Does livestock grazing affect sediment deposition and accretion rates in salt marshes?

Nolte, Stefanie and Müller, Frauke and Schuerch, Mark and Wanner, Antonia and Esselink, Peter and Bakker, Jan P. and Jensen, Kai (2013) Does livestock grazing affect sediment deposition and accretion rates in salt marshes? Estuarine, Coastal and Shelf Science, 135 . pp. 296-305. ISSN 0272-7714

Full content URL: https://www.sciencedirect.com/science/article/pii/...

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Does livestock grazing affect sediment deposition and accretion rates in salt marshes?
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Abstract

Accretion rates, defined as the vertical growth of salt marshes measured in mm per year, may be influenced by grazing livestock in two ways: directly, by increasing soil compaction through trampling, and indirectly, by reducing aboveground biomass and thus decreasing sediment deposition rates measured in g/m² per year. Although accretion rates and the resulting surface elevation change largely determine the resilience of salt marshes to sea-level rise (SLR), the effect of livestock grazing on accretion rates has been little studied. Therefore, this study aimed to investigate the effect of livestock grazing on salt-marsh accretion rates. We hypothesise that accretion will be lower in grazed compared to ungrazed salt marshes. In four study sites along the mainland coast of the Wadden Sea (in the south-eastern North Sea), accretion rates, sediment deposition rates, and soil compaction of grazed and ungrazed marshes were analysed using the 137Cs radionuclide dating method. Accretion rates were on average 11.6 mm yr−1 during recent decades and thus higher than current and projected rates of SLR. Neither accretion nor sediment deposition rates were significantly different between grazing treatments. Meanwhile, soil compaction was clearly affected by grazing with significantly higher dry bulk density on grazed compared to ungrazed parts. Based on these results, we conclude that other factors influence whether grazing has an effect on accretion and sediment deposition rates and that the effect of grazing on marsh growth does not follow a direct causal chain. It may have a great importance when interacting with other biotic and abiotic processes on the marsh.

Additional Information:The final published version of this article can be found online at https://www.sciencedirect.com/science/article/pii/S0272771413004745?via%3Dihub
Keywords:137Cs, dating, geochronology, land use management, compaction, inundation, Wadden Sea
Subjects:F Physical Sciences > F820 Geomorphology
C Biological Sciences > C180 Ecology
Divisions:College of Science > School of Geography
ID Code:32356
Deposited On:13 Aug 2018 10:11

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