Higher soil respiration under mowing than under grazing explained by biomass differences
Different management practices may change the rate of soil respiration, thus affecting the carbon balance of grasslands. Therefore, we investigated the effect of grazing and mowing on soil respiration along with its driving variables (soil water content, soil temperature, above and below ground biomass, vegetation indices and soil carbon) in adjacent treatments (grazed and mowed) at a semi-arid grassland in Hungary (2011–2013). The average soil respiration over three years was higher in the mown (6.03 ± 4.07 µmol CO2 m−2 s−1) than in the grazed treatment (5.29 ± 3.50 µmol CO2 m−2 s−1). While soil water content and soil temperature did not differ between treatments, mowing resulted in 20 % higher soil respiration than grazing, possibly due to 17 % higher average above ground biomass in the mowed than in the grazed treatment. Inclusions of vegetation index VIGreen in the soil respiration model in addition to abiotic drivers improved the explained Rs variance by 16 % in the mowed and by 5 % in the grazed site, respectively. VIGreen alone proved to be a simple and fast indicator of soil respiration (r2 = 0.31 at grazed, r2 = 0.44 at mowed site). We conclude that soil respiration is responsive to the combined effect soil water content, soil temperature, biomass and soil carbon content as affected by the management (grazing vs. mowing) practice.
KeywordsGrassland management Soil CO2 efflux Soil respiration models Vegetation indices
The research leading to these results has been conducted as part of the “AnimalChange” Project which received funding from the European Community’s Seventh Framework Programme (FP7/2007–2013) under the Grant Agreement No. 266018. János Balogh acknowledges the support of the Hungarian Scientific Research Fund (OTKA PD 100575) Project and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. Szilvia Fóti acknowledges the support of the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. We would like to express our thank for the help of the Kiskunság National Park. We are grateful for the intensive soil and biomass sample analysis to Helga Nagy Tiborné Déri, Zsófi Lucsik, Bernadett Surányi, Erika Guba, Berta Roberta, Sipőcz Vivien, Ildikó Maraffai and Tibor Kocsis.
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