African Journal of Ecology最新文献

Lowland and highland forests of the Kahuzi-Biega National Park (KBNP) in the eastern Democratic Republic of Congo were studied to understand their ecology. The lowland ranges from 810 to 1230 m asl and the highland from 1935 to 2760 m asl. Ten 1-ha nested plots were established in each area; trees with ≥ 10 cm of dbh were inventoried for the tree layer. In each area, 10 0.1-ha and 10 0.01-ha subplots were established for the shrub and herbaceous layers, respectively. In the tree layer, plant diversity, species richness and species pool size differed at different altitudes; the lowland is more diverse and richer (140 vs. 88 species). In the shrub layer, only the Fisher-alpha index differed, showing high diversity in the lowland (14 ± 7.1 vs. 8.9 ± 2.9). In the herbaceous layer, the highland had a higher number of species (78 vs. 50). Twenty-eight, twenty-nine and five species were common to both highland and lowland in the tree, shrub and herbaceous layers, respectively. Height and dbh classes and basal area did not differ, but the importance value indexes of species and families did. These results show that the lowland and highland forests of KBNP differ in the three layers, suggesting tailored management plans.

The African forest elephant (Loxodonta cyclotis) has recently been recognised as its own distinct species and classified as critically endangered. There is increased concern regarding how forest elephants will respond to their continuously deteriorating ecosystems due to climate change and habitat loss and fragmentation. Scoring an animal's body condition is non-invasive, quick, and can serve as a proxy for monitoring its health and nutritional status. This study developed the first forest elephant-specific body condition scoring (BCS) system and then investigated how sex, age, rank, and season were associated with adult male and female BCSs at the Dzanga Bai forest clearing, Dzanga-Ndoki National Park (Central African Republic), using photographs taken during the early (December 2022–January 2023) and late (February–March 2023) dry season. The developed BCS system was based on systems used for Asian (Elephas maximus) and African savannah (L. africana) elephants and relied on reference photographs and an accompanying flow chart. Male forest elephants had significantly higher BCSs compared to their female counterparts, while no difference by age or rank was observed. Female forest elephants demonstrated a decline in BCS between the early and late dry season. Together, these results highlight different factors that may impact forest elephant condition, potentially reflecting the individual's overall health state.

Through path analysis, most commonly applied to large animals moving long distances, we evaluated space use of Kalahari Desert lizards. We used sequences of locations to calculate step lengths and turn angles, revealing directed movement towards a central location. Consistent with homing, individuals moved < 30 m from their origin, progressing towards their start before venturing away. We illustrate that fine-scale behavioural resolution can be obtained through movement paths, which can be invisible when applying common metrics focused on levels of movement (i.e., moves/min). Future research incorporating ecological data are needed to identify mechanisms underlying the movement patterns we document.

Protecting the diversity of aquatic macroinvertebrates in ponds requires maintaining their habitat integrity. In areas with livestock grazing, fencing ponds effectively protects aquatic vegetation from grazing and prevents livestock from trampling. In this study, we investigated how fencing affects both α-diversity (species richness and diversity within a pond) and β-diversity (species turnover between ponds) by sampling macroinvertebrates and environmental variables from 10 temporary ponds near Palapye, central Botswana. Among these, six ponds were unfenced, and four were fenced. To ensure accurate comparisons, we rarefied species richness and estimated diversity using Hill numbers. We calculated both incidence and abundance-based β-diversity indices. We analysed the relationship between environmental variables and macroinvertebrate communities using redundancy analysis and employed variation partitioning to determine the influence of environmental and distance-related factors on macroinvertebrate variability. Our results showed that fenced ponds exhibited significantly higher Shannon diversity, Simpson diversity and species richness compared to unfenced ponds. Conversely, unfenced ponds experienced greater taxa turnover, while fenced ponds displayed higher abundance-based nestedness. Variation partitioning revealed that environmental factors primarily drove macroinvertebrate variability. These findings support fencing as an effective management strategy to protect macroinvertebrate diversity in temporary ponds within semi-arid, livestock-grazed landscapes. Although fencing enhances α-diversity, it is unnecessary to fence all ponds to maintain β-diversity. The increased nestedness in fenced ponds indicates that macroinvertebrate taxa respond sensitively to habitat disturbances, highlighting the importance of preserving the integrity of fenced ponds to support higher α-diversity.

This study presents the first systematic assessment of insect communities following fire disturbance in Ghana's Shai Hills Resource Reserve. Using a chronosequence approach, insect assemblages were sampled from one unburnt and three burnt savanna plots (6-, 12-, and 18-month post-fire). Insect richness and abundance increased with time since fire, but remained lower than in the unburnt control. Taxa responded differently: Formicidae showed resilience to fires, while Phasmatodea and Mantodea were absent from all burnt plots. Community composition gradually shifted toward the unburnt control. Findings highlight the ecological impacts of fire and the importance of replication in managing biodiversity in fire-prone grasslands.

Yam species (Dioscorea spp.) are of major economic, ecological and cultural importance in the Comoros, where the genus is particularly diverse. However, several native species are in decline, potentially due to a combination of ecological constraints and increasing anthropogenic pressures. This study used species distribution modelling (SDM), direct population counts and linear models to assess habitat suitability, abundance and their relationship with ecological and soil-related variables for three yam species: the Comoros-endemic D. comorensis, the regional endemic D. sensibarensis and the widely cultivated D. alata. Dioscorea comorensis showed strong habitat specificity, being confined to intact native forests with minimal disturbance, with only 56 individuals recorded across the island. Its abundance was positively associated with natural forest cover and negatively with agriculture and urban areas. D. sensibarensis was found in both natural and degraded vegetation, with an intermediate population size (266 individuals), and its abundance also declined in areas with high human activity. In contrast, D. alata exhibited a broad ecological amplitude, occurring in farmlands, village landscapes and degraded habitats. Its abundance (345 individuals for the Cameroon variety and 690 for the Comoros variety) was positively correlated with agricultural land use and human-modified areas. The results highlight clear ecological niche differentiation among the three species and stress the importance of land-use patterns in shaping yam abundance. Conservation priorities should include (1) preserving native forests to support rare endemic species, (2) limiting secondary forest conversion to maintain semi-endemic populations and (3) promoting agroforestry systems for sustainable cultivation of introduced species.

Trophy hunting of elephants may influence their habitat utilisation, which might have cascading impacts on resource availability and their dynamics. The effects of elephant trophy hunting were investigated in hunting areas in the proximity of Gonarezhou National Park between 2017 and 2023. It was investigated whether elephants were being hunted close to the park boundary and, if so, whether such ‘periphery hunting’ had created a barrier of fear which restricted elephants' movement into, and use of, hunting areas. Utilisation of hunting areas was studied by tracking the movements of 11 bull elephants fitted with GPS collars, and by counting elephant dung along 20 belt transects and in 60 plots distributed across a non-hunting area and an adjacent hunting area. A total of 70 bull elephants were hunted, with more elephants killed in 2021 than in 2020, most likely owing to the effects of the COVID pandemic on international travel. Elephants were hunted at distances from the park boundary of between 0.02 and 7.50 km, with 51% of the kills occurring within less than 1 km. Movement of bull elephants suggested that a ‘barrier of fear’ along the park boundary reduced their movement into, and use of the hunting areas. Dung distribution further indicated that elephants used the non-hunting area more than the hunting area. Periphery hunting was confirmed as an appropriate descriptor of the spatial pattern of hunting.

Wattle rust disease, caused by Uromycladium acaciae, has emerged as a critical challenge to Acacia mearnsii in the Awi Zone of northwestern Ethiopia. This study examined the effect of tree spacing and land use history on disease incidence and severity, and explored local perceptions of management practices. A randomised complete block design (RCBD) with three spacing treatments (0.5 × 0.5, 1 × 1, 1.5 × 1.5 m) was implemented across three districts—Fagita Lekoma, Ankasha Guagusa, and Banja Shekudad in 2021. Additionally, disease occurrence in three-year-old plantations (common spacing: ~0.5 × 0.5 m) on cropland, grazing land, and plantation land was assessed. Community knowledge and preferences for disease management were gathered through structured surveys and focus group discussions with 150 respondents, including both farmers and forest administrators. The findings revealed that wider spacing (1.5 × 1.5 m) significantly reduced disease incidence by up to 54.87% and severity by 45.74% compared to narrow spacing (0.5 × 0.5 m). Trees planted on cropland exhibited significantly lower disease levels compared to those on grazing or plantation land. Local farmers favoured integrated practices such as increased spacing, sanitation pruning, tilling, weeding, and intercropping with cereals, which align with scientific evidence on disease suppression through microclimate modification and improved soil health. Adopting a 1.5 × 1.5 m planting spacing and prioritising post-cropland areas are recommended for new plantations in disease-prone districts. Further research should explore disease-resistant varieties, species diversification strategies, and closer spacing (< 0.5 × 0.5 m), which are currently practised by some smallholders, to further enhance disease management and inform extension programmes.