African Journal of Ecology最新文献

Buckspoor spiders (Araneae: Eresidae: Seothyra Purcell) are a distinct lineage of burrow-inhabiting web-building spiders endemic to the arid and semi-arid parts of southern Africa. We investigated the role of substrate and vegetation characteristics on site selection in Seothyra schreineri Purcell in the xeric Nama Karoo of the western Free State Province, South Africa. We studied web densities in two 0.5 ha plots in an open habitat grazed by sheep and found declining web densities with increasing distance from the border fence. Web densities in the 1 m² plots were negatively correlated with increasing grass density, positively correlated with increasing percentage fine gravel, whereas shrub cover, litter, hard soil and stones had a very weak effect. Our results indicate that the spatial distribution of fine gravel in Nama Karoo landscapes is a key factor determining the occurrence of S. schreineri, a finding that can guide future sampling efforts, leading to a more complete prediction of the species' distribution and, ultimately, its overall conservation status.

Effective management responses to different risks posed by invasive alien plants (IAP) rely on the ability to assess the appropriateness of the decision-making process involved. IAP management is highly dynamic and complex, involving diverse stakeholders and it remains unclear whether the current decision-making processes are appropriate for managing IAP. However, there have been some notable successes both locally and elsewhere in the world. Here, 30 key informant interviews were conducted with private landowners (n = 7), natural resource managers from government parastatals (n = 7), private sector (n = 5), non-governmental organisations (NGO) practitioners (n = 6) and researchers (n = 5) involved in IAP management, to better understand the perspectives on the current decision-making process. In addition, the compliance of the current IAP decision-making process to the principles of robust decision-making was assessed. The availability of a plethora of management plans, science-based decisions, the creation of jobs, flexible process and coordination were frequently identified strengths. Furthermore, the results showed no significant differences among stakeholder groups in how the respondents characterise their current IAP decision-making process, with infrequent mention of the principles of robust decision-making. The findings demonstrate how infrequently the principles of robust decision-making are incorporated into the current IAP decision-making process. Incorporating the principles of robust decision-making offers an avenue for improving the decision-making process for invasive alien plant management.

Mega-herbivore or elephant fences aim to prevent target animals (here: African savanna elephant Loxodonta africana, giraffe Giraffa giraffa) from crossing while allowing others, often with the intention to protect an area against elephants—for conservation, economic or research purposes. However, little is known about mega-herbivore fence effectiveness and impact on non-target species, for example impact on meso-herbivore movement, or fence avoidance. We hypothesised that mega-herbivore fences are effective in excluding mega-herbivores, whereas other species remain unaffected. We tested this hypothesis by comparing mammalian species abundance in (i) full exclosures, (ii) mega-herbivore exclosures and (iii) open plots. These plots were part of the Lapalala Elephant Landscape Experiment (LELE) project in Lapalala Wilderness, South Africa. Systematic dung pile recording and animal track counts—supported with video footage from camera traps—were used to quantify species-specific animal abundance using generalised linear mixed-effect models. The dung piles showed no difference in the abundance of non-target species between mega-herbivore exclosures and open plots, while target species were successfully excluded. Interestingly, we found fewer tracks of large non-target herbivores, such as plains zebra (Equus quagga) and greater kudu (Tragelaphus strepsiceros) crossing mega-herbivore fences compared to open plots, indicating that some individuals avoided crossing the mega-herbivore fence lines. We suggest that this avoidance is due to a combination of species-specific vigilance and deterrence of large specimens. Further research is needed to determine whether this avoidance persists over time, and if the absence of large non-target animals affects ecosystem functioning. Mega-herbivore fences are an effective means to prevent the movement of target species. However, some individuals of non-target species also avoid crossing these fences, likely large animals due to the minimum height of the fence. We recommend monitoring the movement of species once elephant fences are erected, and to increase minimum fence height if non-target species are affected.

Developing comprehensive mammal inventories in protected areas with human presence is essential for effective biodiversity conservation yet remains challenging, particularly for elusive species. Camera trapping has emerged as a valuable tool for documenting mammal diversity, complementary to or as an alternative to traditional direct observation methods. We studied the Dindefelo Community Nature Reserve (Senegal), encompassing a mosaic of vegetation types with a climate characterised by marked seasonality. The local human population depends on its natural resources for subsistence, and livestock roam freely throughout the reserve. Using camera traps, we conducted a 2-year monitoring program across 29 sampling locations, accumulating 3072 trapping days (approximately 60,000 h of observation). We evaluated how vegetation types, seasonality and anthropogenic factors influenced mammal species richness and vegetation type use. We confirmed the presence of 28 medium- and large-sized mammal species. Mammal species richness varied subtly with vegetation types and seasons but no pronounced differences emerged. Human presence within the reserve had limited negative impacts on mammal species richness. Interestingly, livestock presence, exhibited a positive association with wild mammal diversity, suggesting shared resource use or similar environmental preferences. These results highlight complex interactions between wildlife and human activities. They also emphasise the importance of ongoing monitoring to detect additional rare or elusive species, improving conservation strategies in protected savannahs of western Africa where wildlife and human communities coexist.

Historically, subsistence pastoralists and ranchers have used fire as a management tool in grassy rangelands for millennia. The capacity of these ecosystems to function as carbon sinks depends heavily on management interventions. Understanding optimal fire return intervals is essential for determining how prescribed burning influences long-term carbon and nitrogen cycling. This study builds on previous research at the Ukulinga Grassland Fire Experiment (UGFE), extending beyond surface soils to assess whether fire-induced changes in soil organic carbon (SOC) and total nitrogen (TotN) persist at greater depths and over multi-decadal timescales. Using data from 20 years prior as a baseline, and with grazing excluded, we examine SOC and TotN responses directly attributable to fire as a defoliant. Here we assessed the effect of frequency and seasonal timing of prescribed fires on SOC, TotN and carbon-to-nitrogen (C:N) ratios in a South African mesic grassy rangeland system. Our findings suggest that early season, frequent prescribed burns result in greater SOC concentrations and enhanced sequestration rates compared to longer burn intervals. Over the 20-year monitoring period, frequently burnt plots showed continued carbon accumulation, while longer return intervals were associated with reduced subsoil carbon sequestration below 5 cm. These results demonstrate the resilience of mesic grasslands to frequent prescribed fire as a disturbance and highlight fire as a key abiotic driver of SOC accumulation and nutrient cycling. Our findings align with local studies in temperate South African grasslands and savannas and support the potential of frequent prescribed burning as a strategy for enhancing SOC in fire-dependent grassy ecosystems. However, these carbon benefits must be weighed against potential trade-offs, particularly with grazing productivity and plant diversity, which require further consideration in the context of sustainable land management and carbon credit schemes.