7 research outputs found
Distribution of palynomorphs in recent bottom sediments offshore Niger delta: A preliminary study
No full textInternational audienc
Spore characterisation and its taxonomic significance in ferns from Lagos State, Nigeria
No full textNational audienc
Long‐term drivers and timing of accelerated vegetation changes in African biomes and their management implications
No full textAim: Owing to its diverse bioclimatic zones, long human history and intense anthropogenic impacts, Africa provides a model system for studying how global terrestrial ecosystems might respond to accelerated socio-environmental stress. Africa is particularly vulnerable to climate change and human impact, and insufficient baseline data hamper current environmental management efforts. Using palaeoecological data, we seek to identify the timing, pace and drivers of change in African biomes on a long-term scale to inform current ecosystem management frameworks on the continent. Location: Africa. Time period: 0–12 ka. Major taxa studied: African biomes. Methods: Sixty-four pollen records across Africa and nearby sites were retrieved from multiple databases/sources and grouped into biomes. Turnover (quantified using the squared chord distance dissimilarity metric) and rarefaction analyses were conducted on pollen records in each biome group to reconstruct regional temporal vegetation turnover and richness. Reconstructed vegetation turnover and richness were compared with independent records of climate, fire and human activity to identify possible drivers of change. Results: We found that the most stable biomes were those with the greatest floristic richness. Southern Africa's mediterranean-type (SAM) ecosystems were the most stable and northern Africa's mediterranean-type (NAM) ecosystems were the most unstable (mainly owing to fire). Tropical savannas (TS) and SAM ecosystems expressed the most sensitivity to climatic shifts from ≥6 ka, whereas tropical forests (TF) were relatively stable before human activities intensified from c. 2 ka. Floristic richness also declined across the tropics from c. 2 ka. Main conclusions: Our analysis pinpoints NAM ecosystems as undergoing the fastest acceleration in turnover on the continent in response to fire, whereas TF and TS have been undergoing unprecedented changes in biodiversity in the last 2,000 years. We expect further changes in biodiversity where climate becomes warmer and drier and where human impacts are novel and rapid in comparison to long-term baselines.Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, Grant/Award Number: CE17010001
The Late Quaternary vegetational and environmental history of western tropical Africa: the eastern Benin Basin, Lagos, Nigeria
Full text linkA palynological study of a 30 m borehole within the Akoka campus of the University of Lagos, Akoka, Nigeria revealed Late Quaternary paleo-vegetational, climatic and environmental changes. Sixteen samples at a regular interval of 2 m were subjected to standard palynological and sedimentological techniques. Six pollen zones representing six paleoclimatic phases within the Late Quaternary period were recognized. The age model is based on two radiocarbon dates (6 m: 5,495 } 25 14C yr and 12 m: 15,660 } 40 14C yr) and, by extrapolation, the sequence spans approximately the last 35,000 yr BP. The African maximum transgression and the African Humid Period (wet paleoclimate maximum) – the Nouaktchottian, and Pre-Nouaktchottian respectively – were recognized, while the Ogolian II (Erg II) was stratigraphically recognized and the Upper Inchirian extrapolated. Recovered diatom frustules with other proxies were employed for paleoclimatic and paleoecological deductions. Four hydrological cycles and three paleoecological settings were identified. Results from this work indicate the co-eval record of paleoclimatic events across Africa, suspected cooling during the African maximum transgression in Nigeria and the usefulness of coastal freshwater swamp sediments for paleoclimate studies
Comparative palynology of Macrotermes sp. mounds and Vespula vulgaris nests on the University of Lagos campus, Akoka: preliminary study
No full textAbstractIn order to assess the environmental indicator potential of wasp nests and termite mounds, the palynomorph content of three randomly selectedMacrotermessp. mounds (termitaria) and twoVespula vulgarisnests collected on the University of Lagos campus were examined. Palynological analysis showed the presence of 298 well-preserved palynomorphs showing characteristic morphological features. The recovered palynomorphs included pollen, pteridophyte spores and fungal spores, along with insect parts (106), diatoms (7) and a protist (1). The pollen assemblage of termite mounds comprised 78 pollen and pteridophyte spores, with Poaceae and Arecaceae pollen as dominants. In the wasp nest the pollen assemblage comprised 28 pollen and spore taxa, with Poaceae and Arecaceae pollen also dominant. Both mounds and nests had, besides diatoms, six pollen and spore taxa: Poaceae, Amaranthaceae, Pteridophyte spores, Arecaceae,Raffiasp. andRhizophorasp. Vegetational grouping of the recovered pollen and spores indicated five phytoecological groups: secondary forest, mangrove swamp forest, freshwater, open vegetation and Poaceae. In statistical analyses, termite mounds had a higher species richness value (2.08 as compared to 1.99 from the wasp nests), while the wasp nests had a higher species diversity value (0.997 as compared to 0.845 from the termite mounds). Pollen analyses of the termite mounds and wasp nests suggest that both could be useful tools in environmental studies. This is the first attempt to evaluate the potential of termite mounds and wasps nest as natural pollen accumulators in Nigeria. The results suggest new possibilities for the use of the pollen records preserved in termite mounds and wasp nests for environmental studies.</jats:p
