Simulating Carbon Stocks and Fluxes of an African Tropical Montane Forest with an Individual-Based Forest Model

Tropical forests are carbon-dense and highly productive ecosystems. Consequently, they play an important role in the global carbon cycle. In the present study we used an individual-based forest model (FORMIND) to analyze the carbon balances of a tropical forest. The main processes of this model are tree growth, mortality, regeneration, and competition. Model parameters were calibrated using forest inventory data from a tropical forest at Mt. Kilimanjaro. The simulation results showed that the model successfully reproduces important characteristics of tropical forests (aboveground biomass, stem size distribution and leaf area index). The estimated aboveground biomass (385 t/ha) is comparable to biomass values in the Amazon and other tropical forests in Africa. The simulated forest reveals a gross primary production of 24 tcha-1yr-1. Modeling above- and belowground carbon stocks, we analyzed the carbon balance of the investigated tropical forest. The simulated carbon balance of this old-growth forest is zero on average. This study provides an example of how forest models can be used in combination with forest inventory data to investigate forest structure and local carbon balances.

Social motility of African trypanosomes is a property of a distinct life-cycle stage that occurs early in tsetse fly transmission

The protozoan pathogen Trypanosoma brucei is transmitted between mammals by tsetse flies. The first compartment colonised by trypanosomes after a blood meal is the fly midgut lumen. Trypanosomes present in the lumen-designated as early procyclic forms-express the stage-specific surface glycoproteins EP and GPEET procyclin. When the trypanosomes establish a mature infection and colonise the ectoperitrophic space, GPEET is down-regulated, and EP becomes the major surface protein of late procyclic forms. A few years ago, it was discovered that procyclic form trypanosomes exhibit social motility (SoMo) when inoculated on a semi-solid surface. We demonstrate that SoMo is a feature of early procyclic forms, and that late procyclic forms are invariably SoMo-negative. In addition, we show that, apart from GPEET, other markers are differentially expressed in these two life-cycle stages, both in culture and in tsetse flies, indicating that they have different biological properties and should be considered distinct stages of the life cycle. Differentially expressed genes include two closely related adenylate cyclases, both hexokinases and calflagins. These findings link the phenomenon of SoMo in vitro to the parasite forms found during the first 4-7 days of a midgut infection. We postulate that ordered group movement on plates reflects the migration of parasites from the midgut lumen into the ectoperitrophic space within the tsetse fly. Moreover, the process can be uncoupled from colonisation of the salivary glands. Although they are the major surface proteins of procyclic forms, EP and GPEET are not essential for SoMo, nor, as shown previously, are they required for near normal colonisation of the fly midgut.

NMD3 regulates both mRNA and rRNA nuclear export in African trypanosomes via an XPOI-linked pathway

Trypanosomes mostly regulate gene expression through post-transcriptional mechanisms, particularly mRNA stability. However, much mRNA degradation is cytoplasmic such that mRNA nuclear export must represent an important level of regulation. Ribosomal RNAs must also be exported from the nucleus and the trypanosome orthologue of NMD3 has been confirmed to be involved in rRNA processing and export, matching its function in other organisms. Surprisingly, we found that TbNMD3 depletion also generates mRNA accumulation of procyclin-associated genes (PAGs), these being co-transcribed by RNA polymerase I with the procyclin surface antigen genes expressed on trypanosome insect forms. By whole transcriptome RNA-seq analysis of TbNMD3-depleted cells we confirm the regulation of the PAG transcripts by TbNMD3 and using reporter constructs reveal that PAG1 regulation is mediated by its 5'UTR. Dissection of the mechanism of regulation demonstrates that it is not dependent upon translational inhibition mediated by TbNMD3 depletion nor enhanced transcription. However, depletion of the nuclear export factors XPO1 or MEX67 recapitulates the effects of TbNMD3 depletion on PAG mRNAs and mRNAs accumulated in the nucleus of TbNMD3-depleted cells. These results invoke a novel RNA regulatory mechanism involving the NMD3-dependent nuclear export of mRNA cargos, suggesting a shared platform for mRNA and rRNA export.

Resilient Adaptation to Climate Change in African Agriculture

Africa’s agriculture faces varying climate change impacts which mainly worsen production conditions and adversely affect its economies. Adaptations thus need to build the resilience of farming systems. Using “resilient adaptation” as a concept, this study analyses how adaptations at farm and policy/institutional-levels contribute to the resilience of Sub-Saharan African agriculture. The developed tool, “the Resilience Check”, provides socio-economic data which complements existing adaptation tools. The underlying development gaps such as insecure property rights, poverty, low self-organisation, inadequate climate data and infrastructure limit resilient adaptations. If farmers could implement recommended practices, existing measures and improved crops can address most impacts expected in the medium-term. However, resource use efficiency remains critical for all farm management types. Development-oriented adaptation measures are needed to provide the robust foundations for building resilience. Reaching the very poor remains a challenge and the externally driven nature of many interventions raises concern about their sustainability. The study recommends practical measures such as decentralising various services and integrating the action plans of the multilateral environmental agreements into one national action plan.

Legal Aspects of Sino-­African Tied Aid: The Art of Playing with a Legal Grey Area

Sino-African trade has seen a fifty-fold increase in the years 1999 to 2008. In some African regions, particularly in sub-Saharan Africa, China has even replaced the US as the most important trading partner today. But China holds not a single FTA on the African continent, while other major trading partners of African economies rely on an extensive framework of different trade agreements. What is, thus, the legal basis of the recent increase of Sino-African trade? Interestingly, Sino-African trade has seen a particularly strong increase in countries that have entered into tied aid agreements with China. These agreements are commonly known under the term ‘Angola-Model’ and consist of a multifaceted network of barter-trading-systems, aspects of tied aid and concessions for oil and other commodities linked with a state loan. It is likely that these agreements have an impact on the trade-flows between African countries and China. This paper discusses the legal character of this new form of economic cooperation, or modern version of tied aid. Critical legal aspects related to this form of tied aid refer to violation of the principle of most-favoured nation (MFN), illegitimate export subsidies, market access, public procurement and transparency in the international trading system. However, despite the recent outcry of the foremost Western community against the strategy of the Chinese government on the African continent, the practice of the Angola-Model based tied aid is not entirely new, and neither is it against the law. The case of tied aid is situated in a legal grey area that should be examined thoroughly in order to strengthen the international trading system and to support developing countries in their attempt to gain from tied aid arrangements.

Fragmentation of Natural Resources Management: Experiences from Lake Kariba

This book is an output of the Defragmenting African Resources Management (DARMA) Project. Lake Kariba and its environs are a complex transboundary ecosystem with multiple, competing and often contested resource uses. The individual chapters in the book describe the current sectoral approach to natural resource management, the interconnections, and the need to adopt an ecosystem approach. The book is an essential reading for students, researchers, academics and managers in the environmental and natural resources sectors interested in advancing the ecosystems approach in management of commons in general and Southern Africa in particular. - See more at: http://www.plaas.org.za/plaas-publication/DARMA-Kariba-LV#sthash.7giSiWiB.dpuf

Dimensions of Global Change in African Mountains: The Example of Mount Kenya

This paper discusses the effects of global change in African mountains, with the example of Mount Kenya. The geographical focus is the northwestern, semi-arid foot zone of the mountain (Laikipia District). Over the past 50 years, this area has experienced rapid and profound transformation, the respective processes of which are all linked to global change. The main driving forces behind these processes have been political and economic in nature. To these an environmental change factor has been added in recent years – climate change. After introducing the area of research, the paper presents three dimensions of global change that are manifested in the region and largely shape its development: Socio-political change, economic change, environmental change. For the regions northwest of Mount Kenya, climate models predict important changes in rainfall distribution that will have a profound impact on freshwater availability and management. The results presented here are based on research undertaken northwest of Mount Kenya within the framework of a series of long-term Kenyan-Swiss research programmes that began in the early 1980s.

Ethnography of a Land Grab and Gendered Coping Strategies in Northern Sierra Leone

Despite an increased scientific interest in the relatively new phenomenon of large-scale land acquisition (LSLA), data on the implementation of such projects and their impacts on the heterogeneous group of project-affected people are still sparse and superficial. Our ethnographic in-depth research on a Swiss-based bioenergy project in Sierra Leone generates well-documented data and provides insights into gendered access to land and wage employment. In the area where the project is located, customary land tenure applies. Thereby, women are structurally discriminated since they are not entitled to own land. However, user rights grant women and non-landowning men access to land and associated resources. Following the investing development banks’ guidelines, the company considered the local customary law when implementing its project. Nevertheless, the company only consulted and compensated landowners although women and non-landowning men could previously benefit from acquired land as well. Moreover, the company’s policy to enhance employment possibilities for women is barely implemented, and only few local women are hired. In order to cope with the transformed situation some women and non-landowning men continue to engage in subsistence farming on a reduced area of land. Others are involved in informal petty-trade or cooking food for the labourers whereby they subsidize the capitalist production of the company. In one village, women resisted additional land takes of the company. Acting within the framework of a specific power constellation on community level and simultaneously accommodating their claims within policy paradigms on transnational level, they were able to force a landowner to refuse leasing land to the company.