Plant diurnal cycle drives the variation in soil respiration in a C 4 -dominated tropical managed grassland exposed to h
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Plant diurnal cycle drives the variation in soil respiration in a C4-dominated tropical managed grassland exposed to high CO2 and warming Eduardo Augusto Dias de Oliveira & Fernanda Tomita Manchon & Michael P. Ricketts & Matheus Bianconi & Carlos Alberto Martinez & Miquel A. Gonzalez-Meler
Received: 9 March 2020 / Accepted: 15 September 2020 # Springer Nature Switzerland AG 2020
Abstract Aims To identify factors driving soil respiration (Rsoil) in a tropical C4-dominated perennial managed grassland ecosystem exposed to elevated carbon (C) dioxide concentration ([CO2]) and temperature. Methods The perennial grass Panicum maximum was grown at 600 μmol CO2 mol−1 and + 2 °C above ambient temperatures for one full growing cycle (from grazing to regrowth for about ~30–45 days) using a free-air CO2 and infrared warming system. Plant growth and CO2 fluxes were measured during the growing cycle. Results Both high [CO2] and warming increased canopy photosynthesis but warming alone increased biomass by 53% and Rsoil by 26%. There was a strong diel effect Responsible Editor: Timothy J. Fahey. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11104-020-04718-7) contains supplementary material, which is available to authorized users. E. A. Dias de Oliveira (*) : M. P. Ricketts : M. A. Gonzalez-Meler Ecology and Evolution, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA e-mail: [email protected] F. T. Manchon : C. A. Martinez Department of Biological Sciences, University of São Paulo, Ribeirão-Preto, SP, Brazil M. Bianconi Department of Animal and Plant Sciences, The University of Sheffield, Sheffield, UK
on Rsoil, which was 16% greater at noon than at 18:00 h. Rsoil had low sensitivity to soil temperature (Q10 ~ 1) regardless of the CO2 treatment. Conclusions In this tropical managed pasture, diel variation in photosynthesis strongly affected Rsoil, suggesting that Rsoil may be more limited by substrate availability than abiotic factors such as temperature. Predicted changes in climate for the region will likely affect the C dynamics of C4-dominated tropical pastures. Although, the short-term experiment may limit the extrapolations of our findings, the highly controlled settings of the experiment highlighted the role of canopy photosynthesis on Rsoil respiration in tropical C4-pastures. Keywords Elevated CO2 . Warming . Tropical pasture . Soil respiration . C4 grass
Introduction Grasslands have relatively large amounts of carbon (C) stored in the soils (Hungate et al. 1997) and in the Tropics they are historically dominated by C4 plants. Thus, understanding the direct and indirect effects of predicted changes in climate over soil respiration (Rsoil) is fundamental to estimate the future C balance of tropical grassland ecosystems. Rsoil is the largest component of ecosystem respiration (Gonzalez-Meler et al. 2004; Bond-Lamberty et al. 2004; Ryan and Law 2005; Tian et al. 2011) and the second largest terrestrial C flux (≈
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