Potential for a CO(sub 2) fertilization effect in forest trees: An assessment of 58 controlled-exposure studies and estimates of the biotic growth factor.

摘要

Characterizing the response of terrestrial ecosystems to increasing concentrations of atmospheric CO(sub 2) and estimating their biological capacity to either moderate or accelerate predicted changes in the earth's climate, continues to present a formidable challenge to experimentalist and modelers alike. Nevertheless, it is generally recognized that the carbon dynamics of terrestrial vegetation represent an important biospheric feedback to increasing CO(sub 2) concentrations, and hence to global warming, and as such there exists little debate that ecosystems occupy a.potentially pivotal role in determining both the direction and rate of future changes in atmospheric CO(sub 2) concentration. What is currently the subject of much debate, however, is whether terrestrial ecosystems will contribute to global warming by releasing additional CO(sub 2) the atmosphere as a result of increasing respiration and/or decomposition in a warming climate, or whether they will instead sequester additional carbon in response to the enhancing effects of atmospheric CO(sub 2) on plant growth. This latter response, the so-called CO(sub 2) fertilization effect, has been hypothesized as an important negative feedback to global warming, offering the potential to constrain future increases in atmospheric CO(sub 2) concentration, and has often been invoked to either partially or wholly account for the estimated 1.6 Gt C/year imbalance or ''missing sink'' in calculations of the global carbon budget.