The Loobos site is located near Kootwijk (52?10?00? N - 5?44?38? O). The main tree species is Scots pine (Pinus silvestris). In all direc¬tions the forest extends for more than 1.5 km. The trees were planted around 1909 on sand dunes and are widely spaced with some open spots. In a radius of 500 m around the flux tower 89% of the area is covered with Scots pine, 3.3% with Corsican or black pine, 2.3% with birch, 1.3% with Douglas fir, 0.6% with oak and 3.5% of the area is open and mostly covered with heather and grass. The average tree height is 15.1 m. The undergrowth of the forest is a closed cover of mainly grass (Deschampsia). Because of the local topography caused by the sand dunes the distance to the ground water table depends on the location. At the base of the tower the ground water table is at a depth of ? 6.5 m below the surface.