Search

Invasion by invasive alien plants is a global challenge and South Africa has invested billions of Rands to manage invaders through the Working for Water programme. However, regular monitoring after alien plant clearing is hardly done, yet it forms the basis for assessing clearing programme effectiveness, particularly ecosystem recovery trajectories. I monitored both vegetation and soil recovery 6 years after Eucalyptus grandis clearing by Working for Water at Zvakanaka Farm in Limpopo Province of South Africa. Vegetation diversity and soil physical properties were surveyed in 2019 and re‐surveyed in 2022 on fell‐and‐removal and fell‐and‐stackburn cleared treatments and compared to the nearby uninvaded treatment. Results show a significant increase in species richness in 2022 compared to 2019 in the fell‐and‐removal treatment. Cover of both native trees and shrubs as well as forbs was significantly higher in 2022 compared to 2019 in the fell‐and‐removal treatment compared to the fell‐and‐stackburn treatment. Most secondary invaders such as Acacia mearnsii, E. cloeziana, Lantana camara and Rubus rigidus that frequently occurred in 2019 showed decreased occurrence in 2022 on both cleared treatments. Between the two sampling years, soil compaction improved on the fell‐and‐removal treatment only, whereas hydraulic conductivity increased significantly in 2022 compared to 2019 in both the fell‐and‐removal and fell‐and‐stackburn treatments. Soils that were strongly and severely repellent in 2019 in the fell‐and‐stackburn treatment were becoming slightly repellent in 2022. These results show varied vegetation and soil improvements between 2019 and 2022 in both the fell‐and‐removal and fell‐and‐stackburn cleared treatments an indication that recovery is moving towards a positive vegetation and soil recovery trajectory in the direction of the uninvaded treatment. Recommendations for successful passive restoration such as secondary invasion follow‐up clearing are discussed. [ABSTRACT FROM AUTHOR]

Transdisciplinary research has gained traction globally for mapping pathways for sustainable urbanisation. The involvement of local communities is believed to central to knowledge co-production needed to address sustainability challenges. But working with local communities can be challenging. This paper is structured around the authors' personal reflections on undertaking transdisciplinary household energy conservation projects in Ghana and South Africa. The paper reflects on the assumptions and challenges of doing transdisciplinary research in urban Africa and suggests some guidelines for consideration when doing transdisciplinary projects. An inductive analysis of our reflections showed five key challenges: lack of integration, divergent problem identification, tensions in knowledge co-production, asymmetrical power relations, and distrust and managing expectations. We draw on our collective experiences to develop guidelines for conducting transdisciplinary research in urban Africa. These guidelines are not prescriptive but can be useful for a growing and broader audience interested in undertaking transdisciplinary research. [ABSTRACT FROM AUTHOR]

South African terrestrial ecosystems are invaded by hundreds of alien plant species, and large‐scale clearing based on the passive restoration assumption that cleared areas will recover unaided is underway. This study assessed the recovery of vegetation and soil properties, three years following Eucalyptus grandis clearing using fell‐and‐removal and fell‐and‐stackburn methods at Zvakanaka Farm in Limpopo Province, South Africa. The main aim was to ascertain the extent of vegetation and soil recovery, as well as determining which clearing methods facilitate passive vegetation and soil restoration. Results indicate significantly (p < 0.001) lower native species diversity, cover and composition in cleared than in uninvaded sites. However, the recorded low species diversity and composition in cleared sites were more pronounced in the fell‐and‐stackburn than in the fell‐and‐removal sites. Measured soil physical properties varied, with compaction being higher in fell‐and‐removal, whereas soils were more repellent in fell‐and‐stackburn sites. The study concludes that vegetation and soil recovery, following E. grandis clearing, is complex and involves several interacting factors, which are linked to invasion history and intensity. Therefore, for vegetation and soil properties to recover, following E. grandis removal, the clearing programme should consider active restoration techniques, for example soil manipulation and native plant seeding. [ABSTRACT FROM AUTHOR]

Understanding homestead tree holdings is important for developing local conservation and livelihood strategies. However, relative to urban homesteads, tree holdings in rural African homesteads remain little studied, especially in semi‐arid settings. Using ecological and household surveys, this paper examines homestead tree composition, uses and challenges in Checheche, Zimbabwe. In total, 1,594 trees were encountered across 147 homesteads. Nearly, all homesteads (99%) had trees, and most of them were primarily planted for fruits and shade. Fuelwood, traditional medicines, windbreak and homestead decoration were considered as secondary benefits. Overall, tree density was approximately 112 trees/ha, with an average of 11 ± 7.1 trees per homestead. Homestead tree holdings were explained by age and gender of respondent, homestead ownership and importance attached to and knowledge of trees. Challenges to tree planting mentioned include termites, diseases, livestock damage, high temperatures, water shortages and poor quality soils. Overall, this study shows that homestead tree planting is widespread in semi‐arid rural settings but constraints to tree planting ought to be addressed to optimise the benefits from trees. Further research is needed to fully understand the socioecological context that explains tree survival, as a basis for developing interventions for enabling homestead tree planting. [ABSTRACT FROM AUTHOR]

Many studies in South Africa have examined the impacts of alien plants on ecosystems, but none have assessed the impact of guava (Psidium guajava L.) invasion on soil properties. In this study, soils underneath guava‐invaded sites were assessed to determine if they had different soil physico‐chemical properties (pH, P, C, N, Na, K, Ca, Mg, moisture, penetration resistance, infiltration and water repellency) as compared to soils underneath uninvaded sites. Comparisons were made from three different sites over three autumn months. Results show that soil pH was significantly (p < 0.005) higher underneath uninvaded than guava‐invaded sites. Soil P was three times higher underneath guava‐invaded as compared to invaded sites. The soils collected underneath guava‐invaded sites had a significantly (p < 0.001) higher moisture content and were less compact but more repellent than soils from the uninvaded sites. Infiltration rate was significantly (p < 0.001) higher in the uninvaded than the guava‐invaded sites. The study concludes that guava invasion alters some soil properties, thus creating favourable conditions for its growth and making it potentially more invasive. From a management standpoint, guava removal is encouraged; however, given guava's socio‐economic importance more research on cost and benefits is required. [ABSTRACT FROM AUTHOR]

Nurse plants offer microclimates that are favourable to plant growth of understory native vegetation, thus facilitating ecological restoration in degraded old fields. This study examined the impact of three nurse plants on vegetation diversity and soil physical properties in old fields located at Lapalala Wilderness, South Africa. Vegetation surveys in plots measuring 5 m x 5 m under and outside the canopy of nurse plants in both old field and natural sites were conducted. Top soils under and outside the nurse plants canopy were collected in all plots and quantified for soil moisture, soil penetration resistance and soil water repellency. Results indicate that species diversity was high under plant canopy compared to outside plant canopy for all nurse plants. Soils under nurse plants canopy showed improved soil moisture and soil penetration resistance compared to soils outside plant canopy, but no differences were reported for soil water repellency. The study concludes that the presence of native plants under nurse plants canopy points to a positive vegetation recovery trajectory. For vegetation and soil restoration to be effective in Lapalala Wilderness old fields, nurse plants should be protected and active restoration, e.g. seeding or seedling sowing under nurse plants canopy should be considered. [ABSTRACT FROM AUTHOR]

Coastal sand dune ecosystems are subjected to many stress and disturbance factors that are particularly high in the foredunes compared to the backdunes. Although a few studies have been conducted on eastern coastline sand dunes of South Africa, none have examined the relationship between aspect and slope on vegetation composition and soil properties of coastal forest backdunes. Vegetation and soil sampling were conducted in 11 transects, each with four plots measuring 10 × 10 m, located on the seaward and landward sides and on middle and lower slopes of backdunes of Bathurst coastal forest. A total of 39 species were identified, of which 23 were trees and shrubs, thirteen were forbs and three were grasses. The data show that both aspect and slope had limited influence on vegetation community assemblage and soil properties, but had significant effects on individual species distribution. There was a grass-dominated community on the middle slope and a tree- and shrub- dominated community on the lower slope. These two plant communities act as the required coastal forest ecosystem engineer driving variability in soil properties between the slopes, the most prominent being high soil nutrients and moisture in the lower slopes compared to the middle slopes. [ABSTRACT FROM AUTHOR]

Many invasive alien plants drive changes in native community composition, structure and diversity. They alter soil nutrient regimes of native communities and affect native plant recovery outcomes following their removal. We assessed whether E ucalyptus grandis invasion and removal alters the soil physico-chemical properties and native vegetation recovery in the Eastern Cape Province, South Africa. We collected samples from topsoil in E . grandis invaded sites (canopy cover > 75%), cleared sites (eight years ago) and native sites (canopy cover > 80%) and quantified soil moisture, concentrations of soil macro elements ( N, C and P), pH and exchangeable cations ( K, Ca, Mg, Na) as well as measured soil water repellency using the Water Droplet Penetration Time and infiltration. We conducted vegetation surveys in plots measuring 10 × 10 m. Invasion by E . grandis had varying effects on soil physico-chemical properties, causing increase in soil pH and P, while decreasing total N and C. The removal of E . grandis also showed varying effects on soil physico-chemical properties, but seems to have further triggered the loss of some soil nutrients (especially soil P). Soil water repellency (a measure of soil compaction) has improved in cleared sites to non-repellent soils compared to repellent soils in invaded site. E ucalyptus grandis reduced species richness of the invaded sites. The presence of native species on cleared sites indicates a positive trajectory towards vegetation recovery. We conclude that E . grandis invasion and removal trigger varying effects on soil properties (both increases and decreases). For soil and vegetation restoration of cleared sites to be effective, active restoration techniques such as soil transfer, nutrient manipulation and native plant seeding should be considered. [ABSTRACT FROM AUTHOR]

Changes in biotic and abiotic factors may create opportunities for biodiversity recovery in abandoned agricultural fields. This study examined the natural/old field edge effect on plant diversity and soil properties at Lapalala Wilderness in Limpopo Province, South Africa. Detailed vegetation surveys and soil measurements were conducted in three old fields that share a natural/old field road edge boundary. On each site, three transects, each with four plots (10 × 10 m), located 10 m into the natural area and 10, 30 and 50 m into the old field from the edge, were setup. Plant diversity and composition measurements were conducted on each plot. Soil moisture and total N, C and P were measured at the center of each plot. Results indicate that abundance of some woody species was significantly (P < 0.001) higher close to the edge than far into the old fields. However, this was not the case for herbs and grasses which did not increase with edge proximity. All measured soil properties were significantly (P < 0.001) higher close to the edge than far into the old fields. The study concludes that both vegetation and soil properties are influenced by proximity to the edge. [ABSTRACT FROM AUTHOR]