Direct and indirect effects of elevated atmospheric CO2 on net ecosystem production in a Chesapeake Bay tidal wetland. (11th September 2013)

• Record Type: Journal Article
• Authors: Erickson, John E.; Peresta, Gary; Montovan, Kathryn J.; Drake, Bert G.
• Is Part Of: Global change biology. Volume 19:Number 11(2013:Nov.)
• Page Start: 3368
• Page End: 3378
• Publication Date: 2013-09-11
• Subjects: Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.12316
• Languages: English
• ISSNs: 1354-1013

Abstract

<abstract abstract-type="main" id="gcb12316-abs-0001"> <title>Abstract</title> <p>The rapid increase in atmospheric CO<sub>2</sub> concentrations (<italic>C</italic><sub>a</sub>) has resulted in extensive research efforts to understand its impact on terrestrial ecosystems, especially carbon balance. Despite these efforts, there are relatively few data comparing net ecosystem exchange of CO<sub>2</sub> between the atmosphere and the biosphere (NEE), under both ambient and elevated <italic>C</italic><sub>a</sub>. Here we report data on annual sums of CO<sub>2</sub> (NEE<sub>net</sub>) for 19 years on a Chesapeake Bay tidal wetland for <italic>Scirpus olneyi</italic> (C<sub>3</sub> photosynthetic pathway)‐ and <italic>Spartina patens</italic> (C<sub>4</sub> photosynthetic pathway)‐dominated high marsh communities exposed to ambient and elevated <italic>C</italic><sub>a</sub> (ambient + 340 ppm). Our objectives were to (i) quantify effects of elevated <italic>C</italic><sub>a</sub> on seasonally integrated CO<sub>2</sub> assimilation (NEE<sub>net</sub> = NEE<sub>day</sub> + NEE<sub>night</sub>, kg C m<sup>−2</sup> y<sup>−1</sup>) for the two communities; and (ii) quantify effects of altered canopy N content on ecosystem photosynthesis and respiration. Across all years, NEE<sub>net</sub> averaged 1.9 kg m<sup>−2</sup> y<sup>−1</sup> in ambient <italic>C</italic><sub>a</sub> and 2.5 kg m<sup>−2</sup> y<sup>−1</sup> in elevated <italic>C</italic><sub>a</sub>, for the C<sub>3</sub>‐dominated community. Similarly, elevated <italic>C</italic><sub>a</sub> significantly (<italic>P</italic> < 0.01) increased carbon uptake in the C<sub>4</sub>‐dominated community, as NEE<sub>net</sub> averaged 1.5 kg m<sup>−2</sup> y<sup>−1</sup> in ambient <italic>C</italic><sub>a</sub> and 1.7 kg m<sup>−2</sup> y<sup>−1</sup> in elevated <italic>C</italic><sub>a</sub>. This resulted in an average CO<sub>2</sub> stimulation of 32% and 13% of seasonally integrated NEE<sub>net</sub> for the C<sub>3</sub>‐ and C<sub>4</sub>‐dominated communities, respectively. Increased NEE<sub>day</sub> was correlated with increased efficiencies of light and nitrogen use for net carbon assimilation under elevated <italic>C</italic><sub>a</sub>, while decreased NEE<sub>night</sub> was associated with lower canopy nitrogen content. These results suggest that rising <italic>C</italic><sub>a</sub> may increase carbon assimilation in both C<sub>3</sub>‐ and C<sub>4</sub>‐dominated wetland communities. The challenge remains to identify the fate of the assimilated carbon.</p> </abstract>