Vegetation Structure, Root Biomass Distribution and Soil Carbon Stock of Savannah Agrosystems in Sudano-Sahelian Zone of Cameroon

Abstract

The present work aims to provide key knowledge on vegetation structure, root biomass distribution and soil carbon stock of savanna agrosystems in Sudano-Sahelian zone of Cameroon. The transect method is used to carry out the investigations in order to characterize the vegetation. The excavation method was used to soil and roots sampling. The experimental device used is the split plot. These results showed that the highest densities were recorded in Anogeissus leiocarpus stands (408 ± 11.12 stems/ha). Higher values of basal area (11.56 ± 0.57 m²/ha), biovolume (116.78 ± 16.57 m 3 /ha) and eco-volume (157.82 ± 22.12 m 3 /ha) were recorded in Khaya senegalensis stands. The highest total large roots biomass (65.81 ± 5.37 tC/ha) and fine roots biomass (11.42 ± 0.67 tC/ha) were recorded in Khaya senegalensis stands. The highest total medium root biomass is recorded in Burkea Africana stands (23.21 ± 1.15 TC/ha). The soil carbon stock is higher in Khaya senegalensis stands (132.16 ± 16.34 tC/ha). These results show that savannah agrosystems in Sudano-Sahelian zone of Cameroon can be considered as carbon sinks.

Dynamics of soil organic carbon stock under different types of savannah agrosystems in the Sudano-Sahelian zone of Cameroon

“…This result is in the range 24.65 ± 2.51-42.97 ± 4.35 tC/ha reported by (Awé et al, 2019c) for Burkea africana savannah agrosystems in the sudano-sahelian zone of Cameroon. Vegetation types can alter soil carbon stocks due to several key factors, including litterfall and root turnover, soil chemistry, root exudates, and microclimate (Ontl and Schulte, 2012;Awé et al, 2019c). Low carbon stocks of Detarium microcarpum savannah agrosystems are explained by the fact that agricultural practices such as deforestation, turning and frequent tillage, etc., cause a decrease in soil carbon stock (Swiderski et al, 2012).…”

“…This high density means that the stems used to reconstitute the environment are shrubs. This result lies in the range 208 ± 8.57 -408 ± 11.12 individuals/ha found by (Awé et al, 2019c) in savannah agrosystems in the Sudano-Sahelian zone of Cameroon. The highest values of basal area (11.50 ± 1.65 m²/ha) and biovolume (48.65 ± 3.95 m 3 /ha) were recorded in the Tamarindus indica savannah agrosystems (Table 1).…”

“…Results showed a negative and non-significant (P>0.05) correlation between soil organic C stock with % Sand, % Silt, % Clay, % Silt + Clay according to the three depth ranges of 0-10 cm, 10-20 cm and 20-30 cm respectively (Table 10). Soil organic carbon stocks decreased with increasing depth in all types of savannah agrosystems, as indicated in several results (Agboadoh, 2011;Jiao et al, 2012;Bessah et al, 2016;Awé et al, 2019c). On the other hand, there is no correlation between the density of savannah agrosystems and the amount of organic carbon sequestered in the soil.…”

“…Low carbon stocks of Detarium microcarpum savannah agrosystems are explained by the fact that agricultural practices such as deforestation, turning and frequent tillage, etc., cause a decrease in soil carbon stock (Swiderski et al, 2012). The maximum depth of 0 to 10 cm recorded the highest soil organic carbon stock under all types of savannah agrosystems (Bessah et al, 2016;Awé et al, 2019c;Awé et al, 2020). Results showed a positive and significant correlation (P<0.05) between soil organic carbon stock with basal area, biovolume, bulk density, moisture content, C/N ratio, Ca 2+ , Mg 2+ , OM (Table 10).…”

“…The study was carried out in the north region (Cameroon). The zone extends between 8° and 10° North latitude and between 12° and 16° East longitude, and is bounded to the North by the Far North region, to the South by the Adamawa region, to the East by the Republics of Chad and Central African Republic and to the West by the Federal Republic of Nigeria (Awé et al, 2019c (Awé et al, 2020). The vegetation encountered is a shrubby Sudanian savannah with a clear and degraded savannah appearance (Awé et al, 2020).…”