The main aim of this study was to test rehabilitation interventions in a system altered by heavy grazing, and to develop methods of monitoring these interventions.

The main aim of this study was to test rehabilitation interventions in a system altered by heavy grazing, and to develop methods of monitoring these interventions.

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.

Thesis (MScConsEcol(Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / Anglo American Corporation’s Namakwa Sands heavy minerals mining and beneficiation operation has been strip-mining a heavy mineral deposit, rich in the commercially valuable minerals ilmenite, rutile and zircon, since September 1994. The mine is located in the vicinity of Brand-se-Baai on the west coast of South Africa, approximately 385 km north of Cape Town. Strip-mining causes total destruction of natural ecosystems through the removal of vegetation and soil in the area where mining is being undertaken. Namakwa Sands has been rehabilitating mined out areas as the mining front moves forward. Due to the difficulty of rehabilitating mined out areas as a result of harsh environmental factors, Namakwa Sands has initiated various research projects to gain an understanding of the baseline conditions and ecosystem function in order to increase plant cover and biodiversity on post-mined areas. This on-going research and the development of rehabilitation and mining techniques have resulted in the implementation of four rehabilitation techniques varying in investment of topsoil replacement, seeding and plant translocation. This study assesses the success and effectiveness of these techniques in terms of various vegetation and soil parameters. In addition, those parameters that are considered useful for monitoring are identified. This study indicated that topsoil replacement and plant translocation facilitate the return of similarity, species richness, species diversity and vegetation cover to post-mined areas. The rehabilitation site that had the greatest amount of biological input (topsoil replacement and plant translocation) appeared to be the most successful technique in facilitating vegetation recovery similar to reference sites. In comparison, the site that had the least amount of biological input performed the worst and requires adaptive management, e.g. reseeding and / or plant translocation. Namakwa Sands should continue to replace topsoil in all future rehabilitation efforts and, when possible (e.g. after sufficient winter rain), continue to translocate species in multi-species clumps. In terms of species selected for translocation, Othonna cylindrica, Ruschia versicolor and Lampranthus suavissimus should be considered for future large-scale translocation projects. Zygophyllum morgsana appears to be more difficult to re-establish under the current climatic conditions (below average rainfall). The long-term viability of rehabilitated Z. morgsana populations needs to be determined before considering this species for any future large-scale translocation purposes. No translocated Asparagus spp. individuals survived and should therefore not be considered for any further translocation purposes. The grass Ehrharta calycina, which is dominant in the site seeded, should continue to be considered for future seeding. Species and functional diversity appear to be the most limiting factors within all the rehabilitation sites and Namakwa Sands will not be able to meet their long-term objective of small-stock farming if diversity and the number of palatable species do not increase significantly. Adaptive management should seriously be considered in order to speed up this process. Alternatively, an appropriate grazing strategy, which is related to the Tetragonia fruticosa dominated vegetation within rehabilitation sites, would need to be determined and adopted.More time is needed to ameliorate the rehabilitated soil profiles to the same level as in reference sites, especially with regard to carbon, pH and sodium levels. In order to increase organic matter within rehabilitation areas, Namakwa Sands should consider creating clumps with cleared vegetation from the mining front. Since the long-term rehabilitation goal has not been achieved, Namakwa Sands will need to continue to monitor plant and soil changes until it has been achieved. The objectives of the current rehabilitation programme are limited and Namakwa Sands should develop additional objectives relating to the structure and function of the natural vegetation. This will give a better indication of whether rehabilitation sites are progressing towards the desired end point and if adaptive management is required. In addition, the current monitoring programme (vegetation survey) implemented at Namakwa Sands could be improved by increasing the vegetation parameters to be monitored. It is recommended that the following vegetation parameters be monitored as part of the long-term monitoring programme: species composition and similarity, species richness, species diversity, vegetation cover, species dominance, vertical structure and functional diversity of the vegetation (clumps and inter-clumps). It is also recommended that carbon, pH and sodium of soil profiles be monitored as part of the long-term monitoring programme. These parameters should not be seen as exhaustive as this study only considered various vegetation parameters and soil chemistry between rehabilitation and reference sites. The results of other studies on the fauna, mycorrhiza, insects, etc. should also be taken into consideration and the monitoring parameters expanded accordingly.

Degree of Master of Forestry (Conservation Ecology) / Thesis (MSc)--Stellenbosch University, 2003. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: This study investigates the use of top-soiling, irrigation and translocating indigenous plants to facilitate the cost-effective return of a mined landscape to its former land-use (small stock farming) in an arid winter rainfall Succulent Karoo shrub land biome on the West Coast of South Africa. Effects of topsoil stockpiling and subsoil mineral concentration on soil fertility and chemistry were investigated, as soils are likely to determine rates of vegetation recovery on post-mined areas. Results of a radish bioassay show that stockpiling topsoil and mineral concentration subsoil decreased soil fertility. Mineral concentration decreased phosphorus, potassium, calcium, magnesium, carbon and nitrogen levels significantly relative to other soil treatments. Sodium in freshly deposited tailings was at potentially toxic levels and significantly higher than for all other soil treatments. Spreading of stockpiled topsoil over tailings may ameliorate harsh conditions created by mineral separation. Translocation of plants from pre-mined to post-mined areas was carried out on a trial basis in an effort to facilitate the return of natural vegetation and processes to strip-mined landscapes. Five local indigenous plant species: Asparagus spp., Ruschia versicolor, Othonna cylindrica, Lampranthus suavissimus and Zygophyllum morgsana were planted into multi-species clumps in a replicated experiment. Variables examined in the translocation trial included the effects of plant origin, soil treatment and/or irrigation on plant survival and establishment. The proportion of O. cylindrica transplants surviving for 15 months was greater than for other species. Whole plants survived better than salvaged plants, and Asparagus spp., R. versicolor, L. suavissimus and Z. morgsana survived better on stockpiled topsoil spread over tailings than on tailings alone. Irrigation had no consistent effect across species and treatment replicates. Salvaged-plant clumps were significantly larger than whole-plant clumps at planting, however, this effect was not observed after 12 months, indicating that whole-plant clumps grew faster than salvaged-plant clumps. The evergreen, leaf succulent shrubs O. cylindrica, L. suavissimus and R. versicolor appeared to be most suitable for large-scale translocation at Namakwa Sands. The return of biodiversity and changes in soil quality 15 months after translocation trials began were compared for combinations of top-soiling, irrigation, plant translocation and unmodified tailings. Irrigation may reduce biodiversity and seedling densities. Over a 15-month period following back filling and topsoil spreading, sodium, potassium and calcium appeared to return to levels observed for undisturbed soils. Magnesium remains at levels lower than in pre-mined soil conditions. Soil conditions may be more conducive to plant establishment and rehabilitation after back-filling of tailings and topsoil spreading. Electrical resistance increased over time indicating a reduction of free salts and salinity on rehabilitation sites. Phosphorus did not return to pre-disturbance levels, and carbon remained below pre-mining levels for at least 15 months after rehabilitation began, remaining a potential limiting factor in rehabilitation. Each rehabilitation technique that a mine employs has costs and benefits, and it is increasingly important that insights from ecology and economics are coupled if restoration efforts are going to succeed. A review of valuation systems indicates that Discounted Cash Flow Techniques (DCF) are suitable for valuation of rehabilitation operations. / AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die gebruik van bogrond, besproeiing en die oorplanting van inheemse plante om die koste-effektiewe rehabilitasie van 'n stroopmynlandskap in die droë, winter reënval streek, Vetplant Karoo aan die Weskus van Suid-Afrika, wat vroeër gebruik is vir kleinvee boerdery, te bespoedig Die uitwerking van bogrondopberging en minerale konsentrasie op vrugbaarheid en chemise komposisie van grond is ondersoek, aangesien dié gronde gewoonlik die herstelspoed van plantegroei op 'n ou myn terein bepaal. Uitslae van radys proewe toon dat berging van bogrond en minerale konsentrasie van die onderliggende grond vrugbaarheid van grond laat afneem. Mynaktiwiteite en die minerale konsentrasie lei tot 'n betekenisvolle verlies aan fosfaat, kalium, kalsium, magnesium, koolstof en stikstof as die geval met ander bedrywighede. Die vlak van natrium in oorgeblywende sand na die minerale ekstraksie is hoogs giftig en is veel hoër as na ander bedrywighede. Die toediening van bogrond oor die oorblywende sand verbeter die toestand wat deur die skeiding van minerale veroorsaak is. Oorplasing van plante vanaf ongemynde na rehabilitasie gebiede is op proefbasis uitgevoer in 'n poging om die terugkeer van natuurlike plantegroei by die strookmyn te bespoedig. Vyf plaaslike inheemse plantspesies: Asparagus spp., Ruschia versicolor, Othonna cylindrical, Lampranthus suavissimus en Zygophyllum morgsana is in multi-spesie groepe geplant. Veranderlikes getoets tydens hierdie proef sluit in plantoorsprong, grond behandeling, en/of besproeiing, op die oorlewing en vestiging van plante. 'n Groter proporsie O. cylindrical as enige ander spesie het na 15 maande oorleef. Heel plante het beter oorleef as beskadigde plante. Asparagus spp., R. versicolor, L. suavissimus en Z. morgsana het beter oorleef op gebergde bogrond oor oorblywende sand as op oorblywende sand self. Besproeiing het nie 'n volgehoue uitwerking gehad op spesies of op herhaalde replisering nie. Beskadigde plantgroepe was groter as heelplant groepe toe hulle geplant is maar na 12 maande is opgemerk dat die heel-plante vinniger gegroei het. Die immergroen vetplante, 0. cylindrical, L. suavissimus en R. versicolor blyk die mees geskik vir grootskaalse oorplanting by Namakwa Sands. Herstel van biodiversiteit en veranderings in grondeienskappe 15 maande na proewe begin het, is vergelyk m.b.t. die toediening van bogrond, besproeiing, oorplanting en onbehandelde oorblywende sand. Besproeiing kan biodiversiteit en digtheid van saailinge verminder. Vyvtien maande na opvulling en die toediening van bogrond, het kalium, natrium en kalsium teruggekeer na vlakke in onversteurde grond. Magnesium vlakke was nog altyd laer as dié voordat mynaktiwiteite aangevang is. Terugplasing van sand en toediening van bogrond mag die vestiging en rehabilitasie van plante bespoedig. Weerstand vermeerder met tyd wat 'n verlaaging in vry soute en soutagtigheid in die grond wat gebruik is vir rehabilitasie aantoon. Fosfor het nie teruggekeer tot vlakke van voorheen nie en vlakke van koolstofhet na 15 maande verlaag gebly, en kan die potential tot rehabilitasie belemmer. Elke rehabilitasie tegniek wat die myn gebruik bring kostes sowel as voordele mee. Om restorasie pogings te laat slaag moet insigte vanaf ekologie en ekonomie saam ingespan word. 'n Oorsig van waardasie sisteme toon dat Afslag Kontant Vloei Tegnieke geskik is vir die evaluasie van rehabilitasie programme.