A project under the auspices of the International Geosphere Biosphere Program (IGBP), Biospheric Aspects of the Hydrological Cycle (BAHC), assessed the need of monitoring seasonal and spatial water vapor and energy fluxes over natural vegetation. Based on a review of the literature, a lack of significant representation of the Mediterranean region ecosystems is evident. Although they are an important component of the landscape, Mediterranean maquis areas were scarcely represented. The small size of most Mediterranean maquis ecosystem makes them especially vulnerable to disturbance brought about by climate change. Its inherent fragility and geographic characteristics cause major impact of global change as a consequence of extreme events, especially for a possible reduction in rainfall, which could lead to vegetation reduction, soil erosion, and land degradation.
Field experiments were conducted to describe the interactions between the soil-vegetation system and atmosphere in a Mediterranean maquis ecosystem. The experimental site is located within the natural reserve ‘Noah’s Ark’ in North-West Sardinia, Italy. The site is one of more than 100 natural habitats selected in the framework of the European Union Directive, named HABITAT, on the conservation of natural habitats and of wild fauna and flora. In fact, it represents an outstanding example of one of the five European bio-geographical regions that scientific community and decision-makers decided would be preserved. Noah’s Ark site covers approximately 12 km^2 between a 300 m height wavecut cliff and a 360 m tall hill.
The objective of this research was to evaluate water and energy exchanges of a patchy coastal area representative of the Mediterranean maquis in relation to the surface boundary conditions (vegetation types, vegetation and leaf indexes, aerodynamic parameters, canopy radiation balance) and the atmospheric forcing.
Micrometeorological techniques were used for estimating hourly values of energy and mass fluxes and evaluate the energy budget closure. Radiation balance, PAR availability, albedo, and reflectance properties of the prevalent species were determined. Moreover, vegetation aerodynamic properties and turbulence analysis were studied with the final objective to describe and model exchange processes. Physiological and physical control of energy partitioning was studied at leaf, canopy and array level to perform a scaling process.