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Soil erosion is a global environmental problem and a pervasive form of land degradation that threatens land productivity and food and water security. Some of the biggest sources of sediment in catchments are cultivated and abandoned lands. However, the abandonment of cultivated fields is not well-researched. Our study assesses the level of degradation in cultivated and abandoned lands using a case study in South Africa. We answer three main questions: (1) What is the extent of crop field degradation on used, partly used, and abandoned fields? (2) What are the drivers of field abandonment in relation to land degradation? (3) Can proposed sustainable land management interventions tackle the dynamics of land abandonment and associated degradation? To answer these questions, cultivated and abandoned lands were mapped in a pilot catchment with ArcGIS tools and assigned severity codes and classified according to status, degradation, and encroachment. Systems diagrams were developed to show the interactions between agricultural land use and the level of degradation and leverage points in the system, with interventions assessed via a multi-criteria analysis. The results revealed that 37% of the total mapped area of croplands in the pilot site was abandoned and 20% of those lands were highly degraded. We argue that the innovative application of systems thinking through causal loop diagrams (CLDs) and leverage point analysis, combined with spatial and multi-criteria analyses, can assist with planning SLM interventions in similar contexts in the developing world. [ABSTRACT FROM AUTHOR]

• South Africa successfully developed land degradation neutrality targets. • Biomes rather than land cover types form the fundamental unit of analysis. • Subjectively and objectively developed bassline data was combined for identifying priority interventions. • The global indicators proved problematic for identifying interventions. • Alien plant invasions and woody plant densification were the most pressing degradation problems needing intervention. South Africa undertook a national Land Degradation Neutrality (LDN) target setting process during 2017/18 in response to the United Nations Convention to Combatting Desertification's call for signatory countries to voluntarily commit to LDN as also requested under Sustainability Development Goal 15.3. The process was supported by the Global Mechanism (GM) and followed their guidelines. This resulted in an ambitious set of targets being set for 2030. Early in the process it was recognised that biome level or landscape process based (bush encroachment, alien plant species removal) targets were more appropriate than location specific targets. South Africa has used the World Overview of Conservation Technologies and Approaches (WOCAT) Mapping Questionnaire (QM), to conducted two, ten years apart, assessments based on experts' perception of municipal level land degradation. The spatial location and extent of degradation, as identified from these studies, differed substantially from the three global indicators suggested as a baseline for LDN target setting. An analysis of the reasons for the discrepancies between the UNCCD indicators from the perception-based studies, and the implications this has for setting and monitoring South African land degradation is the main focus of this paper. [ABSTRACT FROM AUTHOR]

Using an analysis of aerial photographs from 1942, 1985 and 2004 we assessed the impact of changing land tenure and land-use regimes on the cover of thicket vegetation on the Grahamstown commonage. Land-use impacts were examined by comparing plant species composition within three vegetation types between sites incorporated into commonage for different lengths of time and sites outside the commonage. Results showed that thicket cover increased by 87% between 1942 and 1985 but declined by 11% between 1985 and 2004. The increase in thicket cover was highest on land where goat browsing and wood harvesting was excluded. There was a decline in thicket cover when uncontrolled goat browsing and wood harvesting were introduced. An analysis of plant species composition suggests an increase in the impact of livestock in areas closest to the urban area and with time since inclusion into commonage. Such areas exhibited greater cover of Increaser II grasses and dwarf shrubs in the herbaceous layer and lower cover of succulents within subtropical thicket. We interpret the decline in thicket cover and shift to a less palatable and less productive vegetation as resulting from the open-access land use system that has prevailed on the commonage since 1994. [ABSTRACT FROM AUTHOR]

We examined the effect of changes in land use and land tenure on bush encroachment and vegetation condition. An analysis of aerial photographs from three time steps (1949, 1985 and 2004) was used to document changes in woody plant density in different vegetation types on commonage and an adjacent commercial farm in Fort Beaufort, South Africa. Rangeland condition was assessed in different vegetation units of the area and woody plant density was related to distance from urban settlement. Results showed that there has been an increase in woody plant cover in both commonage and commercial farming areas, particularly between 1949 and 1985. However, since 1985, increased rates of urbanisation have stabilised, and in some areas reduced, woody plant thickening, especially at locations closest to urban settlements. Bush encroachment is being controlled to some extent by fuelwood harvesting and goat browsing, resulting in a reduction in height of favoured woody species such asAcacia karroo(Vachellia karroo). There has been a shift to less palatable browse species on the commonage areas and the condition of the grass sward is poor. Change in woody plant cover is significantly influenced by changing patterns of land use and land tenure over time which, in turn, affect rangeland condition. [ABSTRACT FROM AUTHOR]