Minimising soil organic carbon erosion by wind is critical for land degradation neutrality

Authors: CHAPPELL, ADRIAN - Cardiff University; WEBB, NICHOLAS - New Mexico State University; LEYS, JOHN - Nsw Office Of Environment And Heritage; WATERS, CATHY - Nsw Department Of Primary Industries; ORGILL, SUSAN - Nsw Department Of Primary Industries; EYRES, MICHAEL - Injekta Field Systems

Submitted to: Environmental Science and Policy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2018
Publication Date: 3/1/2019
Citation: Chappell, A., Webb, N., Leys, J., Waters, C., Orgill, S., Eyres, M. 2019. Minimising soil organic carbon erosion by wind is critical for land degradation neutrality. Environmental Science and Policy. 93:43-52. https://doi.org/10.1016/j.envsci.2018.12.020.
DOI: https://doi.org/10.1016/j.envsci.2018.12.020

Interpretive Summary: To address the threat of land degradation to agriculture, ecosystems and society, in 2015 the United Nations Convention to Combat Desertification (UNCCD) endorsed Sustainable Development Goal (SDG) target 15.3 – Land Degradation-Neutrality (LDN), defined as “a state whereby the amount and quality of land resources necessary to support ecosystem functions and services and enhance food security remain stable or increase within specified temporal and spatial scales and ecosystems” (UNCCD, 2015). The concept aims to maintain and / or renew the global resource of healthy and productive land by avoiding, reducing, or reversing land degradation. Three indicators (metrics: vegetation cover, net primary productivity; NPP and soil organic carbon; SOC) were selected as proxies forassessing LDN. In this paper we show there is growing evidence that SOC erosion also reduces SOC stocks, and that not accounting for erosion processes introduces large uncertainty into LDN assessments. We use a wind erosion model to quantify global SOC erosion by wind (2001-2010) and identify global dryland regions where SOC erosion may be a significant problem for achieving LDN. Selected sites in global drylands show SOC erosion accelerating over time. Without targeting and reducing SOC erosion, management practices will fail to sequester SOC and reduce land degradation, thereby undermining the LDN framework. Our research argues for the inclusion of erosion processes in LDN assessments, particularly through its impact on the selected SOC indicator

Technical Abstract: The Land Degradation-Neutrality (LDN) framework of the United Nations Convention to Combat Desertification (UNCCD) is underpinned by three complementary interactive indicators (metrics: vegetation cover, net primary productivity; NPP and soil organic carbon; SOC) as proxies for change in the land-based natural capital. The LDN framework assumes that SOC changes slowly primarily by decomposition and respiration of CO2 to the atmosphere. However, we show there is growing evidence that SOC erosion also reduces SOC stocks and rapidly after land use / cover change. Here we use a physically-based model to quantify global SOC erosion by wind (2001-2010) and identify global dryland regions where SOC erosion may be a significant problem for achieving LDN. Selected sites in global drylands show SOC erosion accelerating over time. Without targeting and reducing SOC erosion, management practices will fail to sequester SOC and reduce land degradation, thereby undermining the LDN framework. We describe the interrelated nature of the LDN indicators, the importance of including SOC erosion and how land cover can be replaced by erosion that better represents the physical effects of land cover on land degradation processes. Therefore, we call for SOC erosion to become an LDN indicator. Furthermore, our results suggest that fluxes of SOC and soil nutrients by soil erosion should be emphasised in the forthcoming Intergovernmental Panel on Climate Change (IPCC) Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.