Thesis (MSc (Botany and Zoology)--University of Stellenbosch, 2006. / Parts of the West Coast Strandveld and adjacent Succulent Karoo on the arid coast of
Namakwaland in the Western Cape of South Africa are subject to surface mining. An
understanding of mycorrhizal association of plants in the natural vegetation of this
area could contribute to the improvement of post-mining re-vegetation of the area.
This study investigated mycorrhizal association of plants in the West Coast
Strandveld, and compared mycorrhizal infection rates of soils taken from natural
vegetation to soils from post-mined rehabilitated vegetations. The study was divided
into two components.
In the first component a pot experiment was conducted in the greenhouse to assess
vesicular-arbuscular mycorrhiza (AM) infectivity of post-mined rehabilitated areas of
Brand se Baai in Namakwa Sands mining areas. Rehabilitated areas used in this study
included sites that has been strip mined for heavy minerals and then progressively
backfilled with sub-soil sand remaining after mineral extraction (tailings), topsoil and
translocated plants in an effort to restore the structure and functional aspects of the
mined site to its original (pre-mining) ecosystem. Rehabilitated sites 1 assessed in this
study included sites backfilled with: tailings + translocated plants (TP); tailing +
topsoil + translocated plants (TSP) and tailings + topsoil only (TS). Natural sites (N)
were also assessed to serve as reference points. AM infection was evaluated as
percent root colonization on wheat planted as bioassay on sterilised sand and
inoculum from rehabilitated sites in the ratio of 3:1 respectively. Results of this study
component showed that mycorrhiza infectivity of rehabilitated soils was high on TSP
and TS because mining disturbance has been remedied by topsoil with or without
translocated plant replacement. The structural and chemical components of topsoil
used as rehabilitation material favoured re-establishment of microbial activities.
Infectivity was however low on soils rehabilitated with tailings and translocated
plants (TP) because this treatment lacked topsoil which is a major source of infective
mycorrhizal propagules. Infectivity was also low in soils from undisturbed sites (N)
probably high phosphorus concentration or presence of perennial vegetation led to low mycorrhiza infection. Results showed that there was no significant effect of
mycorrhiza on plant growth rate, nutrient uptake or carbon cost of mycorrhizal plants
when related to non-mycorrhizal plants, instead the biomass production and nutrient
contents of plants were determined by chemical properties of treatment soils.
The second component of the study investigated presence of mycorrhiza on randomly
selected common indigenous species of Aizoaceae, Asparagaceae, Asteraceae,
Chenopodiaceae, Fabaceae, Lamiaceae, Mesembryanthemaceae, Restionaceae,
families growing on unmined areas of the study site. Total mycorrhiza infection was
recorded on 85% of the assessed species with percent infection level ranging from 8%
in Atriplex lindleyi and Drosanthemum hispidum to 98% in Salvia lanceolata.
Functional mycorrhizal association with arbuscule structures were however only
observed on 15% of all species assessed. Low arbuscules infection observed in
indigenous species assessed in this study could be associated with the timing of
mycorrhiza infection assessment and root competition in the soil. There was no
infection observed on four species belonging to Chenopodiaceae, Zygophyllaceae,
Sterculiaceae, and Asteraceae families, which represented 15% of all species
assessed. Most species belonging to Chenopodiaceae and Zygophyllaceae have been
reported as non-mycorrhizal in other studies, absence of mycorrhiza on the remaining
three families species observed in this study require further confirmation.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1846 |
| Date | 12 1900 |
| Creators | Ndeinoma, Albertina |
| Contributors | Milton, Sue, Valentine, Alex, University of Stellenbosch. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
Page generated in 0.002 seconds