Abandoned Croplands: Drivers and Secondary Succession Trajectories under Livestock Grazing in Communal Areas of South Africa

Abstract

Cropland abandonment has been happening in different parts of the world and is being driven by socio-economic, ecological, edaphic, and environmental factors. Most of the research focusing on drivers of cropland abandonment, succession trajectories, and responses to active restoration initiatives has been conducted in the republic of Nepal and regions such as Europe and America. In South Africa, the impact of cropland abandonment on household livelihoods, changes in vegetation and soil properties, and soil seed bank statuses have been conducted mainly in the Eastern Cape Province. The drivers of cropland abandonment in South Africa are like those observed in other countries, except for a few, which are country-specific such as poor support of communal farmers compared to their counterparts in the highly mechanised commercial farming sector. There is also a shift from low input cropping in the distant fields to high input cultivation in homestead gardens. Research results elsewhere suggest a woody growth suppressive effect of grazing, particularly average grazing intensities, being crucial in suppressing woody proliferation while high grazing intensities are detrimental to herbaceous species’ richness and promote woody species’ encroachment. A combination of fire and grazing alters the natural succession trajectory by promoting fire-tolerant species and arresting woody species. Similar to other countries, cropland abandonment is associated with colonisation by alien invasive species which are favoured by cropping legacies, such as altered soil levels of pH, Nitrogen, and phosphorus. Furthermore, limited moisture in semi-arid areas promotes the encroachment of indigenous woody species. Secondary succession in abandoned croplands can be manipulated for the benefit of livestock production in communal areas by introducing management strategies that will discourage encroachment by both invasive and indigenous woody species which lowers the grazing capacity. Furthermore, active restorative practices, such as reseeding with indigenous mid succession perennial grasses and legumes, will improve forage quality in abandoned croplands. Our understanding of succession trajectories under various unique disturbance regimes experienced in South Africa, such as communal grazing of abandoned croplands, compared to situations in other parts of the world is limited. Furthermore, the influence of other factors such as fire, soil fertility, and moisture needs to be understood.