scholarly journals Are the Fouta Djallon Highlands Still the Water Tower of West Africa?

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2968
Author(s):  
Luc Descroix ◽  
Bakary Faty ◽  
Sylvie Paméla Manga ◽  
Ange Bouramanding Diedhiou ◽  
Laurent A. Lambert ◽  
...  
Keyword(s):  
West Africa ◽  
Vegetation Cover ◽  
Large Share ◽  
Slow Increase ◽  
Surface Water Resources ◽  
Subsequent Decrease ◽  
Important Trend ◽  
Fouta Djallon ◽  
Water Holding

A large share of surface water resources in Sahelian countries originates from Guinea’s Fouta Djallon highlands, earning the area the name of “the water tower of West Africa”. This paper aims to investigate the recent dynamics of the Fouta Djallon’s hydrological functioning. The evolution of the runoff and depletion coefficients are analyzed as well as their correlations with the rainfall and vegetation cover. The latter is described at three different space scales and with different methods. Twenty-five years after the end of the 1968–1993 major drought, annual discharges continue to slowly increase, nearly reaching a long-term average, as natural reservoirs which emptied to sustain streamflows during the drought have been replenishing since the 1990s, explaining the slow increase in discharges. However, another important trend has been detected since the beginning of the drought, i.e., the increase in the depletion coefficient of most of the Fouta Djallon upper basins, as a consequence of the reduction in the soil water-holding capacity. After confirming the pertinence and significance of this increase and subsequent decrease in the depletion coefficient, this paper identifies the factors possibly linked with the basins’ storage capacity trends. The densely populated areas of the summit plateau are also shown to be the ones where vegetation cover is not threatened and where ecological intensification of rural activities is ancient.

Long term evaluation of green vegetation cover dynamic in the Atacora Mountain chain (Togo) and its relation to carbon sequestration in West Africa

2015 ◽  
Vol 12 (4) ◽  
pp. 921-934 ◽  
Author(s):  
Fousseni Folega ◽  
Yao Agbélessessi Woegan ◽  
Dourma Marra ◽  
Kperkouma Wala ◽  
Komlan Batawila ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
West Africa ◽  
Vegetation Cover ◽  
Green Vegetation ◽  
Term Evaluation ◽  
Mountain Chain

Slave Traders by Invitation

2018 ◽  
Author(s):  
Finn Fuglestad
Keyword(s):  
West Africa ◽  
Slave Trade ◽  
Human Settlement ◽  
Local Setting ◽  
Slave Traders ◽  
Atlantic Slave Trade

The small Slave Coast between the river Volta and Lagos, and especially its central part around Ouidah, was the epicentre of the slave trade in West Africa. But it was also an inhospitable, surf-ridden coastline, subject to crashing breakers and devoid of permanent human settlement. Nor was it easily accessible from the interior due to a lagoon which ran parallel to the coast. The local inhabitants were not only sheltered against incursions from the sea, but were also locked off from it. Yet, paradoxically, this small coastline witnessed a thriving long-term commercial relationship between Europeans and Africans, based on the trans-Atlantic slave trade. How did it come about? How was it all organized? Dahomey is usually cited as the Slave Coast's archetypical slave raiding and slave trading polity. An originally inland realm, it was a latecomer to the slave trade, and simply incorporated a pre-existing system by dint of military prowess, which ultimately was to prove radically counterproductive. Dahomey, which never controlled more than half of the region we call the Slave Coast, represented an anomaly in the local setting, an anomaly the author seeks to define and to explain.

scholarly journals Short- and long-term effects of ponderosa pine fuel treatments intersected by the Egley Fire Complex, Oregon, USA

Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Jessie M. Dodge ◽  
Eva K. Strand ◽  
Andrew T. Hudak ◽  
Benjamin C. Bright ◽  
Darcy H. Hammond ◽  
...  
Keyword(s):  
Prescribed Fire ◽  
Vegetation Cover ◽  
Tree Density ◽  
Tree Canopy ◽  
Fuel Treatments ◽  
Dead Tree ◽  
High Severity ◽  
Short And Long Term ◽  
One Year

Abstract Background Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after the 2007 Egley Fire Complex in Oregon, USA. We also assessed short- and long-term fuel treatment impacts on field-measured attributes one and nine years post fire. Results One-year post-fire burn severity (dNBR) was lower in treated than in untreated sites across the Egley Fire Complex. Annual NBR trends showed that treated sites nearly recovered to pre-fire values four years post fire, while untreated sites had a slower recovery rate. Time since treatment and dNBR significantly predicted tree canopy and understory green vegetation cover in 2008, suggesting that tree canopy and understory vegetation cover increased in areas that were treated recently pre fire. Live tree density was more affected by severity than by pre-fire treatment in either year, as was dead tree density one year post fire. In 2008, neither treatment nor severity affected percent cover of functional groups (shrub, graminoid, forb, invasive, and moss–lichen–fungi); however, by 2016, shrub, graminoid, forb, and invasive cover were higher in high-severity burn sites than in low-severity burn sites. Total fuel loads nine years post fire were higher in untreated, high-severity burn sites than any other sites. Tree canopy cover and density of trees, saplings, and seedlings were lower nine years post fire than one year post fire across treatments and severity, whereas live and dead tree basal area, understory surface cover, and fuel loads increased. Conclusions Pre-fire fuel treatments effectively lowered the occurrence of high-severity wildfire, likely due to successful pre-fire tree and sapling density and surface fuels reduction. This study also quantified the changes in vegetation and fuels from one to nine years post fire. We suggest that low-severity wildfire can meet prescribed fire management objectives of lowering surface fuel accumulations while not increasing overstory tree mortality.

scholarly journals Vegetation change (1988–2010) in Camdeboo National Park (South Africa), using fixed-point photo monitoring: The role of herbivory and climate

Koedoe ◽  
2013 ◽  
Vol 55 (1) ◽  
Author(s):  
Mmoto L. Masubelele ◽  
Michael T. Hoffman ◽  
William Bond ◽  
Peter Burdett
Keyword(s):  
South Africa ◽  
Fixed Point ◽  
National Parks ◽  
Vegetation Cover ◽  
National Park ◽  
Vegetation Change ◽  
Growth Form ◽  
Annual Rainfall ◽  
Management Interventions

Fixed-point photo monitoring supplemented by animal census data and climate monitoring potential has never been explored as a long-term monitoring tool for studying vegetation change in the arid and semi-arid national parks of South Africa. The long-term (1988–2010), fixed-point monitoring dataset developed for the Camdeboo National Park, therefore, provides an important opportunity to do this. Using a quantitative estimate of the change in vegetation and growth form cover in 1152 fixed-point photographs, as well as series of step-point vegetation surveys at each photo monitoring site, this study documented the extent of vegetation change in the park in response to key climate drivers, such as rainfall, as well as land use drivers such as herbivory by indigenous ungulates. We demonstrated the varied response of vegetation cover within three main growth forms (grasses, dwarf shrubs [< 1 m] and tall shrubs [> 1 m]) in three different vegetation units and landforms (slopes, plains, rivers) within the Camdeboo National Park since 1988. Sites within Albany Thicket and Dwarf Shrublands showed the least change in vegetation cover, whilst Azonal vegetation and Grassy Dwarf Shrublands were more dynamic. Abiotic factors such as drought and flooding, total annual rainfall and rainfall seasonality appeared to have the greatest influence on growth form cover as assessed from the fixed-point photographs. Herbivory appeared not to have had a noticeable impact on the vegetation of the Camdeboo National Park as far as could be determined from the rather coarse approach used in this analysis and herbivore densities remained relatively low over the study duration.Conservation implications: We provided an historical assessment of the pattern of vegetation and climatic trends that can help evaluate many of South African National Parks’ biodiversity monitoring programmes, especially relating to habitat change. It will help arid parks in assessing the trajectories of vegetation in response to herbivory, climate and management interventions.

scholarly journals Virus-Vectored Ebola Vaccines

Acta Naturae ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 4-11 ◽  
Author(s):  
I. V. Dolzhikova ◽  
E. A. Tokarskaya ◽  
A. S. Dzharullaeva ◽  
A. I. Tukhvatulin ◽  
D. V. Shcheblyakov ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Immune Response ◽  
West Africa ◽  
Protective Immunity ◽  
Viral Vectors ◽  
Ebola Virus ◽  
Virus Disease ◽  
Genetically Engineered ◽  
Preclinical Trials

The Ebola virus disease (EVD) is one of the most dangerous infections affecting humans and animals. The first EVD outbreaks occurred in 1976 in Sudan and Zaire. Since then, more than 20 outbreaks have occurred; the largest of which (2014-2016) evolved into an epidemic in West Africa and claimed the lives of more than 11,000 people. Although vaccination is the most effective way to prevent epidemics, there was no licensed vaccine for EVD at the beginning of the latest outbreak. The development of the first vaccines for EVD started in 1980 and has come a long technological way, from inactivated to genetically engineered vaccines based on recombinant viral vectors. This review focuses on virus-vectored Ebola vaccines that have demonstrated the greatest efficacy in preclinical trials and are currently under different phases of clinical trial. Particular attention is paid to the mechanisms of immune response development, which are important for protection from EVD, and the key vaccine parameters necessary for inducing long-term protective immunity against EVD.

Inscriptions on the Wall

Out of War ◽  
2018 ◽  
pp. 237-255
Author(s):  
Mariane C. Ferme
Keyword(s):  
Cold War ◽  
West Africa ◽  
Sierra Leone ◽  
Rural Landscape ◽  
People’S Republic Of China ◽  
People's Republic Of China ◽  
Republic Of China ◽  
Competing Interests

Drawing on the image of a “Chinese Store” in the author’s photographic archive, this chapter addresses past traces of Chinese presences in remote reaches of the rural landscape of Sierra Leone—and in commodities widely circulating in the country—in contrast to the more monumental scale of present-day Chinese projects in African states. Here Cold War alliances and competing interests of two Chinas (Taiwan and the People’s Republic of China) superimpose themselves on an archaeology of Chinese presence in West Africa that reaches back to the long term.

scholarly journals Changes in Net Global Surface Water Area Since 1985

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 69
Author(s):  
Zahra Kalantari ◽  
Sonia Borja ◽  
Georgia Destouni
Keyword(s):  
Surface Water ◽  
Ecosystem Functioning ◽  
Water Allocation ◽  
Land Use Changes ◽  
Water Area ◽  
Aral Sea ◽  
Surface Water Resources ◽  
Global Surface ◽  
Spatial And Temporal Characteristics

Spatial and temporal characteristics of surface water resources (e.g., extension, connectivity, seasonality) are key elements in water allocation, climate and hydrological regulation, ecosystem functioning, and the food-energy-water nexus. Changes in surface water area due to losses/gains to land could strongly affect these processes on different scales. Previous findings on changes in the Earth’s surface water area are contradictory. Based on water–land year classification datasets, we estimated global surface water area changes between 1985–2000 and 2001–2015. We found a net global gain in surface water of 100,454 km2, attributable to a large net gain in seasonal water (83,329 km2) and a small net gain in permanent water (17,125 km2). In general, net changes were highly heterogeneous in space, with local exceptions of clear drying and wetting trends, e.g., the Aral Sea and Quill Lakes, respectively. These findings raise multiple questions as to why seasonal water gains dominate and how different intertwined drivers (e.g., hydroclimate and human-induced water–land use changes) shape the distribution of the Earth’s surface water. Understanding these long-term changes is essential to predicting water-related pressures and prioritizing management decisions.

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