NATURAL CO2 SPRINGS IN ITALY - A RESOURCE FOR EXAMINING LONG-TERM RESPONSE OF VEGETATION TO RISING ATMOSPHERIC CO2 CONCENTRATIONS

It is estimated that more than 100 geothermal CO2 springs exist in central-western Italy. Eight springs were selected in which the atmospheric CO2 concentrations were consistently observed to be above the current atmospheric average of 354 mumol mol-1. CO2 concentration measurements at some of the springs are reported. The springs are described, and their major topographic and vegetational features are reported. Preliminary observations made on natural vegetation growing around the gas vents are then illustrated. An azonal pattern of vegetation distribution occurs around every CO2 spring regardless of soil type and phytoclimatic areas. This is composed of pioneer populations of a Northern Eurasiatic species (Agrostis canina L.) which is often associated with Scirpus lacustris L. The potential of these sites for studying the long-term response of vegetation to rising atmospheric CO2 concentrations is discussed.