Determinants and rates of land degradation: Application of stationary time-series model to data from a semi-arid environment in Kenya

Abstract

The causes of land degradation in the African drylands have been shown to vary. Some researchers consider climate to be the major contributor to degradation, with anthropogenic factors playing a minor role. Others reverse the significance of these two factors. A third group attributes land degradation to climate and anthropogenic factors equally. This study was undertaken to establish the factors influencing land degradation in a semi-arid environment in southeastern Kenya and the rate of change in vegetation types for a period of 35 years (1973-2007). The reduction in grassland cover was used as an indicator of land degradation. Causes of land degradation were determined by a multiple regression analysis. A log-linear regression analysis was used to establish the rate of vegetation change. The multiple and log-linear regression analyses showed: (1) woody vegetation, livestock population and cultivated area to be the main contributors of reduction in grassland cover in the area, and (2) an increase in undesirable woody species, livestock population and cultivated area had a significant (P<0.05) negative effect on grassland vegetation. Increased human population, low amounts of rainfall and drought showed no significant negative effect on grassland vegetation cover. In conclusion, human and livestock population growth and increased agricultural land have contributed to intensive crop cultivation and overgrazing in the semi-arid lands. This overuse of the semi-arid rangelands has worsened the deterioration of the natural grassland vegetation.

Carbon accumulation by Pinus sylvestris forest plantations after different periods of afforestation in a semiarid sandy ecosystem

“…The carbon storage of the worlds forests is more than twice as much as that of the atmosphere (FAO, 2005), and it plays a crucial role in global carbon cycle as a source and sink of carbon (Aryal, Bhattarai, & Devkota, 2013; Chen, Wang, & Wang, 2016). The sandy land ecosystem in semiarid areas of China is generally fragile, and it generally tends to suffer desertification because of intensive exploitation of forest resources, human actions, and poor land management (D'Odorico, Bhattachan, Davis, Ravi, & Runyan, 2013; Mganga, Nyariki, Musimba, & Amwata, 2018). Desertification commonly leads to the loss of land resources and changes in vegetation composition (D'Odorico et al, 2013; Mganga et al, 2018; Sperry & Hacke, 2002), which has a great impact on the carbon reserves in such environments (Allington & Valone, 2010; Lu, Dong, Li, & Hu, 2014).…”

“…The sandy land ecosystem in semiarid areas of China is generally fragile, and it generally tends to suffer desertification because of intensive exploitation of forest resources, human actions, and poor land management (D'Odorico, Bhattachan, Davis, Ravi, & Runyan, 2013; Mganga, Nyariki, Musimba, & Amwata, 2018). Desertification commonly leads to the loss of land resources and changes in vegetation composition (D'Odorico et al, 2013; Mganga et al, 2018; Sperry & Hacke, 2002), which has a great impact on the carbon reserves in such environments (Allington & Valone, 2010; Lu, Dong, Li, & Hu, 2014). Revegetation has been widely perceived as an effective measure for countering desertification, improving soil quality, and increasing carbon storage (Geeson, Quaranta, Salvia, & Brandt, 2015; Grandy & Robertson, 2007; Lal, 2009; Li, Niu, & Luo, 2012) in arid and semiarid areas.…”

“…Desertification commonly leads to the loss of land resources and changes in vegetation composition (D'Odorico et al, 2013;Mganga et al, 2018;Sperry & Hacke, 2002), which has a great impact on the carbon reserves in such environments (Allington & Valone, 2010;Lu, Dong, Li, & Hu, 2014). Revegetation has been widely perceived as an effective measure for countering desertification, improving soil quality, and increasing carbon storage (Geeson, Quaranta, Salvia, & Brandt, 2015;Grandy & Robertson, 2007;Lal, 2009;Li, Niu, & Luo, 2012) in arid and semiarid areas.…”

Indigenous Grasses for Rehabilitating Degraded African Drylands

“…Degradation can also be defined as the loss of both biological and economic productivity, which includes deterioration of soil, vegetation and water. These processes are attributed to climatic variations, human activities, or a combination of both factors (Mganga et al 2018). Land degradation occurs in the forms of impoverishment and depletion of vegetative cover, loss of biophysical and economic productivity through exposure of the soil surface to wind and water erosion, salinisation and water logging leading to deterioration of physical, chemical and biological soil properties.…”

Predicting Agricultural Potentiality using Land Degradation Factors in East of Rosetta Branch, Nile Delta, Egypt

“…Almost 90% of the drylands are in the developing countries, where LD costs 4-8% of the national Gross Domestic Product (GDP) (D'Odorico et al, 2013). Africa houses nearly 73% of the drylands and LD affects about 268 million people (Mganga et al, 2018).…”