Vegetation improvement and soil biological quality in the Sahel of Burkina Faso

Soil living environment contains macro-fauna that play important role in the soil structure and chemical composition, the degradation process of organic matter and in the resilience of ecosystems. Few studies evaluated the impact of the “re-greening” trend observed in the Sahel on soil biological quality. The objective of this study is to assess the impact of the “re-greening” of the Sahel on soil macro-fauna population and diversity. The method of Tropical Soil Biology and Fertility (TSBF) was used to assess macro-fauna abundance and diversity in different land use types (cropland, shallow land, degraded land and forest). Four sites were selected, in the Sahelian zone of Burkina Faso, with contrasted Normalized Difference Vegetation Index (NDVI). In each site, four repetitions were taken for each land use type. In total, 64 plots samples were used to assess the abundance of macro-fauna. Results showed that there were more individuals (64.92%) and higher macro-fauna density in re-greening zones compared to the degrading zones. There was dominance of Arthropoda phylum (60.85%), Insecta class (59.03%) and Isoptera order (46.97%) in macro-fauna population. There were more species in the shallow land and cropland in re-greening zones and all trophic groups are represented in all sites. Despite this abundance, composition and diversity, it was observed that the re-greening processes have not significantly improved soil biological quality. It is concluded that vegetation improvement might be at the beginning stage in the Sahel, especially in croplands, and clear change of soil biological quality is not perceptible but may be tangible in the future.Keywords: Macro-fauna, ecosystem, soil quality, re-greening, degradation

Les sols developpes sur roches a complexe d'alteration montmorillonitique et kaolinitique dans le centre sud de la Haute Volta (caracteres et fertilite)

SIGLET 56084 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Structure, composition spécifique et diversité des ligneux dans deux zones contrastées en zone Sahélienne du Burkina Faso

Cette étude menée au Sahel burkinabé fait l’état actuel de la végétation ligneuse de cette région afin d’établir le lien entre la réalité du terrain et les observations satellitaires dans deux sites dans chacune des deux zones contrastées, l’une présentant un certain taux de reverdissement et l’autre de dégradation. Elle analyse aussi la composition spécifique, la structure, la diversité des ligneux et les similitudes entre les quatre sites (deux sites par deux zones). L’étude a utilisé une méthode d’échantillonnage stratifiée aléatoire analysant 104 placettes de 20 x 20 m². L’analyse statistique a montré des différences significatives de la densité, du nombre d’espèces, de la classe des hauteurs, de la classe des diamètres et des indices de Simpson et Shannon entre les deux zones. Les valeurs les plus importantes ont été observées dans la zone en reverdissement. Nous avons noté aussi une différence significative de la densité, des diamètres et des hauteurs en fonction de l’occupation des terres. Les champs de la zone en reverdissement possèdent les valeurs les plus importantes de densité et des hauteurs, mais ont les diamètres les moins élevés. Le reverdissement au Sahel est donc plus apparent dans les champs.This study conducted in the Sahel of Burkina Faso presents the current state of woody vegetation in this region so as to establish the link between the reality on the ground and satellite observations in two sites within each of the two contrasted zones ; one presenting a certain rate of re-greening and the other of degradation. It also analyzes the specific composition, the structure, ligneous diversity and the similarities between four sites (two sites by two zones). The study used a stratified random sampling method analyzing 104 plots of 20 x 20 sqm. Statistical analysis showed significant differences in density, number of species, height class, diameter class and Simpson and Shannon indices between the two zones. The highest values were observed in the re-greening zone. We also noted a significant difference in density, diameters and heights according to land use. The fields in the re-greening zone have the highest values of density and height, but the lowest diameters. The re-greening in the Sahel is more apparent in the fields

Structure, composition spécifique et diversité des ligneux dans deux zones contrastées en zone Sahélienne du Burkina Faso

This study conducted in the Sahel of Burkina Faso presents the current state of woody vegetation in this region so as to establish the link between the reality on the ground and satellite observations in two sites within each of the two contrasted zones ; one presenting a certain rate of re-greening and the other of degradation. It also analyzes the specific composition, the structure, ligneous diversity and the similarities between four sites (two sites by two zones). The study used a stratified random sampling method analyzing 104 plots of 20 x 20 sqm. Statistical analysis showed significant differences in density, number of species, height class, diameter class and Simpson and Shannon indices between the two zones. The highest values were observed in the re-greening zone. We also noted a significant difference in density, diameters and heights according to land use. The fields in the re-greening zone have the highest values of density and height, but the lowest diameters. The re-greening in the Sahel is more apparent in the fields