African Journal of Ecology最新文献

Anthropogenic pressure on isolated protected areas without buffer zones is more intense at boundaries and results in an increase in edge effects. These edge effects influence the distribution and composition of various organisms. In this study, we investigated changes in bird community composition and habitat variables along an edge-to-interior gradient in an isolated coastal nature forest reserve near Dar es Salaam. Birds and habitat variables were recorded at 147 sampling points across 49 systematically placed parallel transects in three habitat treatments (edge, near-edge and interior) to determine the response of the avian community to edge effects. In total, we detected 3249 individuals representing 136 species belonging to 46 bird families, with notable variation along the edge–interior gradient. Non-forest species and forest visitors dominated the bird community, accounting for 47% and 24% of detections, respectively. Although there was a variation in avian community along the gradient, the 200 and 400 m communities were not detectably different. The edge had less ground cover compared to areas beyond 200 m from the forest edge, but no edge–interior gradient changes were observed for vertical habitat structure. A Principal Component Analysis (PCA) explained around 63.3% of the total variance across two axes, and the PERMANOVA results indicated a statistically significant difference among the habitats (F = 2.8386, p = 0.022, R² = 0.03793) but the low R² implied that the effect size was small. Although forest bird species were positively associated with vertical habitat structure, low canopy height throughout the study area and the penetration of non-forest bird species into interior habitats served as an indicator of past anthropogenic disturbances. Thus, conservation efforts should be strengthened to allow vegetation recovery, particularly given the reserve's importance for forest species, including those endemic to the coastal forest belt of Eastern Africa.

Given the high rate at which urban landscapes across Africa expand, continuous monitoring of adaptations and responses to ongoing habitat changes is a prerequisite for effective conservation management of key ecosystem components, hereunder important seed dispersers such as fruit bats. We used the widespread and habitat generalist Gambian Epauletted Fruit Bat Epomophorus gambianus as an ecological model species and tested whether environmental variables linked to urbanisation were related to aspects of their roost and foraging behavioural ecology. Within an isolated green zone (the University of Ghana campus), situated in the otherwise heavily urbanised Accra, Ghana, a prime focus was assessing the relationship between habitat and environmental features as against roost and foraging behavioural ecology. We radio-tagged and tracked a total of 11 bats, thereby detecting 22 roosts and 16 foraging trees, in which repeated bat counts, as well as environmental variables, were recorded during 3–4 months in 2022. We show that E. gambianus preferred older, large, shady exotic teak, mango, and the West African legume Millettia thonningii as roost trees, whereas Coastal golden-leaf fruit Bridelia micrantha and mangoes were preferred for foraging. Female roost fidelity was relatively high, with females using fewer trees more evenly than males, indicating sexual dimorphism related to larger roost and foraging ranges, higher territoriality, and more opportunistic male reproductive traits.

Insect pollination relies on flowering plant quality, but pollutants disrupt this balance. We assessed heavy metal effects on insect pollinator diversity along a pollution gradient in Mufulira's district of the Copperbelt province, Zambia. Soil samples showed varying copper, lead, zinc and iron concentrations with distance from sources of mining pollution. Zone B, over 10 km from active mines into agricultural lands, had higher insect pollinator abundance and richness than Zone A, near active mines with heavy metals. Habitat loss from other anthropogenic activities (other than mining) reduced diversity in Zone B. Seasonal insect pollinator diversity variations were greatest in the cool-dry season. Conservation efforts should address mining pollution to protect insect pollinators.

Mammalian communities living in tropical forests, particularly those in ecological transition zones, are under constant threat from human activities. In many regions, baseline data on mammal richness, occupancy, detection probability and the environmental factors that influence these metrics are lacking. As a key metric for guiding conservation decisions, species richness can be underestimated due to varying detection probabilities, leading to species being overlooked. Advances in technology and methodology have revolutionised wildlife monitoring, fostering the increase of multi-species occupancy models (MSOMs) for efficient studies of community, shifting focus from single species to entire communities. MSOMs, hierarchical models that share information across species via random effects, address imperfect detection to provide accurate and unbiased species richness estimates. To fill this information gap, we used cameras trap data from Mpem and Djim National Park, Central Cameroun. We used generalised linear models and a model selection approach to evaluate factors affecting species detection events. Similarly, we used MSOMs within a Bayesian hierarchical framework to evaluate our initial species richness estimate at each camera trap location and to understand the influence of environmental covariates on the occupancy and detection probability of 19 vertebrates recorded in the area to inform management decisions for these species. From 915 independent photographic events obtained over 1700 days of capture, the study results highlight the importance of habitat, distance to river, normalised difference vegetation index and topographic position index (TPI) in explaining patterns of detection events. We found that forest (GLM: B 0.31, IRR 1.36, CI 0.14–0.48, p < 0.001), NDVI (GLM: B 0.31, IRR 1.36, CI 0.21–0.41, p < 0.001) and TPI (GLM: B 0.17, IRR 1.19, CI 0.08–0.26, p < 0.001) were positively associated with species detection events, whereas distance to river (GLM: B −0,19, IRR 0.83, CI 0.0.27 to (−0.11), p < 0.001) was negatively associated with species detection events. However, the mean probability of community occupancy was 0.33 ± 0.10 [2.5%–97.5% CI: 0.17, 0.54], while the mean probability of community detection was 0.07 ± 0.02 [2.5%–95% CI: 0.04, 0.12], indicating that, on average, approximately 33% of the sites are likely to be occupied by the community of interest, with a 7% probability of detection at occupied sites. After accounting for imperfect detection, the maximum occupancy and detection probability estimated from the MSOMs were 0.88 ± 0.07 (2.5%–97.5% CI: 0.71–0.98) and 0.22 ± 0.2 (2.5%–97.5% CI: 0.18–0.27) for Philantomba monticola, respectively. Globally, the community responses were close to zero and relatively weak, probably due to mixed responses at the species level. Despite their weak effect, distance to road (β: −1.53