In:
Global Change Biology, Wiley, Vol. 4, No. 5 ( 1998-06), p. 539-547
Abstract:
The effects of elevated CO 2 on tropical ecosystems were studied in the artificial rain forest mesocosm at Biosphere 2, a large‐scale and ecologically diverse experimental facility located in Oracle, Arizona. The ecosystem responses were assessed by comparing the whole‐system net gas exchange (NEE) upon changing CO 2 levels from 900 to 450 ppmV. The day‐NEE was significantly higher in the elevated CO 2 treatment. In both experiments, the NEE rates were similar to values observed in natural analogue systems. Variations in night‐NEE, reflecting both soil CO 2 efflux and plants respiration, covaried with temperature but showed no clear correlation with atmospheric CO 2 levels. After correcting for changes in CO 2 efflux we show that the rain forest net photosynthesis increased in response to increasing atmospheric CO 2 . The photosynthetic enhancement was expressed in higher quantum yields, maximum assimilation rates and radiation use efficiency. The results suggest that photosynthesis in large tropical trees is CO 2 sensitive, at least following short exposures of days to weeks. Taken at face value, the data suggest that as a result of anthropogenic emissions of CO 2 , tropical rain forests may shift out of steady state, and become a carbon sink at least for short periods. However, a better understanding of the unique conditions and phenomena in Biosphere 2 is necessary before these results are broadly useful.
Type of Medium:
Online Resource
ISSN:
1354-1013
,
1365-2486
DOI:
10.1046/j.1365-2486.1998.t01-1-00178.x
Language:
English
Publisher:
Wiley
Publication Date:
1998
detail.hit.zdb_id:
2020313-5
SSG:
12
