Unchanged carbon balance driven by equivalent responses of production and respiration to climate change in a mixed‐grass prairie
Responses of grassland carbon (C) cycling to climate change and land use remain a major uncertainty in model prediction of future climate. To explore the impacts of global change on ecosystem C fluxes and the consequent changes in C storage, we have conducted a field experiment with warming (+3 °C),...
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Published in | Global change biology Vol. 22; no. 5; pp. 1857 - 1866 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
England
Blackwell Science
01.05.2016
Blackwell Publishing Ltd Wiley-Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | Responses of grassland carbon (C) cycling to climate change and land use remain a major uncertainty in model prediction of future climate. To explore the impacts of global change on ecosystem C fluxes and the consequent changes in C storage, we have conducted a field experiment with warming (+3 °C), altered precipitation (doubled and halved), and annual clipping at the end of growing seasons in a mixed‐grass prairie in Oklahoma, USA, from 2009 to 2013. Results showed that although ecosystem respiration (ER) and gross primary production (GPP) negatively responded to warming, net ecosystem exchange of CO₂ (NEE) did not significantly change under warming. Doubled precipitation stimulated and halved precipitation suppressed ER and GPP equivalently, with the net outcome being unchanged in NEE. These results indicate that warming and altered precipitation do not necessarily have profound impacts on ecosystem C storage. In addition, we found that clipping enhanced NEE due to a stronger positive response of GPP compared to ER, indicating that clipping could potentially be an effective land practice that could increase C storage. No significant interactions between warming, altered precipitation, and clipping were observed. Meanwhile, we found that belowground net primary production (BNPP) in general was sensitive to climate change and land use though no significant changes were found in NPP across treatments. Moreover, negative correlations of the ER/GPP ratio with soil temperature and moisture did not differ across treatments, highlighting the roles of abiotic factors in mediating ecosystem C fluxes in this grassland. Importantly, our results suggest that belowground C cycling (e.g., BNPP) could respond to climate change with no alterations in ecosystem C storage in the same period. |
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Bibliography: | http://dx.doi.org/10.1111/gcb.13192 Jiangsu Specially-Appointed Professors Program istex:A7FB49B5CF768164D761B888B5881516BC352C7B National Science Foundation (NSF) - No. DEB 0743778 Office of Science (BER), Department of Energy - No. DE-SC0004601 Priority Academic Program Development of Jiangsu Higher Education Institutions ark:/67375/WNG-JH5DG24X-W ArticleID:GCB13192 Figure S1. Seasonal dynamics of soil temperature (Tsoil) in unclipped subplots (a) and clipped subplots (b) across the years. Figure S2. Effects of warming (a), altered precipitation (b), and clipping (c) on seasonal dynamics of soil moisture. Figure S3. Effects of clipping on seasonal dynamics of ER (a), GPP (b), and NEE (c). Figure S4. Response ratios of carbon (C) fluxes associated with warming (a, d, g), altered precipitation (b, e, h), and clipping (c, f, i). Values are average ratios of each year of the C fluxes between warmed and unwarmed (a, d, g), between doubled (black) or halved (grey) precipitation and ambient precipitation (b, e, h), and between clipped and unclipped (c, f, i). High ratios of ER (c) and GPP (f) in 2009 resulted probably because measurements began in August 2009 and clipping significantly increased photosynthesis and respiration of the winter annuals. ER, ecosystem respiration; GPP, gross primary production. Table S1. Relationships of ER/GPP with soil temperature and moisture across treatments. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 USDOE |
ISSN: | 1354-1013 1365-2486 |
DOI: | 10.1111/gcb.13192 |