A model-based assessment of C storage potential of French grasslands: a national study
2020
Klumpp, Katja | Martin, R. | Therond, Olivier | Pellerin, Sylvain | Bamière, Laure | Constantin, Julie | Launay, C. | GASTAL, Francois | Graux, Anne-Isabelle | Mosnier, Claire | Chambaut, H. | Brun-Lafleur, L. | Rechauchère, Olivier
From a climate change perspective, grassland soils have the ability to sequester C. However, there are still uncertainties on the magnitude of C sequestration potential, and their use in climate initiatives (i.e. 4p1000). Average values (± standard error) of 0.7±0.1 Mg C ha‑1 yr‑1 for permanent grassland (PG), and 0.4 to 0.8 Mg C ha‑1 yr‑1 for grass-ley (temporary grassland, TG), have been cited by different studies, while soil inventory reports only 0.05±0.3 Mg C ha‑1 yr‑1. These discrepancies can be attributed to differences in pedo-climatic conditions, intensity and type of management, but also to age and lifetime of temporary grasslands (TG). To analyse in detail C sequestration potential of French grasslands, a national study ‘4p1000 France’ was conducted to identify (1) C ‘storing’ practices; (2) their potential to be adopted as mitigation option; and (3) their cost of implementation. Along with a literature review, a modelling approach at fine spatial-scale resolution (1 km2) was used to simulate key grassland managements for PG and TG identified from agricultural statistics. Results showed that insertion of TG gained additional +0.47 Mg C ha‑1 yr‑1, while the replacement of mowing by grazing of intensively used PGs added +0.3 Mg C ha‑1 yr‑1 to soil, compared to baseline (0.26 and 0.21 Mg C ha‑1 yr‑1 for TG and PG). C storage under baseline and mitigation practices was able to offset field-based greenhouse gas emissions over French grassland areas.
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