Using Catchments of Contrasting Hydrological Conditions to Explore Climate Change Effects on Water and Nutrient Flows in Mediterranean Forests

Increased CO2 concentrations can affect ecosystems directly through effects on the plant photosynthetic system, and indirectly through the induced climatic change. Plants respond to a CO2-enriched atmosphere by enhancing photosynthesis, reducing stomatal conductance and transpiration, and consequently increasing their water use efficiency (Eamus and Jarvis, 1989; Bazzaz, 1990). Nevertheless, very few experiments have been carried out in natural ecosystems under field conditions: only four experiments were initiated by February 1992, all with low-height vegetation (Strain and Thomas, 1992).