Biodiversity of Vegetation and Flora in Tropical Africa

A special issue of Diversity (ISSN 1424-2818). This special issue belongs to the section "Plant Diversity".

Deadline for manuscript submissions: closed (30 June 2020) | Viewed by 45621

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Centre for Ecology, Evolution and Environmental Changes (cE3c), CHANGE - Global Change and Sustainability Institute, Faculty of Sciences (FCUL), University of Lisbon, Lisbon, Portugal
Interests: ethnobotany; vegetation ecology; management of natural resources
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Guest Editor
Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Portugal
Interests: tropical biodiversity; botany and vegetation ecology; phylogenetics; conservation; ethnobotany; plant genetic resources; crop wild relatives
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Africa’s major terrestrial and coastal ecosystems and vegetation comprise a wealthy repository of biodiversity, with a high proportion of native and endemic plant species, which makes them biologically unique and provides a wide range of ecosystem services. Nevertheless, many of these ecosystems are being degraded, mostly due to the growing impacts from climate change and other anthropogenic and environmental problems, such as over-exploitation of natural resources, droughts and floods, changes in spatial distribution of species, and land degradation and use. Current land cover change is damaging biodiversity—namely, the conversion of forest and other natural areas, such as wetlands, for food production and urban development is happening at a fast rate following the rapid transformation of African societies. Such conversion leads to habitat and biodiversity loss, which affects livelihoods, water supply, and food security and reduces resilience to extreme events, particularly for people living in rural areas of the African continent.

Africa is extraordinary rich in useful plants and local knowledge on its properties, comprising a strategic strength for sustainable development in the region. Moreover, the continent has an important genetic diversity that reflects its unique variety of plants and several important native crop species, which are adapted to an ever-changing environment.

The knowledge of the huge African plant diversity, as well as the structure, composition, and processes involved in vegetation changes, are crucial to promote their sustainable use and to conserve one of the most understudied regions in the world.

This Special Issue aims to gather contributions to deliver the timely and emerging research in the main topic of Biodiversity of Vegetation and Flora in Tropical Africa, and papers covering a wide and multidisciplinary approaches (e.g., structure and composition of vegetation communities; biogeography; conservation; ecological modeling; genetic diversity; ethnobotany; agroforestry; climate changes and ecosystem service) are welcome.

Dr. Luís Catarino
Prof. Maria Romeiras
Guest Editor

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Published Papers (9 papers)

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Editorial

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3 pages, 182 KiB  
Editorial
Biodiversity of Vegetation and Flora in Tropical Africa
by Luís Catarino and Maria M. Romeiras
Diversity 2020, 12(10), 369; https://doi.org/10.3390/d12100369 - 25 Sep 2020
Cited by 4 | Viewed by 2067
Abstract
African ecosystems comprise a wealthy repository of biodiversity with a high proportion of native and endemic plant species, which makes them biologically unique and providers of a wide range of ecosystem services. A large part of African populations, in both rural and urban [...] Read more.
African ecosystems comprise a wealthy repository of biodiversity with a high proportion of native and endemic plant species, which makes them biologically unique and providers of a wide range of ecosystem services. A large part of African populations, in both rural and urban areas, depends on plants for their survival and welfare, but many ecosystems are being degraded, mostly due to the growing impacts of climate change and other anthropogenic actions and environmental problems. Loss of habitat and biodiversity affects livelihoods, water supply and food security, and reduces the resilience of ecosystems in the African continent. Knowledge of the huge African plant and ecosystem diversity, and on the structure, composition and processes involved in vegetation dynamics, is crucial to promote their sustainable use and to preserve one of the most understudied regions in the world. This Special Issue aimed to gather contributions that update and improve such knowledge. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)

Research

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22 pages, 6054 KiB  
Article
Spatial and Temporal Trends of Burnt Area in Angola: Implications for Natural Vegetation and Protected Area Management
by Silvia Catarino, Maria Manuel Romeiras, Rui Figueira, Valentine Aubard, João M. N. Silva and José M. C. Pereira
Diversity 2020, 12(8), 307; https://doi.org/10.3390/d12080307 - 9 Aug 2020
Cited by 23 | Viewed by 5225
Abstract
Fire is a key driver of natural ecosystems in Africa. However, human activity and climate change have altered fire frequency and severity, with negative consequences for biodiversity conservation. Angola ranks among the countries with the highest fire activity in sub-Saharan Africa. In this [...] Read more.
Fire is a key driver of natural ecosystems in Africa. However, human activity and climate change have altered fire frequency and severity, with negative consequences for biodiversity conservation. Angola ranks among the countries with the highest fire activity in sub-Saharan Africa. In this study, we investigated the spatial and temporal trends of the annual burnt area in Angola, from 2001 to 2019, and their association with terrestrial ecoregions, land cover, and protected areas. Based on satellite imagery, we analyzed the presence of significant trends in burnt area, applying the contextual Mann–Kendall test and the Theil–Sen slope estimator. Data on burnt areas were obtained from the moderate-resolution imaging spectroradiometer (MODIS) burnt area product and the analyses were processed in TerrSet. Our results showed that ca. 30% of the country’s area burned every year. The highest percentage of annual burnt area was found in northeast and southeast Angola, which showed large clusters of decreasing trends of burnt area. The clusters of increasing trends were found mainly in central Angola, associated with savannas and grasslands of Angolan Miombo woodlands. The protected areas of Cameia, Luengue-Luiana, and Mavinga exhibited large areas of decreasing trends of burnt area. Conversely, 23% of the Bicuar National Park was included in clusters of increasing trends. Distinct patterns of land cover were found in areas of significant trends, where the clusters of increasing trends showed a higher fraction of forest cover (80%) than the clusters of decreasing trends (55%). The documentation of burnt area trends was very important in tropical regions, since it helped define conservation priorities and management strategies, allowing more effective management of forests and fires in countries with few human and financial resources. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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19 pages, 2204 KiB  
Article
Diversity of Tree Species in Gap Regeneration under Tropical Moist Semi-Deciduous Forest: An Example from Bia Tano Forest Reserve
by Maame Esi Hammond and Radek Pokorný
Diversity 2020, 12(8), 301; https://doi.org/10.3390/d12080301 - 1 Aug 2020
Cited by 15 | Viewed by 3775
Abstract
In a quest to improve the diversity and conservation of native tree species in tropical African forests, gap regeneration remains all-important nature-promoting silviculture practice and ecosystem-based strategy for attaining these ecological goals. Nine gaps of varying sizes (286–2005 m2) were randomly [...] Read more.
In a quest to improve the diversity and conservation of native tree species in tropical African forests, gap regeneration remains all-important nature-promoting silviculture practice and ecosystem-based strategy for attaining these ecological goals. Nine gaps of varying sizes (286–2005 m2) were randomly selected: three each from undisturbed, slightly disturbed and disturbed areas within Bia Tano Forest Reserve of Ghana. Within individual gaps, four transects (North–South–East–West directions) followed by 10 subsampling regions of 1 m2 at 2 m apart were established along each transect. Data showed 63 tree species from 21 families in the study. Although, all estimated diversity indices showed significant biodiversity improvements in all gaps at p < 0.05 level. Yet, there were no significant variations amongst gaps. Additionally, tree species differed between gaps at the undisturbed and the two disturbance-graded areas while no differences were presented between disturbance-graded areas. Balanced conservation between Green Star and Reddish Star species and imbalanced conservation between Least Concern, Near Threatened and Vulnerable species in the International Union for Conservation of Nature (IUCN) Red List were found, showing the reserve’s long-term prospects for economic and ecological benefits of forest management. Thus, there is a need for higher priority for intensive management to regulate various anthropogenic disturbances so as to protect the biological legacies of the reserve. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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26 pages, 5289 KiB  
Article
Phylogenomic Study of Monechma Reveals Two Divergent Plant Lineages of Ecological Importance in the African Savanna and Succulent Biomes
by Iain Darbyshire, Carrie A. Kiel, Corine M. Astroth, Kyle G. Dexter, Frances M. Chase and Erin A. Tripp
Diversity 2020, 12(6), 237; https://doi.org/10.3390/d12060237 - 11 Jun 2020
Cited by 12 | Viewed by 3656
Abstract
Monechma Hochst. s.l. (Acanthaceae) is a diverse and ecologically important plant group in sub-Saharan Africa, well represented in the fire-prone savanna biome and with a striking radiation into the non-fire-prone succulent biome in the Namib Desert. We used RADseq to reconstruct evolutionary relationships [...] Read more.
Monechma Hochst. s.l. (Acanthaceae) is a diverse and ecologically important plant group in sub-Saharan Africa, well represented in the fire-prone savanna biome and with a striking radiation into the non-fire-prone succulent biome in the Namib Desert. We used RADseq to reconstruct evolutionary relationships within Monechma s.l. and found it to be non-monophyletic and composed of two distinct clades: Group I comprises eight species resolved within the Harnieria clade, whilst Group II comprises 35 species related to the Diclipterinae clade. Our analyses suggest the common ancestors of both clades of Monechma occupied savannas, but both of these radiations (~13 mya crown ages) pre-date the currently accepted origin of the savanna biome in Africa, 5–10 mya. Diversification in the succulent biome of the Namib Desert is dated as beginning only ~1.9 mya. Inflorescence and seed morphology are found to distinguish Groups I and II and related taxa in the Justicioid lineage. Monechma Group II is morphologically diverse, with variation in some traits related to ecological diversification including plant habit. The present work enables future research on these important lineages and provides evidence towards understanding the biogeographical history of continental Africa. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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18 pages, 2209 KiB  
Article
Diversification of African Rainforest Restricted Clades: Piptostigmateae and Annickieae (Annonaceae)
by Baptiste Brée, Andrew J. Helmstetter, Kévin Bethune, Jean-Paul Ghogue, Bonaventure Sonké and Thomas L. P. Couvreur
Diversity 2020, 12(6), 227; https://doi.org/10.3390/d12060227 - 7 Jun 2020
Cited by 11 | Viewed by 3412
Abstract
African rainforests (ARFs) are species rich and occur in two main rainforest blocks: West/Central and East Africa. This diversity is suggested to be the result of recent diversification, high extinction rates and multiple vicariance events between west/central and East African forests. We reconstructed [...] Read more.
African rainforests (ARFs) are species rich and occur in two main rainforest blocks: West/Central and East Africa. This diversity is suggested to be the result of recent diversification, high extinction rates and multiple vicariance events between west/central and East African forests. We reconstructed the diversification history of two subtribes (Annickieae and Piptostigmateae) from the ecologically dominant and diverse tropical rainforest plant family Annonaceae. Both tribes contain endemic taxa in the rainforests of West/Central and East Africa. Using a dated molecular phylogeny based on 32 nuclear markers, we estimated the timing of the origin of East African species. We then undertook several diversification analyses focusing on Piptostigmateae to infer variation in speciation and extinction rates, and test the impact of extinction events. Speciation in both tribes dated to the Pliocene and Pleistocene. In particular, Piptostigma (13 species) diversified mainly during the Pleistocene, representing one of the few examples of Pleistocene speciation in an African tree genus. Our results also provide evidence of an ARF fragmentation at the mid-Miocene linked to climatic changes across the region. Overall, our results suggest that continental-wide forest fragmentation during the Neogene (23.03–2.58 Myr), and potentially during the Pliocene, led to one or possibly two vicariance events within the ARF clade Piptostigmateae, in line with other studies. Among those tested, the best fitting diversification model was the one with an exponential speciation rate and no extinction. We did not detect any evidence of mass extinction events. This study gives weight to the idea that the ARF might not have been so negatively impacted by extinction during the Neogene, and that speciation mainly took place during the Pliocene and Pleistocene. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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20 pages, 4473 KiB  
Article
Diversity and Structure of an Arid Woodland in Southwest Angola, with Comparison to the Wider Miombo Ecoregion
by John L. Godlee, Francisco Maiato Gonçalves, José João Tchamba, Antonio Valter Chisingui, Jonathan Ilunga Muledi, Mylor Ngoy Shutcha, Casey M. Ryan, Thom K. Brade and Kyle G. Dexter
Diversity 2020, 12(4), 140; https://doi.org/10.3390/d12040140 - 3 Apr 2020
Cited by 11 | Viewed by 4788
Abstract
Seasonally dry woodlands are the dominant land cover across southern Africa. They are biodiverse, structurally complex, and important for ecosystem service provision. Species composition and structure vary across the region producing a diverse array of woodland types. The woodlands of the Huíla plateau [...] Read more.
Seasonally dry woodlands are the dominant land cover across southern Africa. They are biodiverse, structurally complex, and important for ecosystem service provision. Species composition and structure vary across the region producing a diverse array of woodland types. The woodlands of the Huíla plateau in southwest Angola represent the extreme southwestern extent of the miombo ecoregion and are markedly drier than other woodlands within this ecoregion. They remain understudied, however, compared to woodlands further east in the miombo ecoregion. We aimed to elucidate further the tree diversity found within southwestern Angolan woodlands by conducting a plot-based study in Bicuar National Park, comparing tree species composition and woodland structure with similar plots in Tanzania, Mozambique, and the Democratic Republic of Congo. We found Bicuar National Park had comparatively low tree species diversity, but contained 27 tree species not found in other plots. Plots in Bicuar had low basal area, excepting plots dominated by Baikiaea plurijuga. In a comparison of plots in intact vegetation with areas previously disturbed by shifting-cultivation agriculture, we found species diversity was marginally higher in disturbed plots. Bicuar National Park remains an important woodland refuge in Angola, with an uncommon mosaic of woodland types within a small area. While we highlight wide variation in species composition and woodland structure across the miombo ecoregion, plot-based studies with more dense sampling across the ecoregion are clearly needed to more broadly understand regional variation in vegetation diversity, composition and structure. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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19 pages, 3139 KiB  
Article
Afromontane Forest Diversity and the Role of Grassland-Forest Transition in Tree Species Distribution
by Iveren Abiem, Gabriel Arellano, David Kenfack and Hazel Chapman
Diversity 2020, 12(1), 30; https://doi.org/10.3390/d12010030 - 15 Jan 2020
Cited by 22 | Viewed by 7433
Abstract
Local factors can play an important role in defining tree species distributions in species rich tropical forests. To what extent the same applies to relatively small, species poor West African montane forests is unknown. Here, forests survive in a grassland matrix and fire [...] Read more.
Local factors can play an important role in defining tree species distributions in species rich tropical forests. To what extent the same applies to relatively small, species poor West African montane forests is unknown. Here, forests survive in a grassland matrix and fire has played a key role in their spatial and temporal dynamics since the Miocene. To what extent these dynamics influence local species distributions, as compared with other environmental variables such as altitude and moisture remain unknown. Here, we use data from the 20.28 ha montane forest plot in Ngel Nyaki Forest Reserve, South-East Nigeria to explore these questions. The plot features a gradient from grassland to core forest, with significant edges. Within the plot, we determined tree stand structure and species diversity and identified all trees ≥1 cm in diameter. We recorded species guild (pioneer vs. shade tolerant), seed size, and dispersal mode. We analyzed and identified to what extent species showed a preference for forest edges/grasslands or core forest. Similarly, we looked for associations with elevation, distance to streams and forest versus grassland. We recorded 41,031 individuals belonging to 105 morphospecies in 87 genera and 47 families. Around 40% of all tree species, and 50% of the abundant species, showed a clear preference for either the edge/grassland habitat or the forest core. However, we found no obvious association between species guild, seed size or dispersal mode, and distance to edge, so what leads to this sorting remains unclear. Few species distributions were influenced by distance to streams or altitude. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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Review

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23 pages, 3180 KiB  
Review
Diversity and Conservation through Cultivation of Hypoxis in Africa—A Case Study of Hypoxis hemerocallidea
by Motiki M. Mofokeng, Hintsa T. Araya, Stephen O. Amoo, David Sehlola, Christian P. du Plooy, Michael W. Bairu, Sonja Venter and Phatu W. Mashela
Diversity 2020, 12(4), 122; https://doi.org/10.3390/d12040122 - 25 Mar 2020
Cited by 10 | Viewed by 7114
Abstract
Africa has the largest diversity of the genus Hypoxis, accounting for 61% of the current globally accepted taxa within the genus, including some endemic species. Using Hypoxis hemerocallidea as a case study, this review addresses the conservation concerns arising from the unsustainable, [...] Read more.
Africa has the largest diversity of the genus Hypoxis, accounting for 61% of the current globally accepted taxa within the genus, including some endemic species. Using Hypoxis hemerocallidea as a case study, this review addresses the conservation concerns arising from the unsustainable, wild harvesting of a number of Hypoxis species. Hypoxis hemerocallidea is one of the wild-harvested, economically important, indigenous medicinal plants of southern Africa, with potential in natural product and drug development. There are several products made from the species, including capsules, tinctures, tonics and creams that are available in the market. The use of H. hemerocallidea as a “cure-all” medicine puts an important harvesting pressure on the species. Unsustainable harvesting causes a continuing decline of its populations and it is therefore of high priority for conservation, including a strong case to cultivate the species. Reviewing the current knowledge and gaps on cultivation of H. hemerocallidea, we suggest the creation of a platform for linking all the stakeholders in the industry. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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16 pages, 2286 KiB  
Review
The Role of Climate and Topography in Shaping the Diversity of Plant Communities in Cabo Verde Islands
by Carlos Neto, José Carlos Costa, Albano Figueiredo, Jorge Capelo, Isildo Gomes, Sónia Vitória, José Maria Semedo, António Lopes, Herculano Dinis, Ezequiel Correia, Maria Cristina Duarte and Maria M. Romeiras
Diversity 2020, 12(2), 80; https://doi.org/10.3390/d12020080 - 19 Feb 2020
Cited by 20 | Viewed by 6476
Abstract
The flora and vegetation of the archipelago of Cabo Verde is dominated by Macaronesian, Mediterranean, and particularly by African tropical elements, resulting from its southernmost location, when compared to the other islands of the Macaronesia (i.e., Azores, Madeira, Selvagens, and Canary Islands). Very [...] Read more.
The flora and vegetation of the archipelago of Cabo Verde is dominated by Macaronesian, Mediterranean, and particularly by African tropical elements, resulting from its southernmost location, when compared to the other islands of the Macaronesia (i.e., Azores, Madeira, Selvagens, and Canary Islands). Very likely, such a geographical position entailed higher susceptibility to extreme climatic fluctuations, namely those associated with the West African Monsoon oscillations. These fluctuations led to a continuous aridification, which is a clear trend shown by most recent studies based on continental shelf cores. Promoting important environmental shifts, such climatic fluctuations are accepted as determinant to explain the current spatial distribution patterns of taxa, as well as the composition of the plant communities. In this paper, we present a comprehensive characterization of the main plant communities in Cabo Verde, and we discuss the role of the climatic and topoclimatic diversity in shaping the vegetation composition and distribution of this archipelago. Our study reveals a strong variation in the diversity of plant communities across elevation gradients and distinct patterns of richness among plant communities. Moreover, we present an overview of the biogeographical relationships of the Cabo Verde flora and vegetation with the other Macaronesian Islands and northwestern Africa. We discuss how the distribution of plant communities and genetic patterns found among most of the endemic lineages can be related to Africa’s ongoing aridification, exploring the impacts of a process that marks northern Africa from the Late Miocene until the present. Full article
(This article belongs to the Special Issue Biodiversity of Vegetation and Flora in Tropical Africa)
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