scholarly journals Soil carbon persistence linked to mineralogy across sub-Saharan Africa

2021 ◽  
Author(s):  
Sophie F. von Fromm ◽  
Alison M. Hoyt ◽  
Benjamin M. Butler ◽  
Asmeret Asefaw Berhe ◽  
Sebastian Doetterl ◽  
...  
Keyword(s):  
Soil Properties ◽  
Soil Carbon ◽  
Aridity Index ◽  
Soil Survey ◽  
Sub Saharan Africa ◽  
Mean Annual Temperature ◽  
Soil Mineralogy ◽  
Diverse Range ◽  
Model Calculations ◽  
Sub Saharan

<p>Recent compilations of global soil radiocarbon data suggest that current Earth System Models underestimate the mean age of soil carbon (C). The discrepancy between data-derived estimates and model calculations might be due to an inadequate representation of processes that control C persistence in soils – especially in understudied regions.</p><p>Here, we investigate the relationships between soil mineralogy, soil properties, climate and radiocarbon (Δ<sup>14</sup>C) in soils sampled as part of a comprehensive soil survey (AfSIS) for sub-Saharan Africa. A total of 510 samples were analyzed, comprised of soils collected from two depths (0–20 cm and 20–50 cm) at 30 sites in 14 countries. To determine soil mineralogy, we analyzed X-ray powder diffraction (XRPD) data, which provides a precise and detailed mineralogical signature of each soil sample. The studied soil profiles vary greatly in their mineralogy, reflecting a diverse range of parent materials and soil forming factors.</p><p>The median soil C age is 182 years in the topsoils and 563 years in the subsoils, corresponding to a total Δ<sup>14</sup>C value range of -432 to 95 ‰. In general, Δ<sup>14</sup>C values decrease (older mean C ages) with increasing clay particle size fractions. This corresponds to an increase in short range-order minerals expressed as oxalate-extractable aluminum and iron (Al<sub>ox</sub> and Fe<sub>ox</sub>). Separately, mineralogically defined variables – derived from the XRPD data using principal component analysis – are found to correlate strongly with a range of soil properties (pH, weathering status, exchangeable calcium, Al<sub>ox</sub> and Fe<sub>ox</sub>, and soil texture) and climatic variables (aridity index and mean annual temperature). This provides a holistic assessment of the processes that have formed each soil along with the properties that it currently exhibits. Our analyses with random forests show that these XRPD-derived mineralogical variables alone can explain up to 30% of the variation in Δ<sup>14</sup>C across sub-Saharan Africa. They also allow the identification of specific minerals that contribute to this variation and how they are linked to the C mean age of the soil. In conclusion, our results suggest that soil mineral data can help to better understand C persistence in subtropical and tropical soils.</p>

Soil carbon sequestration in sub-Saharan Africa: a review

2005 ◽  
Vol 16 (1) ◽  
pp. 53-71 ◽  
Author(s):  
T.-G. Vågen ◽  
R. Lal ◽  
B. R. Singh
Keyword(s):  
Carbon Sequestration ◽  
Soil Carbon ◽  
Soil Carbon Sequestration ◽  
Sub Saharan Africa ◽  
Sub Saharan

scholarly journals Writing African History in France during the Colonial Era

2018 ◽  
Author(s):  
Sophie Dulucq
Keyword(s):  
19Th Century ◽  
Point Of View ◽  
Sub Saharan Africa ◽  
African History ◽  
Colonial History ◽  
Colonial Era ◽  
Diverse Range ◽  
Collège De France ◽  
History Of ◽  
Sub Saharan

In the second half of the 19th century, French imperial expansion in the south of the Sahara led to the control of numerous African territories. The colonial rule France imposed on a diverse range of cultural groups and political entities brought with it the development of equally diverse inquiry and research methodologies. A new form of scholarship, africanisme, emerged as administrators, the military, and amateur historians alike began to gather ethnographic, linguistic, judicial, and historical information from the colonies. Initially, this knowledge was based on expertise gained in the field and reflected the pragmatic concerns of government rather than clear, scholarly, interrogation in line with specific scientific disciplines. Research was thus conducted in many directions, contributing to the emergence of the so-called colonial sciences. Studies by Europeans scholars, such as those carried out by Maurice Delafosse and Charles Monteil, focused on West Africa’s past. In so doing, the colonial context of the late 19th century reshaped the earlier orientalist scholarship tradition born during the Renaissance, which had formerly produced quality research about Africa’s past, for example, about medieval Sudanese states. This was achieved through the study of Arabic manuscripts and European travel narratives. In this respect, colonial scholarship appears to have perpetuated the orientalist legacy, but in fact, it transformed the themes, questions, and problems historians raised. In the first instance, histoire coloniale (colonial history) focused the history of European conquests and the interactions between African societies and their colonizers. Between 1890 and 1920 a network of scientists, including former colonial administrators, struggled to institutionalize colonial history in metropolitan France. Academic positions were established at the Sorbonne and the Collège de France. Meanwhile, research institutions were created in French West Africa (Afrique Occidentale Française [AOF]), French Equatorial Africa (Afrique Équatoriale Française [AEF]), and Madagascar between 1900 and the 1930s. Yet, these imperial and colonial concerns similarly coincided with the rise of what was then known as histoire indigène (native history) centered on the precolonial histories of African societies. Through this lens emerged a more accurate vision of the African past, which fundamentally challenged the common preconception that the continent had no “history.” This innovative knowledge was often co-produced by African scholars and intellectuals. After the Second World War, interest in colonial history started to wane, both from an intellectual and a scientific point of view. In its place, the history of sub-Saharan Africa gained popularity and took root in French academic institutions. Chairs of African history were created at the Sorbonne in 1961 and 1964, held by Raymond Mauny and Hubert Deschamps, respectively, and in 1961 at the École Pratique des Hautes Études, fulfilled by Henri Brunschwig. African historians, who were typically trained in France, began to challenge the existing European scholarship. As a result, some of the methods and sources that had been born in the colonial era, were adopted for use by a new generation of historians, whose careers blossomed after the independences.

scholarly journals The 4 per 1000 goal and soil carbon storage under agroforestry and conservation agriculture systems in sub-Saharan Africa

2019 ◽  
Vol 188 ◽  
pp. 16-26 ◽  
Author(s):  
Marc Corbeels ◽  
Rémi Cardinael ◽  
Krishna Naudin ◽  
Hervé Guibert ◽  
Emmanuel Torquebiau
Keyword(s):  
Soil Carbon ◽  
Carbon Storage ◽  
Conservation Agriculture ◽  
Sub Saharan Africa ◽  
Soil Carbon Storage ◽  
Sub Saharan ◽  
Agriculture Systems

Human Immunodeficiency Virus–Related Gastrointestinal Pathology: A Southern Africa Perspective With Review of the Literature (Part 2: Neoplasms and Noninfectious Disorders)

2012 ◽  
Vol 136 (3) ◽  
pp. 316-323 ◽  
Author(s):  
Tomas Slavik
Keyword(s):  
Human Immunodeficiency Virus ◽  
Southern Africa ◽  
Sub Saharan Africa ◽  
Gastrointestinal Disorders ◽  
Published Data ◽  
Diverse Range ◽  
Gastrointestinal Pathology ◽  
Esophageal Ulceration ◽  
Immunodeficiency Virus ◽  
Sub Saharan

Context.—Human immunodeficiency virus (HIV) infection is rife in sub-Saharan Africa and in southern Africa in particular. Despite the increasing availability of antiretroviral therapy in this region, HIV-associated neoplasms remain common and frequently involve the gastrointestinal tract, which may also demonstrate other noninfectious, HIV-related pathology. Objective.—To review the histopathologic findings and distinguishing features of neoplastic and noninfectious, HIV-associated gastrointestinal disorders in southern Africa and relate those findings to the documented international literature. Data Sources.—The available literature on this topic was reviewed and supplemented with personal experience in a private histopathology practice in South Africa. Conclusions.—In southern Africa, a diverse range of HIV-related neoplasms and noninfectious gastrointestinal disorders is seen, but published data for the region are scarce. The gastrointestinal disorders include drug-associated pathology, gastrointestinal manifestations of the immune reconstitution inflammatory syndrome, idiopathic chronic esophageal ulceration, and the controversial entity of HIV enteropathy.

Food Crop Yields and Soil Properties under Population Pressure in Sub-Saharan Africa: the Case of Cassava in Southeast Nigeria

1997 ◽  
Vol 26 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Charles L. A. Asadu ◽  
Anselm A. Enete
Keyword(s):  
Soil Properties ◽  
Crop Yields ◽  
Exchange Capacity ◽  
Parent Material ◽  
Sub Saharan Africa ◽  
Population Pressure ◽  
Southeastern Nigeria ◽  
Cassava Root ◽  
Sub Saharan ◽  
Major Factors

Cassava root yields in three villages in southeastern Nigeria with marked differences in population pressure were related to soil properties using various models. The soils of the low population village, being formed from a different parent material, were more fertile than those of the medium and high population villages and cassava root yields were significantly higher in this village. The specific soil properties which appeared to promote cassava yields included pH and contents of Mn, silt and sand. Absolute values of exchangeable Mg, Ca, acidity and effective cation exchange capacity, although not significantly correlated with root yield, were also most favourable in the low population village. Thus inherent differences in soil properties rather than population pressure may be the major factors contributing to variations in cassava root yields in these villages.

scholarly journals Predicting Suitable Habitats of the African Cherry (Prunus africana) under Climate Change in Tanzania

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 988
Author(s):  
Richard A. Giliba ◽  
Genesis Tambang Yengoh
Keyword(s):  
Climate Change ◽  
Policy Implications ◽  
Sub Saharan Africa ◽  
Mean Annual Temperature ◽  
Habitat Distribution ◽  
Prunus Africana ◽  
Representative Concentration Pathways ◽  
Sub Saharan ◽  
Suitable Habitats ◽  
The Impact

Prunus africana is a fast-growing, evergreen canopy tree with several medicinal, household, and agroforestry uses, as well as ecological value for over 22 countries in sub-Saharan Africa. This species is under immense pressure from human activity, compounding its vulnerability to the effects of climate change. Predicting suitable habitats for P. africana under changing climate is essential for conservation monitoring and planning. This study intends to predict the impact of climate change on the suitable habitats for the vulnerable P. africana in Tanzania. We used maximum entropy modeling to predict future habitat distribution based on the representative concentration pathways scenario 4.5 and 8.5 for the mid-century 2050 and late-century 2070. Species occurrence records and environmental variables were used as a dependent variable and predictor variables respectively. The model performance was excellent with the area under curve (AUC) and true skill statistics (TSS) values of 0.96 and 0.85 respectively. The mean annual temperature (51.7%) and terrain ruggedness. index (31.6%) are the most important variables in predicting the current and future habitat distribution for P. africana. Our results show a decrease in suitable habitats for P. africana under all future representative concentration pathways scenario when compared with current distributions. These results have policy implications for over 22 countries of sub-Saharan Africa that are facing problems associated with the sustainability of this species. Institutional, policy, and conservation management approaches are proposed to support sustainable practices in favor of P. africana.

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