Carbon sequestration and water yield tradeoffs following restoration of abandoned agricultural lands in Mediterranean mountains

M Khorchani; E Nadal-Romero; T Lasanta; C Tague

doi:10.1016/j.envres.2021.112203

Carbon sequestration and water yield tradeoffs following restoration of abandoned agricultural lands in Mediterranean mountains

Environ Res. 2022 May 1:207:112203. doi: 10.1016/j.envres.2021.112203. Epub 2021 Oct 11.

Authors

M Khorchani¹, E Nadal-Romero², T Lasanta², C Tague³

Affiliations

¹ Instituto Pirenaico de Ecología, Procesos Geoambientales y Cambio Global, IPE-CSIC, Zaragoza, Spain. Electronic address: makki.khorchani@ipe.csic.es.
² Instituto Pirenaico de Ecología, Procesos Geoambientales y Cambio Global, IPE-CSIC, Zaragoza, Spain.
³ Bren School of Environmental Science and Management, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA.

PMID: 34648763
DOI: 10.1016/j.envres.2021.112203

Abstract

Abandoned cropland areas have the potential to contribute to climate change mitigation through natural revegetation and afforestation programs. These programs increase above and belowground carbon sequestration by expanding forest cover. However, this potential to mitigate climate change often involves tradeoffs between carbon sequestration and water availability. Particularly in a water limited environments such as the Mediterranean region, any loss of recharge to groundwater or streamflow can have critical societal consequences. In this study, we used an ecohydrologic model, Regional Hydro-Ecological Simulation System (RHESSys), to quantify these tradeoffs for land management plans in abandoned cropland areas in Mediterranean mountains. Changes to Net Ecosystem Production (NEP), water yield and Water-Use Efficiency (WUE) under different land management and climate scenarios were estimated for Arnás, a catchment with similar geology, vegetation and climate to many of the locations targeted for land abandonment restoration in the Spanish Pyrenees. Results showed significant changes to both carbon and water fluxes related to land management, while changes related to a warming scenario were not significant. Afforestation scenarios showed the highest average annual carbon sequestration rates (112 g C·m^-2·yr^-1) but were also associated with the lowest water yield (runoff coefficient of 26%) and water use efficiency (1.4 g C·mm^-1) compared to natural revegetation (-27 g C·m^-2·yr^-1, 50%, 1.7 g C·mm^-1 respectively). Under both restoration scenarios, results showed that the catchment ecosystem is a carbon sink during mid-February to July, coinciding with peak monthly transpiration and WUE, while during the rest of the year the catchment ecosystem is a carbon source. These results contribute to understanding carbon and water tradeoffs in Mediterranean mountains and can help adapt restoration plans to address both carbon sequestration and water management objectives.

Keywords: Afforestation; Carbon fluxes; Land abandonment; Net ecosystem production; Pyrenees; Streamflow; Water-use efficiency.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Agriculture
Carbon / analysis
Carbon Sequestration*
Ecosystem*
Mediterranean Region
Water

Substances

Water
Carbon