Wind erosion response to past and future agro-pastoral trajectories in the Sahel (Niger)

C. Pierre (1) , P. Hiernaux (2) , Jean-Louis Rajot (1) , L. Kergoat (3) , N. Webb (4) , A. Abdourhamane Touré (5) , B. Marticorena (6) , Christel Bouet (1, 6)

1 iEES Paris - Institut d'écologie et des sciences de l'environnement de Paris
2 PastoC - Pastoralisme Conseil
3 GET - Géosciences Environnement Toulouse
4 USDA-ARS : Agricultural Research Service
5 UAM - Abdou Moumouni University of Niamey = Université Abdou Moumouni de Niamey
6 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques

Context Wind erosion plays a major role in land degradation in semi-arid areas, especially in the Sahel. There, wind erosion is as sensitive to land use and land management as to climate factors. Future land use intensification may increase wind erosion and induce regional land degradation. Objective We aimed to estimate wind erosion responses to changing land management in a Sahelian region. Methods We defined land use intensification scenarios for a study site in southwestern Niger for two historical situations (1950s and 1990s), and two alternative prospective scenarios (2030s: extensive or intensive). We simulated vegetation growth and horizontal sediment flux of wind erosion for the corresponding landscapes. Results Annual amounts of horizontal sediment flux increased with land management changes from 1950s (nil flux) to 1990s (176 kg m-1 yr-1 ) and 2030s (452 to 520 kg m-1 yr-1), mostly because of differences in land use, declining soil fertility, and practices decreasing the dry vegetation. For 2030s, intensive scenario exhibited larger vegetation yields than extensive conditions, but similar large values of horizontal sediment flux, thus questioning the sustainability of both scenarios. Realistic sets of practices had as large an influence as the largest theoretical range of practices on the variability of annual horizontal sediment flux. This variability was as large as that due to meteorological conditions. Conclusions This study demonstrates that the environmental impact of land use and management practices, of which wind erosion is an aspect, must be assessed at the landscape scale to account for the variability in land cover and associated land management.

Mots clés: Wind erosion; Agro-pastoral practices; Land management scenarios; Land use; Modelling Sahel

Domaines: Interfaces continentales, environnement

C. Pierre, P. Hiernaux, Jean-Louis Rajot, L. Kergoat, N. Webb, et al.. Wind erosion response to past and future agro-pastoral trajectories in the Sahel (Niger). Landscape Ecology, 2021, ⟨10.1007/s10980-021-01359-8⟩. ⟨hal-03421069⟩