Afrika südlich der Sahara
365 search hits
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Jahresbericht 2012 / ZIAF - Zentrum für interdisziplinäre Afrikaforschung
(2013)
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Jahresbericht ... / ZIAF - Zentrum für interdisziplinäre Afrikaforschung
(2013)
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Scaling-up what works : experimental evidence on external validity in Kenyan education
(2013)
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Tessa Bold
Mwangi Kimenyi
Germano Mwabu
Alice Ng'ang'a
Justin Sandefur
- The recent wave of randomized trials in development economics has provoked criticisms regarding external validity. We investigate two concerns—heterogeneity across beneficiaries and implementers—in a randomized trial of contract teachers in Kenyan schools. The intervention, previously shown to raise test scores in NGO- led trials in Western Kenya and parts of India, was replicated across all Kenyan provinces by an NGO and the government. Strong effects of shortterm contracts produced in controlled experimental settings are lost in weak public institutions: NGO implementation produces a positive effect on test scores across diverse contexts, while government implementation yields zero effect. The data suggests that the stark contrast in success between the government and NGO arm can be traced back to implementation constraints and political economy forces put in motion as the program went to scale.
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Modelling the impact of future climate and land use change on vegetation patterns, plant diversity and provisioning ecosystem services in West Africa
(2012)
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Jonathan Heubes
- Global climate change and land use change will not only alter entire ecosystems and
biodiversity patterns, but also the supply of ecosystem services. A better understanding
of the consequences is particularly needed in under-investigated regions, such as West
Africa. The projected environmental changes suggest negative impacts on nature, thus
representing a threat to the human well-being. However, many effects caused by climate
and land use change are poorly understood so far.
Thus, the main objective of this thesis was to investigate the impact of climate and
land use change on vegetation patterns, plant diversity and important provisioning
ecosystem services in West Africa. The three different aspects are separately explored
and build the chapters of this thesis. The findings help to improve our understanding of
the effects of environmental change on ecosystems and human well-being.
In the first study, the main objectives were to model trends and the extent of
future biome shifts in West Africa that may occur by 2050. Also, I modelled a trend in
West African tree cover change, while accounting for human impact. Additionally,
uncertainty in future climate projections was evaluated to identify regions with reliable
trends and regions where the impacts remain uncertain. The potential future spatial
distributions of desert, grassland, savanna, deciduous and evergreen forest were
modelled in West Africa, using six bioclimatic models. Future tree cover change was
analysed with generalized additive models (GAMs). I used climate data from 17 general
circulation models (GCMs) and included human population density and fire intensity to
model tree cover. Consensus projections were derived via weighted averages to: 1)
reduce inter-model variability, and 2) describe trends extracted from different GCM
projections. The strongest predicted effect of climate change was on desert and
grasslands, where the bioclimatic envelope of grassland is projected to expand into the
Sahara desert by an area of 2 million km2. While savannas are predicted to contract in the
south (by 54 ± 22 × 104 km2), deciduous and evergreen forest biomes are expected to
expand (64 ± 13 × 104 km2 and 77 ± 26 × 104 km2). However, uncertainty due to different
GCMs was particularly high for the grassland and the evergreen forest biome shift.
Increasing tree cover (1–10%) was projected for large parts of Benin, Burkina Faso, Côte d’Ivoire, Ghana and Togo, but a decrease was projected for coastal areas (1–20%).
Furthermore, human impact negatively affected tree cover and partly changed the
direction of the projected climate-driven tendency from increase to decrease.
Considering climate change alone, the model results of potential vegetation (biomes)
showed a ‘greening’ trend by 2050. However, the modelled effects of human impact
suggest future forest degradation. Thus, it is essential to consider both climate change
and human impact in order to generate realistic future projections on woody cover.
The second study focused on the impact and the interplay of future (2050) climate
and land use change on the plant diversity of the West African country Burkina Faso.
Synergistic forecasts for this country are lacking to date. Burkina Faso covers a broad
bioclimatic gradient which causes a similar gradient in plant diversity. Thus, the impact of
climate and land use change can be investigated in regions with different levels of species
richness. The LandSHIFT model from the Centre of Environmental System research CESR
(Kassel, Germany) was adapted for this study to derive novel regional, spatially explicit
future (2050) land use simulations for Burkina Faso. Additionally, the simulations include
different assumptions on the technological developments in the agricultural sector. Oneclass
support vector machines (SVMs), a machine learning method, were performed with
these land use simulations together with current and future (2050) climate projections at
a 0.1° resolution (cell: ~ 10 × 10 km). The modelling results showed that the flora of
Burkina Faso will be primarily negatively impacted by future climate and land use
changes. The species richness will be significantly reduced by 2050 (P < 0.001, paired
Wilcoxon signed-rank test). However, contrasting latitudinal patterns were found.
Although climate change is predicted to cause species loss in the more humid regions in
Southern Burkina Faso (~ 200 species per cell), the model projects an increase of species
richness in the Sahel. However, land use change is expected to suppress this increase to
the current species diversity level, depending on the technological developments. Climate
change is a more important threat to the plant diversity than land use change under the
assumption of technological stagnation in the agricultural sector.
Overall, the study highlights the impact and interplay of future climate and land
use change on plant diversity along a broad bioclimatic gradient in West Africa.
Furthermore, the results suggest that plant diversity in dry and humid regions of the tropics might generally respond differently to climate and land use change. This pattern
has not been detected by global studies so far.
Several of the plant species in West Africa significantly contribute to the
livelihoods of the population. The plants provide so-called non-timber forest products
(NTFPs), which are important provisioning ecosystem services. However, these services
are also threatened by environmental change. Thus, the third study aimed at developing a
novel approach to assess the impacts of climate and land use change on the economic
benefits derived from NTFPs. This project was carried out in cooperation with Katja
Heubach (BiK-F) who provided data on household economics. These data include 60
interviews that were conducted in Northern Benin on annual quantities and revenues of
collected NTFPs from the three most important savanna tree species: Adansonia digitata,
Parkia biglobosa and Vitellaria paradoxa. The current market prices of the NTFPs were
derived from respective local markets. To assess current and future (2050) occurrence
probabilities of the three species, I calibrated niche-based models with climate data (from
Miroc3.2medres) and land use data (LandSHIFT) at a 0.1° resolution (cell: ~ 10 × 10 km).
Land use simulations were taken from the previous study on plant diversity. Three
different niche-based models were used: 1) generalized additive models (regression
method), 2) generalized boosting models (machine learning method), and 3) flexible
discriminant analysis (classification method). The three model simulations were averaged
(ensemble forecasting) to increase the robustness of the predictions. To assess future
economic gains and losses, respectively, the modelled species’ occurrence probabilities
were linked with the spatially assigned monetary values. Highest current annual benefits
are obtained from V. paradoxa (54,111 ± 28,126 US$/cell), followed by P. biglobosa
(32,246 ± 16,526 US$/cell) and A. digitata (9,514 ± 6,243 US$/cell). However, in the
prediction large areas will lose up to 50% of their current economic value by 2050.
Vitellaria paradoxa and Parkia biglobosa, which currently reveal the highest economic
benefits, are heavily affected. Adansonia digitata is negatively affected less strongly by
environmental change and might regionally even supply increasing economic benefits, in
particular in the west and east of the investigation area. We conclude that adaptive
strategies are needed to create alternative income opportunities, in particular for women
that are responsible for collecting the NTFPs. The findings provide a benchmark for local policy-makers to economically compare different land use options and adjust existing
management strategies for the near future.
Overall, this thesis improves our understanding of the impacts of climate and land
use changes on West African vegetation patterns, plant diversity and provisioning
ecosystem services. Climate change had spatially varying impacts (positive and negative
effects) on the vegetation cover and plant diversity, while predominantly negative effects
resulted from human pressure. Regional contrasting impacts of environmental change
were also found considering the provisioning ecosystem services.
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Grammatische Beschreibung des Nyam - eine westtschadische Minoritätensprache
(2012)
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Heike Andreas
- Die vorliegende Arbeit stellt die Phonologie, Morphologie und Syntax des Nyam, einer westtschadischen Minoritätensprache Nordostnigerias, dar. Es handelt sich um eine Erstbeschreibung, die im Zuge eines von der DFG finanzierten Projekts mit dem Titel „Das Nyam – Dokumentation einer westtschadischen Minoritätensprache“ durchgeführt werden konnte.
Ziel dieser Arbeit ist es, eine grammatische Beschreibung des Nyam – eine bis dato unbekannte Sprache – vorzulegen. Mit nur ca. 5000 Sprechern ist sie schon im Hinblick auf die geringe Zahl, vor allem aber durch die regionale Dominanz der mit ihr genetisch verwandten Verkehrssprache Hausa, akut in ihrer Existenz bedroht. Zudem befindet sich diese Sprache in einer geographisch exponierten Lage, d.h. sie ist weitgehend von Benue-Kongo-Sprachen umgeben. Vor diesem Hintergrund kann die Dokumentation des Nyam einerseits den Nyam-Sprechern selbst zur Erhaltung ihrer kulturellen Identität und der damit verbundenen Traditionen dienen. Andererseits ist dieser wissenschaftliche Beitrag als Ergänzung zu den noch fehlenden Grammatiken innerhalb der tschadischen Sprachfamilie und im Besonderen der Bole-Tangale-Sprachgruppe zu sehen und kann als Grundstein zukünftiger Forschungen für vergleichende Arbeiten mit den benachbarten Benue-Kongo-Sprachen betrachtet werden.
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Flora et Vegetatio Sudano-Sambesica : Volume 15 - 2012
(2012)
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Climate change, environment and migration in the Sahel : selected issues with a focus on Senegal and Mali
(2012)
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Über Geburt, Blüte und Kollaps der Nok-Kultur im subsaharischen Afrika
(2012)
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Ulrike Jaspers
- DFG gibt weitere 1,6 Millionen Euro – Prof. Breunig und sein Team können
ihre Forschungen bis 2020 fortsetzen – Ausstellung im Liebieghaus geplant
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Den Ressourcenfluch zum Segen machen : Perspektiven afrikanischer und europäischer Autoren
(2012)
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Tim Bittiger
- Rezension zu: Jürgen Runge, James Shikwati (Hrsg.) Geological Resources and Good Governance in Sub-Saharan Africa: Holistic Approaches to Transparency and Sustainable Development in the Extractive Sect. Taylor & Francis, London 2011, ISBN 978-0-415-58267-4, 292 Seiten, Hardcover, 16 Abbildungen, 16 Farbtabellen, 80,99 Euro.
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Eduard Pechuël-Loesche : Tagebücher von der Loangoküste (Zentralafrika) (24.2.1875 – 5.5.1876) : sowie Stichworte zu den Tagebuchaufzeichnungen vom 10.7. bis 19.8.1874 ; mit 31 Aquarellen von Eduard Pechuël-Loesche
(2011)
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Eduard Pechuel-Loesche
- Reisetagebücher des deutschen Afrika-Forschers Moritz Eduard Pechuël-Loesche (1840-1913).
