PMS environmental impact

Great care was taken to reduce the impact on the vegetation when putting the device in place. No heavy machines were allowed on the experimental site and walking is only allowed on marked paths or the scaffolding.

Foundations are reduced to a minimum size of 0.8 m x 0.8 m x 0.8 m, and a plastic cover surrounds the foundation as to avoid exchanges of the concrete with the environment. The structure is made of steel and is protected with a water-based paint. The maximum spacing was approached for the crossbars in agreement with the specifications of the automatic covers. In the photomorphogenetic period of leaf development, rain exclusion is restricted to nighttime (<50 µmol quanta m-2 s-1, limit shown for Quercus robur foliage, IM Reiter pers. comm.) to avoid shading. However, some inevitable shading persists. The effect of the shading was integrated using an optical leaf area index measurement (LAI-2000, Li-Cor, NE, USA). The shading due to the structure is comparable to an additional leaf area above the canopy of 0.15 +- 0.02 m². This effect is considered to be negligible, seeing that light is not a very limiting factor in Mediterranean forests. No changes in the temperature profiles have become evident due to the installation of the PMS device.