Impacts of an invasive alien Proteaceae on native plant species richness and vegetation structure

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 by Hakea drupacea, uninvaded sites and cleared sites (sites formerly invaded by H. drupacea). A total of 129 plant species belonging to 75 genera were recorded across all study sites. Invasive Acacia saligna, A. longifolia, A. cyclops (Fabaceae) and Leptospermum laevigatum (Myrtaceae) co-occurred with H. drupacea in the invaded sites. Overall plant species richness, which constituted higher number of native plant species, was recorded in uninvaded sites compared to invaded and cleared sites. Plant species composition was similar between uninvaded and cleared sites, but species composition recorded in uninvaded and cleared sites were significantly different from species composition recorded at invaded sites. Litter depth was significantly higher in invaded sites compared to uninvaded and cleared sites. Hakea drupacea did not affect soil properties in invaded sites. Here we show that H. drupacea probably reduces the diversity of native plant species especially in invaded sites probably through the effect of litter production and canopy cover, pointing to a beneficial effect of removal of H. drupacea. We encourage active restoration of sites invaded by H. drupacea at early stages of invasion before the plants become established and suppress the growth of native species

Montpellier broom (Genista monspessulana) and Spanish broom (Spartium junceum) in South Africa: An assessment of invasiveness and options for management

AbstractThe 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, and provide recommendations for control (including assessing the feasibility of nation-wide eradication). G. monspessulana occurs at nine localities in three quarter-degree cells, covering a total of 22.7ha. S. junceum is much more widespread, occurring in 33 quarter-degree cells and is frequently cultivated in private gardens. All naturalised or invasive populations are in disturbed areas, mostly along roadsides. Once established, G. monspessulana and S. junceum accumulate large, persistent soil-stored seed banks, ranging in size between 909 and 22,727 (median 1970)seeds/m2 and 0 and 21,364 (median 455)seeds/m2 for the two species respectively. Both species resprout vigorously after cutting and stump herbicide application (60% of G. monspessulana and 43% of S. junceum plants resprouted) which necessitates regular follow-ups. We estimate that over 10years, at a cost of about ZAR 81,000 (1 ZAR=0.114 US$ as on 6 October 2012), G. monspessulana could be extirpated from South Africa. S. junceum is far more widespread and coupled with low effectiveness of control, abundance of seeds and seed longevity, eradication is unfeasible. We recommend that control methods used for S. junceum be improved to prevent resprouting, and that areas are managed to limit the movement of seeds and avoid further spread and establishment. Further studies are required to understand why these two species have failed to replicate the invasiveness shown in other parts of the world

Guidelines for restoring Lowland Sand Fynbos ecosystems

CITATION: Holmes, P.M., et al. 2022. Guidelines for restoring Lowland Sand Fynbos ecosystems. Stellenbosch: Stellenbosch Univesity, Department of Conservation Ecology and Entomology.The original publication is available at http://biodiversityadvisor.sanbi.org/planning-and-assessment/ecological-restoration/Lowland Sand Fynbos ecosystems are among the most threatened terrestrial systems in South Africa. Of the ten Sand Fynbos veld types, seven are Critically Endangered or Endangered according to the IUCN Red List of Ecosystems. They are all either poorly protected, or not protected at all in the conservation network. Sand Fynbos ecosystems harbour unique biodiversity, but owing to their lowland locations experience extensive losses to other land uses. Some natural pockets remain scattered within agricultural or urban developments. They are, however degraded due to invasive alien plants, inappropriate fire regimes or pollution and are an urgent priority to restore. National biodiversity targets aim for a minimum proportion of an ecosystem type to be retained in a natural or near-natural state. The minimum target for Sand Fynbos ecosystems is mostly 30% of the original extent – a target no longer attainable for several of these ecosystems, such as Cape Flats Sand Fynbos. For many of these precious systems, this means a necessary focus on their restoration. The purpose of these guidelines is to assist managers and landowners of degraded Sand Fynbos vegetation to restore biodiversity and contribute to the conservation of these threatened ecosystems. The guidelines outline appropriate methods to restore degraded Sand Fynbos ecosystems, based on the latest research and field trial outcomes.Hans Hoheisen Charitable TrustBiodiversity Management Branch, City of Cape TownSANBI - South African National Biodiversity InstituteHans Hoheisen Charitable TrustPublishers versio

Assembly and disassembly of bird pollination communities at the Cape of Africa

Thesis (PhD (Botany and Zoology))--Stellenbosch University, 2011.ENGLISH ABSTRACT: With the current global decline in pollinators, and the concurrent decline in plant species, pollination research is becoming increasingly important. However, studies outside Europe and North-America and on groups other than insects are needed to make generalisations possible. In this thesis I study how pollination structures plant and bird communities in a biodiversity hotspot, the Cape Floristic Region of South Africa. I show that bird-plant pollination mutualisms are an important ecological factor structuring ornithophilous Proteaceae and nectar-feeding bird communities. This close association between plant and bird communities suggests an important role for community wide pollination mutualisms. How these mutualisms disassemble in reaction to a range of anthropogenic impacts is determined. Firstly, I use experimental manipulation of honeybee density to test whether honeybee farming affects nectar-feeding birds. Hive addition increased honeybee abundance far above natural levels but nectar-feeding bird pollinators were not consistently affected. Secondly, I document the impact of a two lane tar road on the bird pollination community. The two-fold decline found in pollination along roadsides, should have important implications for the way we view and manage road verges for ecological processes. Thirdly, I investigated how fragmentation affects bird-pollination communities by assessing an endangered, bird-pollinated plant, Brunsvigia litoralis. The only flower visitor at the urban sites, the shorter billed Greater Double-collared Sunbird is unable to access the nectar due to a long perianth tube. The longer billed Malachite Sunbird was the sole pollinator of B. litoralis at the rural site, significantly increased seed set. The lack of ecological analogs in these urban fragments might place pollinator specialist plants, such as B. litoralis, at risk. Fourthly, fire is a frequent disturbance in communities of bird-pollinated plants. In a before/after fire observation study and a burnt/unburnt transplant study, birds visited flowers in the “before fire” and “unburnt” areas only. The results are surprising given the large number of bird-pollinated plants flowering in the early post-fire vegetation. Lastly, I find that alien invasive plant species are incorporated into the native pollination community in a spectacular way; sunbirds adapt to a hummingbird-like, hovering lifestyle to obtain nectar. Alien invasive plants greatly increase nectar-feeding bird abundance; in turn, birds enhance seed set in these alien plants. I conclude by asking whether the disassembling of bird pollination communities really matters. To answer this question I report on a decade of demographic data on the geophytic bird-pollinated Brunsvigia orientalis. In the demographic analysis, the elasticity component for reproduction was more important than expected for a long lived plant. Reduced population growth in the shade and a large investment in a winged inflorescence, suggest B. orientalis is a light demanding, well dispersed, gap colonising species. The link between pollination and seed has been made before, but I take this one step further and show that pollination intensity predicts population growth rate. By linking plant demography and pollination, I was able to predict the future of plant populations under variable pollination conditions. The disassembly of bird pollination communities only becomes important for population persistence once the mutualism has almost entirely broken down.AFRIKAANSE OPSOMMING: Met die huidige globale afname in bestuiwers en die gelyktydige afname in plant spesies, word bestuiwing navorsing toenemend belangrik. Studies buite Europa en Noord-Amerika en op groepe anders dan insekte is nodig on veralgemenings moontlik te maak. In hierdie tesis bestudeer ek hoe bestuiwing struktuur gee and plant en voël gemeenskappe in 'n biodiversiteit hotspot, die Kaapse Floristiese Ryk van Suid-Afrika. Ek wys dat voël-plant bestuiwings mutualismes 'n belangrike ekologiese faktor is in die strukturering van voël bestuifde Proteaceae gemeenskappe en nektar-etende voël gemeenskappe. Hierdie noue assosiasie tussen plant en voël gemeenskappe impliseer 'n belangrike rol vir gemeenskapwye bestuiwings meganismes. Ek bepaal hoe hierdie mutualismes aftakel in reaksie op 'n verskeidenheid van antropogeniese impakte. Eerstens gebruik ek 'n eksperimentele manipulasie van heuningby getalle om te toets of bye boerdery nektar-etende voëls affekteer. Byekorf toevoeging het heuningby getalle laat toeneem tot ver bo natuurlike vlakke maar nektar-etende voël bestuiwers is nie konsekwent beïnvloed nie. Tweedens dokumenteer ek die impakte van 'n twee baan teerpad op die voël bestuiwings gemeenskap. Die twee-malige afname in bestuiwing langs paaie sal belangrike implikasies hê vir die manier hoe ons pad reserwes sien en bestuur met betrekking tot ekologiese prosesse. Derdens bestudeer ek hoe fragmentasie die voël-plant gemeenskappe affekteer deur die bedreigde voël-bestuifde Brunsvigia litoralis te assesseer. Die enigste besoeker in die meer stedelike area, die Groot-rooibandsuikerbekkie, wat 'n korter snawel het, is nie in staat om die nektar te bereik nie, weens 'n te lang blombuis. Die Jangroentjie suikerbekkie met sy langer snawel is die enigste bestuiwer van B. litoralis in die meer landelike area, met 'n betekenisvolle vermeerdering in saad vorming. Die gebrek aan ekologies analogiese spesies in die stedelike fragmente kan 'n risiko inhou vir bestuiwer gespesialiseerde plante soos B. litoralis. Vierdens, vuur is 'n gereelde versteuring van voël-plant gemeenskappe. In 'n voor/na vuur observasie studie en 'n brand/nie-brand verplasing studie, het voëls blomme net in die “voor brand” en “nie-brand” areas besoek. Hierdie resultate is verrassend siende die groot hoeveelheid voël-bestuifde plante wat blom direk na brande. Laastens het ek gevind dat uitheemse indringer plante geïnkorporeer word in die inheemse bestuiwers gemeenskappe op 'n skouspelagtige manier; suikerbekkies pas aan tot 'n kolibri-tipe, fladderende lewenswyse om nektar te bekom. Uitheemse indringer plante het nektar-etende voël hoeveelhede laat toeneem; in reaksie het voëls saad opbrengs vermeerder. In konklusie vra ek of hierdie aftakeling van die voël bestuiwers gemeenskap belangrik is. Om hierdie vraag te antwoord assesseer ek 'n dekade van demografiese data van die geofietiese, voël-bestuifde plant, Brunsvigia orientalis. In die demografiese analises was die elastisiteit komponent van reproduksie belangriker as verwag vir 'n langlewende plant. Verminderde populasie groei in die skaduwee en 'n hoë investering in 'n gevlerkte bloeiwyse suggereer dat B. orientalis 'n lig afhanklike, goed verspreide, gaping koloniserende spesie is. Die skakel tussen bestuiwing en saadvorming is voorheen gemaak, maar ek neem dit een stap verder en wys dat bestuiwings intensiteit populasie groeikoers voorspel. Deur plant demografie en bestuiwing te koppel was ek in staat om die toekoms van populasies onder variërende bestuiwings kondisies te voorspel. Die aftakeling van voël bestuiwings gemeenskappe word slegs belangrik vir populasies se voortbestaan wanneer die mutualisme amper heeltemal verdwyn het

Invasive alien trees reduce bird species richness and abundance of mutualistic frugivores and nectarivores; a bird’s eye view on a conflict of interest species in riparian habitats.

Invasive alien plants have major ecological ef- fects, 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 plants. Here we use birds as indicators to determine the impacts of an invasive Eucalyptus tree species in riparian areas of the Cape Floristic Region (CFR) of South Africa. Birds are an ideal study group because they are mobile, respond quickly to habitat changes and feed at different trophic levels. Fixed-point bird counts were done during winter and spring at near- pristine and Eucalyptus camaldulensis invaded riparian habitats. A total of 1142 birds from 44 species were re- corded. Bird assemblages in invaded sites are almost a complete subset (24 species) of those in near-pristine areas (42 species). Invaded areas were missing 18 species and contained a total of 128 fewer individuals. This is due to declines in insectivores, frugivores, granivores, raptors and omnivores and the absence of nectarivores in invaded sites. From a bird’s perspective, the prioriti- sation of E. camaldulensis removal from the CFR’s river systems is justified, but whether bird species will return to cleared areas needs to be determined

Introducing Managed Honey Bee Hives Into Natural Fynbos Of South Africa: Effects On Pollinators And Their Dependant Plants

 Ethics number is: 214310272/08/2020  In the Cape Floristic Region (CFR) of South Africa, an indigenous honey bee subspecies, Apis mellifera capensis (Cape honey bee) is used for agricultural pollination services. Agricultural crops are used as forage for bees in spring, eucalyptus trees in summer, and natural vegetation is required throughout the winter months. However, honey bees’ presence in natural areas in high densities could lead to negative impacts on unmanaged pollinators and their dependent plants. These data sets were collected to determine the effect of introducing managed honey bee hives (MHBH) on pollination networks, flower visitation rates, community composition of pollinators, insect diversity and abundance, and plant reproduction (Cullumia reticulata). To examine these effects, two different study sites were sampled under different conditions namely Lourensford and Fruitways. Lourensford investigates these effects with the controlled introduction of 10 MHBH during winter while for the Fruitways data set these effects are investigated through the uncontrolled dumping of  MHBH, data was collected under three different treatments where 66, 400 and 200 MHBH were introduced during summer. For both data sets, data were collected through pollinator flower visit observations and pan traps from four plots within 1 km of MHBH. For Lourensford, data was collected for 10 days with no MHBH present (before hives) and then for 10 days after MHBH were introduced (during hives). For Fruitways data was collected for 3 days under each treatment.</p

Describing sexual dimorphism and fine scale spatial distributions in the Drab Thick-tail Scorpion, Parabuthus planicauda

Southern Africa contains a diverse and endemic scorpion fauna, but with biological aspects remaining largely unexplored for this group. In order to&nbsp; 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 Scorpion (Parabuthus planicauda). The species closely track rocky areas, with the sexes homogenously distributed across habitats. Varying adult sex ratios are evident at each sampling area, likely influenced by differing vegetation cover and predation pressures. When considering size-corrected measurements, several characters are significantly sexually dimorphic in P. planicauda; this sexual dimorphism is not readily observable (&lt;10% difference in size) based on uncorrected measurements, thereby rendering the identification of males and females in the field difficult. Even so, sexually dimorphic characters in females appear to be shaped mainly by natural selection (e.g. carapace width, pedipalp patella and metasoma), likely for enhanced feeding ability, fecundity, parental care and juvenile survival. In contrast, the male morphology may be primarily subject to sexual selection pressures on features used during courtship and mating (e.g. pectines, chela movable finger, pedipalp femur, 2nd and 4th legs). Taken together, the results reported on here add novel preliminary information on the understudied&nbsp; biological aspects of a South African endemic scorpion species. Keywords: Buthidae, Fynbos Biome, lithophilous, morphology, rupicolous, sexual selection, South Afric

Relationship of alien species continues in a foreign land: The case of Phytophthora and Australian Banksia (Proteaceae) in South African Fynbos

Abstract 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 relationships can limit the invasiveness of an alien plant species in a novel range. To test this, we investigate whether the invasiveness of the Australian genus of Proteaceae, Banksia, in South Africa is determined by the alien and major invasive phytopathogen, Phytophthora cinnamomi. The presence of P. cinnamomi in Banksia root and soil was evaluated using morphological and molecular techniques. Isolates were cultured onto selective media and polymerize chain reactions and internal transcribing spacers were used for identification. Acetone leaf extracts of 11 Banksia spp. were screened for antimicrobial activity against P. cinnamomi, using the minimum inhibitory concentration assay. A total of 3840 Banksia individuals from seven localities were surveyed. Phytophthora  cinnamomi was consistently isolated from Banksia species root and soil samples. Out of the 12 Banksia species that were screened for antimicrobial activity, four introduced species, B. burdettii, B. coccinea, Banksia hookeriana, and B. prionotes and the invasive B. integrifolia and B. ericifolia exhibited relatively high antimicrobial activity against P. cinnamomi (strain 696/12). We show that the phytopathogen in the native range has similar impact in the novel range and in doing so may limit invasion success of Banksia species with low antimicrobial activity