Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: This project consists of two botanical investigations in an agricultural area of the Western Cape
Province. A farm known as De Rust, in the Elgin Valley, was used to sample the geographic location,
density, height and life stage of six prominent invasive plant species in various land-use categories.
In the first investigation, the density, height and age structures of the six invasive species populations
were analyzed. The density distribution of the six species was also displayed cartographically. Species
were then ranked according to the potential threat that they pose to the conservation of the remaining
natural areas on the farm. Results indicated that Acacia mearnsii and Acacia saligna are the major
invaders at De Rust and that Hakea sericea can be considered as an emerging invader.
The second investigation explores the statistical relationship between the various land-use categories
and density, height and age of the six prominent invaders identified in the first investigation. The loglikelihood
ratio analysis of observed frequencies resulted in statistically significant (P<0.01; P-values
range between 1.35 x 10-3 and 2.7 x 10-224) relationships between certain land-use types and certain
invasive species. A conclusion was reached that it could be useful to include land-use categories in
simulation models of invasive plant species distribution and spread. / AFRIKAANSE OPSOMMING: Hierdie projek behels twee botaniese ondersoeke in ‘n landbou gebied van die Weskaap. Die plaas
bekend as De Rust, in die Elgin Vallei, was gebruik vir die versameling van data te doen met die
geografiese ligging, plant digtheid, lengte en lewens stadium van ses prominente indringer plant
spesies in verskeie landgebruik kategorieë.
Die digtheid, lengte en ouderdomstruktuur van ses indringerspesies was in die eerste ondersoek
geanaliseer. Die verspreiding van digtheid was ook in kaarte uitgelê. Spesies was daarna volgens hulle
potentiële dreiging teen die bewaring van oorblywende natuurlike dele van die plaas in ‘n rangorde
geplaas. Resiltate dui aan dat Acacia mearnsii en Acacia saligna die belangrikste indringer plante op
De Rust is en dat Hakea sericea as ‘n opkomende indringer beskou kan word.
Die tweede ondersoek kyk na die verhouding tussen verskeie grondgebruik kategorië en die digtheid,
lengte en ouderdom van die ses prominente indringer spesies wat in die eerste ondersoek identifiseër
is. ‘n Log tipe ratios ontleding van bewaarde frekwensies het ‘n statisties belangrike uitkoms gehad
(P<0.01; P-waardes tussen 1.35 x 10-3 en 2.7 x 10-224) vir die verhoudings tussen sekere grondgebruik
tipes en sekere indringer spesies. Die gevolgtrekking was dat dit handig mag wees om grondgebruik
kategorieë in simulasies van indringer plant verspreiding te gebruik.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/20899 |
| Date | 04 1900 |
| Creators | Midgley, John Claude |
| Contributors | McGeoch, M.A., Esler, K.J., Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 75 leaves : ill. |
| Rights | Stellenbosch University |
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