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Rising sea level, temperature, and precipitation impact plant and ecosystem responses to elevated CO 2 on a Chesapeake Bay wetland: review of a 28‐year study
Author(s) -
Drake Bert G.
Publication year - 2014
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12631
Subject(s) - scirpus , environmental science , ecosystem , wetland , primary production , biomass (ecology) , nitrogen cycle , ecology , agronomy , biology , nitrogen , chemistry , organic chemistry
An ongoing field study of the effects of elevated atmospheric CO 2 on a brackish wetland on Chesapeake Bay, started in 1987, is unique as the longest continually running investigation of the effects of elevated CO 2 on an ecosystem. Since the beginning of the study, atmospheric CO 2 increased 18%, sea level rose 20 cm, and growing season temperature varied with approximately the same range as predicted for global warming in the 21st century. This review looks back at this study for clues about how the effects of rising sea level, temperature, and precipitation interact with high atmospheric CO 2 to alter the physiology of C3 and C4 photosynthetic species, carbon assimilation, evapotranspiration, plant and ecosystem nitrogen, and distribution of plant communities in this brackish wetland. Rising sea level caused a shift to higher elevations in the S cirpus olneyi C3 populations on the wetland, displacing the S partina patens C4 populations. Elevated CO 2 stimulated carbon assimilation in the Scirpus C3 species measured by increased shoot and root density and biomass, net ecosystem production, dissolved organic and inorganic carbon, and methane production. But elevated CO 2 also decreased biomass of the grass, S . patens C4. The elevated CO 2 treatment reduced tissue nitrogen concentration in shoots, roots, and total canopy nitrogen, which was associated with reduced ecosystem respiration. Net ecosystem production was mediated by precipitation through soil salinity: high salinity reduced the CO 2 effect on net ecosystem production, which was zero in years of severe drought. The elevated CO 2 stimulation of shoot density in the Scirpus C3 species was sustained throughout the 28 years of the study. Results from this study suggest that rising CO 2 can add substantial amounts of carbon to ecosystems through stimulation of carbon assimilation, increased root exudates to supply nitrogen fixation, reduced dark respiration, and improved water and nitrogen use efficiency.