterranean maquis are present on the experimental site: rosemary (Rosmarinus officinalis L.), Genista corsica (Loisel) DC., Daphne gnidium L., Smilax aspera L., Euphorbia characias L., Helichrysum microphyllum DC., Asphodelus microcarpus Salzm., and Ferula communis L. The vegetation is a secondary succession following a fire event occurred in 1963 and agricultural abandonment in 1970. Currently, this area has limited human activity. The average maquis height ranges between 0.93 and 1.43 m, and the ground cover varies between 42 and 91 %. Total LAI values range from 2.7 to 3.0. The soil is Lithic Xerorthent, 0.3–0.4 m deep, mainly composed of clay, and erosion is common.
2.2.16 Nonantola (IT-Non)
The Nonantola forest is a hardwood plantation located in a flat rural area of the Po valley in the Emilia Romagna region, close to Modena (44.69019° N; 11.09109° E 15 m.a.s.l.). The site was set up in 1992 with European fundings (Set-aside, Reg. CEE 797/85 and, being a re-forestation in a former rural area it is a proper representation of a Kyoto forest—Sect. 3.3 of the Kyoto Protocol). The forest is still growing and has not yet reached the final stage, its dominant species consisting of: Oak (Quercus robur L.) 35 %, Ash (Fraxinus spp.) 25 %, Maple (Acer campestre L.) 12 %, Willow (Salix alba L.) 8 %, Poplar (Populus alba L.) 6 %, Cerry (Prunus mahaleb L.), other 8 %. The total area is 38.6 ha with a tree density of 1,100 trees ha−1 at the plantation stage, and reduced to 826 trees ha−1 10 years after. The soil, by Soil USDA Taxonomy is Fine, Mixed, Mesic Entic Chromusterts with a 60 % of clay, and a soil organic matter (SOM) of 49.8 Mg C ha−1estimated in 1992 and 53.7 Mg C ha−1