African Journal of Ecology最新文献

Phlomis floccosa D. Don populations are distributed in different microhabitats within Al-Akhdar mountainous landscape, in Libya. Five populations were selected for the study. Spatial relationships among individuals were investigated using the spatial point pattern analysis. Functional traits were recorded at the vegetative, flowering and fruiting stages. Seeds were collected at the dispersal stage to estimate the regeneration potential. Greater degree of aggregation was found at higher elevations on both northern and southern sides of the mountain but with different demography and traits. On the northern side, greater degree of aggregation was accompanied by absence of large adults and greater percentage of seedlings, and it was positively associated with the reproductive output, while negatively associated with the size and regeneration indices. On the southern side, greater degree of aggregation was accompanied by greater contribution of large adults and greater percentage of seedlings, and it was positively associated with the size and regeneration indices, while negatively associated with the reproductive output. On the other hand, the population in the wadi (valley) microhabitat showed coarse-scale clumped pattern, higher values for most of the functional traits and higher contribution of seedlings but with lower facilitation offered by adults. The variations in the degree of aggregation and the functional traits trade-offs in P. floccosa populations ensured successful survival and regeneration in the heterogeneous microhabitats. Meanwhile, stressed conditions greatly affect the survival and regeneration of the species suggesting the need for conservation measures to overcome the adverse effects of climate change.

In landscapes with high elephant density, trees often exhibit more open canopies with fewer branches and foliage due to browsing pressure. This can result in altered tree morphology, with trees exhibiting stunted growth, multiple stems or unusual branching patterns in response to repeated damage from browsing. The objectives of this research were to (i) model the vegetation structure allometries, (ii) assess the impact of African savannah elephant (Loxodonta africana) herbivory on the vegetation structure and (iii) assess tree cover change and vegetation performance over time in Mana Pools National Park in Zimbabwe. We established 26 plots of 30 × 30 m size. Selection of sampling plots was done following several steps. First, a fish net grid with 30 × 30 m polygons was created and projected on the polygon of Mana Pools National Park. The polygons for exclusion zones were then clipped from the fish net grid using the clip tool in ArcGIS Pro 3.0. Then, selection of sampling plots was done initially by stratified random sampling using the Sampling Design Tool add in for ArcGIS Pro 3.0. Landsat images for the years 2003, 2013 and 2023 were used to assess land use land cover (LULC) time series and to calculate Normalised Difference Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) for the period. A generalised linear model (GLM) was used to analyse tree allometries. Further statistical investigations were performed using Bayesian piecewise regression (BPR) and Bayesian regression modelling (BRM). Basal area, number of stems, height, long canopy, diameter and basal circumference were all significantly different (p < 0.05) across all sampled plots. The change in growing conditions occurring as a tree grows beyond the reach of the African savannah elephant browsing indicates a natural system breakpoint. The best-fitting models were a simple linear model and a two breakpoint model for the plant population exposed to elephant herbivory. LULC, NDVI and SAVI confirm evidence of high tree regeneration over 2 decades. Understanding the dynamics in vegetation and LULC changes is critical for effective conservation and management of the habitats for African savannah elephants, as well as for maintaining the health and resilience of forest ecosystems.

Harpagophytum zeyheri (devil's claw) tubers are manually harvested for its pharmaceutical properties (anti-inflammatory) in the sandier regions, especially the communal areas in north-eastern Namibia, with various authors having questioned the sustainability and viability of current harvesting practices. Although regulation in the form of a quota system is implemented, this is not based on scientifically established density estimates or sustainable harvesting quotas. There is a dearth of published data regarding density estimates for H. zeyheri from Namibia. The average linear density from the Zambezi Region (all areas; this study) is 22.4 plants/km while other estimates from Namibia for H. procumbens vary between < 1 and 2000 plants/ha. The aim of this study was to contribute to the poorly known distribution and density of H. zeyheri from the Zambezi Region where most of Namibia's resource for the export market originates from and to highlight the potential threat of not conducting scientifically based preharvest counts on sustainability of this valuable resource.

The present work reports on new records of the flat-headed or Cameroon cusimanse (Crossarchus platycephalus) obtained from camera trap surveys carried out between 2021 and 2023 in central and northwestern Gabon. These records—in the form of high-definition videos—extend the southern limit of the species' known range by 172 km, as well as provide additional evidence of group living and co-occurrence with the blue duiker (Philantomba monticola) and moustached guenon (Cercopithecus cephus). These findings suggest that C. platycephalus may be more widespread than previously thought in Gabon, and that a review of existing camera trap datasets could help determine its precise distribution and habitat requirements.

Species conservation mainly depends on the conservation of their habitats where an understanding of the role that habitats have in supporting species diversity and richness is important. This study aimed to determine how heterogeneous habitats in growing agriculture corridors support the biodiversity of birds in terms of their diversity and abundance. We assessed the diversity, richness and abundance of bird species in six different habitats: miombo woodland, montane forests, lowland forests, agro-ecosystems, wetland and riverine in Tanzania's growing agriculture corridor. We assumed that heterogeneous habitats significantly influence species abundance, richness and diversity. We recorded 299 bird species which were categorised into 10 trophic guilds. Among the guilds, invertebrate-eating (52%) was the species-rich guild and nectarivore (1%), herbivore aquatic (0.67%), herbivore terrestrial (0.67%) and scavenger (0.34%) were the least guilds in terms of species richness, abundance and diversity. The six habitats differed in terms of bird species richness, abundance and diversity; miombo woodlands had the highest levels of diversity. There was an even distribution of birds, despite the fact that wetlands and agro-ecosystems had few species reported there. A number of endangered bird species were recorded in habitats with minimum disturbance. These species include Gyps africanus (CR), Ardeola idea, Polemaetus bellicosus and Terathopius ecaudatus (EN). In order to implement effective conservation measures for corridors and heterogeneous habitats, we advocate proper land use, conservation-friendly agriculture and the implementation of conservation connectivity on small and large scales.

The increasing demand for food and settlement in response to human population explosion is an issue of major concern recently. Conservation planning for biodiversity in anthropogenic landscapes is crucial given the dramatic changes within landscapes with human population growth; and understanding how avian species utilise such landscapes is especially important. This study investigated the impacts of vegetation structure and human activities on avian diversity; it also explored the stability of bird communities in northern Nigeria. We collected bird count, vegetation and anthropogenic data from four study sites over a period of 1 year. A total of 168 species were recorded. Vegetation variables were significant predictors of species abundance and richness, while human activities exerted little effect on them. Community stability varied considerably among the study sites, and a positive covariance and asynchronous relationship were observed among species. Since the drylands of northern Nigeria provide a refuge for many bird species, the protection and monitoring of this landscape are critical in order to cope with the management needs of avian communities.