Distribution and socio-ecological impacts of the invasive alien cactus <Emphasis Type="Italic">Opuntia stricta</Emphasis> in eastern Africa

Many cactus species have been introduced around the world and have subsequently become major invaders, inducing social and ecological costs. We recorded the distribution of Opuntia stricta in eastern Africa, and conducted 200 household interviews using semi-structured questionnaires to assess local perceptions of O. stricta in Laikipia County, Kenya. Opuntia stricta was widespread and abundant in parts of Kenya, Tanzania and Ethiopia and present at low densities in Uganda. In Laikipia County, pastoralists identified that O. stricta had been present for more than 10 years, and were of the opinion that it was still spreading and increasing in density. Two-thirds of respondents estimated that 50–75% of valuable grazing land had been invaded, and all felt that it contributed to the ill-health and death of livestock. Other negative impacts included reductions in native plant populations, rangeland condition, human health, and mobility of humans and animals. These negative impacts resulted in economic losses of US$ 500–1000 per household per year for 48% of households. Only 20% of respondents reported actively managing O. stricta, yet all respondents believed a reduction in the abundance of this weed would improve well-being. Management interventions are needed to reduce negative impacts.     

The conservation and status of threatened fishes in southern Africa

The conservation status of 24 threatened freshwater fishes and seven estuarine fishes from southern Africa is discussed against the background of natural and anthropogenic environmental factors. The majority of threatened species are endemic temperate forms with restricted ranges. Major threats include introduced alien fishes and a wide spectrum of environmentally destructive causes. Research on threatened species includes distribution surveys, biological and ecological studies and methods of artificial propagation. Long-term remedies based on ecosystem conservation are also being promoted. The perceptions and attitudes of nature conservation authorities are adjusting to the new challenges offish conservation. The number of threatened fishes in Africa is likely to increase in the face of escalating problems of habitat destruction and degradation.     

Ecological Assessment of Two Species of Potamonautid Freshwater Crabs from the Eastern Highlands of Zimbabwe,with Implications for Their Conservation

The spatial ecology of freshwater crabs and their conservation status is largely understudied in Africa. An ecological assessment was conducted at 104 localities in 51 rivers and/or streams in the Eastern Highlands of Zimbabwe whereby the distribution and abundances of freshwater crab species were mapped and the possible drivers of the observed trends in population structure explored. In addition, information on crab utilisation as a food resource by local communities was assessed via face to face interviews across the region. Finally, the conservation status of each species was assessed using the IUCN Red List criteria. Only two crab species Potamonautes mutareensis and Potamonautes unispinus were recorded within the region of study. Potamonautes mutareensis was largely restricted to less impacted environments in the high mountainous river system, whereas P. unispinus was found in low laying areas. In stretches of river where both species were found to co-occur, the species were never sampled from the same site, with P. mutareensis occurring in shallower, faster flowing environments and P. unispinus in deeper, slow flowing sites. Interview results revealed that the local communities, particularly in the southern part of the Eastern Highlands around the Chipinge area, had a considerable level of utilisation (55% of households) on the harvesting of crabs for household consumption during the non-agricultural season (May to September). Results from the IUCN Red List assessment indicate that both species should be considered as “Least Concern”. Threats to freshwater crabs in the Eastern Highlands, however, include widespread anthropogenic impacts such as habitat destruction associated with gold and diamond mining, inorganic and organic pollution and possibly exploitation for human consumption. The current study provides important information and insight towards the possible development of a freshwater crab conservation action plan within the region.     

转型期城市生态学前沿研究进展

城市是一类以人类活动为中心听社会－经济－自然复合生态系统。城市人类活动对局地、区域和全球环境的胁迫效应,自然生态系统的响应机制,城市时、空、量、构、序的耦合规律、动力学机制和控制论方法是当前国际社会和学术界关注的热点。介绍了转型期城市人类生态影响研究的一些主要国际科学计划,如ＳＣＯＰＥ及ＩＨＤＰ等,综述了城市生态学研究三大前沿领域的国际研究动向和案例,即人居生态学、产业生态学和城镇生命支持系统生态     

Household Extension and Fragmentation: Investigating the Socio-Environmental Dynamics of Mossi Domestic Transitions

Recent studies in West Africa and other parts of the world suggest that globalization and modernization make extended forms of domestic organization untenable in the face of modern economic and ecological circumstances. Unlike the large and extended domestic groups of pre-industrial and pre-colonial periods, households today tend to be small and nuclear. Thirty years ago, a series of case studies conducted on the Central Plateau of Burkina Faso documented this nucleation process among Mossi rural communities and predicted the decline and demise of Mossi extended households. This article tests the degree to which these predictions were correct based on ethnographic fieldwork in three villages in 2004. The results indicate that extended households indeed persist. Their persistence is explained by analyzing the roles of environmental and social change on the twin processes of household extension and fragmentation. Regional desiccation, off-farm income-generating opportunities, and agricultural intensification have created conditions that equally promote both household extension and fragmentation.     

Multiple states in river and lake ecosystems

Nonlinear models of ecosystem dynamics that incorporate positive feedbacks and multiple, internally reinforced states have considerable explanatory power. However, linear models may be adequate, particularly if ecosystem behaviour is primarily controlled by external processes. In lake ecosystems, internal (mainly biotic) processes are thought to have major impacts on system behaviour, whereas in rivers, external (mainly physical) factors have traditionally been emphasized. We consider the hypothesis that models that exhibit multiple states are useful for understanding the behaviour of lake ecosystems, but not as useful for understanding stream ecosystems. Some of the best-known examples of multiple states come from lake ecosystems. We review some of these examples, and we also describe examples of multiple states in rivers. We conclude that the hypothesis is an oversimplification; the importance of physical forcing in rivers does not eliminate the possibility of internal feedbacks that create multiple states, although in rivers these feedbacks are likely to include physical as well as biotic processes. Nonlinear behaviour in aquatic ecosystems may be more common than current theory indicates.     

Assessing the efficiency and effectiveness of rangeland restoration in Namaqualand,South Africa

South Africa’s Succulent Karoo is home to unmatched numbers of dryland plant species. Unfortunately, decades of overstocking these rangelands with small livestock and historical ploughing for fodder have led to extensive degradation. Some areas are severely degraded, negatively affecting both agricultural livestock productivity and ecosystem health. Land degradation reduces land use options and leaves land users, and the ecosystems on which they depend, more vulnerable to environmental and economic stressors. Ecological restoration is promoted as an effective and cost-efficient option for building the resilience of local and regional ecosystems. However, dryland restoration confronts many environmental challenges that have limited its success to date. Here, we present the results of a local-scale participatory restoration trial and an assessment of the costs of regional-scale ecological restoration in the Nama Khoi area in Namaqualand, South Africa. In combination, these analyses are useful for identifying opportunities and barriers for the improved efficiency and effectiveness of dryland restoration. In Namaqualand, we find that ecological restoration is difficult and expensive. The expected impacts of climate change will only exacerbate these challenges. However, we argue that a holistic suite of land management actions that include sound management, the prevention of further degradation, and prudent investments in restoration even where costs are high is likely to be the only real option for sustaining land-based livelihoods in this region over the longer term.     

Is Cassava the Answer to African Climate Change Adaptation?

This paper examines the impacts of climate change on cassava production in Africa, and questions whether cassava can play an important role in climate change adaptation. First, we examine the impacts that climate change will likely have on cassava itself, and on other important staple food crops for Africa including maize, millets, sorghum, banana, and beans based on projections to 2030. Results indicate that cassava is actually positively impacted in many areas of Africa, with ?3.7% to +17.5% changes in climate suitability across the continent. Conversely, for other major food staples, we found that they are all projected to experience negative impacts, with the greatest impacts for beans (?16%?±?8.8), potato (?14.7?±?8.2), banana (?2.5%?±?4.9), and sorghum (?2.66%?±?6.45). We then examined the likely challenges that cassava will face from pests and diseases through the use of ecological niche modeling for cassava mosaic disease, whitefly, brown streak disease and cassava mealybug. The findings show that the geographic distribution of these pests and diseases are projected to change, with both new areas opening up and areas where the pests and diseases are likely to leave or reduce in pressure. We finish the paper by looking at the abiotic traits of priority for crop adaptation for a 2030 world, showing that greater drought tolerance could bring some benefits in all areas of Africa, and that cold tolerance in Southern Africa will continue to be a constraint for cassava despite a warmer 2030 world, hence breeding needs to keep a focus on this trait. Importantly, heat tolerance was not found to be a major priority for crop improvement in cassava in the whole of Africa, but only in localized pockets of West Africa and the Sahel. The paper concludes that cassava is potentially highly resilient to future climatic changes and could provide Africa with options for adaptation whilst other major food staples face challenges.     

Climate Change and Health in Sub-Saharan Africa: A Case-Based Perspective

Over the coming decades, sub-Saharan Africa will face profound stresses and challenges from global climate change. Many of these will manifest as adverse health outcomes. This article uses a series of five hypothetical cases to review the climate impacts on the health and well-being of individuals and populations in sub-Saharan Africa. This approach fosters insights into the human dimensions of the risks to health, their interaction with local human ecology, and awareness of the diverse health ramifications of external environmental changes. Each case illustrates the health impact resulting from a specific environmental or social consequence of climate change, including impacts on agriculture and food security, droughts, floods, malaria, and population displacement. Whereas the article focuses on discrete manifestations of climate change, individuals will, in practice, face multiple stresses from climate change (i.e., floods and malaria) concomitant with other non-climate stressors (i.e., HIV/AIDS, globalization, etc.). These multiple sources of vulnerability must be considered when designing climate change and socioeconomic development interventions.     

Socioeconomic status and the prevalence of fever in children under age five: evidence from four sub-Saharan African countries

ABSTRACT: BACKGROUND: The burden of fevers remains enormous in sub-Saharan Africa. While several efforts at reducing the burden of fever have been made at the macro level, the relationship between socioeconomic status and fever prevalence has been inconclusive at the household and individual levels. The purpose of this study was to examine how individual and household socioeconomic status influences the prevalence of fever among children under age five in four sub-Saharan African countries. METHODS: The study used data from the 2008 Demographic and Health Survey (DHS) from Ghana, Nigeria, Kenya and Sierra Leone with a total of 38,990 children below age five. A multi-level random effects logistic model was fitted to examine the socioeconomic factors that influence the prevalence of fever in the two weeks preceding the survey. Data from the four countries were also combined to estimate this relationship, after country-specific analysis. RESULTS: The results show that children from wealthier households reported lower prevalence of fever in Ghana, Nigeria and Kenya. Result from the combined dataset shows that children from wealthier households were less likely to report fever. In general, vaccination against fever-related diseases and the use of improved toilet facility reduces fever prevalence. The use of bed nets by children and mothers did not show consistent relationship across the countries. CONCLUSION: Poverty does not only influence prevalence of fever at the macro level as shown in other studies but also the individual and household levels. Policies directed towards preventing childhood fevers should take a close account of issues of poverty alleviation. There is also the need to ensure that prevention and treatment mechanisms directed towards fever related diseases (such as malaria, pneumonia, measles, diarrhoea, polio, tuberculosis etc) are accessible and effectively used.     

Livestock Diversification: an Adaptive Strategy to Climate and Rangeland Ecosystem Changes in Southern Ethiopia

Pastoral cattle production in southern Ethiopia is becoming increasingly vulnerable to impacts of climate variability and rangeland resource degradation, giving rise to livestock diversification. Using a household (n?=?242) survey among herders, the relative functions, adaptability and vulnerability of four livestock species and factors influencing livestock diversification were analyzed. The stated major drivers of livestock diversification were recurrent droughts, bush encroachment, increased vulnerability of cattle and growing demand for adaptive species. Different livestock species are kept to fulfill various livelihood priorities with subsistence objectives outweighing production goals of the herders. Adaptability and vulnerability analyses of the livestock species showed camels and cattle to be the most and least adaptable species, respectively. Livestock species diversification varied significantly with family size and per capita holding of cattle, implicating the influence of labor and economic factors on adoptions. Multispecies herding emerged as the dominant local adaptation strategy, likely because it enhances resilience of households to climate and rangeland ecosystem changes by broadening the set of existing strategies.     

<Emphasis Type="Italic">Chromolaena odorata</Emphasis> (Siam weed) in eastern Africa: distribution and socio-ecological impacts

Invasive alien plant species such as Chromolaena odorata have negative impacts on biodiversity, ecosystem services and human well-being. Ecological impacts of this shrub are relatively well understood, but its impacts on local livelihoods and perceptions are poorly documented. We mapped C. odorata distribution in eastern Africa (Ethiopia, Kenya, Rwanda, Tanzania and Uganda) and compared perceptions and quantified the impacts of this species across Tanzanian villages with varying degrees of invasion density. Data were collected through 240 household questionnaires. Results indicate that C. odorata is a relatively new invader that already has severe negative impacts and is threatening livelihoods and the environment. Impacts include reductions in native biodiversity and the amount of available forage for livestock, reduced crop and water yields, and impaired mobility. Continued spread will cause additional negative impacts on poor rural communities. Implementation of a biological control programme targeting C. odorata is needed as a cost effective management approach along with other control and restoration measures.     

Environment,livelihood and household: The ethno‐history of Rana Tharus Badaghar households

This paper focuses on the changes occurring in households in the indigenous Rana Tharus community. I discuss the household not in terms of physical structure but instead on the social aspects: how people relate to each other through the lens of the household context. I argue that the fluid nature of households makes its flexible to different ecological environments and socio‐economic scenarios. My ethnography of Rana households clearly illustrated that the formation, structure and management of Rana households was fundamentally linked to people's livelihoods. Before 1950s, abundant land resources allowed Ranas to live in joint‐type households. This particular household arrangement not only fulfilled labour needs but also secured the mutual security for every household member. Gradually, undivided and big households (known in Rana as Badaghar) became the ideal model for Ranas as soon as such establishments did not become divided or separated. This household structure also served as an important safety net for most Ranas and fundamental to other social relationships especially Mukhiya (household head system) and Kurmaa (patrilineal kin). However, since the 1950s, new socio‐economic landscapes have significantly challenged the maintenance of traditional Rana households. Within the lifetime of most Ranas, they first experienced household fission and the disappearance of the Mukhiya system. The dynamic relationships between Rana household and new ecological, social and economic landscapes are explored here. It is concluded that the household is a critical institution allowing anthropologists to better understand the long‐term social impacts caused by state policies and ecological changes. This is because people often practice their new household relations in their everyday life as a response to environmental and livelihood changes.     

重点生态功能区农户相对贫困程度及影响因素——以陇南山区为例

重点生态功能区是全球生态系统保护与支撑人类可持续发展的核心区域。农户作为重点生态功能区生态保护的主体,其福祉水平直接关系到重点生态功能区主体功能的实现。科学评估重点生态功能区农户的相对贫困程度,精准识别相对贫困人口并揭示其影响因素对于促进重点生态功能区生计与生态协同发展至关重要。以地处秦巴山重要水源涵养区与生物多样性生态功能区的陇南山区为案例区,基于可持续生计分析框架,利用农户调查数据,通过构建相对贫困测度指标体系,系统识别相对贫困农户,并利用分层线性模型在"家庭-村庄"双重尺度上探索相对贫困的关键影响因素。结果发现：（1）陇南山区农户相对贫困程度存在分化,其中,高山区农户、补贴型农户和高家庭抚养比农户相对贫困程度较高。相对贫困农户占受访户的20.39%,且主要集中在高山区、家庭抚养比较高以及补贴型农户中。（2）农户的家庭属性是导致农户陷入相对贫困的决定性因素,脱贫内生动力及生计多样性提升是缓解相对贫困的关键因素,而医疗负担和教育负担增加会导致农户陷入相对贫困。（3）村庄特征放大了家庭特征对相对贫困程度的影响,村庄自然条件、社会经济条件、对外联系等通过影响家庭特征而强化了对农户相对贫困程度的影响。     

The Importance of Bushmeat in the Livelihoods of West African Cash-Crop Farmers Living in a Faunally-Depleted Landscape

Bushmeat is an important resource in the livelihoods of many rural communities in sub-Saharan Africa and may be a crucial safety-net for the most vulnerable households, especially during times of economic hardship. However, little is known about the impacts of wildlife depletion on these functions. This study quantifies the role of bushmeat in diversified rural household economies in a wildlife depleted forest-farm landscape in Ghana, assessing its importance overall, as well as differentiated by the relative vulnerability of households. Using repeat socioeconomic questionnaires (N=787) among 63 households over a one-year period, the following hypotheses were tested: (a) vulnerable households harvest more bushmeat; (b) bushmeat contributes a greater proportion of household production in vulnerable households; (c) bushmeat is more important for cash income than consumption in vulnerable households; and (d) bushmeat sales are more important for vulnerable households. The bushmeat harvest value averaged less than US$1.0 per day for 89% of households and comprised less than 7% of household production value. Household wealth and gender of the household head had little effect on the importance of bushmeat. However, bushmeat harvest and sales were highest during the agricultural lean season. Overall, most harvested bushmeat (64%) was consumed, enabling households to spend 30% less on meat/fish purchases. These findings suggest that, despite heavily depleted wildlife and diversified livelihoods, bushmeat continues to have an important role in rural livelihoods by acting as a safety net for income smoothing and reducing household expenditure during times of economic hardship.     

Ecological indicators of fruit and vegetable consumption (EIFVCs): A case study

Food and drink consumption was found to be responsible for around 20–30% of environmental impacts. Environmental impacts occur during all stages of the food production chain. However, households influence these impacts with through their choice of diet and habits, thus directly affecting the environment through food-related energy consumption and waste generation. With the multiplication of local policies for sustainable consumption, it has become increasingly useful to gather information on the evolution of the ecological impacts associated with household food consumption. Dealing with the indicators of household consumption of fruits and vegetables will enable changes in the population's lifestyles and the effectiveness of local policies to be monitored.The aims of this article are twofold: to provide a conceptual framework on the purposes of ecological indicators of fruit and vegetable consumption (EIFVCs) and to provide a methodological approach for selecting and measuring the most relevant EIFVCs at a local scale. Considering the great diversity of ecological impacts, the large number of potential EIFVCs must be reduced to obtain fewer EIFVCs, but that are relevant at local scale. To be relevant, the EIFVCs must provide information on the three phases of consumption (acquisition, use, and disposal) and on the upstream and downstream phases of the consumption process; they should evaluate the more problematic ecological impacts at the local scale (level of concern); and they have to only point out the ecological impacts that households can significantly reduce through their consumption rates. To measure relevant EIFVCs, three approaches must be combined: monitoring the ecological impacts, measuring the material and energy fluxes associated with household consumption, and analysing the consumer behaviours that result in the observed ecological impacts.As an illustration, the methodology is applied to the Bordeaux Metropolitan Area (France). In this area, eleven EIFVCs seem relevant. The use of surveys characterises all eleven of the EIFVCs, despite the difficulty of establishing quantified relationships between household behaviours and measured ecological impacts. The measuring of fluxes is possible for eight of them, whereas the monitoring of ecological impacts is only feasible for two of them.     

Urban ecological footprints in Africa

Africa’s rate of urbanization is the highest in the world. This is relevant to ecologists working in Africa because urban growth is strongly associated with habitat destruction, and also creates new fields of study. The ecological footprint concept is used to illustrate how urban settlements in Africa impact on rural ecosystems. At an aggregate level, African countries have the lowest ecological footprints in the world. However, there is little available data for individual cities, so evidence is fragmented making concerted policy initiatives difficult. Wood fuel continues to be a major source of energy for urban households and there is a long running debate as to what extent providing wood fuel for urban use damages forest ecosystems. Growing evidence contests the assertion that urban wood fuel markets are responsible for forest degradation. Although there are other options available, the social consequences of switching energy sources need to be taken into account. Outright bans, for example on charcoal, would lead to a loss of livelihoods in rural and urban households, and may not solve deforestation as well as increasing fossil fuel use would increase the ecological footprint.     

Calliandra (Leguminosae) in continental Africa

The mainly neotropical genus Calliandra Benth. (Leguminosae–Mimosoideae–Ingeae) is reported for the first time as native in continental Africa. There are two species known, C. gilbertii Thulin & Hunde sp. nov. in E Kenya and Somalia and C. redacta (J. H. Ross) Thulin & Hunde comb. nov. in South Africa near the Namibia border. On pollen morphological grounds they are supposed to be most related to certain neotropical species but the pollen does not agree entirely with any previously known group of the genus. The distribution of C gilbertii and C. redacta stresses the phytogeographical link between the arid zones of northern and southern Africa.     

The Government of Kenya's Cash Transfer Program Reduces the Risk of Sexual Debut among Young People Age 15-25

The aim of this study is to assess whether the Government of Kenya''s Cash Transfer for Orphans and Vulnerable Children (Kenya CT-OVC) can reduce the risk of HIV among young people by postponing sexual debut. The program provides an unconditional transfer of US$20 per month directly to the main caregiver in the household. An evaluation of the program was implemented in 2007–2009 in seven districts. Fourteen Locations were randomly assigned to receive the program and fourteen were assigned to a control arm. A sample of households was enrolled in the evaluation in 2007. We revisited these households in 2011 and collected information on sexual activity among individuals between 15–25 years of age. We used logistic regression, adjusted for the respondent''s age, sex and relationship to caregiver, the age, sex and schooling of the caregiver and whether or not the household lived in Nairobi at baseline, to compare rates of sexual debut among young people living in program households with those living in control households who had not yet entered the program. Our results, adjusted for these covariates, show that the program reduced the odds of sexual debut by 31 percent. There were no statistically significant effects on secondary outcomes of behavioral risk such as condom use, number of partners and transactional sex. Since the CT-OVC provides cash to the caregiver and not to the child, and there are no explicit conditions associated with receipt, these impacts are indirect, and may have been achieved by keeping young people in school. Our results suggest that large-scale national social cash transfer programs with poverty alleviation objectives may have potential positive spillover benefits in terms of reducing HIV risk among young people in Eastern and Southern Africa.     

A cross-sectional study of factors associated with dog ownership in Tanzania

Background

Mass vaccination of owned domestic dogs is crucial for the control of rabies in sub-Saharan Africa. Knowledge of the proportion of households which own dogs, and of the factors associated with dog ownership, is important for the planning and implementation of rabies awareness and dog vaccination programmes, and for the promotion of responsible dog ownership. This paper reports the results of a cross-sectional study of dog ownership by households in urban and rural communities in the United Republic of Tanzania.

Results

Fourteen percent (202) of 1,471 households surveyed were identified as dog-owning, with an average of 2.4 dogs per dog-owning household. The percentage of dog-owning households was highest in inland rural areas (24%) and lowest in coastal urban communities (7%). The overall human:dog ratio was 14:1. Multivariable logistic regression revealed that households which owned cattle, sheep or goats were much more likely to own dogs than households with no livestock. Muslim households were less likely to own dogs than Christian households, although this effect of religion was not seen among livestock-owning households. Households were more likely to own a dog if the head of the household was male; if they owned a cat; or if they owned poultry. Dog ownership was also broadly associated with larger, wealthier households.

Conclusion

The human:dog ratios in Tanzania are similar to those reported elsewhere in sub-Saharan Africa, although cultural and geographic variation is evident. Estimation of the number of owned dogs, and identification of household predictors of dog ownership, will enable targeted planning of rabies control efforts.