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.     

Localization and characterization of populations vulnerable to climate change: Two case studies in Sub-Saharan Africa

Future climate change potentially can have a strong impact on the African continent. Of special concern are the effects on food security and the restricted adaptive capacity of Africa's poverty stricken population. Targeted policy interventions are, therefore, of vital importance. While there is a broad consensus on selection of climate and agricultural indicators, a coherent spatial representation of the populations' vulnerability is still subject to debate, basically because important drivers at household and institutional level are captured at the coarser (sub)-national level only. This paper aims to address this shortcoming by capitalizing on available spatially explicit information on households, food security institutions and natural resources to identify and characterize vulnerable groups in climate change prone areas of East and West Africa. First, we identify and localize groups with varying degrees of vulnerability, using food security and health indicators from georeferenced household surveys. Second, we characterize these vulnerable groups using statistical techniques that report on the frequency of occurrence of household characteristics, social bonding, remittances and agro-ecological endowments. Third we localize areas where climate change conditions affect production of major staple crops even after a maximum adaptation of crop rotations. Fourth, we characterize the vulnerable groups in the climate change affected areas and compare their profiles with the overall assessment to elucidate whether generic or climate change targeted policies are required. Since climate change will impact predominantly on agricultural production, our analysis focuses on the rural areas. For West Africa, we find that vulnerable groups in areas likely to be affected by climate change do not fundamentally differ from vulnerable groups in the study area in general. However, in East Africa there are remarkable differences between these groups which leads to the conclusion that in this part of Africa, poverty reducing strategies for climate change affected areas should differ from generic ones.     

The projected impact of climate and land use change on plant diversity: An example from West Africa

In West Africa, plant diversity is threatened by future climate and land use change, however, synergistic forecasts for this area are lacking to date. We investigated the impact and the interplay of future (2050) climate and land use change on plant diversity in Burkina Faso, which covers the major bioclimatic gradient in West Africa. Thus, regions with different levels of species richness can be investigated. The LandSHIFT model was adapted for this study to derive novel future (2050) land use simulations. One-class support vector machines (SVMs) were performed with these land use simulations together with current and future (2050) climate projections at a 0.1° resolution. Our modeling results show that the flora of Burkina Faso will be primarily negatively impacted by future climate and land use changes. However, we found contrasting latitudinal patterns. The more humid regions in Southern Burkina Faso would be more affected in terms of species loss than the Sahel. Climate change is more important than land use change under the assumption of technological stagnation in the agricultural sector. Our results suggest that, in general, the plant diversity in dry and humid regions of the tropics might respond differently to climate and land use change.     

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.     

中非农产品贸易强度及其国际地位演变分析

近年来中国和非洲农业合作日渐频繁,中非农产品贸易也逐渐受到学术界的广泛关注,中非农产品贸易在全球中的横向对比、中国与非洲各国之间的横向对比研究也显得尤为重要。为掌握在全球背景下中非农产品贸易关系及强度的历史状况,利用FAOSTAT中的农产品贸易数据,对中非农产品贸易与其他国家或地区农产品贸易展开横向对比,并对中国与非洲各国之间贸易强度的历史变化进行系统分析。研究结果显示：1）尽管非洲农产品进出口贸易额不断上升,但在世界贸易中的份额持续徘徊在低位,并无显著变化;2）中非之间的贸易关系在1986-2013年间的变化并不突出,欧美仍是其主要的贸易伙伴;3）大多数非洲国家对华年次贸易频率低且贸易量小;4）南非、坦桑尼亚、埃塞俄比亚、马里、尼日利亚、阿尔及利亚、马达加斯加、毛里塔尼亚和尼日尔等国不仅拥有较多农用地资源,且具有较好的对华农业贸易的历史基础。     

农业物候动态对地表生物物理过程及气候的反馈研究进展

地表过程对全球变化的响应和反馈是地球系统科学研究的核心课题之一,目前的研究多关注全球变化对地表过程的影响,而地表动态过程对地表生物物理过程及气候的反馈研究较少。系统认识地表物候动态对生物物理过程及气候的反馈对深化地球系统科学研究有着重要的意义。本文从农业物候动态的事实、农业物候动态在陆面过程模型中的参数化表达、农业物候动态对地表生物物理过程及气候的反馈等方面进行综述,发现在气候变化和管理措施影响下,以种植期和灌浆期为代表的农业物候期发生了显著的规律性变化;耦合农业物候动态,改善了模型对地表动态过程、生物物理过程和大气过程的数字化表达;农业物候变化对地表净辐射、潜热、感热、反照率和气温、降水、环流等过程产生了影响,并表现出以地表能量分配为主的气候反馈机理。针对农业物候动态对地表生物物理过程及气候效应的时空重要性,需要继续开展以下方面的工作：① 加强全球变化对地表物候动态的影响及其反馈的综合研究;② 不同光谱波段地表反射率与农业物候动态的关系研究;③ 农业物候动态引起的作物生理学特征变化在地表生物物理过程中的贡献;④ 重视不同气候区物候动态对气候反馈效应的差异。     

Influences of agricultural phenology dynamic on land surface biophysical process and climate feedback

Response and feedback of land surface process to climate change is one of the research priorities in the field of geoscience. The current study paid more attention to the impacts of global change on land surface process, but the feedback of land surface process to climate change has been poorly understood. It is becoming more and more meaningful under the framework of Earth system science to understand systematically the relationships between agricultural phenology dynamic and biophysical process, as well as the feedback on climate. In this paper, we summarized the research progress in this field, including the fact of agricultural phenology change, parameterization of phenology dynamic in land surface progress model, the influence of agricultural phenology dynamic on biophysical process, as well as its feedback on climate. The results showed that the agriculture phenophase, represented by the key phenological phases such as sowing, flowering and maturity, had shifted significantly due to the impacts of climate change and agronomic management. The digital expressions of land surface dynamic process, as well as the biophysical process and atmospheric process, were improved by coupling phenology dynamic in land surface model. The agricultural phenology dynamic had influenced net radiation, latent heat, sensible heat, albedo, temperature, precipitation, circulation, playing an important role in the surface energy partitioning and climate feedback. Considering the importance of agricultural phenology dynamic in land surface biophysical process and climate feedback, the following research priorities should be stressed: (1) the interactions between climate change and land surface phenology dynamic; (2) the relations between agricultural phenology dynamic and land surface reflectivity at different spectrums; (3) the contributions of crop physiology characteristic changes to land surface biophysical process; (4) the regional differences of climate feedbacks from phenology dynamic in different climate zones. This review is helpful to accelerate understanding of the role of agricultural phenology dynamic in land surface process and climate feedback.     

The causes and environmental effects of land use conversion during agricultural restructuring in Northeast China

During the last decade of the 20th century, extensive conversion in agricultural land use took place in Northeast China. The goal of this study is to ascertain its spatial distribution and regional differentiation, determine its causes, and analyze its environmental impact. Especially we attempt to elucidate how institutional constraints have facilitated the change at a time of agrarian restructuring when newly emerging free market was hybridized with the former planned economy. Information on six categories of land use was mapped from interpretation of Landsat TM images recorded in 1990, 1995 and 2000. Most of land use changes took place during the first half of the decade, coinciding with abrupt and chaotic changes in government directives. Farmland was changed mainly to woodland, water body and built-up areas while woodland and grassland were converted chiefly to farmland. Spatially, the change from farmland to woodland was restricted to the west of the study area. The change from grassland to farmland took place in the grazing and farming interlocked west. These chaotic and occasionally conflicting changes were largely caused by lack of stability and consistency in agricultural land use policies promulgated. They have exerted adverse impacts on the local environment, including land degradation, increased flooding, and modified climate regime.     

东北地区农业结构转型时期土地利用变化的成因与效应

During the last decade of the 20th century, extensive conversion in agricultural land use took place in Northeast China. The goal of this study is to ascertain its spatial distribution and regional differentiation, determine its causes, and analyze its environmental impact, Especially we attempt to elucidate how institutional constraints have facilitated the change at a time of agrarian restructuring when newly emerging free market was hybridized with the former planned economy. Information on six categories of land use was mapped from interpretation of Landsat TM images recorded in 1990,1995 and 2000. Most of land use changes took place during the first half of the decade, coinciding with abrupt and chaotic changes in government directives. Farmland was changed mainly to woodland,water body and built-up areas while woodland and grassland were converted chiefly to farmland.Spatially, the change from farmland to woodland was restricted to the west of the study area. The change from grassland to farmland took place in the grazing and farming interlocked west. These chaotic and occasionally conflicting changes were largely caused by lack of stability and consistency in agricultural land use policies promulgated. They have exerted adverse impacts on the local environment, including land degradation, increased flooding, and modified climate regime.     

The causes and environmental effects of land use conversion during agricultural restructuring in Northeast China

1IntroductionLand use change has received lots of attention internationally (Turner etal., 1994). Understanding of the mechanism of land use change and its adverse effect on the environment is conducive to understanding of population, resources, environment and sustainable economic development on the global, national and regional scales. With the rapid rise in human population, human-induced changes in land use form an important component of regional environmental change. In China, to emphasi…     

Spatiotemporal changes in agricultural land cover in Nepal over the last 100 years

In order to advance land use and land cover change (LUCC) research in Nepal, it is essential to reconstruct both the spatiotemporal distribution of agricultural land cover as well as scenarios that can explain these changes at the national and regional levels. Because of rapid population growth, the status of agricultural land in Nepal has changed markedly over the last 100 years. Historical data is used in this study, encompassing soils, populations, climatic variables, and topography. Data were revised to a series of 30 m grid cells utilized for agricultural land suitability and allocation models and were analyzed using a suite of advanced geographical tools. Our reconstructions for the spatiotemporal distribution of agricultural land in Nepal reveal an increasing trend between 1910 and 2010 (from 151.2 × 10² km² to 438.8 × 10² km²). This expanded rate of increase in agricultural land has varied between different eco, physiographic, and altitudinal regions of the country, significantly driven by population changes and policies over the period of this investigation. The historical dataset presented in this paper fills an existing gap in studies of agricultural land change and can be applied to other carbon cycle and climate modeling studies, as well as to impact assessments of agricultural land change in Nepal.     

干旱半干旱区农田土壤风蚀特征及参数化研究进展

干旱半干旱地区是中国的农业后备战略基地,然而近年来该地区农田土壤风蚀现象严重,沙/尘释放量显著增大,威胁农业的可持续发展和生态系统平衡。目前绝大部分的天气和气候模式仅考虑了沙漠地表起沙,忽视退化农田的土壤风蚀起沙,导致起沙通量模拟存在很大的不确定性。对20世纪50年代以来干旱半干旱区农田土壤风蚀起沙特征及参数化做了详细的分析总结,回顾并梳理了干旱半干旱区农田土壤风蚀观测和数值模拟的研究脉络以及存在的问题,为提高农田起沙的模拟精度提供了有效参考,对中国干旱半干旱区农田土壤风蚀防治、土地荒漠化治理以及理解未来土地利用改变对大气污染的影响具有重要意义。     

LUCC研究的最新进展评述

土地利用/土地覆被变化(LUCC)是全球环境变化的重要组成部分和主要原因之一,进入新世纪以来,LUCC研究一直是地理学研究的前沿与热点。本文综述了2002年8月在南非德班国际地理学联合会(IGU)"2002年区域地理大会"上有关LUCC的主要研究成果,认为国际上LUCC研究在应用RS、GIS技术开展土地利用/土地覆被变化监测、评价与制图;农村与农业土地利用/土地覆被变化分析;城市土地利用/土地覆被变化分析;土地利用/土地覆被变化动力学;土地利用/土地覆被变化与生态环境等五个方面取得最新进展,反映出LUCC研究范围在进一步拓展,研究内容在进一步深化。     

中国生态脆弱区全球变化风险及应对技术途径和主要措施

自工业革命以来,全球环境发生深刻变化。生态脆弱区生态系统稳定性差、抗干扰和自我恢复能力弱,在全球变化背景下,自然资源供给能力下降、土地退化、生物多样性减少、灾害频发,生态系统面临巨大风险,亟需开展生态脆弱区全球变化风险应对研究。本文重点对中国典型生态脆弱区全球变化风险来源、全球变化对生态脆弱区的影响、全球变化风险应对等研究进行总结,并提出未来全球变化应对策略,以期促进中国典型生态脆弱区生态系统对全球变化响应的深入理解,提高生态脆弱区应对全球变化的能力。生态脆弱区全球变化风险源于环境变化对自然、社会、经济复杂系统的影响。全球变化对生态脆弱区的影响是显著的,以气候变化为主要标志,人类活动为主要驱动力,引起极端气候事件、灾害频发、土地退化、植被生产力降低、生物多样性减少、冰川冻土消融和水资源格局改变等环境问题,并在未来全球变化持续影响下可能加剧,而生态建设工程的实施显著改善了生态环境。今后应加强自然、社会、经济系统耦合,加强资源环境要素监测和全球变化风险评估与预警等方面的研究。     

Advances in monitoring vegetation and land use dynamics in the Sahel

Vegetation dynamics of the West African Sahel has attracted great scientific interest over the last 40?years because of the dramatic inter-decadal variability observed in the resource base of the region directly impacting on the livelihoods of the West African population. From farmers to pastoralists, agro-pastoralists and forest-users, all depend on the availability of vegetation resources and are affected by fluctuations in the available vegetation resource. Vegetation dynamics are controlled by both natural and human factors, including climate change and variability, increased concentration of CO₂ in the atmosphere, grazing pressure, bush fires and agricultural expansion or contraction. The use of satellite data in combination with field data played a major role in the monitoring of vegetation dynamics and land use in the Sahel, since the mega drought of the 1970s and the 1980s. This paper briefly reviews the advance of satellite-based monitoring of vegetation dynamics over these 40?years. We discuss the promises of current and likely future data sources and analysis tools, as well as the need to strengthen in situ data collection to support and validate satellite-based vegetation and land use monitoring and modelling.     

FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND‐REDISTRIBUTION PROGRAM*

ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land‐reform programs. In this study we examine land‐redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross‐section of projects in these two locales we develop a political ecology of stymied land‐reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white‐owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land‐redistribution beneficiaries, as well as on an analysis of land‐use change in Limpopo Province.     

Estimating the spatial and temporal impacts of climate change on rainfall reliability: An example in a Mediterranean agricultural region

Rainfall is the major driver of crop growth in Mediterranean agricultural regions and its spatial and temporal distributions determine yield potential. This study uses a long term spatial archive of rainfall observations for the Eyre Peninsula (South Australia) to estimate the spatial and temporal impacts of climate change on wheat yield. The three step process involved: (1) cluster analysis and statistical comparison to spatially distinguish heterogeneous “hazardscapes” (places that represent the physical susceptibility to hazards (Khan, 2012)); (2) using historical rainfall reliabilities to estimate the probability of receiving rainfall within a range of predefined thresholds and season for each hazardscape; (3) applying 2030 and 2070 climate change projections to determine the potential future impacts on rainfall. Nine hazardscapes were spatially differentiated each having temporally different historical seasonal rainfall reliabilities. Variations over space and time mean that the impacts of climate change will be spatially explicit. Projected rainfall reductions for 2030 showed marginal impact on hazardscapes with low seasonal reliabilities, primarily in winter and spring. The 2070 projections showed that some hazardscapes were unlikely to receive past rates of rainfall thus limiting the ongoing prospects of current and perhaps the potential adoption of alternative rain-fed land uses. Reductions in rainfall for hazardscapes with higher historical rainfall reliabilities will cause negative impacts on crop development. The ability to quantify the potential spatial and temporal impacts of climate change on seasonal trends will inform land managers' climate change mitigation and adaptation pathways.     

山区土地利用/覆被变化对土壤侵蚀的影响

本文以福建省山区为例,在对福建省水土保持实验站、建瓯市牛坑龙水土保持试验站长期观测、实验资料深入分析对比的基础之上,探讨了土地利用/土地覆被变化对土壤侵蚀的影响规律。分析结果表明,土地利用/土地覆被变化对径流的产生和土壤侵蚀有重要影响,植被的覆盖度的变化直接影响着径流系数和土壤侵蚀模数;植被的覆盖度和径流系数呈负线性关系,随着覆盖度的增加径流系数逐渐减小;植被覆盖度和土壤侵蚀模数为负指数关系,随着植被覆盖度的增大,土壤侵蚀模数急剧下降。     

Land desertification and restoration in Middle East and North Africa (MENA) region

The Middle East and North Africa (MENA) region is characterized by high population growth, degraded and fragile nat-ural ecosystems, and a limited amount of arable lands. It is one of the most water-sc...