Land degradation and climate change in South Africa

This paper considers the potential impact of future climate change on the nature and extent of land degradation in South Africa. The basis of the assessment is the comprehensive review published by the Department of Environmental Affairs and Tourism (DEA&T) as a contribution to the South African effort in respect of the United Nations Convention to Combat Desertification. The DEA&T report is founded on information collated from 34 workshops, one in each of the agricultural regions of South Africa, involving some 453 participants consisting mainly of agricultural extension officers and soil conservation technicians. This analysis reveals that land degradation is underpinned by poverty and its structural roots in colonial and apartheid political planning. Nevertheless, future climate change represents a key challenge to the developing economies of countries like South Africa. Regionally downscaled models predicting the nature and degree of rainfall changes in the future are used to assess the possible impact of future change on the South African land degradation situation. It is concluded that the most severely degraded areas of the country, including large areas of the former 'homeland' states, are likely to become even more susceptible under predicted climate change scenarios.     

Apartheid spatial engineering and land use change in Mankweng, South Africa: 1963–2001

Land use change studies permeate the geographic literature. While these studies have helped researchers understand the dynamics and importance of such changes, they have less often taken a deeper historical approach in combination with their traditional strengths of geographic information analysis. In this study, we explore historical land use changes in one of South Africa's former bantustans, Lebowa, from 1963 to 2001. We argue that changes in land use arise from both current socioeconomic dynamics but also from historical precedent established by the apartheid regime. Our methods couple historical aerial photography to recent household surveys to elucidate the national, regional and local influences over land use change. We conducted extensive field research in the study site between 2003 and 2006. Our findings show a high degree of urbanization, a loss of grassland and agricultural land and a dramatic pattern of increasing spatial concentration near growth points. We outline three recommendations for policymakers planning post-apartheid rural spaces and conclude with future research needs.     

The nature, extent and causes of land degradation in South Africa: legacy of the past, lessons for the future?

The aim of this paper is to reassess the land degradation and desertification problem in South Africa. The country has a wide range of interrelated environmental and development challenges existing in a socio–political context recently subject to substantial change. The paper outlines the fundamental environmental constraints and opportunities that underlie degradation phenomena and illustrates the nature, extent and geographical distribution of the major forms of soil and vegetation degradation in the country. The principal causes of degradation are identified and some important land use and land tenure questions that need to be addressed in the near future are posited.     

Seasonal diet of black-backed jackal in the Eastern Karoo,South Africa

The ability of small canids to consume a variety of resources in an opportunistic manner has been cited as a reason for their wide distribution across many habitats. Black-backed jackals Canis mesomelas have varied diets that reflect changes in food availability as a result of seasonal fluctuations in resources. Seasonal fluctuations can include variations in food type availability, as well as variations in the phenology of food resources (i.e. ungulate birth peaks). Additionally, the presence of apex predators can affect opportunistic predator diets through the provision of carrion. We investigated the diet of black-backed jackals on a reserve in the semi-arid Karoo, South Africa. Ungulates (>5 kg) were the dominant prey item across all seasons, reflecting either active predation or scavenging. Most seasonal comparisons in percent occurrence of prey groups revealed significant seasonal fluctuations in black-backed jackal diet. However, in terms of biomass consumed, the diet remained stable, dominated by small ungulates across all seasons with no clear seasonal change in ungulate composition. These results suggest that in this study black-backed jackals, although being opportunistic in terms of diet composition, had a seasonally stable food resource, most likely facilitated by the presence of cheetahs Acinonyx jubatus providing scavenging opportunities.     

Patterns of resource use by livestock during and after drought on the commons of Namaqualand, South Africa

The aim of this study was to determine the effect of drought on grazing patterns of livestock in a communal rangeland in Namaqualand. Water points were the foci of almost all grazing routes even after the drought, and the areas away from the water points were less heavily utilized. The mountains could be regarded as key resource areas for livestock since the grazing intensity was higher in the elevated areas of the rangeland than on the surrounding low lying areas during and immediately after drought. Spatial patterns of resource use by livestock on the commons did not differ during the drought and post-drought period. The lengths of the daily grazing routes were similar for both periods. This may be a consequence of the weakness of animals during the drought when forage was scarce which prevented them from walking further. The size of home ranges of the herds did not change during the two monitoring periods. We attribute this to social reasons because herders try to avoid the mixing of herds. In the commons of Namaqualand, herders are also spatially constrained and this restricts their options to adapt to drought, and hence many animals died.     

Effects of heuweltjies and utilization on vegetation patterns in the Succulent Karoo,South Africa

Heuweltjies are large circular earth mounds created by termites and are important features of the landscape in the Succulent Karoo biome in South Africa. This study demonstrates that heuweltjies and livestock grazing act together to shape vegetation patterns in the region. Using a multifactorial approach, we investigated the combined effects of heuweltjie-induced habitat conditions, grazing pressure and physical disturbance by livestock and native animals as well as the interactions among two distinct plant functional groups, on the composition and cover of vascular plant vegetation. Heuweltjie soils had significantly higher pH-values, finer texture, and higher concentrations of carbon, nitrogen, and phosphorus than those of the surroundings. Neither perennial nor ephemeral cover was different on- and off-mounds. However, species richness, cover of highly palatable plants and livestock grazing pressure were significantly higher between mounds. Grazing pressure generally resulted in a loss of perennial species and a shift to more ephemeral species, probably through the competitive release of annuals and geophytes from perennial plants. We propose that the apparent contradiction between superior nutrient conditions and inferior plant food quality on heuweltjies is caused by a combination of otherwise unfavourable soil properties and historic overgrazing of heuweltjies resulting in local degradation of the vegetation.     

Stratigraphic evolution of the upper slope and shelf edge in the Karoo Basin, South Africa

The Permian Ecca Group of the Karoo Basin, South Africa preserves an extensive well-exposed siliciclastic basin floor, slope and shelf-edge delta succession. The Kookfontein Formation includes multiple sedimentary cycles that display clinoform geometries and are interpreted to represent the deposits of a slope to shelf succession. The succession exhibits progradational followed by aggradational stacking of deltaic cycles that is related to a change in shelf-edge trajectory, and lies within two depositional sequences. Sediment was transferred to the slope via overextension of deltas onto and over the shelf edge, resulting in failure and re-adjustment of local slope gradients. The depositional facies and architecture of the Kookfontein Formation record the change from a bypass- to accretion-dominated margin, which is interpreted to reflect a decrease in sediment transport efficiency as the slope gradient decreased, slope length increased and shelf-edge trajectory rose. During this time the delivery system changed from point-sourced basin-floor fans fed by slope channels to starved basin-floor with sand-rich slope clinoforms. This is an example of a progradational margin in which the younger slope system is interpreted to be of a different style to the older slope system that fed the underlying sand-rich basin floor fans.     

乾安县土地利用变化及其生态效应

Based on GIS and statistical methods, with the help of searching historical literatures andcalculating the landscape indices, the land use changes of Qian'an County in both spatial and temporalaspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changesand their ecological effects are discussed too. The main findings of this study are as follows:(1)Landuse changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetlandand water bodies,and an increase in cultivated land, saline-alkali land, and the land for housing andother construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by     

The role of facilitation in seedling recruitment and survival patterns, in the Strandveld Succulent Karoo, South Africa

Several studies in arid ecosystems have demonstrated that seedling establishment and survival were greater underneath the canopies of shrubs than in the open spaces between shrubs. These results led to the formulation of the hypothesis that seedling recruitment and survival were dependent on the shelter provided by shrub species (nurse-plant hypothesis). Seedling emergence and survival beneath and between the canopies of selected perennial shrub species were investigated at five localities in the Strandveld Succulent Karoo, each dominated by a different shrub species. Seedling emergence and survival were also examined at three localities dominated by annual species. In general, species richness and seedling densities were significantly higher in open areas than underneath shrubs, while seedling survival percentages did not differ significantly between microsites. Therefore, no evidence could be found to support the hypothesis that seedling recruitment and survival were facilitated by the presence of shrub species. Although most species will be able to establish in the absence of shrubs, the presence of woody species may have other advantages when restoring vegetation in mined areas.     

Rural Local Economic Development and Land Restitution in South Africa: The Case of Schmidtsdrift,Northern Cape

Local Economic Development is (LED) an activity of increasing importance in the developing world as globalisation produces new roles for local governments. As compared to a growing number of urban initiatives for LED, rural LED initiatives are relatively undeveloped. In this paper, the focus is upon South Africa, where the post‐apartheid government has sought to encourage both urban and rural LED initiatives. Programmes of land reform and restitution in South Africa result in the resettlement or return to the land of communities formerly dispossessed under apartheid. A critical element of planning for successful resettlement is the implementation of LED programmes. Schmidtsdrift in Northern Cape is examined as an example of participatory LED in a developing rural context. Rural LED in South Africa is distinguished by its focus upon poverty alleviation in the context of addressing the legacies of apartheid.     

Land use change and its ecological effect in Qian'an County of Jilin Province

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors.　(3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability.     

Land use change and its ecological effect in Qian＇an County of Jilin Province

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian‘an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian‘an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors. (3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening, of landscaoe suitability.     

Land-cover change and human–environment interactions in a rural cultural landscape in South Africa

This paper presents an historical analysis (1974–97) of associations between land-cover change and socio-economic factors for three villages in a former bantustan region of South Africa. The notion of social–ecological systems is used as the conceptual framework for this analysis, in which the former bantustan region of Bushbuckridge is posited as a cultural landscape. The local landscape showed distinctive modifications over the study period, broad trends including the growth of human settlements and the decrease in woodland cover. However, changes were not uniform across sites, and the direction and magnitude of changes in land cover were often nonlinear and site-specific. Analysis of associations between biophysical and socio-economic changes at different scales revealed a range of important interacting forces such as population growth, drought, shortages of land, grazing and wood resources, weakening institutional governance of natural resources, and the diversification of livelihood strategies, including the sale of fuelwood, concurrent with declining employment security and cattle ownership. Evidence suggests a possible erosion of resilience in these social–ecological systems at various scales, with important implications for socio-economic development and sustainable resource management.     

Population Pressure,Deforestation, and Land Degradation: A Case Study from the Dominican Republic

Population pressure, deforestation, and land degradation are major ecological concerns in developing countries. This research investigates causal linkages among interrelated physical and social processes in a case study conducted within the Plan Sierra resource management region of the Cordillera Central, Dominican Republic. Results of bivariate regression analysis, based on a sample of 450 traditional hillslope farms, support a linear relationship between population pressure and deforestation at two spatial scales. However, the strength of the relationship between population pressure and forest cover change decreases over a twenty-year time frame. Results also confirm a positive relationship between deforestation and land degradation. This case study contributes to an understanding of the precise nature of these relationships at sub-national scales of analysis.     

基于斑块层次的土地利用变化对土地质量影响的初步分析——以河北省张北县为例

利用SPOT2/4、SPOT5 等遥感数据源, 以人工目视解译为主, 分析了1999 年到2003 年河 北省张北县土地利用( 耕地) 变化情况; 运用GIS 和统计分析的方法, 初步分析林草地转变为耕 地、耕地转变为林草地和未变化耕地斑块等的土地退化特征。从1999 年到2003 年, 张北县耕地 减少20229.5ha, 耕地的主要流向为林草地, 其中又以旱地转化为人工草地为主, 2003 年新增耕 地的主要来源为牧草地。除耕地转为疏林地外, 耕地转为林草地的其余类型未退化斑块的面积较 大; 林草地转化为耕地的情况比较复杂: 林地转化为旱地、牧草地转化为水浇地的斑块发生了比 较明显的土地退化; 而牧草地转化为旱地、其它土地转化为旱地、牧草地转化为菜地斑块中退化 斑块数和面积比例都不大。和未变化耕地斑块的退化特征比较, 旱地转化为牧草地, 退化斑块与 未退化斑块数量比例比较接近, 但未退化斑块面积比例远远高于未变化耕地斑块; 而牧草地转为 旱地的退化与未退化斑块数量和面积比例没有明显差别。旱地转化为林地的未退化斑块数量和 面积比例要大于林地转化为旱地的斑块。说明旱地向林草地转化有助于提高区域土地质量。     

黄土台塬区土地利用转移流及空间集聚特征分析

提出了土地利用转移流和土地利用活跃度的概念,基于Landsat 遥感影像数据,采用土地利用变化测度模型,以5 年和25 年两种时间尺度对黄土台塬区土地利用时空动态特征进行分析,并将密度制图法应用到土地利用变化的空间集聚特征识别中.研究表明：① 黄土台塬区耕地占绝对优势,后备耕地资源严重不足,林地、草地、水域比例较低,存在较大生态风险;② 耕地与建设用地、草地、林地之间的转移关系是黄土台塬区土地利用转移的关键关系,决定着台塬区土地利用变化特征;③ 1985-2010 年耕地转建设用地流高达26668.80 hm²,占土地转移流40.75%,草地转耕地流18923.90 hm²,占28.91%,建设占用耕地情况严重,耕地占补平衡主要通过挤占草地实现;④ 25 年以来,土地利用变化对水域扰动最大,其次为森林,草地第三;⑤ 土地利用变化存在阶段性,1990-2000 年土地利用变化速率高于其他时段;⑥不同时间尺度下土地利用变化的空间集聚特征不同,25 年尺度下城镇附近土地变化幅度较高,5 年尺度下土地利用变化热点区由台塬中部向东西边缘区推移.     

北京近百年城市用地变化与相关社会人文因素简论

北京是中国的历史名城之一。历史上,其地域范围内的土地利用与土地覆被随人类活动强度而变化,各个时期的城市用地扩张是其中最明显的变化之一。本文将北京的历史发展过程划分为两个阶段,前一阶段从辽代建都到1911年封建王朝的瓦解;第二阶段从1911年到现在。本文围绕后一阶段进行探讨。指出:在过去的大约100年中,通过城市化表现的北京土地利用与土地覆被变化巨大,在过去的50年间尤为明显。北京的城市用地扩张及由此推动的土地利用/土地覆被变化之所以更为显著,与政治及社会意识形态改变、政策和制度变化、以及人口增长、科技进步和经济实力增强等社会、经济、人文因素密切相关。它们与土地利用/土地覆被变化相关关系的量化研究值得深入开展     

Resilient geographies: land, boundaries and the consolidation of the former bantustans in post-1994 South Africa

This paper focuses on the spatial impact of land reform and the redrawing of internal boundaries on South Africa's former bantustans. It argues that, in contrast to the democratic government's intention to use land reform and boundary demarcation to effectively change the spatial legacy of apartheid, these processes tend to cement the geography of the former bantustans. Though earlier research correctly projected that post-apartheid policies could result in the enlargement of the areas of the former bantustans, the ways in which this could happen were still unclear. This paper draws on experiences of land reform and boundary demarcation to demonstrate how and why the areas of the former bantustans have been enlarged over the 12 years of democracy in South Africa.     

Reciprocal flexural behaviour and contrasting stratigraphies: a new basin development model for the Karoo retroarc foreland system, South Africa

The main Karoo Basin of South Africa is a Late Carboniferous–Middle Jurassic retroarc foreland fill, developed in front of the Cape Fold Belt (CFB) in relation to subduction of the palaeo-Pacific plate underneath the Gondwana plate. The Karoo sedimentary fill corresponds to a first-order sequence, with the basal and top contacts marking profound changes in the tectonic setting, i.e. from extensional to foreland and from foreland to extensional, respectively. Sedimentation within the Karoo Foreland Basin was closely controlled by orogenic cycles of loading and unloading in the CFB. During orogenic loading, episodes of subsidence and increase in accommodation adjacent to the orogen correlate to episodes of uplift and decrease in accommodation away from the thrust-fold belt. During orogenic unloading the reverse occurred. As a consequence, the depocentre of the Karoo Basin alternated between the proximal region, during orogenic loading, and the distal region, during orogenic unloading. Orogenic loading dominated during the Late Carboniferous–Middle Triassic interval, leading to the accumulation of thick foredeep sequences with much thinner forebulge correlatives. The Late Triassic–Middle Jurassic interval was dominated by orogenic unloading, with deposition taking place in the distal region of the foreland system and coeval bypass and reworking of the older foredeep sequences. The out of phase history of base-level changes generated contrasting stratigraphies between the proximal and distal regions of the foreland system separated by a stratigraphic hinge line. The patterns of hinge line migration show the flexural peripheral bulge advancing towards the craton during the Late Carboniferous–Permian interval in response to the progradation of the orogenic front. The orogenward migration of the foreland system recorded during the Triassic–Middle Jurassic may be attributed to piggyback thrusting accompanied by a retrogradation of the centre of weight within the orogenic belt during orogenic loading (Early Middle Triassic) or to the retrogradation of the orogenic load through the erosion of the orogenic front during times of orogenic unloading (Late Triassic–Middle Jurassic).