*2.1. Study Areas*

Four EC sites were used to assess the relationship between both ECI and WDI with ET. The Renon site [47–49] is located in the province of Bolzano/Bozen in the Alps, in the municipality of Renon/Ritten at an elevation of 1740 m asl. The EC tower is located in a *Picea abies*-dominated forest (around 85 %), but also including *Pinus cembra* L., (12%) and *Larix decidua* Mill., (3%). The forest canopy is irregular, with maximal height of around 30 m. The annual average temperature is around 4.6 °C, and the average annual precipitation is approximately 900 mm.

The Monte Bondone site [50] is located on a mountain plateau (called "Viote del Monte Bondone") near the city of Trento at 1550 m asl. The mean annual air temperature is 5.5 °C and the mean annual rainfall is 1190 mm. The site is managed as productivity-extensive meadow, typical of the alpine regions, characterized by the presence of *Festuca rubra* (basal cover of 25%), *Nardus stricta* (13%) and *Trifolium* sp. (14.5%).

The Lavarone EC tower [47] is situated near the town of Lavarone in the province of Trento at an elevation of around 1350 m asl. The tower is located in uneven-aged mixed forest dominated by *Abies alba* (around 70%), *Fagus sylvatica* (15%) and *Picea abies* (15%). The forest canopy reaches an elevation of approximately 35 m. The average annual precipitation is approximately 1290 mm and the mean annual temperature is around 7.8 °C.

Finally, the Bosco della Fontana site [51,52] is located near the city of Mantova (at an elevation of 19 m asl.) in the middle of the Po valley, within a forest nature reserve of around 235 ha. The wood canopy is 26 m high and dominated by *Carpinus betulus* L. and *Quercus robur* L. (57%), with a minor presence of *Acer campestre* L., *Prunus avium* L., *Fraxinus ornus* L. and *Ulmus minor* Mill., with *Alnus glutinosa* L. along the little rivers. The average annual precipitation is approximately 930 mm and the mean annual temperature is around 13.9 °C. The EC tower data are measured from a 42 m tall tower Figure 1.

**Figure 1.** Google Earth image with the location of the four study sites in Italy. (A) Renon (Fluxnet code: IT-Ren); (B) Monte Bondone (Fluxnet code: IT-MBo); (C) Lavarone (Fluxnet code: IT-La2); (D) Bosco della Fontana (ICOS code: IT-BFt). CRS map: WGS84 /UTM zone 32N.
