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Front. Ecol. Evol. | doi: 10.3389/fevo.2019.00151

No Detectable Broad-Scale Effect of Livestock Grazing on Soil Blue-Carbon Stock in Salt Marshes

 Rachel J. Harvey1*, Angus Garbutt2, Stephen J. Hawkins3 and  Martin W. Skov4
  • 1Bangor University, United Kingdom
  • 2Centre for Ecology & Hydrology - Bangor, United Kingdom
  • 3Department of Ocean and Earth Science, National Oceanography Centre Southampton, Faculty of Natural and Environmental Sciences, University of Southampton, United Kingdom
  • 4School of Ocean Sciences, College of Environmental Sciences and Engineering, Bangor University, United Kingdom

Grassland carbon capturing and storage (CCS) is thought to benefit from regulation of grazing. The impact is likely to depend on livestock density. Yet, few studies have tested this principle or evaluated the consistency of grazer-carbon relationships across multiple sites. We sampled 4 intertidal zones across 22 salt marshes along a 650 km stretch of coast in the UK to examine the impact of livestock density on globally important saltmarsh ‘blue carbon’ stocks. Although there were marked impacts of grazing pressure on above ground vegetation composition, structure and biomass, there was no detectable relationship between grazing intensity and soil organic carbon, irrespective of tidal zone in the marsh or soil depth-layer analysed. A substantial spatial variation in soil carbon was instead explained by contextual environmental variables. There was evidence that compensatory responses by vegetation, such as increased root growth, countered carbon loss from grazing impacts. Our work suggests that grazing effects on carbon stocks are minimal on broader scales in comparison with the influence of environmental context. The benefits of grazing management to carbon stores are likely to be highly context dependent.

Keywords: Blue carbon, grazing, salt marsh, Broad-scale, Environmental context

Received: 31 Oct 2018; Accepted: 17 Apr 2019.

Edited by:

Divya Karnad, Ashoka University, India

Reviewed by:

Peter Mueller, Universität Hamburg, Germany
Reza Erfanzadeh, Tarbiat Modares University, Iran  

Copyright: © 2019 Harvey, Garbutt, Hawkins and Skov. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Rachel J. Harvey, Bangor University, Bangor, United Kingdom, rachelharvey14@gmail.com