The biogeography of South African terrestrial plant invasions

Thousands of plant species have been introduced, intentionally and accidentally, to South Africa from many parts of the world. Alien plants are now conspicuous features of many South African landscapes and hundreds of species have naturalised (i.e. reproduce regularly without human intervention), many of which are also invasive (i.e. have spread over long distances). There is no comprehensive inventory of alien, naturalised, and invasive plants for South Africa, but 327 plant taxa, most of which are invasive, are listed in national legislation. We collated records of 759 plant taxa in 126 families and 418 genera that have naturalised in natural and semi-natural ecosystems. Over half of these naturalised taxa are trees or shrubs, just under a tenth are in the families Fabaceae (73 taxa) and Asteraceae (64); genera with the most species are Eucalyptus,Acacia, and Opuntia. The southern African Plant Invaders Atlas (SAPIA) provides the best data for assessing the extent of invasions at the national scale. SAPIA data show that naturalised plants occur in 83% of quarter-degree grid cells in the country. While SAPIA data highlight general distribution patterns (high alien plant species richness in areas with high native plant species richness and around the main human settlements), an accurate, repeatable method for estimating the area invaded by plants is lacking. Introductions and dissemination of alien plants over more than three centuries, and invasions over at least 120 years (and especially in the last 50 years) have shaped the distribution of alien plants in South Africa. Distribution patterns of naturalised and invasive plants define four ecologically-meaningful clusters or “alien plant species assemblage zones”, each with signature alien plant taxa for which trait-environment interactions can be postulated as strong determinants of success. Some widespread invasive taxa occur in high frequencies across multiple zones; these taxa occur mainly in riparian zones and other azonal habitats,or depend on human-mediated disturbance, which weakens or overcomes the factors that determine specificity to any biogeographical region

Successes and failures in rangeland restoration- an Icelandic case study

Rangeland restoration is a multilayered process aimed at improving land condition, often parallel to utilization. To ensure the long-term progress that restoration programmes are expected to deliver, they must be designed, implemented and maintained in partnership with local stakeholders. Each programme should have clear goals, followed up by measurable ecological and/or socio-economic objectives, to facilitate their evaluation in the long run. In this research, we examine if a large-scale rangeland restoration programme in Iceland had contributed to the expected attitudinal and behavioural changes among the participating sheep farmers, as described in the initial objectives of the programme. A survey, based on a questionnaire on sheep farmers' attitude and behaviour related to rangeland restoration and land management practices, was used to gauge the perception of participating farmers, in comparison with non-participating farmers. Our results show that participating farmers are more aware of the potential of rangeland restoration and are more motivated to engage in further collaboration, when compared with non-participating farmers. Nevertheless, our results indicate that, despite extensive areas of degraded land already successfully treated within the restoration programme, the programme has not facilitated other anticipated attitudinal and behavioural changes among its participants as expected. Furthermore, it seems that the direct incentives provided by the programme are pushing participating farmers towards favouring agronomic instead of ecological approaches in their restoration activities, when compared with the non-participating farmers. Our results also point to several organizational errors embedded in the programme management that might be halting its further progress