151 |
Old field restoration : vegetation response to soil changes and restoration efforts in Western Cape LowlandsMemiaghe, Herve Roland 12 1900 (has links)
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.
|
152 |
Effects of gaseous emissions from the Namakwa Sands Mineral Separation Plant near Lutzville on the adjacent succulent Karoo vegetation : a pilot studyLukama, Beatice M. K. 03 1900 (has links)
Thesis (MSc (Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / A pilot study was conducted at the Namakwa Sands Mineral Separation Plant, to investigate the
effects of acidic gaseous emissions from the Mineral Separation Plant on the adjacent Succulent Karoo
vegetation. Sulphuric acid fumes, a major gaseous emission of the mineral processing, was the subject
of investigation of the present study, due to the potential high negative impact of elevated
concentrations thereof on vegetation in the ecosystem.
Permanent sample plots along three transects radiating from the Mineral Separation Plant were laid out
in the eastern, south-eastern and southern directions following the prevailing wind directions and
practical consideration of land accessibility.
The ecological components assessed as indicators of possible pollution levels in the environment
included percentage plant mortality, foliar sulphur content of selected plant species, chemical
composition of solubles in mist and dust samples, and soil pH. In addition, the vegetation was
screened for plant species suitable to be used as potential bioindicators.
Potential bioindicator plant species were selected on the basis of their relatively wide distribution in
the study area and apparent sensitivity to the ambient air pollutants. The percentage of dead plants of
each species that occurred on the sample plots was used as a criterion of the possible sensitivity of the
plant species towards air pollution. The bioindicator plant species selected for potential monitoring
purposes were: Galenia fruticosa, Lampranthus suavissimus, Lycium ferocissimum and a Ruschia sp.
(SP 9). Plant mortality was greater nearer the emission source, with 28 + 5 % dead plants at 400 m, 19
+ 6 % at 800 m and only 10 + 4 % at 1,200 m from the Mineral Separation Plant. Data summed for all
species recorded and pooled for all three transects per sampling distance.
With the methods used in this study, in the case of all sample plots on the three transects, no
significant difference was found between the mean pH values of soil samples collected from open
spaces without plant cover (8.01 + 0.46) and those collected underneath shrubs (8.91 + 0.96).
Subsequently only the pH values of soil samples collected on open spaces were used to investigate the
variation in soil acidity with distance and direction from the emission source. The means represent
total number of samples from open space versus those collected from underneath shrubs. The pH of soil samples increased with distance from the emission source along the transects to the
south and south-east of the emission source. Eastward of the emission source, soil pH values remained
relatively low at all sample distances. This pilot study could not determine whether the continuous
acidity of the soil along the eastern transect in the direction of the prevailing wind, was caused by
increased deposition of gaseous emissions on the higher lying hilly terrain in this area, or by the
underlying geology.
Ion chromatographic analysis of mist and dust samples collected on each sample plot indicated the
presence of several chemicals that had probably originated from the gaseous emissions from the
Mineral Separation Plant as well as wind blown constituents from the adjacent surroundings of the
sample plots. Of these chemicals, only the sulphate concentrations of the mist and dust samples were
further evaluated, since that could be related to the emission of sulphuric acid fumes by the Mineral
Separation Plant. Results indicated that the mean sulphate concentration of mist and dust samples
collected from sample plots relatively close to the Mineral Separation Plant, 118.8 + 31.6 mg/litre (400
m), were higher than further afield, decreasing to 57 + 30.1 mg/litre at 800 m and 43.1 + 19.6 mg/litre
at 1,200 m. These values, representing the mean sulphate concentrations of mist and dust samples at
each sampling distance (data of the three transects pooled), differ significantly at the 85 % confidence
level.
Statistical evaluation of the data of the mist and dust pH measurements, pooled for the three transects
on the basis of distance, indicated a gradual increase of the mean values from 400 m (7.3 + 0.26),
through 800 m (7.7 + 0.34), to 1,200 m (8.2 + 0.83), although these values were not significantly
different.
A decreasing trend in accordance with that in the case of the sulphate concentrations of mist and dust
samples with distance from the mineral processing plant, was also observed in the sulphur content of
the leaves of selected plant species, with mean sulphur content higher at 400 m sampling distance
(0.29 + 0.091 %) than at 800 m (0.264 + 0.086 %) and a further decline at 1,200 m (0.232 + 0.079 %),
data of the three transects pooled. However, these values were also not significantly different. Although not significantly so, the decreasing trend in the results of the sulphate concentration of mist
and dust samples, the sulphur content of plant leaf samples as well as plant mortality observed, and
increasing soil pH values with distance from the Mineral Separation Plant, suggest that the gaseous
emissions from the Mineral Separation Plant could probably have had a detrimental effect on the
adjacent Succulent Karoo vegetation. A more detailed study is necessary to confirm this trend. In
addition it is recommended that in order to clarify the soil pH measurements outcome along the
eastern transect that were contradicted by the results of the mist and dust pH measurements, a more
intensive survey over a greater distance (at least further than 1.2 km from the Mineral Separation
Plant), be conducted to quantify vegetation damage and acid deposition to the east of the emission
source.
|
153 |
Gap regeneration in the Tsitsikamma forest (Easter Cape, South Africa) : the effect of gap size and originElla, Ghislain 12 1900 (has links)
Thesis (MSc(For))--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Recognizing the biological significance of gaps, the South African Department of Water Affairs and
Forestry (DWAF) in 1989 initiated a Gap Dynamics Project in the indigenous forests of
Tsitsikamma (Eastern Cape, South Africa). This consists of three sub-projects: Koomansbos (9300
m2), created by a ground fire in 1989; Plaatbos (1600 m2), made by a Podocarpus falcatus (Thunb.)
R. Br. ex Mirb. (Podocarpaceae) windfall in 1994; and nine gaps of different sizes, artificially
created by selective tree felling in 1995: three small (100-150 m2), three medium (300-500 m2) and
three large (800-1000 m2). All the gaps were surveyed after creation and permanent plots were
established for subsequent monitoring. The current timber harvesting system practiced in South
African indigenous forests attempts to minimize gap size. It has been proposed by Euston-Brown et
al. (1996) that this practice is likely to benefit the more shade tolerant species, but may inhibit the
regeneration of less shade tolerant plants in the forest. Therefore, the present study aimed to verify
two hypotheses: gaps may close in a process that is determined by their size, their origin and the
plant species characteristics; soil quality might change inside those gaps. For the purpose of the
study, the gaps cited above were re-surveyed between 2002 and 2003. It was found that: 1) there
was little clear difference in the community structure of plant species between gaps of different
sizes and origins; as expected from the species-area relationship, large gaps had higher species
richness, plant diversity and herbaceous percentage cover than medium and small gaps; diversity
indices were higher in the large windfall gap than in the large fire and artificial gaps; generally,
context and stochastic events were largely more important in determining gap diversity and
regeneration than gap sizes and origins; 2) diversity indices in the gaps were higher than recorded
previously; 3) soil pH and Electrical Conductivity were respectively lower and higher inside the
gaps than adjacent to them; these variations were statistically significant. Present data on the
vegetation in the gaps were compared to past measurements, and future vegetation structure has
been predicted, as a function of current gap vegetation. Recommendations have been made for
sustainable management of the indigenous forest of Tsitsikamma. / AFRIKAANSE OPSOMMING: Voortspruitend uit die erkenning van die biologiese belang van gapings, het die Suid-Afrikaanse
Departement van Waterwese en Bosbou (DWB) in 1989 'n projek oor gapingsdinamika in die
inheemse woude van Tsitsikamma (Oos-Kaap, Suid-Afrika) geïnisieer. Dit bestaan uit drie
subprojekte: die gaping in Koomansbos (9300 m2) wat in 1989 deur 'n grondvuur geskep is; die
gaping in Plaatbos (1600 m2) wat veroorsaak is toe bome van die spesie Podocarpus falcatus
(Thunb.) R. Br. ex Mirb. (Podocarpaceae) in 1994 omgewaai is; en nege gapings van verskillende
groottes wat in 1995 kunsmatig deur geselekteerde boomkappery geskep is: drie is klein (100-150
m2), drie mediumgrootte (300-500 m2) en drie groot (800-1000 m2). Alle gapings is ná hulle
ontstaan opgemeet en ondersoek en permanente terreine is vir daaropvolgende monitering gevestig.
Die stelsel wat tans vir die oes van hout in Suid-Afrikaanse inheemse woude gebruik word, poog
om die grootte van gapings te minimaliseer. Euston Brown et al. (1996) doen aan die hand dat
hierdie praktyk spesies wat meer skaduweeverdraagsaam is waarskynlik sal bevoordeel, maar die
regenerasie van plante in die woud wat minder skaduweeverdraagsaam is, kan inhibeer. Hierdie
studie het dus ten doel gehad om twee hipoteses te verifieer: Gapings kan toegroei in 'n proses wat
deur hul grootte, oorsprong en die eienskappe van die plantspesies bepaal word; en die gehalte van
die grond binne daardie gapings kan verander. Die gapings waarna hierbo verwys is, is vir die doel
van hierdie studie tussen 2002 en 2003 weer gemonitor. Daar is bevind dat: 1) daar min duidelike
verskille was tussen die gemeenskapstruktuur van plantspesies tussen gapings van verskillende
groottes en oorsprong; soos van die verhouding tussen spesies en area verwag kan word, het groter
gapings 'n hoër spesierykheid, plantdiversiteit en persentasie niehoutagtige dekking as medium- en
klein gapings gehad; diversiteitsindekse was hoër in die groot Plaatbosgaping as in die groot
Koomansbosgaping of die kunsmatige gapings; in die algemeen was konteks en stochastiese
gebeure grootliks belangriker in die bepaling van gapingsdiversiteit en -regenerasie as
gapingsgrootte of -oorsprong; 2) diversiteitsindekse in die gapings was hoër as wat voorheen
aangeteken is; en 3) grond-pH en elektriese geleidingsvermoë was onderskeidelik laer en hoër binne
die gapings as neffens hulle; hierdie variasies was statisties beduidend. Huidige data oor die
plantegroei in die gapings is met vorige metings vergelyk, en 'n toekomstige plantegroeistruktuur is
as 'n funksie van huidige gapingsplantegroei voorspel. Aanbevelings is gemaak rakende die
volhoubare bestuur van Tsitsikamma se inheemse woud.
|
154 |
Conservation in human-influenced areas : epigaeic arthropods in the Cape Floristic Region LowlandsBoonzaaier, Carmen 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The conservation of biodiversity is becoming increasingly challenging as habitats are
disturbed, fragmented or destroyed. Although nature reserves now cover more than 10 %
of the earths’ surface it has become clear that more will have to be done to ensure the
long-term survival of species. Therefore, focus is increasingly shifting towards
conserving biodiversity in natural and semi-natural remnants in human-influenced areas.
This study aimed to determine the contribution of remnants in human-influenced areas to
the conservation of biodiversity in the Cape Floristic Region (CFR) lowlands, using
ground-dwelling arthropods, specifically ants, as the focal taxon. Initially, base-line
information of arthropods and in particular ants was obtained. Sampling arthropods
generally involves a large sample effort. Therefore maximizing sampling effort for ants
in the CFR was investigated by trapping ground-dwelling ants at a single locality.
Doubling the number of grids of pitfall traps was found to be more effective in trapping a
greater number of species than doubling the duration of sampling. Therefore increasing
spatial sampling intensity rather than sampling duration maximizes sample effort for CFR
ants. Also, the seasonal changes of ground-dwelling arthropods, including ants, were
determined by sampling four times during the year at a single locality. Overall arthropod
abundance was found to peak in summer while dropping to a minimum in winter. This
pattern was mirrored by that of the ants, indicating that ant results have a broader
relevance than to ants only. The ground-dwelling fauna was dominated by ants
emphasizing their importance in the CFR lowlands, and demonstrating that ants are an
appropriate flagship taxon for epigaeic arthropod diversity in the CFR. Finally the
contribution of remnants in human-influenced areas to the conservation of the CFR was
investigated. A nested hierarchical approach was used, where five localities were selected
across the CFR, each containing one reserve site and one site with natural remnants. Ants
were sampled, along with environmental variables, namely weather, vegetation and soil.
Overall, remnants were found to support similar ant assemblages to those of reserves.
However for individual localities some remnants were significantly different to their
reserve counterparts. Differences in ant assemblages were found to be greater between
localities than between reserves and remnants. The relatively high heterogeneity of ants found in this study emphasizes the conservation significance of invertebrates along with
that of plants in the CFR. Remnants clearly show the potential to conserve ant
assemblages, however correct management is needed for these areas to maximize their
potential. Disturbances such as the presence of the invasive Argentine ant and increasing
soil nutrients by fertilization, pose a distinct threat to the ability of remnants to conserve
ant assemblages. This study has shown that remnants currently support ant assemblages
representative of those present in the CFR today. Therefore, some remnant patches of
habitat in agricultural areas currently do contribute highly to the conservation of a
functional important taxon in this global biodiversity hotspot, and if managed correctly,
may continue to do so in the future. / AFRIKAANSE OPSOMMING: Die vernietiging en fragmentering van habitatte maak die bewaring van biodiversiteit al
hoe meer van ‘n uitdaging. Alhoewel natuur reservate reeds meer as 10 % van die aarde
se oppervlak beslaan is dit duidelik dat meer gedoen sal moet word vir die lang-termyn
voortbestaan van spesies. Dus word die fokus van biodiversiteit-bewaring toenemend
gerig op bewaring van natuurlike en semi-natuurlike fragmente in menslik-beinvloede
gebiede. Die doel van hierdie studie was om te bepaal wat die bydrae van fragmente van
natuurlike veld in menslik-beinvloede gebiede is tot die bewaring van die streek. Dit is
gedoen deur van grond-lewende geleedpotiges en spesifiek, miere in die Kaapse floraryk
(CFR) gebruik te maak. Aanvanklik is kennis ingewin oor die geleedpotiges en spesifiek
miere in die omgewing. Omdat die versameling van geleedpotige diere gewoonlik baie
moeite vereis is ‘n maksimum steekproef gedoen by ‘n enkele lokaliteit. Daar is gevind
dat ‘n verdubbling van die aantal ruitsteekproefnemings met vanggate meer effektief is
om miere te vang as ‘n verdubbling in die tydperiode wat vanggate oop is. Dus, is ‘n hoër
ruimtelike steekproef intensiteit meer effektief in vergelyking met ‘n langer tydsduur vir
miere in die CFR. Die seisoenale veranderinge van grond-lewende geleedpotiges, sowel
as miere, was ook bepaal. Dit was gedoen deur vier seisoenale steekproewe te doen by ‘n
enkele lokaliteit. Die totale geleedpotige-talrykheid was die meeste gedurende die somer
en die minste in die winter. Die miertalrykheid het ook hierdie patroon weerspieël. Dit
dui daarop dat veranderinge in mier versamelings van breër belang is vir alle grondlewende
geleedpotiges. Miere was die dominante grond-lewende geleedpotiges en
beklemtoon die belangrikheid van miere in die CFR, sowel as hulle toepaslikheid as
vlagskip taksa vir grond-lewende geleedpotige diversiteit in die CFR. Laastens was die
bydrae van gefragmenteerde natuurlike veld in menslik–beinvloede gebiede tot die
bewaring van die CFR ondersoek. ’n Krimpende/ genestelde hiërargies benadering is
gebruik in vyf geselekteerde lokaliteite, elk het bestaan uit ‘n area in ‘n natuur reservaat
en ‘n area in ‘n naasliggende fragment. Miere was versamel saam met ‘n verskeidenheid
omgewings veranderlike, naamlik weer, plantegroei en grond. In die algemeen is gevind
dat fragmente en reservate gelyksoortige mier versamelings het. Daar was wel gevind dat
party fragmente aansienlik verskillend was van die reservaat teenstuk. Verskille in mier versamelings tussen lokaliteite was groter as verskille tussen reservate en fragmente. Die
relatief hoë heterogeniteit van miere beklemtoon die bewaringsbelang van invertebrate
saam met dié van plante in die CFR. Dit is duidelik dat fragmente wel ‘n potensiale
bydrae kan maak om die mier versamelinge te bewaar, maar gepaste bestuur is nodig om
hierdie potentiaal te maksimaliseer. Versteurings soos die teenwoordigheid van die
indringer Argentynse mier en toenemende grondvoedingstofkonsentrasie as gevolg van
bemesting is ‘n groot bedreiging tot die vermoë van fragmente om mier versamelings te
bewaar. Hierdie studie wys dat mier versamelings in gefragmenterde areas
verteenwordigend is van die algemene mier versamlings wat op die oomblik in die CFR
is. Dus lewer party fragmente in landbou gebiede op die oomblik ‘n wesenlike bydrae tot
die bewaring van ‘n funksioneel belangrike takson in hierdie globale
biodiversiteitsbrandpunt en die bydra sal volhoubaar wees met korekte bestuur.
|
155 |
Monitoring rehabilitation success on Namakwa Sands heavy minerals mining operations, Namaqualand, South AfricaBlood, 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.
|
156 |
Evaluation of macro-invertebrates as bio-indicators of water quality and the assessment of the impact of the Klein Plaas dam on the Eerste RiverBredenhand, Emile 12 1900 (has links)
Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2005. / A semi-arid country, like South Africa, with unpredictable seasonal rainfall, is subject
to great scarcity in water and an ever-increasing demand from the rising human
population. Therefore, efficient reservoirs as well as monitoring methods are needed
to manage the South African water supply.
This study was undertaken on the Eerste River in the Western Cape, South Africa,
focusing on the impact of the Klein Plaas dam system on the benthic
macroinvertebrates. The study also examined the use of benthic macroinvertebrates
as bioindicators of water quality with special reference to the South African Scoring
System Version 5(SASS5) that is currently being used nationally.
The impoundment of the water, as well as the inter-basin transfer programme and the
experimental cage-culture trout farm, all play a significant role in the disturbance
impact of the dam on the Eerste River system. The disturbance is manifested as a
drop in water quality that can be seen in the distribution of keystone species, changes
in the riparian vegetation, as well as in physical-, chemical-, and biomonitoring
evaluations.
The study also indicated that the SASS5 is effective, but needs some adjustments,
such as inclusion of a prediction phase, finer spatial-scale methodologies and greater
consideration of the rarity of species.
|
157 |
Vegetation patterns and dynamics of Renosterveld at Agter-Groeneberg Conservancy, Western Cape, South AfricaWalton, Benjamin Alan 03 1900 (has links)
Thesis (MSc (Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / Swartland Shale Renosterveld is restricted to fertile fine-grained soils in the winter rainfall region of
the Western Cape. Between 91% and 97% of this vegetation type is transformed, mostly due to
agriculture. Remaining fragments have an irreplaceable conservation value due to a high richness of
endemic geophytes. Information on renosterveld vegetation composition and response to
disturbance is sparse. Research occurred at three sites near Wellington: Voëlvlei Provincial Nature
Reserve (CapeNature), Elandsberg Private Nature Reserve (Elandsberg Farms (Pty.) Ltd.), and
Krantzkop munitions factory (Armscor/Somchem) forming a contiguous fragment in the Agter-
Groeneberg Conservancy. The primary research aim was to identify or ascertain patterns of plant
succession in Swartland Shale Renosterveld and associated different-aged old fields (previously
ploughed), with the interaction of grazing. The key research questions are: (1) What are the plant
communities of unploughed renosterveld and different-aged old fields which originated in habitats
of ploughed renosterveld? (2) What are the most characteristic features of the floristic and
ecological relationship between the described plant communities in terms of ecological factors
operating within the studied system? (3) Does total species and life-form group richness differ
between natural vegetation and old fields? (4) Is life-form richness influenced by ploughing and
grazing or the interaction between these disturbances? (5) Is life-form cover-abundance influenced
by ploughing and grazing or the interaction between these disturbances? (6) Does alien plant
species richness differ amongst seres, and with different levels of grazing intensity? A comparison
of life-form richness and cover-abundance of old field vegetation was made with adjacent natural
unploughed “controls”. The effects of ploughing on community structure, with the inclusion of
grazing was established. These life-form richness comparisons also occur across a gradient of
increasing large mammalian herbivore grazing intensity. Sampling was conducted in winter and
spring using nested 1000m2 relevés.
A hierarchical classification, description and floristic interpretation of renosterveld and old field
vegetation were made using TWINSPAN, SYN-TAX 2000 and CANOCO. The samples were
classified with TWINSPAN and two communities were described at the association level, namely:
Ursinia anthemoides–Cynodon dactylon Grassland Community (with two variants) and the
Pterygodio catholici–Elytropappetum rhinocerotis Shrubland Community (with two subassociations),
respectively. The vegetation data were further hierachically classified using SYNTAX
2000 which revealed similar clustering of sample objects to that resulting from classification and ordination. Following ordination of sample objects with CANOCO, select groups of species
were used to depict their response curves in relation to seral development.
Briefly it was found that the effects of grazing vs. non-grazing was more pronounced on old fields
than in unploughed vegetation. Overall total species and life-form richness was reduced by
ploughing with old fields requiring a recovery period of 30 years to resemble unploughed
vegetation.
Keywords: Swartland Shale Renosterveld, phytosociology, vegetation patterns, life-forms,
succession, disturbance, ploughing, grazing, old fields.
|
158 |
Synergies between biodiversity conservation and sustainable rural development of adjacent communities: a case study of the Tsitsikamma National ParkFaasen, Helena 03 1900 (has links)
Thesis (MScConsEcol (Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / The Constitution of the Republic of South Africa promotes participatory, cooperative
governance and environmental conservation. This constitutional directive is enhanced into the
National Environmental Management Act and other conservation laws. These legal
requirements for active community participation in natural resources management, including
benefit sharing are sufficiently captured in the SANParks’ policy and strategy for the
management of national parks.
|
159 |
Understanding plant resource use by the ≠Khomani Bushmen of the southern KalahariMannetti, Lelani 03 1900 (has links)
Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Previously, conservation activities were mainly focussed upon the establishment of protected
areas that safeguarded and shielded the natural world from misuse, often resulting in the forced
removal of indigenous communities. In South Africa, the ≠Khomani Bushmen, were one such
group forcibly evicted from their homelands. Today, the community has regained access to their
ancestral lands in the form of a land claim, settled in 1999, that awarded the community land rights
in the form of six farms and land use rights within the now Kgalagadi Transfrontier Park (KTP).
This gave them the right to use and manage their property falling within the park together with the
conservation authority responsible for the Park, South African National Parks (SANParks).
This study aims to improve our understanding of the use of resources by the ≠Khomani
Bushmen. By obtaining insight on resource use and how knowledge of this use is transferred and
shared, information on how to better involve and integrate the community in management
processes is generated. The study identified the most important plants currently used within the
≠Khomani community and assessed this use. Additionally, social network analysis (SNA) was
used to investigate how the social network structure depicts the distribution of knowledge which
affects the community’s ability to manage their natural plant resources effectively. In an
ethnobotanical survey, over 90 individuals were interviewed, using semi-structured interviews, on
the farms awarded to the community. In total, 59 plant species from 28 families were found to be
in use. Medicinal plants were most frequently cited (60%), with edible plants comprising a further
20%. Data was also collected on social relations surrounding the acquisition, generation and
transfer of plant use knowledge. The knowledge networks all depict isolated individuals on the
periphery and a few individuals loosely connected to central structures.
This study demonstrates that wild plant use remains an important practice for the ≠Khomani
people, primarily for medicinal purposes. It serves as baseline data on plant resources being used
by the community and adds to our understanding of how traditional knowledge is being transmitted.
The insight provided by SNA depicts the current distribution of knowledge and should be used by
the community, as supported by network weavers and SANParks, to achieve their joint
management goals. Network weaving can potentially counteract ecologically unsustainable
practices, promoting collaboration and the transfer of traditional ecological knowledge. / AFRIKAANSE OPSOMMING: Voorheen was bewaringsaktiwiteite meestal gefokus op die vestiging van beskermde areas
wat die natuurlike wêreld beveilig en beskerm het van misbruik wat dikwels die gevolg was van die
geforseerde verwydering van inheemse gemeenskappe. In Suid-Afrika was die ≠Khomani
Boesman groep een van die sodanige groepe wat op ʼn indrukwekkende manier van hulle tuislande
uitgesit is. Vandag het die gemeenskap weer toegang gekry tot die land van hulle voorvaders in
die indiening van ʼn grond eis wat in 1999 vasgestel is, en wat die gemeenskap grond regte
toegeken het in die vorm van ses plase en grond regtelike gebruik binne die sogenoemde
Kgalagadi Transfrontier Park (KTP). Dit het hulle die reg gegee tot die gebruik en bestuur van
hulle eiendom wat binne die park val saam met die bewaringsowerhede wat verantwoordelik is vir
die Park, Suid-Afrikaanse Nasionale Parke (SANParks). Die doel van hierdie studie is om ons
begrip te verbeter van die gebruik van hulpbronne deur die ≠Khomani Boesman. Met die
verkryging van insig oor hulpbron gebruik en hoe die kennis van hierdie gebruik oorgedra en
gedeel word, is inligting oor hoe om ʼn beter betrekking en integrering van die gemeenskap in die
bestuursprosesse gegenereer. Die studie het die belangrikste plante geïdentifiseer wat tans
gebruik word binne die ≠Khomani gemeenskap met die doel om die gebruik van hierdie plante te
assesseer. Sosiale netwerkanalise (SNA) is addisioneel gebruik om ondersoek in te stel oor hoe
sosiale netwerk struktuur die verspreiding van kennis uitbeeld wat die gemeenskap se vermoë om
hulle natuurlike plant hulpbronne effektief te bestuur affekteer. In ʼn etnobotaniese opname, was
oor 90 individuele ondervra op die plase wat aan die gemeenskap toegeken was, met die gebruik
van semi-gestruktureerde onderhoude. Dit is gevind dat in totaal 59 plant spesies uit 28 families
gebruik word. Medisinale plante was meer dikwels aangehaal (60%) met eetbare plante
bestaande uit 20%. Data was ook versamel oor sosiale verwantskappe omringende die
verkryging, generering en oordra van kennis in die gebruik van plante. Hierdie netwerk van kennis
word alles uitgebeeld in geïsoleerde individue op die periferie en ʼn paar individue wat losweg
verbonde is tot sentrale strukture. Hierdie studie identifiseer dat die gebruik van wildeplante ʼn
belangrike praktyk bly vir die ≠Khomani mense, hoofsaaklik vir medisinale doeleindes. Dit dien as
basis inligting van plant hulpbronne wat tans gebruik word deur die gemeenskap en wat by ons
begrip gevoeg word oor hoe tradisionele kennis oorgedra word. Die insig wat deur SNA voorsien
word beeld die huidige verspreiding van kennis uit, wat deur die gemeenskap gebruik moet word,
as ondersteuning van “network weavers” en SANParks om hulle gesamentlike bestuur doelwitte te
bereik. “Network weavers” kan potensieel ekologiese onvolhoubare praktyke teenwerk, wat die
samewerking en die oordra van tradisionele ekologiese kennis bevorder.
|
160 |
Impact of Prosopis (mesquite) invasion and clearing on ecosystem structure, function and agricultural productivity in semi-arid Nama Karoo rangeland, South AfricaNdhlovu, Thabisisani 03 1900 (has links)
Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: I evaluated the impact of Prosopis invasion and clearing on ecological structure, function and
agricultural productivity in heavily grazed Nama Karoo rangeland on two sheep farms near the
town of Beaufort West in the Western Cape Province of South Africa. My aims were to (1)
determine the effects of invasion and clearing on rangeland vegetation composition, diversity
(alien and indigenous species richness) and structure (alien and indigenous species cover), soil
vegetation cover (plant canopy and basal cover) and agricultural productivity (grazing capacity),
(2) describe the vegetation processes that underlay the invasion and clearing impacts and (3)
evaluate the success of clearing in facilitating unaided restoration of ecological structure,
function and agricultural productivity in formerly invaded rangeland. I hypothesised that
invasion would significantly change rangeland vegetation composition and structure, leading to
greater alien species richness and cover and lower indigenous species richness and cover while
clearing would lead to lower alien species diversity and cover and greater indigenous species
richness and cover. In addition I hypothesized that invasion would reduce rangeland plant
canopy and basal cover and grazing capacity while clearing would substantially increase them.
Finally I predicted that vegetation composition, alien and indigenous species cover and richness,
plant canopy and basal cover and grazing capacity would revert to pre-invasion status and levels
within four to six years of clearing.
My results suggest that in heavily grazed Nama Karoo rangeland Prosopis invasion (~15
percent canopy cover) and clearing can significantly change rangeland vegetation composition,
with invasion leading to greater alien species cover and lower indigenous species richness, while
clearing leads to lower alien species richness and cover and greater indigenous species richness
and cover. However invasion seems to have no effect on alien species richness and overall
indigenous species cover. Clearing appears to facilitate the spontaneous restoration of alien
species cover and indigenous species richness within four to six years but not species
composition, alien species richness and indigenous species cover. In addition my results also
indicate that Prosopis invasion can lower rangeland plant canopy and basal cover and grazing
capacity while clearing, even under heavy grazing, can substantially raise them. Clearing
however does not seem to facilitate the restoration of rangeland plant canopy and basal cover
and grazing capacity to pre-invasion levels within four to six years after clearing. / AFRIKAANSE OPSOMMING: Ek het die impak van Prosopis indringing en verwydering van indringers op ekologiese
struktuur, funksie en landbou produktiwiteit in ‘n swaar beweide Nama Karoo gebied op twee
skaapplase naby Beaufort-Wes in die Wes-Kaap provinsie van Suid-Afrika geëvalueer. My
doelwitte was om (1) te bepaal wat die gevolge van die indringing en verwydering van
indringers op die natuurlike plantegroei samestelling, diversiteit (uitheemse en inheemse
spesiesrykheid) en struktuur (uitheemse en inheemse spesies bedekking) sal wees, sowel as die
effek op plantegroei bedekking (kroon en basalebedekking) en landbou produktiwiteit
(weidingkapasiteit), (2) die plantegroei prosesse te beskryf wat onderliggend deur die impakte
van indringing en verwydering van indringers veroorsaak word, en (3) die sukses van die
verwydering van indringers te evalueer deur die fasilitering van blote restorasie van ekologiese
struktuur en funksie en landbou produktiwiteit in voorheen ingedringde gebiede. My hipotese is
dat indringing ‘n aansienlike verandering in natuurlike plantegroeisamestelling en struktuur sal
veroorsaak, wat sal lei tot groter uitheemse spesiesrykheid en bedekking met minder inheemse
spesiesrykheid en bedekking, terwyl die verwydering van indringers sou lei tot minder
uitheemse spesie diversiteit en bedekking met 'n groter inheemse spesiesrykheid en bedekking.
Verder vermoed ek dat indringing die natuurlike kroon- en basalebedekking en
weidingkapasiteit sal verminder, terwyl die verwydering van indringers dit aansienlik sal
verhoog. Ten slotte voorspel ek dat plantegroei samestelling, uitheemse en inheemse
spesiesbedekking en -rykheid, kroon- en basalebedekking en weidingkapasiteit sou terugkeer na
voor-indringing status en vlakke binne vier tot ses jaar na die verwydering van indringers.
My resultate daarop dat die indringing van Prosopis (~ 15 persent kroonbedekking) en die
verwydering van indringers in swaar beweide Nama Karoo gebiede ‘n aansienlike verandering
in die gebied se natuurlike plantegroei samestelling toon, waar indringing gelei het tot groter
uitheemse spesiesbedekking en minder inheemse spesiesrykheid, terwyl die verwydering van
indringers lei tot minder uitheemse spesiesrykheid en groter inheemse spesiesrykheid en -
bedekking. Dit lyk egter of indringing geen effek op uitheemse spesiesrykheid en algehele
inheemse spesiesbedekking het nie. Die verwydering van indringers blyk om die spontane
herstel van indringerbedekking en inheemse spesiesrykheid binne vier tot ses jaar te fasiliteer,
maar nie spesiesamestelling, uitheemse spesiesrykheid of inheemse spesiesbedekking nie.
Benewens dui my resultate ook aan dat Prosopis indringing die natuurlike kroon- en
basalebedekking sowel as weidingskapasiteit verlaag, terwyl die verwydering van indringers,
selfs onder swaar beweiding, die bedekking aansienlik kan verhoog. Verwydering van
indringers lyk egter nie asof dit die herstel van die gebied se natuurlike kroon- en
basalebedekking en weidingkapasiteit na voor-indringing vlakke toe kan fasiliteer binne vier tot
ses jaar na die verwydering van indringers nie.
|
Page generated in 0.2398 seconds