Thesis (MScConsEcol (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / In the Mediterranean climate regions of the world, agricultural practices have caused
considerable landscape transformation and lead to introduction of alien species that now
dominate secondary succession on abandoned agricultural fields. Various restoration attempts
have been made to reduce alien plant species cover, and to enhance the re-establishment and
cover of native plant species. However, results and successes were mostly short-term due to
re-growth and persistence of the weedy alien species, which has been suggested to be caused
by land use history, especially the nutrient enrichment of soil, and particularly phosphorus
and nitrogen.
This study investigated different soil properties (pH, electrical conductivity (EC), soil
moisture, as well as available phosphorus (P) and total nitrogen (N)) on 10 and 20 year old
abandoned fields, as a function of depth in three habitats (ridge (old cultivated area), ditch
(old drainage line) and slope (intermediate zone between ridge and ditch)) on the old fields.
The relationship between these soil properties and the vegetation occurring on the two old
fields was established. At the same time, restoration treatments (autumn burn, combination of
autumn burn and herbicide, herbicide application alone, as well as spring burn) were
conducted to reduce the cover and abundance of non-native plant species and Cynodon
dactylon, and to enhance cover of native species.
Results from the study show that levels of all investigated soil properties were higher on the
younger field. The highest difference was observed in EC and pH. Seasonal differences in
both soil properties could also be observed. A principal component analysis indicated that the
dynamic of all soil properties shaped the vegetation type on old fields, with the main soil
properties being dependent on land-use history and time since abandonment. This study
suggests that EC and pH could be part of parameters that drive the persistence of undesirable
species persistence on old fields and inhibit native plant species instead.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1956 |
| Date | 12 1900 |
| Creators | Memiaghe, Herve Roland |
| Contributors | Krug, Cornelia B., Rozanov, A., Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | Stellenbosch University |
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