title: Unchanged carbon balance driven by equivalent responses of production and respiration to climate change in a mixed-grass prairie.
abstract: 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.
authors.affiliation: Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, Jiangsu Province, 210037, China.|Department of Microbiology & Plant Biology, University of Oklahoma, 101 David L. Boren Blvd., Norman, OK, 73019, USA.
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Microbiology & Plant Biology, University of Oklahoma, 101 David L. Boren Blvd., Norman, OK, 73019, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Microbiology & Plant Biology, University of Oklahoma, 101 David L. Boren Blvd., Norman, OK, 73019, USA.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Geography, University of California, Santa Barbara, CA, 93106, USA.
authors.forename: Yang
authors.identifier: http://orcid.org/0000-0001-7923-0789
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Shuli
authors.initials: S
authors.lastname: Niu
authors.affiliation: Department of Microbiology & Plant Biology, University of Oklahoma, 101 David L. Boren Blvd., Norman, OK, 73019, USA.
authors.forename: Lifen
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Forestry Intelligent Monitoring and Information Technology Research of Zhejiang Province, Zhejiang A&F University, Lin'an, Zhejiang, 311300, China.
authors.forename: Ruiseng
authors.initials: R
authors.lastname: Luo
authors.affiliation: Department of Microbiology & Plant Biology, University of Oklahoma, 101 David L. Boren Blvd., Norman, OK, 73019, USA.
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Luo
mesh_terms: D057486:Carbon Cycle; D057231:Climate Change; D057232:Global Warming; D065948:Grassland; D060434:Herbivory; D009825:Oklahoma; D011891:Rain
keywords: altered precipitation; clipping; ecosystem respiration; grasslands; gross primary production; net ecosystem exchange; net primary production; warming