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This study investigated the autogenic recovery potential of native vegetation after clearing of dense stands of invasive alien trees in two critically endangered vegetation types in South Africa's Cape Floristic Region: Cape Flats Lowland Fynbos and Swartland Alluvium Fynbos. Sampling was done in areas previously occupied by the invasive tree Acacia saligna and plantations of Pinus radiata and in a fynbos reference site. Treatments varied in terms of the length of invasion and management histories. Plots previously under pines recovered well in terms of indigenous perennial species richness, but indigenous species cover decreased with increasing number of planting rotations. Areas cleared of acacia recovered poorly in terms of indigenous species cover (after one cycle of invasion), and indigenous species richness exhibited a declining trend with increasing cycles of invasion. Proteoid overstorey was lost in all previously invaded/planted plots and this element will need to be re-introduced to areas after one cycle of invasion regardless of the invasive species. Acacias changed some abiotic variables after two cycles of invasion. Follow-up clearing generally promoted better vegetation recovery in terms of overall species richness and structure but care should be taken not to damage indigenous ericoid shrubs. Overall, acacia invasion caused a greater change in biodiversity and vegetation structure than pine plantations. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAPs) are a major threat to biodiversity in South Africa's Cape Floristic Region (CFR). Activities like agricultural development, the establishment of forestry plantations and urbanization change environments and provide opportunities for IAPs to spread. We examine the factors that have contributed to plant invasions on a privately-owned farm in the CFR. The objectives of the study were: (1) to determine what land-use changes took place that could have influenced the spread of IAPs; and (2) to document the patterns of spread of IAPs. Aerial photographs from 1938, 1966, 1977, 1989 and 2004 were used to determine the types and rates of land-use change over time. Key land-use changes involved agriculture, commercial plantations, urban development and the spread of IAPs. The spatial analysis identified the main drivers of change. Agricultural development was the main land-use change driver and affected 40% of the study area by 1977. Areas occupied by IAPs increased with landuse change from 8% cover in 1938 to 40% in 2004, and then declined to 15% in 2013 following the initiation of control operations in 2004. The study illustrated a clear link between human activities, changes in land-use and the spread and proliferation of IAPs. [ABSTRACT FROM AUTHOR]

Alien plant invasions are a major threat to biodiversity and ecosystem functioning in South Africa’s Cape Floristic Region (CFR). Large-scale government-funded management initiatives are underway to reduce the extent of invasions in this region. Among the many challenges are the huge spatial extent of the invasions and difficulties in coordinating management efforts across large areas of invaded land in private ownership. Very little information is available on the success of privately-funded alien plant control initiatives. This study investigated the effectiveness of one large project in reducing alien plant cover, the challenges faced and the costs associated with long-term clearing operations on privately-owned land in the CFR. Results for the study area (Vergelegen) show that the cover of dense invasive plant stands declined by 70% over 10 years since management operations began, but that operations cost 3.6 times more than was originally estimated (ZAR 43.6 vs 12.19 million, respectively). The challenges associated with managing invasive alien plants (IAPs) on private land are very similar to those faced on state-owned land, with the efficiency of management being constrained by multiple interacting environmental and socio-economic factors. However some success in managing IAPs can be achieved by adhering to basic principles, including careful planning with clear achievable goals in mind, a commitment to stable long-term funding and regular monitoring. Most private land owners cannot afford the substantial investment of resources that would be required to clear large stands of IAPs and to ensure that cleared areas are maintained to prevent re-invasion, and finding ways to fund this remains a challenge. [ABSTRACT FROM AUTHOR]

Soil compaction is a major threat to natural resources. However, little information is available on the impacts of soil compaction on arthropod diversity especially relative to different types of vegetation, land use and restoration activities. In response to this dearth of information, we studied soil compaction, as well as percentage soil moisture and mean leaf litter depth, associated with four vegetation types: natural vegetation (fynbos, the historic condition), agricultural land (vineyards), invasive alien trees, and vegetation cleared of invasive alien trees (recovering vegetation). Our study took place in the Cape Floristic Region, South Africa, a biodiversity hotspot, yet also an area of intense viticulture and heavy invasion by alien plants. We sampled soil surface-active arthropods using pitfall traps, and compared species richness and abundance in different vegetation types with various levels of soil compaction and other soil variables. Overall, vineyards had the highest soil compaction while natural fynbos and aliens had low and comparable compaction. For both arthropod species richness and abundance, the order of the four vegetation types was, from highest to lowest: natural fynbos, alien cleared sites, vineyards, and alien infested sites. Level of soil compaction negatively correlated with arthropod species richness but not with abundance. Neither soil moisture nor leaf litter depth on their own significantly affected arthropod species richness or abundance. While alien trees overall had a strong negative effect on both arthropod species richness and abundance, and much more so than vineyards, the situation is reversible, with removal of aliens being associated with rapid recovery of soil structure and of arthropod assemblages. This is an encouraging sign for restoration. [ABSTRACT FROM AUTHOR]