Julius Atlhopheng

Land use intensification and implications on land degradation in the Boteti area: Botswana

Abstract Arid and semi-arid areas worldwide face challenges of over utilization of rangelands, with a possibility of declining into degraded lands. Overgrazing by livestock and persistent deforestation of woodlands has been reported in the rangelands of Boteti Sub- District of Botswana. This study focuses on depicting changing patterns of land use that have come about as a result of a forcing from natural phenomenon. Periodic droughts and the drying up of the Boteti river which has been a source of livelihood for a long time has manifested on land utilization trends around the villages of Boteti District. New patterns of land use have since emerged as an adaptation strategy against the drier environment. The study mapped land use and land cover around two ‘river village settlements’. Land degradation indicators were identified within the various land cover categories. Results show that communities have shifted from flood recession farming to dry-land farming with emphasis on livestock. The latter are ironically privileged by government policies that are skewed toward livestock production, especially the introduction of fenced private ranches and conservation areas. As a result, they have relentlessly exerted more pressure on the communal land, manifesting itself through moderate to severe incidents of land degradation.

Southern African Arid Lands: Current Status and Future Prospects

Southern Africa south of 150° S latitude includes all or part of several countries. The situation in the dryland portion of each of them is described and the underlying factors are explained. Land degradation affects significant areas of most of the countries. Measures taken to arrest and reverse land degradation are explained. Climate change, trends and projections are discussed. Various scenarios are offered.

Variations on soil carbon dioxide flux with land-use type and selected soil properties in the hardveld of Botswana

The dynamics of carbon dioxide (CO2) flux in the hardveld regions of Botswana are poorly understood, with previous studies having concentrated on sandveld and pan environments. In particular, soil organic carbon (SOC) has a positive influence on CO2 emissions to the atmosphere. To examine the effects on soil CO2 flux of land use, namely conventional tillage, horticultural and grazing land uses, measurements were carried out in sites having similar climatic conditions. To enhance the understanding of soil carbon dynamics in these typical land uses, an investigation on the influence of soil pH, moisture content, organic carbon and temperature on CO2 flux rates was carried out. The results showed a relatively stronger dependence of CO2 flux rates on soil temperature for conventional tillage (R 2 = 0.71) and grazing (R 2 = 0.56) compared with horticultural land use (R 2 = 0.05). High SOC content in the grazing and horticultural land uses was due to increased oxidation of organic matter following soil disturbance. High organic matter turnover was probably from animal wastes and plant decomposition. Similarly, a decrease in CO2 flux with pH in the conventional tillage and grazing land uses suggests there is clear potential for these land uses to become carbon sources depending on the acidity of the soil.