Soil organic carbon accumulation rates on Mediterranean abandoned agricultural lands

Stephen M Bell; César Terrer; Carles Barriocanal; Robert B Jackson; Antoni Rosell-Melé

doi:10.1016/j.scitotenv.2020.143535

Soil organic carbon accumulation rates on Mediterranean abandoned agricultural lands

Sci Total Environ. 2021 Mar 10:759:143535. doi: 10.1016/j.scitotenv.2020.143535. Epub 2020 Nov 5.

Authors

Stephen M Bell¹, César Terrer², Carles Barriocanal³, Robert B Jackson⁴, Antoni Rosell-Melé⁵

Affiliations

¹ Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain. Electronic address: stephen.bell@uab.cat.
² Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain; Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA, USA; Department of Earth System Science, Stanford University, Stanford, CA, USA.
³ Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain; GRAM, Department of Geography, Universitat de Barcelona (UB), Barcelona, Spain.
⁴ Department of Earth System Science, Stanford University, Stanford, CA, USA; Woods Institute for the Environment, Precourt Institute for Energy, Stanford University, Stanford, CA, USA.
⁵ Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain; Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain.

PMID: 33190903
DOI: 10.1016/j.scitotenv.2020.143535

Abstract

Secondary succession on abandoned agricultural lands can produce climate change mitigation co-benefits, such as soil carbon sequestration. However, the accumulation of soil organic carbon (SOC) in Mediterranean regions has been difficult to predict and is subject to multiple environmental and land management factors. Gains, losses, and no significant changes have all been reported. Here we compile chronosequence data (n = 113) from published studies and new field sites to assess the response of SOC to agricultural land abandonment in peninsular Spain. We found an overall SOC accumulation rate of +2.3% yr^-1 post-abandonment. SOC dynamics are highly variable and context-dependent. Minimal change occurs on abandoned cereal croplands compared to abandoned woody croplands (+4% yr^-1). Accumulation is most prevalent within a Goldilocks climatic window of ~13-17 °C and ~450-900 mm precipitation, promoting >100% gains after three decades. Our secondary forest field sites accrued 40.8 Mg C ha^-1 (+172%) following abandonment and displayed greater SOC and N depth heterogeneity than natural forests demonstrating the long-lasting impact of agriculture. Although changes in regional climate and crop types abandoned will impact future carbon sequestration, abandonment remains a low-cost, long-term natural climate solution best incorporated in tandem with other multipurpose sustainable land management strategies.

Keywords: Agricultural land abandonment; Chronosequence; Ecological succession; Land use change; Soil carbon sequestration; Spain.