Anthropogenic emissions have caused a 30% increase in atmospheric CO2 concentrations since the beginning of the industrial revolution. It is becoming clear that the terrestrial biosphere plays an important role in regulating atmospheric CO2 concentration (Woodward, 2002), and that the continued increases in atmospheric CO2 concentrations may directly affect growth, transpiration and the production of secondary metabolites of terrestrial ecosystems. Mediterraneantype ecosystems are predicted to be especially sensitive to increasing CO2 and global climate change (Strain & Bazzaz, 1983; Oechel et al., 1995) but their response remains largely unexplored. In particular, the role of rising CO2 in the emission of biogenic volatile organic compounds (BVOC), such as isoprene and monoterpenes, is a subject of active debate since the production of these trace gases by the vegetation is of importance for local and regional tropospheric ozone pollution, and yields relatively nonvolatile secondary oxidant products that form aerosols (Griffin et al., 1999; Pio et al., 2001). Here we evaluate, in situ, the CO2 response of a regenerating chaparral ecosystem exposed to CO2 concentrations ranging from preindustrial to 750 ìmol mol.1 for an extended period of time. This ecosystem is dominated by the resprouting shrub species Adenostoma fasciculatum, the most common species of the southern California chaparral, and the obligate seeder, Ceanothus greggii, a nitrogen fixer. The approach used in these experiments provided an efficient system to assess the effects of rising atmospheric CO2 on natural Mediterranean ecosystems both in terms of carbon uptake and the emission of volatile organic compounds.
Monoterpene emission responses to elevated CO2 in a Mediterranean-type ecosystem
2004
Abstract
Anthropogenic emissions have caused a 30% increase in atmospheric CO2 concentrations since the beginning of the industrial revolution. It is becoming clear that the terrestrial biosphere plays an important role in regulating atmospheric CO2 concentration (Woodward, 2002), and that the continued increases in atmospheric CO2 concentrations may directly affect growth, transpiration and the production of secondary metabolites of terrestrial ecosystems. Mediterraneantype ecosystems are predicted to be especially sensitive to increasing CO2 and global climate change (Strain & Bazzaz, 1983; Oechel et al., 1995) but their response remains largely unexplored. In particular, the role of rising CO2 in the emission of biogenic volatile organic compounds (BVOC), such as isoprene and monoterpenes, is a subject of active debate since the production of these trace gases by the vegetation is of importance for local and regional tropospheric ozone pollution, and yields relatively nonvolatile secondary oxidant products that form aerosols (Griffin et al., 1999; Pio et al., 2001). Here we evaluate, in situ, the CO2 response of a regenerating chaparral ecosystem exposed to CO2 concentrations ranging from preindustrial to 750 ìmol mol.1 for an extended period of time. This ecosystem is dominated by the resprouting shrub species Adenostoma fasciculatum, the most common species of the southern California chaparral, and the obligate seeder, Ceanothus greggii, a nitrogen fixer. The approach used in these experiments provided an efficient system to assess the effects of rising atmospheric CO2 on natural Mediterranean ecosystems both in terms of carbon uptake and the emission of volatile organic compounds.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
