Perspectives on the assumed causes of land degradation in the rangelands of Sub-Saharan Africa

Abstract

Soil erosion and land degradation are serious problems in tropical Africa, especially Sub-Saharan Africa, where they are widely recognized as more serious problems than in non-tropical areas. Sub-Saharan Africa experiences deleterious levels of soil erosion, largely due to the interaction between harsh climates of high erosivity, fragile soils of high erodibility, steep slopes, and poor natural resource management. The fundamental challenge is to separate purely background-level soil erosion due to biophysical, geomorphic, topographic, and climatic conditions from what is caused by humans. This review shows that the human-induced causes of soil erosion and land degradation in Sub-Saharan Africa are not fully understood and some of the commonly listed causes may not always stand the test of critical scrutiny. The popular views of human-induced soil erosion and land degradation not only fail to take into consideration the fact that land degradation is primarily a physical process, but also they do injustice to adaptive ecosystem management by the local inhabitants. The review specifically questions the stereotypes of overpopulation, overgrazing, deforestation, overstocking, and general rangeland degradation due to human resource use in Sub-Saharan Africa. Empirical evidence suggests that biophysical factors including soil properties, climatic characteristics, topography, and vegetation can sometimes interact among themselves to yield high soil erosion and degradation rates independent of anthropogenic impacts.

Modeling vegetation and carbon dynamics of managed grasslands at the global scale with LPJmL 3.6

“…Overgrazing or trampling play a role especially in arid areas or under high livestock density (Dlamini et al, 2016). Mismanagement also plays a role in the increase in desertification and is the main reason of soil degradation of 15 % in the drylands in Sub-Saharan Africa (Kiage, 2013).…”

“…The daily intake varies between 18 and 41 g C day −1 MBW −1 (40 to 90 g DM day −1 MBW −1 ) which gives a range of the daily intake as 2300 to 5200 g C day −1 LSU −1 . For livestock in organic farming, Kristensen et al (2011) give estimates for feed intake and the portion of pasture feed that result in 2100 g C day −1 LSU −1 on average (minimum 780 and maximum 3450 g C day −1 LSU −1 ). We assume the daily demand at 4000 g C LSU −1 day −1 (corresponding to 8.9 kg DM LSU −1 day −1 ), assuming that high productive livestock requires a certain portion of grass feed along with concentrates from other sources.…”

“…Whereas our implementation of grassland management options is a necessary first step that establishes a major improvement in modeling capacities, the list of Kipling et al (2016) suggests a range of further improvement strategies for grassland modeling and climate change impact assessments with these. It remains to be tested which of these suggestions are suitable for an implementation in a global-scale model and how sensitive modeling results are to these changes.…”

The Contribution of Physical Geographers to Sustainability Research

“…Thus, there are biotic-geomorphic, biotic-pedogenic, pedogenic-geomorphic, and biotic-pedogenic-geomorphic feedback processes. High rates of soil erosion and degradation can sometimes be explained by the interaction of biophysical factors, such as soil properties, climatic characteristics, topography, and vegetation, without any need to reference anthropogenic processes [81]. The impacts of soil erosion on weed seedbanks, with consequent impacts on biodiversity, have also been discussed [82].…”

Effect of Stocking Rate on Forage Availability and Growth Performance of Goat Kids in Mediterranean Kermes Oak Shrublands

“…This finding is consistent with that of Manzano and Navar (2000). Grazing lands are the most degraded land use type in the world as a result of overgrazing (Papanastasis, 2009) which leads to the impoverishment of species composition, reduction of VC, exposure of soil to erosion, and ultimately to desertification (Thornes, 2007;Aksakal et al, 2011;Kiage, 2013). Vegetation cover is important in the ground to protect soils from exposure and overgrazing has been destroying this protective vegetation.…”