intro - Precipitation Management System

The O3HP is a field site dedicated as to gain fundamental knowledge about the functioning  of a Downy Oak forest ecosystem. Special emphasis is put on the investigation of effects related to climate change. Hence, the field site is equipped with a precipitation management system (PMS) to simulate drier climate.

A device is installed above 300 m² of canopy, that dynamically excludes a defined fraction of precipitation (rain & hail) by extending automated covers, and which allows to re-irrigate part of the excluded water. The system manages a reduction in precipitation by 40 % using temperature derived functions based on 50 year records of local meteorological data. This results in a scenario of 500 mm annual precipitation corresponding to about 2°C temperature increase, which is in line with climate predictions for the Mediterranean region (Giorni & Mearns, 2002). The reduction is piloted dynamically between 20% and 60% for year 2100 in relation to year 2000. Therein lays the originality of the system, whilst environmental conditions are hardly affected. During leaf development in spring, exclusion of precipitation events is performed at night-time as not to disturb photomorphogenesis. Intercepted precipitation will be evacuated to a temporary reservoir. An irrigation (sprinkler) system attached to the metal structure will use this water to fine-tune the fraction of excluded precipitation.