Plant community patterns and diversity in sites impacted by Eucalyptus camuldulensis Dehnh. : insights from the Berg River, Western Cape / Alison Midgley
Bachelor Thesis
2013
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University of Cape Town
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Alien Eucalyptus and Acacia species are amongst the most prolific invaders of the Berg River catchment, in the Western Cape. This study assessed the effects of invasive species and the potential for passive successional restoration in a heavily invaded riparian site (>80% aerial cover), a cleared riparian site and a pristine reference site. Three plots were demarcated per site, and transects were taken perpendicular to the river on the lower, middle and upper bank. Three 2m2 quadrats were intensively sampled per transect. Species diversity and community composition of indigenous and alien species were compared by measuring herbaceous, shrub and tree cover. Soil conditions, such as texture, salinity, acidity and moisture, were also compared. Distinctly different plant communities were found in each site, although cleared and invaded sites were more similar to each other. Cleared sites showed >45% cover by invasive successional species and grasses atypical of natural succession patterns. It was proposed that restoration constraints (e.g. method of clearance, intensity of prior invasion, land-use) were encouraging alien re-colonisation. However, there was evidence that the overall the trajectory of successional was favourable for indigenous trees and species. It was suggested that active re-vegetation of indigenous tree species, and adherence to correct clearance methods would aid site restoration.
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Midgley, A. 2013. Plant community patterns and diversity in sites impacted by Eucalyptus camuldulensis Dehnh. : insights from the Berg River, Western Cape / Alison Midgley. University of Cape Town.