Distribution of Articles published per year
(1978 - 2016)
(1978 - 2016)
Total number of journals
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Article 1 Read 2 Citations Restoration of invaded Cape Floristic Region riparian systems leads to a recovery in foliage-active arthropod alpha- and... Published: 12 January 2016
Journal of Insect Conservation, doi: 10.1007/s10841-015-9842-x
Article 1 Read 6 Citations Resilience of Invaded Riparian Landscapes: The Potential Role of Soil-Stored Seed Banks Published: 23 September 2014
Environmental Management, doi: 10.1007/s00267-014-0374-z
We investigated the potential role of soil-stored seed banks in driving vegetation recovery under varying intensities of invasion by the alien tree Eucalyptus camaldulensis along the Berg River in South Africa’s Western Cape Province. We asked: How do richness, diversity, and composition of soil-stored seed banks vary with invasion intensity? What is the difference between the seed banks and above-ground vegetation with respect to species richness, diversity, composition, and structure? To what extent do soil-stored seed banks provide reliable sources for restoring native plant communities? Through a seedling-emergence approach, we compared seedling density, richness, and diversity in plots under varying Eucalyptus cover. Seed bank characteristics were also compared with those of the above-ground vegetation. Except in terms of diversity and density, the richness and composition of native species varied significantly among invasion conditions. Despite the paucity of native tree and shrub species in the seed bank, it was more diverse than extant vegetation. Some species occurred exclusively either in the seed bank or in the above-ground vegetation. Although this ecosystem has been degraded by several agents, including Eucalyptus invasion, soil-stored seed banks still offer modest potential for driving regeneration of native plant communities, but secondary invasions need to be managed carefully. Remnant populations of native plants in the above-ground vegetation remaining after E. camaldulensis clearing provide a more promising propagule source for rapid regeneration. Further work is needed to elucidate possible effects of invasion on successional pathways following E. camaldulensis removal and the effects of hydrochory on seed bank dynamics.
Article 1 Read 11 Citations Eucalyptus invasions in riparian forests: Effects on native vegetation community diversity, stand structure and composit... Published: 01 June 2013
Forest Ecology and Management, doi: 10.1016/j.foreco.2013.02.016
Article 2 Reads 13 Citations Xylem Transport Safety and Efficiency Differ among Fynbos Shrub Life History Types and between Two Sites Differing in Me... Published: 01 June 2012
International Journal of Plant Sciences, doi: 10.1086/665267
Article 1 Read 2 Citations Wood anatomical traits as a measure of plant responses to water availability: invasive Acacia mearnsii De Wild. compared... Published: 25 April 2012
Trees, doi: 10.1007/s00468-012-0726-3
Riparian ecotones in the fynbos biome of South Africa are heavily invaded by woody invasive alien species, which are known to reduce water supply to downstream environments. To explore whether variation in species-specific functional traits pertaining to drought-tolerance exist, we investigated wood anatomical traits of key native riparian species and the invasive Acacia mearnsii across different water availability proxies. Wood density, vessel resistance against implosion, vessel lumen diameter and vessel wall thickness were measured. Wood density varied significantly between species, with A. mearnsii having denser wood at sites in rivers with high discharge. As higher wood density is indicative of increased drought tolerance and typical of drier sites, this counter-intuitive finding suggests that increased wood density was more closely related to midday water stress, than streamflow quantity per se. Wood density was positively correlated with vessel resistance against implosion. Higher wood density may also be evidence that A. mearnsii is more resistant against drought-induced cavitation than the studied native species. The observed plastic response of A. mearnsii anatomical traits to variable water availability indicates the ability of this species to persist under various environmental conditions. A possible non-causal relationship between wood anatomy and drought tolerance in these riparian systems is discussed.
Article 0 Reads 6 Citations Drought-tolerance of an invasive alien tree, Acacia mearnsii and two native competitors in fynbos riparian ecotones Published: 16 September 2011
Biological Invasions, doi: 10.1007/s10530-011-0103-y
Invasive alien plants (IAPs) have successfully invaded many riparian zones in South Africa, especially Australian Acacia spp. which are prevalent along riverbanks in the south-western Cape of South Africa. This Mediterranean-type climate region is predicted to endure severe future water shortages under likely scenarios of increased population growth and climate change, and IAPs aggravate this problem due to their profligate water use. Acacia mearnsii competes aggressively with native species, however, it remains unclear what physiological advantage the species has over co-occurring native species under the predicted reduced streamflow scenarios. A mechanistic approach was used to investigate how key native fynbos riparian woody tree species compare in vulnerability to drought-induced cavitation against A. mearnsii by comparing findings from three Mediterranean-type fynbos river systems that differ in streamflow. A. mearnsii showed lower water potential at 50% hydraulic conductivity loss (P50 values) compared to native species at certain sites, an indication of drought-tolerance. This suggests it is likely to persist under future drier conditions and it therefore remains a top priority for control. The native Brabejum stellatifolium had consistently higher water potentials across all sites than the other studied species, and is a potentially valuable species for restoration of south-western Cape riparian zones. Consistency in the shapes of species vulnerability curves across sites illustrated a species-specific hydraulic response to different water availability, strengthening the argument that this approach to distinguish site-level drought-tolerance between trees is a practical technique, with great application in understanding future geographic distribution under climate change, and potential for use in restoration research. Additionally, streamflow was an inaccurate predictor of species drought-tolerance along these riparian systems.