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Introduction
Additional affiliations
September 2018 - present
Education
January 2007 - December 2010
Publications
Publications (78)
Outside their natural range, honeybees (Apis mellifera) are known to have detrimental effects on indigenous pollinators through exploitative or interference competition, but little
is known about the effect of honeybee farming in areas where honeybees occur naturally. In the Cape Floristic Region of South
Africa, where honeybees are indigenous, man...
Reproduction is a crucial part of the successful establishment and spread of an in-vasive species. Invasive plants often produce seeds prolifically to spread into new ranges, yet the invasive macrophyte, Pontederia cordata L., does not appear to produce seeds in South Africa, limiting its invasive potential. Here, we aimed to determine what limits...
African farmers are facing numerous natural disasters, such as flooding, fires and extended droughts. In addition, crop pests have had major impacts on yields for several decades. At the same time, farmers continue to explore pest management strategies that are not only affordable but safe and sustainable. Here we review the knowledge from genomics...
Fungal invasions only recently started to receive more attention in invasion biology. This is largely attributed to little or non-existent information about these inconspicuous organisms. Most invasion hypotheses focus on factors that increase invasion success; few try to explain why invasions fail. Here we hypothesize that a host-pathogen relation...
To support and scale‐up global restoration efforts, the United Nations (UN) has proclaimed 2021–2030 the “UN Decade on Ecosystem Restoration”. The Decade offers significant opportunities for and challenges to restoration, in particular for Africa, a continent that has a large need and potential for restoration. We thus argue that the Decade must be...
The New Zealand bottlebrush, Metrosideros excelsa (Myrtaceae), was introduced into South Africa in the 1940s as an ornamental plant and subsequently naturalized in coastal parts of the Cape Floristic Region. Knowledge of M. excelsa 's propagule pressure and response to fire in South Africa can inform evaluation of the species' invasion potential an...
Forest canopies provide important resources for insect communities via flowers.
Yet, pollination systems of tall forest trees are poorly studied, resulting from the
difficulties in observing pollinator activity at the canopy level and great temporal
variation in flower production. In temperate forest canopies of the southern hemisphere, small, whit...
Aim: Climate change influences species distribution in space and time, but predicting
the overlap in the range of interacting species under different climate scenarios
remains a challenge. Here, we explore how climate change influences shifts in species
ranges among mutualists.
Location: Cape Floristic Region (CFR), South Africa.
Taxon: Proteaceae...
The successful restoration of endangered habitat types at a low cost is of vital importance. We tested how successful and cost-effective six combinations of restoration treatments were in the Cape Floristic Region of South Africa. Treatments were applied to an area that was primarily covered invasive alien grasses. Treatments that tested combinatio...
Fire‐adapted species invading fire‐prone ecosystems in Mediterranean climate regions are difficult to control because they are equally responsive to restoration treatments. We assessed the efficacy of delaying a prescribed burn to promote the recruitment of native species in a Lowland Sand Fynbos ecosystem invaded by alien Acacia saligna . Acacia s...
Livestock guardian dogs are one of several predator control methods employed by livestock farmers around the
world, but little is known about the factors that predict their use. Here we aim to understand the dimensions
which influence guardian dog use by farmers. In a quantitative survey among 113 livestock farmers in South
Africa, using Boosted Re...
Pollination is an important ecosystem service. Animal-mediated pollination (mostly insects) increases the production of 35% of global crops. Honey bees (Apis mellifera) are considered important crop pollinators globally , but are under pressure and therefore the value of wild pollinators for crop production is receiving more attention. The importan...
Background and Aims
Is the increase in species diversity patterns towards lower latitudes, linked to reproductive traits? Plant reproductive organs influence reproductive isolation and hence species divergence. Abiotic differences between temperate and tropical regions can also directly impact on plant reproductive traits. Here we provide a novel o...
With well-developed tourism infrastructure and high biodiversity, including charismatic mammals, wildlife tourism is popular in South Africa. But where and when do people encounter wildlife, how does this vary among species and land-tenures, and how do people feel about their encounters? To assess the potential of social media to provide insights i...
Invasive alien plants (IAPs) pose a serious threat to biodiversity, agriculture, health, and economies globally. Accurate mapping of IAPs is crucial for their management, to mitigate their impacts and prevent further spread where possible. Remote sensing has become a valuable tool in detecting IAPs, especially with freely available data such as Sen...
The method of clearing alien species and the nature of the soil seedbank influence the quality of restoration outcomes, particularly in fire‐prone ecosystems heavily invaded with fire‐adapted alien species. One of the challenges encountered is reducing the likelihood of reinvasions when the invading species are equally responsive to restoration tre...
Several Melaleuca (Myrtaceae) species are invasive globally. Recently an increase in invasive species from this genus have been reported in South Africa. Here we document the first detailed assessment of the distribution and invasive potential of Melaleuca rugulosa in South Africa. We assess population structure, determine the current and potential...
After the clearing of invasive alien plants, non-target alien species often move in. This is known as secondary invasion and these alien species can suppress native plant species’ recovery. This is a global problem that has only recently received attention in South Africa. But whether secondary invaders in riparian areas have similar effects than t...
The shrub Hypericum canariense L. (Hypericaceae) is an emerging invader in several parts of the world. In this study we determined the current invasive distribution in South Africa, assessed soil seedbanks, determined size at reproduction, and evaluated the current management protocols. We further assessed the feasibility of eradication and provide...
Sexual dimorphism in scorpions is generally retrieved for a similar
subset of body parts and is presumed to result from alternative
types of selection operating on homologous structures in
each sex. Even so, investigations which use static allometry as a
method for testing specific hypotheses relating to selection
remain limited. Sexual dimorphism...
The appropriate fire return interval of prescribed burns is critical in many fire-driven systems. I use a mediterranean-type ecosystem-Cape fynbos, South Africa-to test guidelines for fire return intervals. Guidelines state that at least 50% of a population of the slowest-maturing obligate seeder Protea species must have flowered for three successi...
Habitat fragmentation – in terms of a combination of habitat loss and separation – is a major threat to the renosterveld of the Cape Floristic Region (CFR) of which 85% has been transformed, mostly for agriculture. The effects thereof has not been well studied, in particular in the Eastern inland areas. In this study we seek to understand how habit...
https://bit.ly/3zvKXTu
The influence of invasive alien plants on plant community structure and above ground biomass in their novel range is poorly understood, as the magnitude and direction of these effects are often species and ecosystem specific. Here we compared community metrices of native plants and soil properties between study sites invaded...
The potential of an alien plant to spread rapidly and colonize new habitat may be related to the mode of reproduction and the ability to attract pollinators. Most studies focus on widespread invasive plants, in which pollinators are rarely limiting. Here, we assess the ability of a recent invader in South Africa, the tristylous Lythrum salicaria to...
• Invasive alien plants often influence pollinator visitation to native plants when sharing pollinator guilds. It is of conservation concern when the invasive alien plant is characterized by floral resources that attract pollinators, thereby reducing the reproductive success of native species. This is well studied for insects, but whether the same...
The potential of an alien plant to spread rapidly and colonize new habitat may be related to the mode of reproduction and the ability to attract pollinators. Most studies focus on widespread invasive plants, in which pollinators are rarely limiting. Here, we assess the ability of a recent invader in South Africa, the tristylous Lythrum salicaria to...
Pollinators are among the first to be lost when natural habitat is reduced to small patches and this can have cascading effects on multiple plant species. Simultaneously, the loss of natural habitat cuts people off from nature and, when people are out of touch with nature they do not care for biodiversity, resulting in further losses. Theoretically...
Appendix with supplementary tables and figures for:
Mnisi, Geerts, Smith and Pauw 2021. Nectar gardens on school grounds reconnect plants, birds and people. Biological Conservation 257: 109087.
https://doi.org/10.1016/j.biocon.2021.109087
Scorpions exhibit extreme forms of sexual dimorphism, with a number of recent studies highlighting general patterns. Explanations surrounding the potential drivers of these patterns remain speculative, even though static allometry offers a method for testing specific hypotheses. Importantly, a recent study describes a method of reference character...
Southern Africa has a diverse endemic scorpion fauna, but a paucity of information currently confounds conservation of the group. Phylogeographic approaches represent a useful tool to identify the patterns and processes which underpin scorpion diversity, but these studies are lacking for southern African species. Among southern African scorpions, t...
The regulation of biological invasions is often focussed at the species level. However, the risks posed by infra-and inter-specific entities can be significantly different from the risks posed by the corresponding species, to the extent that they should be regulated and managed differently. In particular, many ornamental plants have been the subjec...
Southern Africa contains a diverse and endemic scorpion fauna, but with biological aspects remaining largely unexplored for this group. In order to gain biological insights into an understudied scorpion species, the current study investigates fine-scale spatial distributions and sexual dimorphism in the South African endemic Drab Thick-tail Scorpio...
Clearing invasive alien plants often facilitates secondary invasion and/or weedy native species dominance instead of native biodiversity recovery. Secondary invasion and/or weedy native species dominance in turn can present significant barriers to restoration by hindering the recovery of key native species. The problem of secondary invasion and wee...
The cycad aulacaspis scale, Aulacaspis yasumatsui Takagi (Hemiptera: Coccoidea: Diaspididae), is native to Southeast Asia but an invasive pest of the gymnosperm order Cycadales in many parts of the world. Aulacaspis yasumatsui was recently reported on the cycad genus Encephalartos in South Africa and is currently categorized as a 'prohibited terres...
With the current global concerns about pollinators, relationships between species interactions and diversity are pivotal. If pollinator communities depend strongly on the diversity of flowering plants and vice versa, anthropogenic influences—whether positive or negative—on one partner will cause changes in the other. Here we ask whether nectarivoro...
Ecological interactions, especially those that are beneficial (i.e. mutualism) or detrimental (i.e. parasitism), play important roles during the establishment and spread of alien species. This chapter explores the role of these interactions during biological invasions in South Africa, covering a wide range of taxonomic groups and interaction types....
South Africa is a megadiverse country in terms of biodiversity, with continental South Africa composed of nine terrestrial biomes. This diversity is in part due to the wide range of climatic and topographic conditions that exist in the country. This chapter explores how these environmental features influence biological invasions (focusing on terres...
Invasive alien plant species can be a major cause of ecosystem degradation in South Africa, and ecosystem recovery may require restoration interventions beyond controlling the target alien species. Active restoration interventions are usually required if legacy effects result from the invasion. Legacy effects may induce regime shifts when threshold...
Urban areas are considered hotspots for invasions by alien plant communities. Anthropogenic activity within these areas often facilitates the introduction and spread of invasive alien plants, with urban gardens acting as a significant source of propagules. This makes natural areas within and surrounding urban areas particularly vulnerable to invasi...
Eucalyptus camaldulensis can be seen as an iconic tree of superlatives. It is the eucalypt with the widest native range, and one of the most widely planted eucalypts around the globe. In South Africa, it is the most widespread and the most aggressively invasive eucalypt. It has many uses, but also causes major impacts. However, little is known abou...
Alien species can have major ecological and socioeconomic impacts in their novel ranges and so effective management actions are needed. However, management can be contentious and create conflicts, especially when stakeholders who benefit from alien species are different from those who incur costs. Such conflicts of interests mean that management st...
Plant species that receive significant human introduction effort and assistance generally are the most problematic invaders. Despite this, invasive ornamental species in urban settings have received relatively little attention if not invading natural areas. Here we consider Centranthus ruber in an urban setting in South Africa as a case study and e...
Invasive alien plants have major ecological effects, in particular in riparian habitats. While effects of alien tree invasions on riparian plants are well studied, effects on animals are less well understood. Invasive alien trees can have a positive effect by adding habitat and food sources, or have a negative effect, by replacing native food plant...
The second outcome of target three of the South African Strategy for Plant Conservation is focused on the monitoring of threatened plant species. The Custodians of Rare and Endangered Wildflowers (CREW) programme based at SANBI finds and monitors these species, fulfilling this outcome. Further, CREW started a demographic monitoring project to colle...
The genus Banksia L.f. (Proteaceae) is native to Australia and was
introduced to South Africa in the late 1970s. Currently there are fourteen Banksia species grown in the Cape Floristic Region (CFR) for floriculture and horticulture. Of these fourteen species, namely B. ericifolia L.f. and B. integrifolia L.f. are invasive and another two species h...
The legume, Pueraria montana var. lobata (kudzu vine) is one of the worst plant invaders globally. Here we present the first study of P. montana in South Africa. We found only seven P. montana populations covering an estimated condensed area of 74 hectares during the height of the growing season. Based on a species distribution model, it appears th...
Can short-billed nectar thieving sunbirds replace long-billed sunbird pollinators in transformed landscapes?
Termites, and in particular species that remove live plant material, play an important role in rangeland deterioration in the arid areas of the world. In the arid parts of southern Africa, where the sparse vegetation is important for subsistence and large-scale game farming, it is vital to understand termite ecology and feeding behaviour. Here, we...
Pollinator specialisation through exploitation barriers (such as long floral tubes) does not necessarily mean a lack of pollination when the favoured pollinator is rare or absent. Theory predicts that suboptimal visitors will contribute to plant reproduction in the absence of the most effective pollinator. Here I address these questions with Chasma...
Reproduction is a crucial stage in the naturalization of introduced plant species. Here, using breeding system experiments and observations of floral visitors, we investigate whether a lack of pollinators or an inability to autonomously self-fertilize limits naturalization in five Australian Banksia species and the co-familial Hakea salicifolia in...
The outcome of plant introductions is often considered in binary terms (invasive or non-invasive). However, most species experience a time lag before naturalization occurs, and many species become naturalized at some sites but not at others. It is therefore important to understand the site-specific mechanisms underlying naturalization. Proteaceae i...
Bird-pollinated plants typically have reddish flowers, but it is not clear whether this trait can be attributed to selection by birds. Here we experimentally test for the first time the foraging behaviour of sunbirds in relation to flower colour, using the Orangebreasted Sunbird Anthobaphes violacea (Nectariniidae) and the colour dimorphic Erica pe...
The transition from a species introduction to an invasion often spans many decades (a lag phase). However, few studies have determined the mechanisms underlying lag phases. Such a mechanistic understanding is vital if the potential ecosystem-level impacts are to be predicted and the invasion risks to be managed proactively. Here we examine Banksia...
A major aim of invasion ecology is to identify characteristics of successful invaders. However, most plant groups studied in detail (e.g. pines and acacias) have a high percentage of invasive taxa. Here we examine the global introduction history and invasion ecology of Proteaceae—a large plant family with many taxa that have been widely disseminate...
The legumes (Fabaceae) Genista monspessulana and Spartium junceum are major invaders in several other parts of the world, but not yet so in South Africa. We determine their current distributions in South Africa at different spatial scales, assess population structure (soil seed banks and size at reproduction) evaluate current manage-ment activities...
Bird-pollinated plants typically have reddish flowers, but it is not clear whether this trait can be attributed to selection by birds. Here we experimentally test for the first time the foraging behaviour of sunbirds in relation to flower colour, using the Orange-breasted Sunbird Anthobaphes violacea (Nectariniidae) and the colour dimorphic Erica p...
The legumes (Fabaceae) Genista monspessulana and Spartium junceum are major invaders in several other parts of the world, but not yet so in South Africa. We determine their current distributions in South Africa at different spatial scales, assess population structure (soil seed banks and size at reproduction) evaluate current management activities,...
The transition from a species introduction to an invasion often spans many decades (a lag phase).
However, few studies have determined the mechanisms underlying lag phases. Such a mechanistic understanding
is vital if the potential ecosystem-level impacts are to be predicted and the invasion risks to be managed proactively.
Here we examine Banksia...
The legumes (Fabaceae) Genista monspessulana and Spartium junceum are major invaders in several other parts
of the world, but not yet so in South Africa. We determine their current distributions in South Africa at different
spatial scales, assess population structure (soil seed banks and size at reproduction) evaluate current management
activities,...
Interactions with pollinators are thought to play a significant role in determining whether plant species become invasive, and ecologically generalised species are predicted to be more likely to invade than more specialised species. Using published and unpublished data we assessed the floral biology and pollination ecology of the South American nat...
The transition from a species introduction to an invasion often spans many decades (a lag phase). However, few studies have determined the mechanisms underlying lag phases. Such a mechanistic understanding is vital if the potential ecosystem-level impacts are to be predicted and the invasion risks to be managed proactively. Here we examine Banksia...
The impacts of habitat fragmentation and reduced population sizes on ecological processes deserve more attention. In this study we examine pollination in rural and urban populations of Brunsvigia litoralis (Amaryllidaceae), an endangered endemic and a flagship species for plant conservation in South Africa. B. litoralis has flowers conforming to th...
Nectar-feeding birds are important pollinators in fire-prone regions of the world, but the impact of fires on these bird communities
has seldom been studied. Nectar-feeding bird communities were censused during peak flowering, before and after fire in the
Cape fynbos of South Africa. The abundance and species richness of nectar-feeding birds decrea...
Most legislation pertaining to non-native organisms is implicitly focussed at the individual species level. However, in some cases interspecific hybrids can be more invasive than any of the parent species. This is problematic for policy makers, and for horticulturists developing or trading in new ornamental cultivars. We explore these issues in the...
Road traffic is one of the most pervasive forms of anthropogenic disturbance, but its impact on pollination, a potentially sensitive ecosystem process, has not been investigated. Such an assessment is needed in order to evaluate the potential for roadside verges to act as biodiversity refugia and corridors in otherwise transformed landscapes. Here,...
Background/Question/Methods
Anthropogenic impacts and subsequent pollen limitation has been demonstrated in a divers range of pollination systems. Although vital in understanding the role of pollination in the entire life cycle of a plant, to our knowledge no field studies exists determine the strength of the link between pollination and populati...
A large diversity of floral morphological types exists within the bird pollination syndrome in the Cape Floral Region of South Africa. Here we focus on species with tubular flowers and ask: “Do differences in tube length among plant species correspond to differences in bill length among the birds that serve as pollinators?” To answer this question,...
Why do hummingbirds hover while Old World nectar-feeding birds perch? A unique opportunity to explore this question is presented by the invasion into Africa of a plant adapted for pollination by hovering hummingbirds. Like other hover-pollinated plants of the New World, the flowers of the tree tobacco Nicotiana glauca lack perches and are oriented...
Questions
Question (1)
Are there good examples in which the lack off pollinators prevent plant invasions? So a direct relation between the lack of pollinators and subsequent failure to become invasive. There are number of examples in which the lack of pollinators does limit plant invasions, but other than fig-wasp interactions, are there any good examples in which the lack of a plant species becoming invasive can be ascribed to the lack of pollination?
