Effects of restoration of degraded lands on soils physicochemical properties and adaptability of planted woody species in southwestern Niger

This study examines the effects of restoration of degraded lands on soils physicochemical properties and adaptability of planted woody species over a period of 4-6 years. It is based on: (1) Physicochemical analyses of soils (granulometry, calcimetry, and organic matter); (2) measures carried out for the dimensioning of anti-erosion structures; (3) dendrometric measurements on planted woody species on a density from 96 to 625 plants/ha, and the excavations of their root systems. The soils are characterized by low levels of organic matter (<1%), and no calcium carbonate. Soil tillage through deep sub-soiling resulted in an improvement in soils quality marked by average proportions of clay (28.3%), silt (27.3%) on the anti-erosion structures, whereas the control sites are dominated by sand particles (64%) on average. The degradation mechanism of anti-erosion structures is mainly controlled by natural factors including topography, rainfall, and sand content of the soils with strong positive correlations (r=0.84$$ r=0.84 $$; r=0.79$$ r=0.79 $$; r=0.63$$ r=0.63 $$ respectively). Restoration activities have led to the reconstitution of vegetation cover on degraded soils. Eucalyptus camaldulensis groups showed better adaptation as evidenced by their high structural shape parametres including Lorey's mean height (5.16-8.03 m), and mean crown diameter (1.66-3.3 m) with a tracer-type root system and high root density (74-88 roots) observed at 30 cm from the main stem. This study provides substantial information on the contribution of erosion control measures and their interactions with soil and vegetation resources. It constitutes a scientific tool that is well-adapted to the Sahelian (Niger, Mali, Burkina Faso, Chad, Mauritania and Senegal) context indispensable for the implementation of sustainable development strategies. The results thus obtained can be used as a reference for the choice of woody species to be planted according to the toposequence and the nature of the anti-erosion structures made, with a good control of their durability while taking into account the productivity of the soils.

Automated summary

This study examines the effects of restoration of degraded lands on soil physicochemical properties and adaptability of planted woody species. The results show that soil improvement and restoration measures play a positive role in soil quality and plant growth. In addition, Eucalyptus camaldulensis is found to be a suitable woody species for planting on degraded lands.