• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 1
  • Tagged with
  • 12
  • 12
  • 12
  • 12
  • 6
  • 6
  • 6
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The conservation status of some unique plant communities in the Eastern Cape

Everard, David Alexander 14 March 2013 (has links)
In response to a growing concern over the rising rates of extinction of the world's plants and of habitat destruction, studies of Southern African threatened plants were initiated in the 1970's. These studies, which have largely concentrated on Western Cape flora, led to the publication of "Threatened Plants of Southern Africa" by Hall et al., 1980, which attempted to list as many threatened or possibly threatened species as possible. It was however marred by a lack of recent herbarium records and detailed studies from many parts of the region, the Eastern Cape being one of these. In order to extend these detailed studies to gain a clearer picture of the numbers of threatened species in the Eastern Cape and evaluate the conservation status of Eastern Cape vegetation this project was initiated. Initially lists of possibly threatened and endemic taxa of the Eastern Cape were compiled from various sources. These listed taxa were then checked against herbarium records, all available information being filled onto index cards for filing purposes. This paper-based filing system was then transferred into a computer-based data bank to facilitate the efficient storage and retrieval of information. Results from this data bank show that there are 662 variously threatened plant taxa in the Eastern Cape, many of which fall into temporary categories which need to be clarified by investigation in the field. Primarily based on the above results, a table ranking the various vegetation types into an order of priority for investigations about conservation requirement was developed.Subtropical Thicket was found to be the vegetation type in most need of investigation and so an extensive phytosociological survey was carried out in the Valley Bushveld which forms the major portion of Subtropical Thicket in the Eastern Cape. Twelve sites were sampled for floristic and environmental variables along a rainfall gradient of between 300 mm yr⁻¹ and 1 000 mm yr⁻¹ and along a longitudinal gradient from the Buffalo River in the east to the Gamtoos-Kromme complex in the west. Floristic data W(re analysed using multivariate techniques of classification and ordination. A classification by two-way species indicator analysis revealed the Valley Bushveld to consist of two orders of thicket, the Kaffrarian Succulent Thicket containing the two suborders, Inland Succulent Thicket and the Coastal Succulent Thicket and the Kaffrarian Thicket containing Coastal Kaffrarian Thicket and Inland Kaffrarian Thicket. Ordina tion by detrended correspondence analysis also grouped sites according to these vegetation categories in a sequence along one axis, to which the rainfall gradient could be related. Variables such as diversity indices, numbers of endemics, numbers of threatened taxa and structural features were also extracted from the data and these were correlated with environmental variables by multiple regression analysis. Species richness and the percent woody component w\!re positively correlated with rainfall while endemism and percent succulent component were strongly negatively correlated with rainfall. Most of the other relationships were explained by interrelationships with rainfall. Finally the sites were evaluated according to floristic criteria indicative of conservation value. The Coastal Succulent Thicket appeared to have the highest conservation value mainly owing to high endemism, while Inland Kaffrarian Thicket was also important as it supports a high number of species. The thickets with high conservation value are therefore the thickets of coastal areas in the western parts of the Eastern Cape which receive a low rainfall and the thickets which receive a rainfall in excess of 800 mm. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in
2

Towards an understanding of plant rarity in Kwazulu-Natal, South Africa

Church, Brigitte 31 July 2014 (has links)
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2014. / The persistence of rare plants is an important dimension in the conservation of biodiversity. Consequently an improved understanding of the nature and determinants of plant rarity and its relation with vulnerability to extinction could provide a basis for “proactive conservation” instead of the present day tendency for conservation actions to be “reactive”. In this dissertation I explore the relation between plant rarity and anthropogenic pressures (land transformation and use), biophysical factors, and plant traits in KwaZulu-Natal Province. Rarity was defined as the product of plant species abundance (population size) and its distribution (extent of occurrence). A number of a priori hypotheses regarding plant rarity were developed from the literature and these were then tested on a sample of plant species from KwaZulu-Natal. Species were selected in a stratified random manner to include species from different levels of threat and rarity or commonness. As the interest of this study was KwaZulu-Natal, only KwaZulu-Natal records were used for the analysis. Although the study suffered from a paucity of data particularly on the biological traits and behaviour of each species I was able to explore rarity in terms of seed dispersal distance, stress tolerance, habitat specificity and ecological niche width. I also explored potential island effects based on a species affinity to isolated erosional land surfaces and the anthropogenic effects of utilization and land transformation. To get an initial insight into relations, rarity was compared with each explanatory variable independently prior to using a multiple regression analysis approach aimed at understanding the potential interactive effects of suitable variables on rarity. Three different analytical techniques were used to provide a more robust understanding of the variable associations. These included Regression tree analysis (CART Salford Systems Inc., USA) and two generalized linear regression approaches; Generalized Linear Modelling (GLM) and Generalized Additive Modelling (GAM). All three multiple regression methods indicated that niche width had the strongest influence on rarity. Although Land Surface was shown to be the second strongest variable this, according to the GLM and GAM analyses, was due to a positive correlation between species with no affinity to land surface and species commonness. Visual representation of the regression tree analysis showed inconsistent partitioning of this variable throughout the tree indicating that land surfaces are not good predictors of rarity. Although the relation between Rarity Index and Habitat Transformation is not linear it was shown to be significant (p <0.1(p=0.0549)) after “smoothing” in GAM analysis. A smoothing curve on the bivariate analysis and the regression tree analysis indicated that species start to become rare after approximately 36% of their habitat is transformed. While GLM and GAM showed little or no relation between life history, dispersal distance, habitat specificity and rarity, the regression tree selected habitat specificity as the third most important splitter in the tree and dispersal distance was selected as a primary splitter for species with a niche width of greater than four. These differences observed in the three multiple regression analyses highlight the value of using more than one method to explore relations in ecological data. Considering all three analyses Niche Width is the strongest determinant of Rarity in KwaZulu-Natal, followed by Habitat Transformation and then Habitat Specificity. This improved understanding of the determinants of rarity will enhance our ability to prioritise plant species for conservation action. Key Words: ecological niche width, habitat specificity, habitat transformation, rarity, seed dispersal distance, stress tolerance, human use.
3

Genetic variation within and between some rare and common taxa of Cape Proteaceae and the implications for their conservation

Brown, Susan Ann January 2000 (has links)
No description available.
4

The influence of soil properties on the growth and distribution of Portulacaria Afra in subtropical thicket, South Africa

Becker, Carina Helene January 2013 (has links)
Subtropical Thicket is the dominant vegetation biome in the Eastern Cape, and extends through to parts of the Western Cape. It is dominated by Portulacaria afra (spekboom), a woody succulent plant recognised for its importance as an ecosystem engineer and its carbon sequestration potential. Due to excessive grazing from domestic stock, spekboom has been completely removed from some areas. The Subtropical Thicket Restoration Programme (STRP) initiated a large scale restoration programme of planting spekboom cuttings in these degraded areas. Their efforts have been met with varying levels of success and improvement of the programme relies on continuous monitoring and scientific evaluation. I investigated the influence of selected soil properties on spekboom growth, mortality and landscape distribution, at both restoration sites and natural intact areas, and through experiments. Site or location was the most important factor influencing spekboom success at restoration plots, whereby sites in the eastern end of spekboom distribution perform better. Moving westwards slope orientation emerged as an important factor, whereby north facing slopes are preferred by spekboom. Although high levels of soil salinity (NaCl) restricted spekboom growth and affected its health, it could tolerate the levels it was exposed too. Soil pH, above 7, and phosphorous concentration, above 70 mg.kg-1, were the only limiting factors to spekboom survival found in the restoration sites. This preference for acidic soils was mirrored in intact Thicket. However in general, soil is not a major factor influencing spekboom growth and distribution, and spekboom is tolerant of a wide range of soil conditions. Spekbooms constraint is most likely a function of climate, which varies greatly across the biome. This study answered some vital questions regarding the possible influence of soil in spekboom growth and distribution. It disapproved the theory that a catena effect may be responsible for the lack of spekboom growing in bottomland areas. The study also indicates and supports the versatility of spekboom as a plant for restoring degraded lands across a range of different geologies and soil types. To maximise spekboom survival rates, restoration efforts should be focussed towards the eastern end of its distribution and to avoid planting in soils with pH levels higher than 7.
5

The conservation status of subtropical transitional thicket, and regeneration through seeding of shrubs in the Xeric succulent thicket of the Eastern Cape

La Cock, Graeme Dennis January 1992 (has links)
The historically poorly conserved subtropical transitional thicket (STT) of the Eastern Cape is overutilised by domestic stock and game in the more xeric areas, and has shown no signs of recovery from this grazing pressure. It has been postulated that no regeneration through seeding occurs. This project was undertaken to determine: 1) how much STT has disappeared between 1950 and present, and what the current conservation status is; and 2) whether regeneration of the xeric succulent thicket is taking place through seeding, and if so, where. The study was conducted at the Andries Vosloo Kudu Reserve near Grahamstown. Approximately one-third less STT was mapped in this study, based on 1981 Landsat images, than was mapped in 1950. Approximately 10 % of all remaining STT is conserved. The order Kaffrarian thicket is poorly conserved. Newly germinated seedlings of a wide range of shrub species occurred under the canopies of a wide range of shrubs which served as nurse plants, throughout a gradient of veld condition. Seedlings of Portulacaria afra, the dominant shrub in xeric succulent thicket, were most common. Similarly all saplings recorded in a survey of saplings were associated with bushclumps. One-third of all saplings have the potential to contribute to the spread of bushclumps. Regeneration of xeric succulent thicket through seeding probably does occur, contrary to current ideas. Ptareoxylon obliquum was the most common sapling, despite mature trees now being scarce following earlier heavier utilisation . P. obliquum was also the nurse plant which supported the highest density of newly germinated seedlings. The possible role of P. obliquum in the functioning of xeric succulent thicket is discussed. The confinement of seedlings and saplings to areas under the canopies of trees and shrubs implies that the xeric succulent thicket will not recover rapidly if allowed to rest. Active management techniques will be necessary if rapid recovery is required. Bare areas between bushclumps may no longer be suitable germination habitats because of high Al concentrations. There was no evidence to support the idea that germination and establishment of shrubs in clear areas is linked to episodic climatic events. Dung middens of recently reintroduced black rhinoceros may however aid in germination of seeds and establishment of seedlings under certain climatic conditions. Recommendations for further studies, based on the findings of this project, are made. Possible management techniques aimed at the rapid recovery of this veld are suggested, and management proposals for the Sam Knott Nature Reserve/Andries Vosloo Kudu Reserve complex are made.
6

Conservation incentives for private commercial farmers in the thicket biome, Eastern Cape, South Africa

Cumming, Tracey Lyn January 2007 (has links)
This study sought opportunities to mitigate the pressures of land transformation and alien invader plants on commercial farm land in the thicket biome in the lower reaches of the Fish Kowie Corridor. It had two aims. Firstly, to determine the role incentives could play in mitigating these pressures. Secondly, to determine the characteristics of an incentive programme that would most effectively achieve this. In order to do this, an understanding of landowner activities, needs, opinions and barriers to behaviour; the nature of the pressures on thicket and the nature of the required behaviour to reduce these pressures; and current and past institutional arrangements needed to be achieved. This was done predominantly through a current literature review and personal interviews with landowners and key informants. These findings were used to make recommendations for an effective incentive programme. Landowners showed a preference towards tangible incentives, in particular management assistance, financial compensation and law enforcement. They indicated an aversion to an incentive programme implemented by a government agency, particularly district and provincial government. Rather, landowners showed a propensity towards a nongovernment organisation (NGO) or a farmers group implementing an incentive programme. It was recommended that the two major pressures, namely land transformation and alien invader plants, required different interventions by different agencies in order to be mitigated. The pressure of land transformation required a stewardship model response, with the primary drive being a non-contractual environmental extension service to landowners. The extension service should focus on promoting pro-conservation practises, raising awareness and disseminating information. It should also build a relationship of trust between landowners and the implementing agency. The pressure of alien invader plants would be most effectively addressed through the Working for Water programme. Tangible incentives must be provided to the landowner to induce the costly exercise of alien invader plant control. In particular, the high cost of labour must be addressed. The regulatory incentive of applying laws requiring landowners to control alien invader plants on their land should also be enforced.
7

Restoration of degraded subtropical thickets in the Baviaanskloof Megareserve, South Africa: the role of carbon stocks and Portulacaria afra survivorship

Powell, Michael John January 2009 (has links)
The semi-arid forms of subtropical thicket in the Eastern and Western Cape have been heavily degraded through unsustainable pastoralism over the last century or more. The degraded areas exhibit a significant loss of above-ground and belowground carbon stocks, and consequently provide an opportunity for restoration through the formal and informal carbon markets. A prerequisite for the attainment of carbon credits is to ensure sound carbon stock baselines prior to effecting restoration. I report on the carbon stocks (including sub-pools) for a number of intact subtropical thicket types, as well as the differentials between the intact and degraded states (including the sub-pools). Total carbon stocks (TCS in t C ha⁻¹) for intact vegetation (to a soil depth 0–25 cm), ranged from 87.73±6.51 to 70.64±17.24. For degraded vegetation (including old lands), TCS (t C ha⁻¹) ranged from 34.05±3.61 to 21.03±2.70. For all vegetation types, the differentials in TCS along the degradation gradient (0–25 cm) are highly significant and strengthen the possibility for carbon credit financing to catalyse the restoration of the degraded semi-arid subtropical thickets. This study has shown a mean loss of 57.23 t C ha⁻¹ in Baviaanskloof spekboom thickets, when measured to a soil depth of 25 cm. Portulacaria afra is a key species within the semi-arid subtropical thickets, being a canopy dominant and a driver of soil nutrient status, but has been largely lost from the degraded landscapes. Degraded semi-arid subtropical thicket vegetation lacks regeneration via seedling recruitment; restoration therefore requires the manual replanting of P. afra using cut truncheons. Survivorship trials were undertaken infield in 2005 to establish restoration protocols for P. afra, with survivorship being recorded in 2006 and 2008. Overall survivorship for all treatments was found to be 43.2±2.8% in 2006, dropping to 35.8±2.7% in 2008. Planting posture (flat or upright) showed the most significant results of all the factors tested in 2006 and 2008. Micro-damming also influenced survivorship in that micro-damming was associated with marginally higher survivorship (47.4 ±2.0% with damming vs. 39.1±1.5% without damming in 2006, and 39.3±1.9% vs. 32.3±1.5% in 2008). Higher planting density only showed a significant positive impact on survivorship in 2008. Neither stem diameter nor clumping significantly affected degree of survival. A key finding in the study has been the non-static nature of P. afra truncheon survivorship, even after being well established (three years since planting). The results from the study will guide the restoration protocols for the restoration of degraded subtropical thickets, where P. afra requires replanting.
8

Monitoring rehabilitation success on Namakwa Sands heavy minerals mining operations, Namaqualand, South Africa

Blood, Jeremy Russell 12 1900 (has links)
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.
9

Strip mining rehabilitation by translocation in arid coastal Namaqualand, South Africa

Mahood, Kirsten 03 1900 (has links)
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.
10

Population assessments of priority plant species used by local communities in and around three Wild Coast reserves, Eastern Cape, South Africa

Fearon, Joclyn Joe January 2011 (has links)
The project was initiated by Eastern Cape Parks (ECP) as a request for the construction of inventories of priority species and their population levels inside three nature reserves on the Eastern Cape Wild Coast, South Africa, and to develop a strategic management plan to manage these natural resources in each reserve. Thirty key species were identified by local communities in and around Dwesa-Cwebe, Silaka and Mkambati Nature Reserves through community workshops. For forested areas belt transects of 100 m x 6 m where used. The basal circumference of key tree species within the belt transect was measured as well as the height of saplings (height < 150 m). Tree species were categorized based on densities, size class distribution (SCD) curves and values, and spatial grain. For grassland areas straight transects of 200 m long were used, along which ten 3 m x 3 m quadrates were placed at 20 m intervals. Within each grassland transect the height of herbs or tuft diameter of grasses was recorded and percentage cover estimated. Grassland species were categorized based on density, SCD curves and percentage cover. All species were placed into harvesting categories based on analysed ecological data that was collected in the field. Category 1 species were very rare or not found in the reserve and it was recommended that species be conserved and monitored. Category 2 species had low densities in the reserve indicating declining populations and was suggested that these be monitored and not harvested. Category 3 species had high densities and have potential for harvesting with strict limitations. Category 4 species were most abundant with very high densities and can be harvested within management guidelines. These categories were grouped further using social and ecological data such as harvesting risk, frequency of collection, use value and number of uses. This highlighted which species have conservation priority within each category and a decision can be made as to how intense or limited extraction should be. By incorporating GIS the distribution of each species was looked at and harvesting and non-harvesting zones established to determine where species can be extracted. Monitoring plans must consider the quantity of plant material collected, fire regimes, optimal harvesting rates and harvesting zones, and be able to pick up changes in populations. Also, it is important that the community be involved in conserving and monitoring these species. Adaptive monitoring and management must be used to steer harvesting practices in the Wild Coast reserves. This allows for the development of harvesting practices through ‘learning by doing’, and the evolution of good questions to guide monitoring decisions

Page generated in 0.168 seconds