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dc.contributor.authorGalatowitsch, S
dc.contributor.authorRichardson, DM
dc.date.accessioned2007-04-25T08:37:26Z
dc.date.available2007-04-25T08:37:26Z
dc.date.issued2005-04
dc.identifier.citationGalatowitsch, S.M. & Richardson, D.M. 2005. Riparian scrub recovery after clearing of invasive alien trees in headwater streams of the Western Cape, South Africa. Biological Conservation 122, 509-521.en
dc.identifier.issn0006-3207en
dc.identifier.urihttp://hdl.handle.net/123456789/256
dc.description.abstractHeadwater rivers are the predominant kind of aquatic ecosystem in South Africa's Cape Floristic Region. Invasion by alien woody taxa (especially Acacia longifolia and Acacia mearnsii) have altered these rivers in recent decades, replacing indigenous vegetation and altering ecosystem functioning. Aliens have been systematically cleared in watercourses since 1995 as part of a national program ("Working for Water") to increase water production and improve water quality. Cleared sites are mostly left to recover to their pre-invasion state without additional intervention. We compared the vegetation of seven rivers that vary in their extent of invasion and clearing to identify factors limiting recolonization. Dense invasions cleared 3-6 years before the survey differ in vegetation structure and composition from uninvaded or lightly invaded/cleared riparian reaches in the following ways: (1) diminished extent of indigenous trees in the canopy and increased importance of shrubs or reinvading alien trees, (2) reduced species richness, (3) reduced likelihood of occupancy for more than one-third of common, indigenous species, and (4) reduced incidence of indigenous tree regeneration. Overall, indigenous tree regeneration is very low and not disturbance-triggered which will likely result in slow recovery without additional intervention. We recommend focusing active revegetation on common riparian scrub trees (i.e., Metrosideros angustifolia, Brachylaena neriifolia, Brabejum stellatfolium, and Erica caffra). These species tolerate open habitats favored by alien trees, eventually forming closed canopies required by shade-tolerant species. Accelerating establishment of these small trees is likely critical for shifting cleared riparian corridors from a state that favors alien reinvasion. Effective establishment strategies will need to be developed in the context of hydrologic impairment, since alien-invaded rivers in this region typically have reduced flow. (C) 2004 Elsevier Ltd. All rights reserved.en
dc.description.sponsorshipInst Plant Conservat, Dept Bot, Univ Cape Townen
dc.format.extent615422 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherELSEVIER SCI LTDen
dc.subjectbiological invasionsen
dc.subjectforest regenerationen
dc.subjectinvasionen
dc.subjectrestorationen
dc.subjectsuccessionen
dc.titleRiparian scrub recovery after clearing of invasive alien trees in headwater streams of the Western Cape, South Africaen
dc.typeJournal Articlesen
dc.cibjournalBiological Conservationen
dc.cibprojectNAen


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