Carbon balance of a grazed savanna grassland ecosystem in South Africa

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http://hdl.handle.net/10138/178984

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Räsänen , M , Aurela , M , Vakkari , V , Beukes , J P , Tuovinen , J-P , Van Zyl , P G , Josipovic , M , Venter , A D , Jaars , K , Siebert , S J , Laurila , T , Rinne , J & Laakso , L 2017 , ' Carbon balance of a grazed savanna grassland ecosystem in South Africa ' Biogeosciences , vol. 14 , no. 5 , pp. 1039-1054 . DOI: 10.5194/bg-14-1039-2017

Title: Carbon balance of a grazed savanna grassland ecosystem in South Africa
Author: Räsänen, M.; Aurela, M.; Vakkari, V.; Beukes, J. P.; Tuovinen, J.-P.; Van Zyl, P. G.; Josipovic, M.; Venter, A. D.; Jaars, K.; Siebert, S. J.; Laurila, T.; Rinne, J.; Laakso, L.
Contributor: University of Helsinki, Earth Change Observation Laboratory (ECHOLAB)
University of Helsinki, Department of Physics
University of Helsinki, Division of Atmospheric Sciences and Geophysics (Department of Physics) (-2009)
University of Helsinki, Division of Atmospheric Sciences and Geophysics (Department of Physics) (-2009)
Date: 2017-03-07
Language: eng
Number of pages: 16
Belongs to series: Biogeosciences
ISSN: 1726-4170
URI: http://hdl.handle.net/10138/178984
Abstract: Tropical savannas and grasslands are estimated to contribute significantly to the total primary production of all terrestrial vegetation. Large parts of African savannas and grasslands are used for agriculture and cattle grazing, but the carbon flux data available from these areas are limited. This study explores carbon dioxide fluxes measured with the eddy covariance method for 3 years at a grazed savanna grassland in Welgegund, South Africa. The tree cover around the measurement site, grazed by cattle and sheep, was around 15 %. The night-time respiration was not significantly dependent on either soil moisture or soil temperature on a weekly temporal scale, whereas on an annual timescale higher respiration rates were observed when soil temperatures were higher. The carbon dioxide balances of the years 2010-2011, 2011-2012 and 2012-2013 were 85 +/- 16, 67 +/- 20 and 139 +/- 13 gCm(-2) yr(-1), respectively. The yearly variation was largely determined by the changes in the early wet season fluxes (September to November) and in the mid-growing season fluxes (December to January). Early rainfall enhanced the respiratory capacity of the ecosystem throughout the year, whereas during the mid-growing season high rainfall resulted in high carbon uptake.
Subject: 114 Physical sciences
1172 Environmental sciences
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