Determination of land restoration potentials in the semi-arid areas of Chad using systematic monitoring and mapping techniques

The restoration of degraded lands has received increased attention in recent years and many commitments have been made as part of global and regional restoration initiatives. Well-informed policy decisions that support land restoration, require spatially explicit information on restoration potentials to guide the design and implementation of restoration interventions in the context of limited resources. This study assessed ecosystems indicators of land degradation using a systematic approach that combines field surveys and remote sensing data into a set of multi-criteria analyses to map restoration potentials in the semi-arid areas. The indicators considered were soil organic carbon, erosion prevalence, enhanced vegetation index, Normalized differences water index and the Net Primary productivity. Three classes of restoration potential were established: (1) areas not in need of immediate restoration due low degradation status, (2) areas with high potential for restoration with moderate efforts required and (3) areas in critical need of restoration and require high level of efforts. Of the total area of the study site estimated at 88,344 km2, 59,146.12 km2, or 66.94% of the theoretically recoverable area, was considered suitable for restoration, of which 38% required moderate efforts while 28% require less efforts. The recoverable areas suitable for restoration could be restored through tree planting, soil and water conservation practices, farmers managed natural regeneration, and integrated soil fertility management. These results can help to spatially identify suitable multifunctional restoration and regeneration hotspots as an efficient way to prioritize restoration interventions in the context of limited resources

An assessment of the variation of soil properties with landscape attributes in the highlands of Cameroon. Land Degradation and Development

Soil properties are useful for assessing the potential of landscapes to provide terrestrial ecosystem services, but they are affected by anthropogenic activities and environmental factors including landscape attributes. This study assessed how soil properties are influenced by landscape attributes and their interactions in the highlands of Cameroon using the Land Degradation Surveillance Framework as a data collection tool. Soil properties (soil organic carbon [SOC], clay content, exchangeable bases [ExBas], electric conductivity [EC], boron [B], manganese [Mn], phosphorus [P], pH) were quantified within classes of landscape attributes. Soil samples were collected on 160 (1,000 m2) plots randomly located in a sentinel site of 100 km2 and were analyzed using a combination of conventional laboratory methods and mid‐infrared spectroscopy. Soil properties were highly affected by soil depths, land use types, slope gradients, and topographic positions, but less by their interactions. Significant interactions existed between land use types and topographic positions for SOC, EC, ExBas, and pH, and between slope gradients and topographic positions for pH, whereas Mn was influenced by the interaction between land use types and slope gradients. Most soil properties were higher in low altitude plots and those with higher vegetation cover but decreased in the upslope direction. The pH and clay contents were less affected by slope gradient confirming the inherent nature of the properties. These results are useful for site‐specific implementation of ecological intensification in areas with complex topography such as the highlands of Cameroon, offering a reference for future ecological policies and landscape restoration

An assessment of the variation of soil properties with landscape attributes in the highlands of Cameroon

Soil properties are useful for assessing the potential of landscapes to provide terrestrial ecosystem services, but they are affected by anthropogenic activities and environmental factors including landscape attributes. This study assessed how soil properties are influenced by landscape attributes and their interactions in the highlands of Cameroon using the Land Degradation Surveillance Framework as a data collection tool. Soil properties (soil organic carbon [SOC], clay content, exchangeable bases [ExBas], electric conductivity [EC], boron [B], manganese [Mn], phosphorus [P], pH) were quantified within classes of landscape attributes. Soil samples were collected on 160 (1,000 m2) plots randomly located in a sentinel site of 100 km2 and were analyzed using a combination of conventional laboratory methods and midinfrared spectroscopy. Soil properties were highly affected by soil depths, land use types, slope gradients, and topographic positions, but less by their interactions. Significant interactions existed between land use types and topographic positions for SOC, EC, ExBas, and pH, and between slope gradients and topographic positions for pH, whereas Mn was influenced by the interaction between land use types and slope gradients. Most soil properties were higher in low altitude plots and those with higher vegetation cover but decreased in the upslope direction. The pH and clay contents were less affected by slope gradient confirming the inherent nature of the properties. These results are useful for site‐specific implementation of ecological intensification in areas with complex topography such as the highlands of Cameroon, offering a reference for future ecological policies and landscape restoration

Landscape approach to assess key soil functional properties in the highlands of Cameroon Repercussions of spatial relationships for land management interventions

Understanding spatial variability of soil properties is essential to support land management decisions. However, despite the growing worldwide emphasis on integrated landscape management, soil variations resulting from land use changes have rarely been documented. The study used the land health surveillance concept in combination with simple geostatistical approaches to describe key soil properties among land use types and characterize their spatial variability in the highlands of Cameroon. A total of 320 soil samples were collected in two sites with contrasting land uses (agricultural and pasture) and were analyzed for granulometric fraction, soil organic carbon (SOC), nitrogen (N), soil reaction (pH), phosphorous (P), calcium (Ca), potassium (K), magnesium (Mg), aluminum (Al) and zinc (Zn). The spatial correlations between the soil properties revealed the factors responsible for the observed differences and showed that wide ranges were obtained in agricultural site as opposed to pasture. SOC and N decreased in the order of forest > grassland > fallow > croplands > pasture due to inherent soil properties, anthropogenic activities, land cover/land use and topographic factors. Kriged maps provided detailed visualization of soil properties at landscape scale, and helped to identify critical areas for targeted land management interventions to improve land quality. The spatial distribution of selected soil properties showed a well-defined pattern of higher concentrations in the lowlands and valleys and areas with permanent vegetation cover in both sites. These results are useful for improving the efficient use of inputs such fertilizers. Context-specific land management based on spatial variability of soil properties is highly recommended and more research is required to generalize our knowledge about spatial variability of soil health indicators and the casual factors in the highlands of Cameroon

Landscape approach to assess key soil functional properties in the highlands of Cameroon: Repercussions of spatial relationships for land management interventions

Understanding spatial variability of soil properties is essential to support land management decisions. However, despite the growing worldwide emphasis on integrated landscape management, soil variations resulting from land use changes have rarely been documented. The study used the land health surveillance concept in combination with simple geostatistical approaches to describe key soil properties among land use types and characterize their spatial variability in the highlands of Cameroon. A total of 320 soil samples were collected in two sites with contrasting land uses (agricultural and pasture) and were analyzed for granulometric fraction, soil organic carbon (SOC), nitrogen (N), soil reaction (pH), phosphorous (P), calcium (Ca), potassium (K), magnesium (Mg), aluminum (Al) and zinc (Zn). The spatial correlations between the soil properties revealed the factors responsible for the observed differences and showed that wide ranges were obtained in agricultural site as opposed to pasture. SOC and N decreased in the order of forest > grassland > fallow > croplands > pasture due to inherent soil properties, anthropogenic activities, land cover/land use and topographic factors. Kriged maps provided detailed visualization of soil properties at landscape scale, and helped to identify critical areas for targeted land management interventions to improve land quality. The spatial distribution of selected soil properties showed a well-defined pattern of higher concentrations in the lowlands and valleys and areas with permanent vegetation cover in both sites. These results are useful for improving the efficient use of inputs such fertilizers. Context-specific land management based on spatial variability of soil properties is highly recommended and more research is required to generalize our knowledge about spatial variability of soil health indicators and the casual factors in the highlands of Cameroon

Assessment of soil health indicators for sustainable production of maize in smallholder farming systems in the highlands of Cameroon

Agricultural intensification has been recognized as one of the solutions to increase food production to feed the ever-increasing population in sub-Saharan Africa. This can partly be achieved if quantitative and up-to-date information on soil health indicators are not available. This study used the land health surveillance framework, which combines ground-sampling schemes based on sentinel site and infrared spectroscopy to select a minimum dataset of soil health indicators to identify key land constraints for maize production and target potential interventions. We found high variability in soil properties in the study area which was mainly due to inherent soil conditions and land management practices. The most variable soil properties (CV > 0.38) were nitrogen (N), electric conductivity (ECd), exchangeable bases (ExBas), boron (B), calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn) and phosphorus (P). Moderate variability (0.2 < CV < 0.38) was observed for carbon (C), silt and sand, while properties with least variability (CV < 0.2) were pH and aluminium (Al). The effects of land-use and soil depth were significant (p < 0.05) for most of the soil properties. Principal component analysis (PCA) identified soil nutrient availability, metal concentration and texture as the three main factors that explain most of the variability observed. Significant interactions were observed between soil properties confirming the need for a minimum dataset of indicators. ExBas, B, pH, Mn, ECd, P and clay content formed the minimum dataset of soil health indicators for the study area. The results also showed that the soils of the study site are marginally suitable for the production of maize (Zea mays L.). Low limitations with respect to exchangeable bases (Ca, Mg, K and Na) and severe limitations with respect to B (<0.15 mg kg-1), pH (<6.20), P (<6.5 mg kg-1 soil) and clay content (>63%) were detected. However, potential for improvement exists through integrated soil management practices that include the use of organic and inorganic fertilizers, minimum soil tillage, and inclusion of legumes in crop rotations that could improve soil physical and chemical properties. © 2015 Elsevier B.V