Potential Futures of Biological Invasions in South Africa

Biological invasions are having a moderately negative impact on human livelihoods and the environment in South Africa, but the situation is worsening. Predicting future trends is fraught with many assumptions, so this chapter takes an outcome-orientated approach. We start by envisaging four scenarios for how biological invasions might look like 200–2000 years from now: (1) “Collapse of Civilisation, but no return to Eden”, there is no advanced human civilisation left on Earth and current biological invasions play out in full; (2) “New Pangea”, a combination of the unregulated and rapid movement of species around the world and other global change drivers leads to the biotic homogenisation of areas that were previously distinct biogeographic regions such that the concept of biological invasions no longer has meaning; (3) “Preserve or Use”, while parts of the Earth continue to be utilised, some areas are actively managed and native biodiversity and biogeographic distributions are maintained; and (4) “Conservation Earth”, a highly advanced civilisation restores the Earth to a state prior to the human-mediated movement of organisms (i.e. biological invasions are reversed). Based on various horizon-scanning exercises and our own deliberations, we discuss how technological, socio-political, trade, global change, and ecological-evolutionary processes in South Africa might affect biological invasions by 2070 (i.e. when people born today will be the key decision-makers). Finally, we explore how planning, regulation, funding, public support, and research might affect invasions by 2025 (i.e. over the next planning/management/political cycle). There are many things we can neither predict nor influence, but, in part based on the insights from this book, we highlight some actions that could enable the next generation to decide what they want their future to be. A greater focus on appropriate and innovative training opportunities would increase the efficacy and responsiveness of the management of biological invasions. A shift in regulatory approach from “identify and direct” to a variety of flexible, inclusive, and sophisticated approaches underpinned by evidence might provide more societally acceptable means of addressing the multitude of competing interests. Greater co-operation on biosecurity and implementation with neighbouring countries would assist prevention measures. Finally, monitoring and research aimed at documenting, tracking, and predicting invasions and their impacts would assist with efforts to identify priorities and help us to understand the consequence of different management and policy decisions. While this was a sobering exercise, it was also empowering. If South Africans can agree on a long-term trajectory for how they want to deal with biological invasions, the potential consequences of decision-making over the short-term will become much clearer

Complexities of shrub encroachment: are shrubs important for the maintenance of diversity in Themeda-dominated assemblages on coastal headlands in eastern Australia?

Shrub encroachment is an issue worldwide with consequences which may have both positive and negative outcomes for landscape and community health. Themeda- dominated communities on headlands are listed as endangered within New South Wales, Australia with shrub encroachment listed as threat. Coastal headlands are considered harsh environments and positive effects on species diversity patterns may occur due to variables that ameliorate these conditions or through indirect mechanisms. Shrubs are a natural component of coastal headlands in eastern Australian and tall shrub encroachment may have both positive and negative effects on non-shrub communities. I test whether tall shrubs may have a functional role that positively affects species diversity within and between plots and the distribution of species within Themeda- dominated communities on headlands. 352 2 × 2 m plots were placed on 46 headlands along a 530 km stretch of coastline on the North Coast Bioregion, New South Wales, Australia. Within plots vascular plant species were scored on cover and frequency. Species density, diversity, evenness, turnover and gamma diversity were calculated. Variables tested include cumulative tall shrub height from circular transects at 2, 4 and 8 m from plots, slope, aspect, altitude, ground layer height, distance to closest seaward edge and macropod grazing intensity. Rarefaction was performed on a subset of sites that had no shrubs and sites within shrubs within 8 m of plots. The relative interaction intensity (RII) was calculated for all taxa with more than one observation against plots without shrubs and plots with shrubs within 8 m radius. Analyses were performed using Canonical Correspondence Analysis (CCA) and Generalised Additive Modelling (GAM) on species frequency data. A total of 303 native taxa were recorded within plots. The most significant positive effects on species density, evenness and species accumulation included increasing proximity to, and density of tall shrubs. Tall shrubs may allow direct facilitation of less stress tolerant plants to colonise but may have an indirect interaction by reduction in the dominance of Themeda triandra . Other minor significant variables included distance from headland seaward edge, southern and western facing slopes, higher altitudes and a decrease in ground layer height. 178 (80%) of species were found to have a positive RII score associated with the presence of nearby taller shrubs. Tall shrubs may directly facilitate greater species diversity by ameliorating local conditions and indirectly facilitate by reducing the over- dominance of some taxa. In spite of the positive effect of shrubs on diversity eventually tall shrub encroachment may cause replacement of the Themeda- dominated communities with shrubland. Encroaching taller shrubs are therefore shown to be both of benefit to floristic species diversity at all scales within these Themeda- dominated communities on headlands in eastern Australia but also a potential threat. These results highlight the complex nature of community interactions requiring nuanced and potentially novel approaches to management

Colorectal cancer screening by non-invasive metabolic biomarker fecal tumor M2-PK

As Earth’s climate rapidly changes, species range shifts are considered key to species persistence. However, some range-shifting species will alter community structure and ecosystem processes. By adapting existing invasion risk assessment frameworks, we can identify characteristics shared with high-impact introductions and thus predict potential impacts. There are fundamen- tal differences between introduced and range-shifting species, primarily shared evolutionary histories between range shifters and their new community. Nevertheless, impacts can occur via analogous mechanisms, such as wide dispersal, community disturbance and low biotic resistance. As ranges shift in response to climate change, we have an opportunity to develop plans to facilitate advantageous movements and limit those that are problematic