African Journal of Ecology最新文献

Sclerocarya birrea (marula) trees are important components of dry and semi-dry African savanna environments due to their ecological and economical importance, including carbon storage. However, functional characteristics of these dioecious trees, such as their photosynthetic rates, remain largely unstudied. We quantified the diurnal cycle in leaf-level net photosynthetic rate (A), stomatal conductance (g_sw) and transpiration (E) in sun and shade leaves of male and female individuals of 14 Sclerocarya birrea trees in a northern Namibian semi-arid agroforestry system and explained the observed trends by three environmental drivers (light, temperature and humidity). A generalised additive model with a thin-plate regression spline smoother was applied to describe non-linear diurnal variation in A, g_sw and E. Results revealed a pronounced pre-midday decline in A for sun leaves, from 5.5 μmol CO₂ m⁻² s⁻¹ in the morning to 2.4 μmol CO₂ m⁻² s⁻¹ in the late afternoon, while shade leaves showed a continuous decrease from 3.0 to 1.8 μmol CO₂ m⁻² s⁻¹. Correspondingly, g_sw declined from 0.07 to 0.04 mol m⁻² s⁻¹, and E from 0.0012 to 0.0008 mol m⁻² s⁻¹ between morning and afternoon hours for sun leaves. Male trees exhibited higher A, g_sw and E than females, suggesting secondary sexual dimorphism in gas-exchange traits. Light was the best predictor of net photosynthetic rate and transpiration, whereas temperature was the best predictor of stomatal conductance. These findings highlight the complex interplay between environmental factors, leaf position and tree-specific traits in shaping the photosynthetic performance of Sclerocarya birrea. Consequently, this knowledge enables better-informed management and conservation strategies for this key savanna species.

Soil mesofauna are an integral part of the functioning of an ecosystem. They are relatively small in body size, occur in varying habitats and operate in a range of ecological niches. Soil mites are quite sensitive to changes in their environment and contribute to several important ecosystem services in their environments. This investigation aimed to determine how soil mite communities change in and around lawns in the Bontebok National Park (BNP). Sites that were sampled were categorised into lawns, ecotones and natural vegetation. Soils were collected to analyse physio-chemical parameters and to evaluate species composition of soil dwelling mites. Shannon and Simpson indices were used to determine species diversity of the different zones sampled and soil properties were used to generate PCAs and boxplots. There were changes in mite populations and community structure that were noticed in and around grazing lawns in the park, with a great reduction in diversity in lawns and the highest diversity seen in the ecotones. Lawns had higher proportions of macro and micronutrients, in addition to higher heavy metal content, which affected the oribatid mite populations inhabiting those areas. The establishment of lawns in the BNP had a negative impact on the mite populations in the park. This can be a major concern to soil mite communities in the park as they act as a vital component of the ecosystem, and contribute importantly to the overall functioning of their environment.

Uganda is home to remarkable biodiversity, supports diverse ecosystems ranging from glacier-topped mountains, tropical rain forests, to semi-arid systems, has a well-established and effective protected areas system, and benefits substantially from nature tourism. However, Uganda will face significant challenges if it is to maintain these riches. For example, the country's population is growing rapidly and is expected to surpass 100 million by 2050, more than 80% of households depend directly on natural resources for their livelihoods, and agricultural land has expanded by about 1% per year. Furthermore, Uganda is one of the world's most climate-vulnerable countries, and flooding and droughts are predicted to become much more common. Such changes will increase demands on natural resources, including those in protected areas. Uganda's government is aware of these challenges and has become a regional leader in environmental policy by taking a proactive approach. However, Uganda is struggling to educate its citizens and build the capacity for effective protection. Here we evaluate Uganda's conservation status and the threats to biodiversity from societal and climate change. We consider the current capacity and institutional infrastructure available to conserve the country's biodiversity, focusing on training and research, policy implementation and capacity in the field. Despite major challenges, clear pathways to a bright future are available.

Research using natural history collections to track anthropogenic activities has recently been on the rise. Natural history collections have been utilised beyond their traditional taxonomic and systematic roles, generating data that shape present and future research. We evaluated the value of natural history collections in answering questions about the changes in the occurrence of freshwater mollusc species in KwaZulu-Natal, South Africa, over the past 124 years. The historical records were sourced from four natural history collections databases in South Africa. Specimen records were curated and validated against two independent online platforms. The number of shells and diversity among collections were compared, and trends in the database were analysed. We recorded a significant decline in the number of specimens collected between 1897 and 1960, and after 1980 and 2021, respectively. The majority of freshwater mollusc specimens that were collected belonged to Bulinus tropicus (Krauss, 1848) (307 records), followed by Pseudosuccinea columella (Say, 1817) (270 records) and Radix natalensis (Krauss, 1848) (268 records), while 34% of specimens collected received one observation each. Three species database records exhibited positive observation trends, while two species showed negative database record trends. We also found that potentially declining species database records accounted for 52% of the total freshwater molluscs in KwaZulu-Natal. The broad-scale compositional shift of endemic species and the greater prevalence of invasive species may be exacerbated by inadequate sampling and a lack of long-term monitoring programs at selected sites. We argue that random sampling and donations are insufficient to sustain the growth of these collections. National programs, such as the River Eco-Status Monitoring Programme (REMP) and Freshwater Biodiversity Information System (FBIS), have the opportunity to identify and include new key biodiversity sites for biomonitoring of biodiversity. Thus, an increase in financial and skills investment is advocated to monitor biodiversity and the emergence of future diseases.

In this paper, we explore spider diversity and the effects of habitat types on spider distribution in the three different types of habitats in Eastern Cape Province of South Africa. This serves as an invaluable tool for biodiversity assessment while documenting the presence of spiders taxa across different habitats in the selected study areas. Spiders were collected using pitfall traps in Langeni forest, Kambi forest and Silaka Nature reserve. Two of these sites are situated in Mthatha and one in Port St Johns. A total of 12 families represented by 19 genera and 43 species/morphospecies were recorded. Habitat type did not significantly influence spider abundance. This present study provides an important insight into the composition and relative abundance of epigeic spiders in the a priori selected study sites. Even though the analysis of the sampling effort points the low species richness to under sampling, the dataset provides an indication of the families and guilds present in the studied forests during the period of study. The results also indicate that local habitat conditions may have an influence on the spider community structure. These data contribute to the growing knowledge of South African arachnology knowledge but due to limitations associated with the sampling, the data should be viewed as preliminary.

Armed conflicts and humanitarian crises across Africa generate profound yet understudied ecological consequences, reshaping ecosystems through complex processes of degradation and regeneration. This review synthesises evidence from across the continent to examine how warfare, displacement, and refugee settlements alter land use, biodiversity, and conservation outcomes. Conflicts weaken governance, disrupt protected area management, and enable illegal logging, mining, poaching, and unsustainable resource extraction, driving deforestation, habitat fragmentation, and wildlife decline. Refugee settlements, often located near ecologically sensitive areas, intensify pressures on forests, water, and arable land through high demand for fuelwood, food, and construction materials. Quantitative studies, including standardised biodiversity surveys in northern Uganda, reveal striking declines in amphibian, reptile, and plant diversity in refugee-impacted areas compared to nearby controls. Moreover, empirical evidence from Central and East Africa documents sharp increases in bushmeat trade and consumption during and after periods of armed instability. Yet conflict can also produce paradoxical positive effects, where human abandonment allows vegetation recovery and wildlife resurgence, as documented in Mozambique's Gorongosa National Park and other war-affected landscapes. These contrasting dynamics highlight the dual role of conflict as both a driver of ecological collapse and a catalyst for ecosystem resilience. Integrating social science, ecology, and conflict studies is essential to develop conservation strategies that address both human welfare and biodiversity protection. By framing conflict and displacement as intertwined socio-ecological processes, our study highlights the urgent need for interdisciplinary approaches to manage Africa's vulnerable ecosystems under conditions of chronic instability.