Extracted from the Mendeley GBIF Public Library.
Cheek, M., 2015.
First official record of a naturalised population of Mimosa albida Humb. & Bonpl. ex Willd. var. albida in Africa
BioInvasions Records 4.
Mimosa albida var. albida is a woody shrub indigenous to Central and South America that is well adapted to disturbed habitats. This paper is the first formal report of this species outside of cultivation in Africa. A total of 61 plants were recorded along a 1.5km arc of the Mkhomazi River in KwaZulu-Natal, South Africa. Effort s are underway to eradicate the population.
Keywords: South Africa, ornament al plants, riparian weeds
González-Moreno, P., Diez, J., Richardson, D., Vilà, M., 2015.
Global Ecology and Biogeography n/a-n/a.
Aim Analysing how species niches shift between native and introduced ranges is a powerful tool for understanding the determinants of species distributions and for anticipating range expansions by invasive species. Most studies only consider the climatic niche, by correlating widely available presence-only data with regional climate. However, habitat characteristics and disturbance also shape species niches, thereby potentially confounding shifts attributed only to differences in climate. Here we used presence and abundance data for Oxalis pes-caprae, a species native to South Africa and invading areas globally, to understand how niche shifts may be influenced by disturbance at habitat and landscape scales in addition to climate. Locality Mediterranean climate areas world-wide. Methods We used available presence-only data and also conducted extensive surveys of the abundance of Oxalis (c. 11,000 plots) across different habitats in South Africa and in the introduced range in the Mediterranean Basin. We extended principal component analysis methods for measuring niche shifts by using Bayesian generalized linear models to identify climatic and disturbance niche shifts. Results We found a large climatic niche expansion towards stronger seasonality and lower temperature in the introduced range, but this expansion was greatly reduced when considering only conditions available in both ranges. Oxalis occupied more natural landscapes in the native range that remained unoccupied in the introduced range (‘niche unfilling’). In contrast to the similar abundances in natural and disturbed habitats in its native range, Oxalis was more abundant in disturbed habitats in the introduced range. Conclusions The large climatic niche expansion most likely reflects significant plasticity of Oxalis rather than rapid evolution. Furthermore, the unfilling of its disturbance niche in the introduced range suggests high potential for further invasion of natural areas. Together, these findings suggest that the potential for future spread of invasive species may be underestimated by approaches that characterize species niches based only on climate or partial information about their distributions.
Keywords: Bayesian, Oxalis pes-caprae, biological invasions, invasion risk, niche conservatism, non-native species, reciprocal distribution modelling
Jacobs, L. E. O., van Wyk, E., Wilson, J., 2015.
Recent discovery of small naturalised populations of Melaleuca quinquenervia (Cav.) S.T. Blake in South Africa
BioInvasions Records ( 4.
The discovery of a naturalised population of Melaleuca quinquenervia in South Africa in 2009 prompted an evaluation of the species’ distribution across South Africa. We found reco rds at seven localities in two of the nine provinces of South Africa, with natur alised populations at two sites — ~300 plants were discovered over 0.3ha in a confined-seep on a mountain slope, while at an old arboretum 12 large, planted trees and 9 naturalised trees were found. An additional herbarium record from Mozambique suggests that this glob al invader is present at other sites within the sub-region, and so while th e extirpation of populations in South Africa is recommended and lo oks feasible, further work is required to de termine the status and evaluate whether eradica tion from the sub-region as a whole is possible.
Keywords: Myrta, early detection, eradication, invasive tree
Richardson, D., Le Roux, J., Wilson, J., 2015.
Australian acacias as invasive species: lessons to be learnt from regions with long planting histories
Southern Forests: a Journal of Forest Science 1-9.
Problems associated with invasiveness of non-native tree species used in forestry are increasing rapidly worldwide and are most severe in areas with a long history of plantings. Lessons learnt in areas with long histories of plantings and invasions may be applicable to areas with shorter planting histories. Most research towards understanding such tree invasions has focused on Pinus species, though all groups of trees that have been widely used in forestry are invasive to some extent. This paper explores the experience of Australian Acacia species (wattles). Unlike some other groups of trees, no particular set of traits clearly separates highly invasive from less- or non-invasive wattles. All species that have been widely planted over a long period have become invasive; the extent of invasions is largely a function of human usage. These findings imply that propagule pressure in concert with residence times are the main drivers of invasiveness in wattles (many factors mediate these drivers, including fire,...
Keywords: biological invasions, forestry, sustainable forestry, tree invasions, wattles
Blanchard, R., O'Farrell, P., Richardson, D., 2014.
Anticipating potential biodiversity conflicts for future biofuel crops in South Africa: incorporating spatial filters with species distribution models
GCB Bioenergy Forthcoming.
Liquid biofuel production will likely have its greatest impact through the large-scale changes in land use that will be required to meet the production of this energy source. In this study, we develop a framework which integrates species distribution models, land cover, land capability and various biodiversity conservation data to identify natural areas with (i) a potentially high risk of transformation for biofuel production and (ii) potential impact to biodiversity conservation areas. The framework was tested in the Eastern Cape of South Africa, a region which has been earmarked for the cultivation of biofuels. We expressly highlight the importance of biodiversity conservation data that enhance the protected area network to limit potential losses by comparing the overlap of areas likely to become cultivated with (i) protected areas; (ii) biodiversity hot spots not currently protected; and (iii) ‘ecological corridors’ (areas deemed important for the migration of species and linkages between important biodiversity areas). Results indicate that the introduction of spatial filters reduced available land from 54% to 45%. Including all biodiversity scenarios reduced available land to 15% of the Eastern Cape should avoiding conflict with biodiversity conservation areas be prioritized. The assumption that agriculturally marginal land offers a unique opportunity to be converted to biofuel crops does not consider the biodiversity value attached to these areas. We highlight that decisions relating to large-scale transformation and changes in land cover need to take account of broader ecological processes. Determining the spatial extent of threats to biodiversity facilitates the analysis of spatial conflict. This article demonstrates a proactive approach for anticipating likely habitat transformation and provides an objective means of mitigating potential conflict with existing land use and biodiversity.
Keywords: MaxEnt, agricultural land, biodiversity, bioenergy crops, conflict, land suitability, spatial analysis, spatial filters
Blanchard, R., 2014.
Biofuels are being promoted as a global necessity to meet climate change targets through the replacement of fossil fuels. Many countries have identified biofuels as a potential mechanism to meet these challenges, with policy directives driving biofuel production. The South African government has proposed that biofuels form part of the country’s future renewable energy and has proposed a draft biofuel strategy. This study aims to investigate appropriate approaches to determine potential biodiversity impacts from biofuel production. Since biofuels are not currently grown to any large extent in South Africa, impact was modelled using future scenarios of converting available land within the Eastern Cape Province of South Africa. Suitable species were identified using the species distribution modelling programme MaxEnt. Some of the proposed biofuel crops were considered as invasive (i.e. they spread from sites where they are cultivated) or are very likely to be invasive in South Africa. This study also highlighted the considerable overlap between suitable growing areas and areas considered important for future biodiversity conservation. The biodiversity intactness index (BII), a broad based biodiversity indicator, was used to assess the biodiversity implications of transforming available land to biofuels. The BII indicates losses of biodiversity between 17.6% and 42.1% for the land use scenarios identified. An important finding was that excluding important biodiversity areas that occur outside of protected areas can reduce biodiversity losses by as much as 13% and maintain an overall intactness of ~70%. Currently the BII does not account for fragmentation or landscape configuration. This was addressed by developing a revised biodiversity intactness index (R-BII) which included the effect of patch-size and habitat fragmentation on biodiversity intactness. This study found that although the original BII reported on the biodiversity trends of large-scale shifts in land-use across multiple scales it could not detect changes in landscape configuration which was reflected by the R-BII. Land-use change can impact on ecosystem processes that underpin the provisioning of ecosystem services by changing the combinations of species and the plant functional traits within communities. The impacts of cultivating potential biofuel species (Acacia mearnsii, Sorghum halepense and Eucalyptus species) were investigated using a plant functional traits approach. These species were shown to affect the leaf nitrogen content, leaf phosphorous content and leaf dry matter content associated with important ecosystem functions within an ecosystem service hotspot in the Eastern Cape. A decline in functional diversity was reported for all transformed land-uses by as much as ~40%. These shifts may be used to identify potential changes to ecosystem services associated with natural vegetation. The methods used in this thesis highlight the overall relevance of this work and its importance to minimising biodiversity resulting from biofuel production. Some of the key findings address resolving spatial conflict, using biodiversity indicators, assessing impacts of potential invasive species and planning for ecosystem services. New drivers of change to land-use, such as biofuel production, are a major challenge to conservation biologists and planners and the insights derived in from this study can be successfully applied to guide biofuel production.
Keywords: MaxEnt, agricultural land, biodiversity, bioenergy crops, conflict, land suitability, spatial analysis, spatial filters
Donaldson, J., Hui, C., Richardson, D., Robertson, M., Webber, B., Wilson, J., 2014.
Global Change Biology 20(5) 1527-37.
Global change is driving a massive rearrangement of the world's biota. Trajectories of distributional shifts are shaped by species traits, the recipient environment and driving forces with many of the driving forces directly due to human activities. The relative importance of each in determining the distributions of introduced species is poorly understood. We consider 11 Australian Acacia species introduced to South Africa for different reasons (commercial forestry, dune stabilization and ornamentation) to determine how features of the introduction pathway have shaped their invasion history. Projections from species distribution models (SDMs) were developed to assess how the reason for introduction influences the similarity between climatic envelopes in native and alien ranges. A lattice model for an idealized invasion was developed to assess the relative contribution of intrinsic traits and introduction dynamics on the abundance and extent over the course of simulated invasions. SDMs show that alien populations of ornamental species in South Africa occupy substantially different climate space from their native ranges, whereas species introduced for forestry occupy a similar climate space in native and introduced ranges. This may partly explain the slow spread rates observed for some alien ornamental plants. Such mismatches are likely to become less pronounced with the current drive towards 'eco gardens' resulting in more introductions of ornamental species with a close climate match between native and newly introduced regions. The results from the lattice model showed that the conditions associated with the introduction pathway (especially introduction pressure) dominate early invasion dynamics. The placement of introduction foci in urban areas limited the extent and abundance of invasive populations. Features of introduction events appear to initially mask the influence of intrinsic species traits on invasions and help to explain the relative success of species introduced for different purposes. Introduction dynamics therefore can have long-lasting influences on the outcomes of species redistributions, and must be explicitly considered in management plans.
Keywords: Acacia, biological invasions, intrinsic species traits, introduction pathways, invasive distributions, niche shift
Faulkner, K., Robertson, M., Rouget, M., Wilson, J., 2014.
Biological Conservation 179 25-32.
Biosecurity schemes aim to prevent the introduction of species with a high invasion potential, without unduly restricting personal freedom and commercial activities. But invasive species risk assessments are time consuming, data intensive and expensive. Consequently, resource poor nations cannot imple- ment these schemes. Here we develop a method for creating watch lists using the consistent predictors of invasion success—history of invasion, environmental suitability, and propagule pressure (measured respectively using the Global Invasive Species Database (GISD), environmental modelling, and tourism and trade data). We tested the approach for South Africa, at a national level for various taxa and at a pro- vincial level for plants. Of 884 alien species listed in the GISD, 400 were potential invaders, with most occurring in high risk regions. When alien species in South Africa were evaluated there were many false-negatives (sensitivity of 32% for terrestrial and 40% for marine species), because the GISD is not comprehensive, but few false positives (specificity of 91% for terrestrial and 89% for marine species). The methodology was easy to apply at different political levels, but we found substantial overlaps between the national and provincial watch lists of plants. This simple technique is rapid, easily repeat- able, flexible, transparent, works across taxa, and does not require substantial financial or scientific input. It can be used in any region of the world and at various political levels as an initial assessment of key threats. As such it may be an important step in developing biosecurity schemes for resource poor regions.
Keywords: Biosecurity, Invasive elsewhere, Pre-border control, Propagule pressure, Risk assessment, biological invasions
Fritsch, P., Manchester, S., Stone, R., Cruz, B., Almeda, F., 2014.
Journal of Biogeography n/a-n/a.
Aim We sought to reconstruct the historical biogeography of the amphi-Pacific tropical disjunct plant family Symplocaceae in the context of competing Northern Hemisphere (boreotropical) versus Southern Hemisphere (West Gondwanan) hypotheses for its origin and spread. Location Americas, western Pacific Rim, fossil localities in Europe. Methods We derived a dated phylogeny using a relaxed clock on a data set of 114 terminals, four genic regions (three plastid regions and the nuclear ribosomal internal transcribed spacer region) and six fossil calibrations. We inferred ancestral geographical ranges with maximum likelihood under a dispersal–extinction–cladogenesis model, with the probability of dispersal constrained by areal distance and palaeogeography. Results We inferred a Eurasian origin for crown-node Symplocaceae at c. 52 Ma, followed by dispersal to North America (including Mesoamerica) at c. 52–38 Ma. Most of the highest likelihood intra-American dispersals recovered in the analysis trended from north to south, with none from south to north. Six intra-American dispersals were inferred to have originated in North America, with lineages either terminating in the Antilles or migrating to South America at various times. One additional North American lineage emigrated back to Eurasia in the late Miocene. Main conclusions The predominantly southwards American migrations inferred here for the Symplocaceae conform to the boreotropics hypothesis, apparently driven by cooling and drying climates in the later Cenozoic. The inferred Eurasian origin for the family corroborates a more specific European origin, as suggested independently by its fossil fruit record. Of the lineages ultimately arriving in South America from North America, two are inferred to have migrated through the Antilles (by island-hopping) and three through Mesoamerica. The timing of one of the Mesoamerican events, inferred to be between 8.9 and 7.5 Ma, implies over-water dispersal under the prevailing model of Isthmus of Panama formation, but also accords with overland migration under a model of earlier formation.
Keywords: Amphi-Pacific tropical disjunctions, Cenozoic era, Cordyloblaste, Symplocaceae, Symplocos, ancestral geographical range analysis, divergence time estimation, fossil fruits, historical biogeography
Higgins, S., Richardson, D., 2014.
Proceedings of the National Academy of Sciences of the United States of America 111(29).
Invasive species cost the global economy billions of dollars each year, but ecologists have struggled to predict the risk of an introduced species naturalizing and invading. Although carefully designed experiments are needed to fully elucidate what makes some species invasive, much can be learned from unintentional experiments involving the introduction of species beyond their native ranges. Here, we assess invasion risk by linking a physiologically based species distribution model with data on the invasive success of 749 Australian acacia and eucalypt tree species that have, over more than a century, been introduced around the world. The model correctly predicts 92% of occurrences observed outside of Australia from an independent dataset. We found that invasiveness is positively associated with the projection of physiological niche volume in geographic space, thereby illustrating that species tolerant of a broader range of environmental conditions are more likely to be invasive. Species achieve this broader tolerance in different ways, meaning that the traits that define invasive success are context-specific. Hence, our study reconciles studies that have failed to identify the traits that define invasive success with the urgent and pragmatic need to predict invasive success.
Keywords: biological invasion, ecological niche, physiology, range size, tree invasions