Field study of the effects of elevated CO2 concentration on physiology an ecosystem processes in Chesapeake Bay Wetland. (Annual) progress report, 1989--1990.

摘要

Research during 1988--1989 focused on several new aspects of the response of the salt marsh ecosystem to elevated CO(sub 2) of the effect of CO(sub 2) on biomass production into above and belowground tissues, nitrogen content, light response of photosynthesis of single leaves, leaf water potential and carbon dioxide and water vapor exchange between the plant canopy and the ambient air. Result from the work in 87 and 88 had shown that the C(sub 3) plant, Scirpus olneyi, responded vigorously to elevated CO(sub 2) but the two C(sub 4) species, Spartina patens and Distichlis spicata did not. The responses of photosynthesis were also reflected in the canopy and ecosystem processes: Carbon accumulated in the C(sub 3) community into belowground tissues but not in the C(sub 4) community suggesting that the main factor in the ecosystem responses would be photosynthesis and that the environmental controls on this process would determine the long-term ecosystem responses to rising CO(sub 2). The main question at the outset of this project was: How much more carbon will be accumulated in the salt marsh ecosystem in a high CO(sub 2) atmosphere than is being accumulated under present CO(sub 2) concentration. This experiment has raised the possibility that rising CO(sub 2) will make the salt marsh ecosystem a bigger sink for carbon than we have previously thought it to be. By extrapolation, this finding suggests that other, terrestrial ecosystems may also become larger sinks for carbon.