The impact of Alder on Soil Carbon Storage in Agricultural Hedgerows.

Hedgerows are prominent features of Jersey’s arable landscape and important elements for climate-smart farming. Whilst recognised for their role in biodiversity conservation and climate change mitigation through soil carbon storage, little is known about how hedge composition influences soil carbon dynamics. Soil carbon stocks were quantified beneath 15 hedgerows of contrasting make up (Alder, Alder with Others, Other Species & No Vegetation) and compared with adjacent arable controls. Samples were analysed for carbon concentration, bulk density and, for a subset, elemental carbon & nitrogen. Generalised linear mixed models were used to assess the datasets. Carbon concentrations were consistently higher in surface soils and declined with depth while bulk density was consistently lower under hedgerows. Other Species hedgerows showed the highest carbon stocks outperforming Alder and Alder with Others. These finding confirm that hedgerows in Jersey enhance soil carbon stocks relative to open cropland with reduced bulk density indicating improved soil structure. While Alder was the central focus of the study the greatest carbon gains were found beneath Other Species hedges, especially near the surface. Hedgerow management therefore offers a substantial opportunity to support soil health and increase carbon storage in agricultural systems.