Australian acacias have significant impacts on the habitats that they invade. For example, they can increase nutrient input and alter natural nutrient cycles. Here we assessed how the invasive Acacia ...mearnsii and native Virgilia divaricata, both nodulating legume trees with similar growth forms and general ecologies, compared in terms of N and P nutrient content, nutrient resorption and their Biological Nitrogen Fixation (BNF) capacities where they co-occur within forest margins in South Africa. Fresh and senesced leaf samples were collected in sympatric populations and analysed for N and P concentrations. We also measured the δ15N/δ14N isotope ratio, and used it to calculate percentage nitrogen derived from the atmosphere. The two species were very similar in their total nutrient content, but V. divaricata showed strong dependence on available P which determined its dominant source of N. It had a higher use of BNF, an energetically-expensive process, than the invasive species. Acacia mearnsii was also more efficient in N resorption than the native species. Our results highlight nutritional economy differences between these two ecologically similar species and provide further data on reasons for the success of A. mearnsii compared to native tree species.
•Acacia mearnsii (invasive) had similar nutrient content as a co-occurring native legume, Virgilia divaricata in Afromontane forests.•A. mearnsii acquired more inorganic mineral N from the soil and was more efficient in N resorption than the native species.•A. mearnsii seems better adapted to limited nutrient environments, while V. divaricata shows evidence of being P limited.
The native forest-tree pathogen Ceratocystis tsitsikammensis infects native trees (e.g. Virgilia divaricata) and Acacia mearnsii, an invasive alien and important forestry tree in South Africa. We ...explored the physiological effects of infection by this fungus on these two tree species, within the context of the Biotic Resistance Hypothesis (BRH). The effects of infection on physiological and resource capture parameters were measured, in conjunction with lesion length. Infected V. divaricata trees changed their N economy by relying more on soil derived N and less on biological nitrogen fixation. Infected A. mearnsii trees altered their biomass allocation into below ground investments. The species responded differently to infection, hence it was not clear which was most negatively affected. Results do support numerous studies that base tests of pathogenicity on lesion length. These results hold important conservation and economic relevance as A. mearnsii is both an invasive tree species and a forestry tree.
The native forest-tree pathogen Ceratocystis tsitsikammensis infects native trees (e.g. Virgilia divaricata) and Acacia mearnsii, an invasive alien and important forestry tree in South Africa. We ...explored the physiological effects of infection by this fungus on these two tree species, within the context of the Biotic Resistance Hypothesis (BRH). The effects of infection on physiological and resource capture parameters were measured, in conjunction with lesion length. Infected V. divaricata trees changed their N economy by relying more on soil derived N and less on biological nitrogen fixation. Infected A. mearnsii trees altered their biomass allocation into below ground investments. The species responded differently to infection, hence it was not clear which was most negatively affected. Results do support numerous studies that base tests of pathogenicity on lesion length. These results hold important conservation and economic relevance as A. mearnsii is both an invasive tree species and a forestry tree.
•First record of the physiological responses of a native and an exotic tree to infection by Ceratocystis tsitsikammensis.•Native tree (Virgilia divaricata) changes its N economy in infected plants.•Invasive tree (Acacia mearnsii) changes its biomass allocation, to below ground storage in response to infection.•Support is found for use of lesion length as proxy for disease development.•These results have important conservation and economic implications.
The invasive and predatory harlequin lady beetle, Harmonia axyridis, has been introduced as a biological control agent to many agricultural areas worldwide and has now spread from agricultural to ...natural habitats where it threatens native arthropod biodiversity. The aim of this study was to determine how H. axyridis uses the local landscape during different times of the year in the Western Cape Province, South Africa. We also determined its association to native arthropod diversity. Harmonia axyridis adults and larvae, as well as arthropod herbivores, predators and other ladybeetles were sampled every second month for a year with a vacuum sampler in vineyards, natural habitats, edges between natural habitats and vineyards, and urban areas. Highest adult and larval H. axyridis abundance occurred in urban areas during all sampling periods, with a peak in May and July (winter). Vineyards and natural vegetation had very low abundances of H. axyridis. Harmonia axyridis had some, but limited effect on the local arthropod community abundance. There was also a negative relationship between H. axyridis and the overall arthropod community as well as a positive relationship between H. axyridis abundance and that of other ladybeetles. Harmonia axyridis appeared to influence the assemblage composition of other ladybeetles and herbivores. Overall, the native arthropod assemblage responded primarily to season and habitat and secondary to the presence of H. axyridis. Harmonia axyridis has a strong association with the urban environment, seemingly in association with the exotic aphid Tuberculatus annulatus that feeds on cultivated oak trees. Outside of the urban area, H. axyridis numbers were very low and its ecological impacts may be negligible.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Novel species of fungi described in this study include those from various countries as follows: Australia , Agaricus albofoetidus , Agaricus aureoelephanti and Agaricus parviumbrus on soil, Fusarium ...ramsdenii from stem cankers of Araucaria cunninghamii , Keissleriella sporoboli from stem of Sporobolus natalensis , Leptosphaerulina queenslandica and Pestalotiopsis chiaroscuro from leaves of Sporobolus natalensis , Serendipita petricolae as endophyte from roots of Eriochilus petricola , Stagonospora tauntonensis from stem of Sporobolus natalensis , Teratosphaeria carnegiei from leaves of Eucalyptus grandis × E. camaldulensis and Wongia ficherai from roots of Eragrostis curvula . Canada , Lulworthia fundyensis from intertidal wood and Newbrunswickomyces abietophilus (incl. Newbrunswickomyces gen. nov.) on buds of Abies balsamea . Czech Republic , Geosmithia funiculosa from a bark beetle gallery on Ulmus minor and Neoherpotrichiella juglandicola (incl. Neoherpotrichiella gen. nov.) from wood of Juglans regia . France , Aspergillus rouenensis and Neoacrodontium gallica (incl. Neoacrodontium gen. nov.) from bore dust of Xestobium rufovillosum feeding on Quercus wood, Endoradiciella communis (incl. Endoradiciella gen. nov.) endophytic in roots of Microthlaspi perfoliatum and Entoloma simulans on soil. India , Amanita konajensis on soil and Keithomyces indicus from soil. Israel , Microascus rothbergiorum from Stylophora pistillata . Italy , Calonarius ligusticus on soil. Netherlands , Appendopyricularia juncicola (incl. Appendopyricularia gen. nov.), Eriospora juncicola and Tetraploa juncicola on dead culms of Juncus effusus , Gonatophragmium physciae on Physcia caesia and Paracosmospora physciae (incl. Paracosmospora gen. nov.) on Physcia tenella , Myrmecridium phragmitigenum on dead culm of Phragmites australis , Neochalara lolae on stems of Pteridium aquilinum , Niesslia nieuwwulvenica on dead culm of undetermined Poaceae , Nothodevriesia narthecii (incl. Nothodevriesia gen. nov.) on dead leaves of Narthecium ossifragum and Parastenospora pini (incl. Parastenospora gen. nov.) on dead twigs of Pinus sylvestris . Norway , Verticillium bjoernoeyanum from sand grains attached to a piece of driftwood on a sandy beach. Portugal , Collybiopsis cimrmanii on the base of living Quercus ilex and amongst dead leaves of Laurus and herbs. South Africa , Paraproliferophorum hyphaenes (incl. Paraproliferophorum gen. nov.) on living leaves of Hyphaene sp. and Saccothecium widdringtoniae on twigs of Widdringtonia wallichii . Spain , Cortinarius dryosalor on soil, Cyphellophora endoradicis endophytic in roots of Microthlaspi perfoliatum , Geoglossum laurisilvae on soil, Leptographium gemmatum from fluvial sediments, Physalacria auricularioides from a dead twig of Castanea sativa , Terfezia bertae and Tuber davidlopezii in soil. Sweden , Alpova larskersii , Inocybe alpestris and Inocybe boreogodeyi on soil. Thailand , Russula banwatchanensis , Russula purpureoviridis and Russula lilacina on soil. Ukraine , Nectriella adonidis on overwintered stems of Adonis vernalis . USA , Microcyclus jacquiniae from living leaves of Jacquinia keyensis and Penicillium neoherquei from a minute mushroom sporocarp. Morphological and culture characteristics are supported by DNA barcodes.
Ophiostoma (Ophiostomatales) represents a large genus of fungi mainly known from associations with bark beetles (Curculionidae: Scolytinae) infesting conifers in the northern hemisphere. Few southern ...hemisphere native species are known, and the five species that consistently occur in the infructescences of Protea spp. in South Africa are ecologically unusual. Little is known about the vectors of Ophiostoma spp. from Protea infructescences, however recent studies have considered the possible role of insects and mites in the distribution of these exceptional fungi. In this study we describe a new species of Ophiostoma and a new Sporothrix spp. with affinities to Ophiostoma, both initially isolated from mites associated with Protea spp. They are described as Ophiostoma gemellus sp. nov. and Sporothrix variecibatus sp. nov. based on their morphology and comparisons of DNA sequence data of the 28S ribosomal, β-tubulin and internal transcribed spacer (ITS1, 5.8S, ITS2) regions. DNA sequences of S. variecibatus were identical to those of a Sporothrix isolate obtained from Eucalyptus leaf litter in the same area in which S. variecibatus occurs in Protea infructescences. Results of this study add evidence to the view that mites are the vectors of Ophiostoma spp. that colonize Protea infructescences. They also show that DNA sequence comparisons are likely to reveal additional cryptic species of Ophiostoma in this unusual niche.
Ophiostoma represents a genus of fungi that are mostly arthropod-dispersed and have a wide global distribution. The best known of these fungi are carried by scolytine bark beetles that infest trees, ...but an interesting guild of Ophiostoma spp. occurs in the infructescences of Protea spp. native to South Africa. Phylogenetic relationships between Ophiostoma spp. from Protea infructescences were studied using DNA sequence data from the β-tubulin, 5.8S ITS (including the flanking internal transcribed spacers 1 and 2) and the large subunit DNA regions. Two new species, O. phasma sp. nov. and O. palmiculminatum sp. nov. are described and compared with other Ophiostoma spp. occurring in the same niche. Results of this study have raised the number of Ophiostoma species from the infructescences of serotinous Protea spp. in South Africa to five. Molecular data also suggest that adaptation to the Protea infructescence niche by Ophiostoma spp. has occurred independently more than once.
Taxonomic novelties:Ophiostoma phasma Roets, Z.W. de Beer& M.J. Wingf. sp. nov., Ophiostoma palmiculminatum Roets, Z.W. de Beer & M.J. Wingf. sp. nov.
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