Above ground biomass and tree species richness estimation with airborne lidar in tropical Ghana forests

Estimates of forest aboveground biomass are fundamental for carbon monitoring and accounting; delivering information at very high spatial resolution is especially valuable for local management, conservation and selective logging purposes. In tropical areas, hosting large biomass and biodiversity resources which are often threatened by unsustainable anthropogenic pressures, frequent forest resources monitoring is needed. Lidar is a powerful tool to estimate aboveground biomass at fine resolution; however its application in tropical forests has been limited, with high variability in the accuracy of results. Lidar pulses scan the forest vertical profile, and can provide structure information which is also linked to biodiversity. In the last decade the remote sensing of biodiversity has received great attention, but few studies focused on the use of lidar for assessing tree species richness in tropical forests.This research aims at estimating aboveground biomass and tree species richness using discrete return airborne lidar in Ghana forests. We tested an advanced statistical technique, Multivariate Adaptive Regression Splines (MARS), which does not require assumptions on data distribution or on the relationships between variables, being suitable for studying ecological variables.We compared the MARS regression results with those obtained by multilinear regression and found that both algorithms were effective, but MARS provided higher accuracy either for biomass (R² = 0.72) and species richness (R² = 0.64). We also noted strong correlation between biodiversity and biomass field values. Even if the forest areas under analysis are limited in extent and represent peculiar ecosystems, the preliminary indications produced by our study suggest that instrument such as lidar, specifically useful for pinpointing forest structure, can also be exploited as a support for tree species richness assessment.     

VARIABILITY OF DIURNAL TEMPERATURE RANGE IN EAST AFRICA DURING 1921–2010

This study investigates the long-term spatiotemporal variability of diurnal temperature range(DTR) in East Africa(EA). The study carries out non-parametric trend analysis of gridded DTR monthly data sourced from Climatic Research Unit(CRU). The DTR exhibits mixed signals in space and time over EA. The DTR correlates negatively with rainfall over EA. Reduction in DTR coincides with the summer season in the northern and southern hemispheres respectively, suggesting the influence of cloud cover on it. There was a non-uniform pattern of DTR changes across the region with time. Lake Victoria basin recorded the highest warming rates. The Indian Ocean coast recorded the least spatiotemporal variability in DTR. A reduction in DTR is evident in the two seasons: hot and cold. The start of the study period; 1921—1930, was the coolest decade in the study period. Most parts of EA recorded negative DTR anomalies in 1961—1970. The overall reduction in DTR throughout the study period highlights the ongoing warming which is a global phenomenon. There remains need for investigating the causation of the observed DTR variability for effective monitoring of the variability in future.     

Overview of West African fisheries under climate change: Impacts,vulnerabilities and adaptive responses of the artisanal and industrial sectors

Climate change affects ocean conditions, fish stocks and hence fisheries. In West Africa, climate change impacts on fisheries were projected to be mainly negative through multi-facet ways. However, analysis of adaptation responses of fishers to climate change impacts is scarce. This paper reviews the impacts on climate change on fisheries in West Africa and discusses the potential adaptation strategies adopted by both the artisanal and industrial fishing sectors. Overall, climate change and over-exploitation have altered species composition of fisheries catches in West Africa. The effect of ocean warming on fisheries is indicated by the increase in dominance of warmer water species in the landings, shown from an increase in Mean Temperature of Catch, in the region. Climate change induced changes in potential catch and species composition, which inherently have similar symptoms as over-exploitation, are expected to have repercussions on the economic and social performance of fisheries. Both artisanal and industrial sectors may adapt to these changes mainly through expansion of fishing ground that increases operation costs. Our results highlight that historical changes in target species are more common in industrial than artisanal fisheries. This result challenges the prevailing assumption that artisanal fisheries, given their limited movement capacity, would adapt to climate change by shifting target species and/or gear type.     

Disentangling seafood value chains: Tourism and the local market driving small-scale fisheries

Identifying socio-economic drivers of small-scale fisheries is a fundamental step to understand impacts and pressures on fishery resources, and the behaviour of seafood trade actors. It is especially relevant for developing countries where such information is usually lacking and fisheries management is greatly needed. To address this gap, this study maps the structure of value chains of fish and marine invertebrates caught by small-scale fisheries from São Vicente, Cape Verde (West Africa), and examines the main socio-economic drivers behind the seafood trade on the island. Specifically, it shows how drivers, such as tourism and the local market, shape the preferences for certain species and how they affect the distribution of income among actors involved in the seafood trade. To collect this information, interviews were done with fishers, small-scale traders, market vendors, and restaurant owners, in all fishing communities of the island of São Vicente, in 2015. Tourism and the local market drive the exploitation of a wide variety of marine species, from small demersal low trophic level fish and marine invertebrates, to large pelagic high trophic level fish species. Moreover, the local seafood market, and especially tourism dynamics, contribute to the unequal distribution of income among actor groups, benefiting mostly restaurant owners due to their direct access to tourist consumers. Such findings have implications for local fishery resources management, food security, and fishing communities’ livelihoods.     

Analysis of a lower jurassic geomagnetic reversal based on a model that relates transitional fields to variations of flux on the core surface

Summary For the last 12 Myr the transitional virtual geomagnetic poles (VGPs) of different reversals lie close to two preferred and practically antipodal longitudinal paths. In spite of some controversies about these transitional paths, it has been pointed out that they are linked to geomagnetic phenomena. Jurassic transitional VGP paths are quite similar to those of the last 12 Myr. Paleomagnetic data recorded in Stormberg Lavas (195 ± 5 Ma) belonging to two sampling localities of South Africa have been rotated according to an absolute palaeoreconstruction of Africa for the lower Jurassic. In order to avoid the hypothesis about dipolarity implicit in the VGPs calculations, the transitional directions recorded in the lavas were compared with others that were simulated on the basis of a model that relates transitional fields to variations of flux on the Earth's core surface. They were quite similar. For both, recorded and simulated data, the VGPs showed similar paths. Similar conditions could thus have driven both late Cenozoic and Jurassic reversals.     

Kenya's regional ambitions or China's Belt‐and‐Road? News media representations of the Mombasa‐Nairobi Standard Gauge Railway

Kenya's Standard Gauge Railway (SGR), and its construction and financing by China, exemplifies the prominence accorded to mega‐infrastructural projects in contemporary economic development, as well as the dependence this has engendered on external loans. Alongside, multiple geographies intertwine in the SGR which is both a component of China's global ‘Belt and Road Initiative’ (BRI), as well as an East African regional link between coastal Kenya and neighbouring landlocked countries. In most popular and academic analyses, the role of China is emphasized over the SGR's positioning within East Africa. Does this then lead to an undermining of the meanings that are attached to the SGR within Kenya? This article seeks to add Kenyan perspectives to the debate over China's infrastructural loans by examining the range of news media discourses that have emerged around the SGR. Utilizing the theoretical lens of South‐South cooperation and African agency, this study analyzes how material infrastructure becomes meaningful within the context of a political superstructure. For Kenya, this political superstructure is shaped not only by Kenya‐China relations, but also by infrastructural competitions within East Africa, as well as within Kenya itself.     

非洲欠发达地区首都新城开发策略研究

近年来,以各国首都为代表的非洲城市呈现高速扩张态势,由此催生了新城开发的浪潮。本文梳理了非洲新城开发的理论和实践,总结了其背景和驱动力、关键性角色及面临的挑战。以刚果共和国首都布拉柴维尔市东部新城开发实践为例,通过实地调研获取资料,总结其驱动因素,概述了所在国政府、企业、金融机构等的作用,以及其存在的政治经济形式不稳定、土地交易市场不成熟、地质灾害风险等现实挑战。以新城概念规划方案为蓝本,提出设计弹性城市规划方案、建立完善土地管理制度、政企协同开发、多渠道筹备资金、工程设计保障地质安全、建设通达的道路交通系统、各类需求或文化背景人群分片开发住宅区、建造经济便捷的住宅产品、配建符合各方需求的公共服务设施、设立与当地经济发展相适应的产业园区开发策略。     

The Knysna Basin, South Africa: geomorphology, landscape sensitivity and sustainability

The Knysna Basin, a southern Cape catchment, drains into the Knysna estuary. The landscape characteristics are the product of a long geomorphic evolution resulting in high sensitivity to change. Consideration of the geomorphology is followed by examples of impacts on the estuary and adjacent areas. The need for sustainability in the context of development is argued. The paper is a southern African contribution to the landscape sensitivity issue.     

Negotiating Expectations in the Field: Gatekeepers, Research Fatigue and Cultural Biases

This paper considers disjunctures between my expectations and experience of doing dissertation fieldwork, which I conducted in Benin between the autumns of 1997 and 1998. The research examined the nature of women's livelihood strategies and their associated outcomes in terms of material well‐being. I now believe that my feminist worldview, and my growing exhaustion as the project progressed, resulted in my minimising the importance of key aspects of fieldwork in an African context. Specifically, I downplayed the importance of negotiating with male “gatekeepers” in gaining access to the women with whom I wanted to work. While most of the time I was able to manage this well enough, one day, in particular, stands out as a time when I handled these negotiations very poorly. This paper compares the experiences of that day with another much more productive and fruitful one to examine how and why expectations and experience can diverge. A consideration of some of the issues that resulted in the “lost day” might prove instructive for other researchers.