IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Drivers of C cycling and sequestration on plant-soil system in a grazed mountain grassland of Sierras Grandes of Córdoba
Autor/es:
SARQUIS, AGUSTÍN; MERILES, JOSÉ; PESTONI, SOFÍA; PÉREZ HARGUINDEGUY, NATALIA
Lugar:
Harpenden
Reunión:
Simposio; 6th International Symposium on Soil Organic Matter ?Healthy soils for sustainable agriculture: the role of SOM?; 2017
Institución organizadora:
British Society of Soil Science
Resumen:
Drivers of C cycling and sequestration on plant-soil system in a grazed mountaingrassland of Sierras Grandes of Córdoba.Introduction. Studies of decomposition and stabilization of soil organic matter (SOM) have been historically separated. Recently there have been several efforts on integrating those aspects of SOM dynamics but we are still far from a common ground for work on it.Objectives. We aim at contributing in this sense by studying some of the mechanisms by which changes in vegetation affect C pools and C fluxes on plant-soil systems.Methods. We measured litter and root dry mass and C:N ratio on two vegetation physiognomies (thick tussocks and grazing lawns) at 5, 15 and 30 cm soil depth. At 5 cm depth we also determined fluorescein diacetate activity of microbial communities. Within the following months we will determine microbial community structure (PLFA analysis) and SOC content in particulate OM and mineral associated OM.Results. We found over 200 times more C in aboveground litter in tussock patches than in grazing lawns, while C in roots was almost 5 times higher in grazing lawns compared to tussock. Thin roots were between half of total (in grazing lawns 0-5 cm depth) and 50 times (in tussock 15-30 cm depth) more abundant than thick roots. C:N ratios were around 40 and 50 for thin and thick roots, respectively. Microbial activity was similar in the two physiognomies.Conclusion. Contrasting C inputs to soil like those found here, has been found in other grazed grasslands without nutrient and water deficit. This pattern make difficult to predict their impact on SOC. If roots are the main source of SOC, as many studies have shown, SOC should be higher in lawns. However, even if only a fraction of aboveground litter is incorporated to SOC it may counteract thepattern of root C and we may find no differences between SOC from the physiognomies. In addition, the higher proportion of fine roots (a more labile input) in tussocks compared to lawns may also enhance the impact of that source of C on SOC. We hope our future results will help to shed light on this.Figure legend. Plant carbon inputs to soil in physiognomies under study in Sierras Grandes, Córdoba.