title: Legacy effects of grassland management on soil carbon to depth.
abstract: The importance of managing land to optimize carbon sequestration for climate change mitigation is widely recognized, with grasslands being identified as having the potential to sequester additional carbon. However, most soil carbon inventories only consider surface soils, and most large-scale surveys group ecosystems into broad habitats without considering management intensity. Consequently, little is known about the quantity of deep soil carbon and its sensitivity to management. From a nationwide survey of grassland soils to 1 m depth, we show that carbon in grassland soils is vulnerable to management and that these management effects can be detected to considerable depth down the soil profile, albeit at decreasing significance with depth. Carbon concentrations in soil decreased as management intensity increased, but greatest soil carbon stocks (accounting for bulk density differences), were at intermediate levels of management. Our study also highlights the considerable amounts of carbon in subsurface soil below 30 cm, which is missed by standard carbon inventories. We estimate grassland soil carbon in Great Britain to be 2097 Tg C to a depth of 1 m, with ~60% of this carbon being below 30 cm. Total stocks of soil carbon (t ha(-1) ) to 1 m depth were 10.7% greater at intermediate relative to intensive management, which equates to 10.1 t ha(-1) in surface soils (0-30 cm), and 13.7 t ha(-1) in soils from 30 to 100 cm depth. Our findings highlight the existence of substantial carbon stocks at depth in grassland soils that are sensitive to management. This is of high relevance globally, given the extent of land cover and large stocks of carbon held in temperate managed grasslands. Our findings have implications for the future management of grasslands for carbon storage and climate mitigation, and for global carbon models which do not currently account for changes in soil carbon to depth with management.
authors: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
authors: Susan E
authors: SE
authors: Ward
authors: Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP, UK.
authors: Simon M
authors: SM
authors: Smart
authors: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
authors: Helen
authors: H
authors: Quirk
authors: Rothamsted Research, North Wyke, Okehampton, Devon, EX20 2SB, UK.
authors: Jerry R B
authors: JR
authors: Tallowin
authors: School of Agriculture, Policy and Development, Centre for Agri-Environmental Research, The University of Reading, Earley Gate, PO Box 237, Reading, RG6 6AR, UK.
authors: Simon R
authors: SR
authors: Mortimer
authors: School of Agriculture, Food and Rural Development, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK.
authors: Robert S
authors: RS
authors: Shiel
authors: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
authors: Andrew
authors: A
authors: Wilby
authors: Faculty of Life Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK.
authors: Richard D
authors: RD
authors: Bardgett
mesh_terms: D002244:Carbon / Q000032:analysis*; D057231:Climate Change; D065948:Grassland; D012987:Soil / Q000737:chemistry*; D006113:United Kingdom
chemical_list: D012987:Soil; D002244:Carbon
keywords: carbon inventory; grassland; legacy effect; management intensity; soil carbon; soil carbon stocks; soil depth