Tognetti R, Longobucco A, Raschi A
Abstract: The Mediterranean region is characterized by hot, dry summers which alternate with cool, humid periods. Mediterranean-type ecosystems are expected to exhibit large responses to increasing atmospheric CO2 concentrations ([CO2]), since the system is extremely sensitive to changes in summer drought. There is, however, uncertainty associated with the lack of long-term experiments in representative Mediterranean natural ecosystems. Natural CO2 springs, continuously exposing the surrounding vegetation to elevated [CO2], constitute one approach to long-term elevated [CO2] experiments. This analogy, though CO2 springs lack controlled manipulations, may provide information concerning plant responses to elevated [CO2] which is otherwise unobtainable. In this work, variations in several water relation parameters of Mediterranean species were analyzed under field conditions by comparing plants at two locations in a Mediterranean environment during twelve months. A distinct environmental gradient exists between the two sites with higher [CO2] in the proximity of a natural CO2 spring. Segregation by species in seasonal relations suggests that the coexistence of these species in the same environment with similar water availability is partially based on differential strategies for water relations and water use patterns. Considerable between-species variation in the studied characters to elevated [CO2] were observed. Elevated [CO2] effects on water relations persist in the long-term, but the three shrubs growing in the same environment show species-specific responses. Differential responses of species provide the mechanism for changing competitive interactions among plant species, in the perspective of climate change on a larger scale.
Citazione: Tognetti R, Longobucco A, Raschi A (1999). The impact of long-term elevated CO2 concentrations on field water relations of selected plants in a Mediterranean-type ecosystem . 2° Congresso Nazionale SISEF, Bologna, 20 – 22 Ott 1999, Contributo no. #c2.6.43