African Journal of Ecology最新文献

Understanding whether structural traits reliably reflect species identity is crucial for advancing automated tree classification, particularly in complex disturbance-prone ecosystems like the West Sudanian savannas. In this study, we assessed the ecological consistency and taxonomic discriminability of 17 architectural traits, spanning crown, stem branch and whole-tree components, derived from close-range photogrammetry point clouds across five dominant savanna tree species. Using a trait-by-trait analysis grounded in the Trait Probability Density (TPD) framework, we quantified intraspecific versus interspecific variation through functional richness (FRic) and pairwise trait overlap. We computed a composite score combining these two indicators to rank traits according to their species-discriminatory potential. ANOVA and the Student Newman Keuls post hoc test were performed on the composite score to identify groups of significantly distinct traits. Our findings showed that while structural traits exhibit considerable within-species variability, a subset of traits, particularly crown evenness, stem branch angle and stem taper factor, demonstrated relatively high interspecific structuring and low trait overlap. Crown and stem branch traits emerged as the most reliable for distinguishing species. However, the top performing traits were distributed across all architectural domains, underscoring the value of a multi-trait approach. We also observed species-specific inconsistencies even among high-ranking traits, emphasising the need to account for intraspecific plasticity in classification tasks. These results suggest that no single architectural trait offers universal taxonomic resolution, and call for further research into identifying context-specific structural features, particularly those robust to environmental disturbance and ecotypic variation, for advancing automated tree species classification in savanna systems.

It is well established that different habitats support different levels of species richness, abundance, and diversity. This is true when it comes to heterogeneous habitats with different habitat conditions. With that focus, we present the findings of our results, which aimed to determine how species richness, abundance, and diversity of rodents vary across different habitats of an East African woodland ecosystem. The study was carried out during the rainy season (January–June 2023), and study grids were marked in four randomly selected habitats, including miombo woodland, Acacia–Combretum woodland, riverine, and farmland. Sherman live traps, pitfall traps, and havarhat traps were used to capture rodents in the selected habitats. A total of 219 individuals of rodents were captured in 28,224 trap-nights. These comprised 6 species of rodents, namely Mastomys natalensis, Mus munitoides, Acomys wilson, Gerbilluscus leucogaster, Graphiurus murinus, and Paraxerus ochracerus. The highest abundance of rodents was recorded in farmland and miombo woodland, while the least abundance was recorded in riverine and Acacia–Combretum woodland. Species diversity was highest in farmland and miombo woodland and lowest in riverine and Acacia–Combretum woodland. The distribution of species varied among habitats. Acomys wilson was the most widely distributed species, whereas Paraxerus ochracerus was the least. This study suggests that habitat heterogeneity is a key factor influencing rodent richness, abundance, and diversity; hence, it emphasizes the role of wildlife managers and conservationists to protect and conserve these habitats for the survival of small mammal communities.

Analysing a decade of records on fence-related springbok mortalities at an 8000 ha farm with 36 km of internal (height: 1 m) and 48 km of boundary fences (height: 1.4 m) resulted in an average mortality occurrence of 0.25 and 0.61 mortalities/km (over the 10 years period) for boundary (1.4 m) and internal (1 m) fences, respectively. Male mortalities occur mainly during summer (hot/wet season) with equal numbers killed in internal and boundary fences, while female mortalities are mainly associated with winter (cold/dry season) and internal fences. Mitigations to minimise mortalities include varying the width of the upper fence strands and leaving camp gates open when livestock are not present to facilitate the movement of springbok.

Stingless bees (Apidae, tribe Meliponini) play a crucial role as pollinators in tropical ecosystems, including across the Afrotropical realm. However, the ecology of these bees, particularly the predation pressure they face from various natural enemies, remains underexplored. Here, we document opportunistic predation events of Hypotrigona and Liotrigona species by both native (Menemerus bivittatus) and exotic (Plexippus petersi) jumping spiders (Salticidae). Across Guinea, Kenya, Tanzania and Madagascar, jumping spiders were observed ambushing foragers at nest entrances and successfully capturing prey, with repeated instances recorded over multiple days. This phenomenon, which we term meliponophagy, has received very little attention to date and our observations provide the first evidence of jumping spiders preying upon Liotrigona species in the Afrotropical realm, adding new records to the limited literature on these rarely documented but ecologically relevant interactions.

The timing of avian migration for Palearctic passerine birds across the Western Africa region remains relatively unexplored. This study investigates the changing wintering phenology of nine Afro-Palearctic migratory species in relation to their time spent in Western Africa. We examined the annual first arrival and last departure dates for these nine migratory species within their non-breeding ranges using two datasets: The Gambia (1964–2021) and Nigeria (1974–2021). We employed phylogenetic linear mixed models to explore trends in pre-breeding (European spring) departure, post-breeding (European autumn) arrival, and duration of stay on the non-breeding grounds. Our results show that pre-breeding timing is advancing for migrant birds departing from The Gambia compared to those from Nigeria. Migrant species in The Gambia are departing earlier than their counterparts in Nigeria. This finding suggests that population in The Gambia may be responding to different environmental cues than those in Nigeria. The duration of stay was longer for species wintering in Nigeria than for birds in the Gambia. This difference could be driven by local environmental factors but might equally be driven by changes in another period and area during the migratory year. Post-breeding arrival for populations in both The Gambia and Nigeria were similar, commencing in late August. This suggests that post-breeding migration patterns may be affected by similar factors en route to African wintering areas. We discussed the phenological differences in pre-breeding departure and duration of stay of bird populations using the two counteries. These differences highlight the complexity of migratory timing and suggest how local environmental conditions might shape migratory behaviour. Our findings suggest that phenological changes in migratory species can vary significantly across the West African wintering grounds, reflecting the spatio-temporal phenological shifts observed on their breeding grounds.

Sea turtle populations around the world are seriously threatened by coastal pollution, which jeopardises their survival, habitats and health. This study examines the impact of coastal pollution on sea turtle habitat use in Delta State, Nigeria, a region characterised by intense oil and gas operations. During an intensive study spanning for 21 months between November 2019 and August 2021 along the river mouths of the Benin, Escravos and Forcados estuaries, three sea turtle species were recorded: Dermochelys coriacea, Chelonia mydas and Lepidochelys olivacea, with L. olivacea being the most preponderant, accounting for 59.5% of the total sightings. Other important findings include poor health conditions and uneven species diversity. Others include alarming trends in the erosion of the coastline (approximately 462 m between 2006 and 2021), which threatens the long-term survival of these iconic species. To assess the vulnerability of sea turtle habitats to pollution, we employed a Habitat Sensitivity Index (HSI). Our results show that sea turtle habitats in the study area are highly sensitive to pollution, with HSI scores ranging between 0.6 and 0.9. The main parameters influencing habitat sensitivity were identified as total hydrocarbon, dissolved oxygen and conductivity. Our research provides important highlights on how sea turtle distribution patterns relate to coastal pollution, emphasising the critical need for conservation and management measures to save these vulnerable creatures. The study's findings have significant ramifications for stakeholders, conservationists and legislators working to save the area's sea turtle populations.