**1. Introduction**

Rangelands, including grasslands, scrublands and tundra, cover approximately 50% of the world's land surface [1]. The Land Degradation Assessment in Drylands (LADA) estimates that 16% of rangelands are currently undergoing degradation, with 20–25%

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

of the total land area being degraded, ultimately affecting the livelihoods of about 1.5 billion people worldwide [2]. Notably, this soil degradation is occurring in addition to historic degradation.

The degradation of rangelands is a consequence of several key activities, including overgrazing, livestock trampling and soil erosion [3, 4]. The widespread occurrence of soil degradation is also due to the mismanagement of marginal lands (semiarid, steep, shallow soils) in harsh and highly variable climates [5, 6]. With increasing population densities and the associated pressures on land, soil degradation is intensifying [7, 8].

Land degradation adversely depletes soil nutrients, which in turn directly affects their fertility, productivity and overall soil quality [9]. According to Vanlauwe et al. [8], soil fertility decline is directly linked to low productivity and food insecurity and is at the heart of rural poverty. Because soils are one of the largest stores of carbon that are in direct exchange with the atmosphere, soil degradation also negatively affects society through climate change feedbacks [10].

Because soil fertility depletion is one of the major threats to the sustainability of rangelands, precise determination of changes in soil quality is important in understanding the role of soils in the global cycle [11, 12]. A better understanding of the mechanisms of land degradation is crucial, not only to limit its consequences but also for mitigation and sustainable soil management [13]. While environmental degradation is expanding globally at an alarming rate, there is a major gap in our knowledge on the extent, severity and intensity of land degradation [14].

For many smallholder farmers in Sub-Saharan Africa (SSA), communal rangelands are grazed by livestock, which provide rural people with meat and dairy products and a source of income. However, one of the greatest challenges is that the rangelands are in a state of degradation due to an increase in human activities on marginal lands, misuse and mismanagement (overgrazing) and the associated problems of soil erosion [7, 9, 15, 16]. Soil fertility depletion and soil quality decline are major threats to the sustainability of these communal rangelands, partly because fertilizer inputs are not available or affordable in sufficient quantities [12].

Little is known on the impact of different intensities of land degradation on soil quality, with the most pertinent key issue being the threshold at which the effect of degradation will lead to a decline in soil quality. The main objective of this study was to evaluate the impact of a decrease in grass aerial cover as a consequence of land degradation on the quality of soil in a communal rangeland in the uplands of the Drakensburg region, KwaZulu-Natal Province, South Africa, that is managed by smallholder farmers. Grass cover was used as an indicator of land degradation, and quantification of such a land degradation indicator was done to help identify areas under threat and provide a basis for developing effective land management and rehabilitation options to improve the quality of communal rangeland soils [17, 18].
