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  • 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.
11

Alien grass invasion of Renosterveld : influence of soil variable gradients

Muhl, Sara Ann 12 1900 (has links)
Thesis (MScConsEcol (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / This thesis examines the role of agricultural activity in the process of invasion of west coast renosterveld fragments by annual alien grass species. This highly endangered vegetation type has less than 5% remaining, it is vital to understand the mechanisms allowing invasion of annual alien grasses in order to effectively prevent the loss of the many rare and endemic species found in west coast renosterveld. This study was divided into three major components. Firstly the distribution of indigenous and alien plant species in relation to fence lines, separating active agricultural fields from untransformed vegetation, was described. Regression analysis was used to test for relationships between distances from agricultural fields and soil physical and chemical characteristics in natural vegetation. Cover by annual alien invasive grasses in untransformed vegetation decreased significantly with distance away from agricultural land. Secondly alien and indigenous grass seed banks were sampled along the transects, at the same sites, in order to establish whether the seed banks correlated with above ground cover. Results varied among sites and seed banks were correlated with the vegetation cover at only one site. It appears that there are a multitude of factors determining the distribution of annual alien grass cover. Thirdly a greenhouse experiment established the role that nitrogen plays in the success of the alien grass Avena fatua. This species was grown in competition with three indigenous species, an annual forb (Dimorphotheca pluvialis), a geophyte (Oxalis purpurea) and an indigenous perennial grass (Tribolium uniolae) at three levels of soil nitrogen. The geophyte was largely unaffected, while growth of the annual and indigenous perennial grasses was negatively affected by competition with A. fatua. Nitrogen did not seem to affect competitive interactions. Management of these renosterveld patches, in order to conserve them effectively, will require a multi-faceted approach, including prevention of further invasion and removal of invasive grasses already present.
12

Comparative impacts of fragmentation on birds in two bioregions in a biodiversity hotspot, the Cape Floristic Region

Kieck, Marius Burger 03 1900 (has links)
Thesis (MScConsEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2009. / Habitat loss and fragmentation are two of the most pressing threats to biodiversity. Avifaunal diversity and integrity is under immense pressure from these two processes. We have made major advances in our understanding of avifaunal responses to habitat fragmentation, but mostly focus on either fragment scale and/or landscape scale influences of fragmentation on birds. A more comprehensive approach to assessing the impacts of fragmentation was used in this study. The avifaunas of two different geographical regions and bioregions were surveyed and a multiscale analysis of avifaunal responses to fragmentation was attempted. The study sites include the West Coast and East Coast Renosterveld Bioregions in the Cape Floristic Region, South Africa. Assemblage shifts, feeding guild compositional changes, species abundance variation and species persistence were examined at the three spatial scales. Time- and distance-restricted point counts were used to document birds that were directly dependent on the habitat fragments. Forty fragments were selected in each bioregion and a once-off snapshot of the avifaunal richness and diversity was obtained. Results indicate that the avifauna of the two bioregions responded differently to habitat fragmentation. In the East Coast Renosterveld Bioregion, the assemblages, guild composition and species abundances were most accurately predicted by landscape configuration. An assemblage shift occurred at 20 ha fragment area, compared to the 50 ha fragment area threshold of the West Coast Renosterveld Bioregion’s avifauna composition. In the West Coast Renosterveld Bioregion, fragment area was the better predictor of assemblage, guild composition and species abundances. However in both bioregions, the persistence of common species was equally sensitive to area and landscape scale effects.
13

Attitudes and behaviour of landholders towards the conservation of Overberg Coastal Renosterveld, a threatened vegetation type in the Cape Floral Kingdom

Winter, Susan Jean 12 1900 (has links)
Thesis (MScConsEcol) -- Stellenbosch University, 2003. / ENGLISH ABSTRACT: This thesis describes the findings of a survey to investigate the attitudes and behaviour of private landholders towards the conservation of Overberg Coastal Renosterveld, a highly endangered grassy-shrubland of the Cape Floral Region (CFR) lowlands, now 94% transformed. Personal interviews were conducted with 36 farmers in the Overberg region of the Western Cape, by administering a questionnaire. The following aspects were quantitatively described using the Statistical Package for Social Scientists (SPSS): Renosterveld management and utilisation behaviour, perceived value of Overberg Coastal Renosterveld; landholder knowledge of its conservation importance and willingness to conserve it. Attitudes towards incentives for conservation; conservancies; and the provincial conservation authorities were also investigated. Willingness to conserve was explored further using SPSS cross-tabulation analyses. It was found that farmers who were more willing to conserve were younger, did not necessarily have a better education, and owned larger farms (> 500 ha) with a greater amount of remnant renosterveld (> 300 ha) than farmers less willing to conserve. Attitudes towards Overberg Coastal Renosterveld were largely negative, due to certain associated plants and animals which are problems for farmers, and because it is not economically advantageous to retain it. However, provision of incentives (of which assistance with fencing and land management was most attractive) and increased extension support will provide practical positive inducements for conservation. There is also a need for more landholder education regarding the scarcity of coastal renosterveld to prevent transformation of remaining fragments. The second component of the study aimed to construct a user-friendly index to measure the conservation attitudes of landholders towards conserving Overberg Coastal Renosterveld. An interative item analysis was executed on the data, using Spearman Rank Order correlations and Cronbach's Alpha. Results yielded an index with two dimensions and a Cronbach Alpha co-efficient of 0.67. The dimensions or components of conservation attitude towards renosterveld included: (i) a landholders' perception of the perceived benefit of Overberg Coastal Renosterveld; and (ii) their willingness to conserve it. The mean conservation attitude score was 0.6 (± 0.03), indicating that landholder attitudes were generally sympathetic towards renosterveld conservation. This suggests that while many landholders do not place a high value on Overberg Coastal Renosterveld due to its low agricultural value, their willingness to conserve it is in some cases higher than expected, which possibly explains the above-average mean conservation attitude score. An analysis of variance showed that the following variables were significantly, positively correlated with conservation attitude: (i) area of Overberg Coastal Renosterveld; (ii) landholder environmental group membership status; (iii) presence of ecotourism activities on the property; and (iv) how long the property had been in the owner's family. The intended application of the index is that index scores (amenable for use in a Geographical Information System database) can assist conservation practitioners in deciding where resources should be allocated, on the assumption that high-scoring individuals are more likely to want to take part in conservation initiatives. / AFRIKAANSE OPSOMMING: Hierdie proefskrif beskryf die bevindings van 'n opname waarin die houdings en gedrag van private grondeienaars ten opsigte van Overberg Kustelike Renosterveld ondersoek word. Altesaam 94% van die oorspronklike renosterveld, 'n hoogs bedreigde, grasagtige struikveld in die laaglande van die Kaapse Planteryk (KPR) , is reeds getransformeer en verander. Persoonlike onderhoude is met 36 boere in die Overbergstreek van die Wes-Kaap gevoer en 'n vraelys is aan hulle gestel. Die "Statistical Package for Social Scientists" (SPSS) is gebruik om die volgende aspekte kwantitatief te beskryf: die bestuur en benutting van Overberg Kustelike Renosterveld; die waarde wat toegeskryf word aan hierdie renosterveld; asook grondeienaars se kennis oor die bewaringsbelang van Overberg Kustelike Renosterveld en hul bereidwilligheid om dit te bewaar. Houdings jeens aansporingsmiddele om bewaring te bevorder, bewareas en die provinsiale bewaringsowerhede is ook ondersoek. Private grondeienaars se bereidwilligheid om betrokke te raak by bewaringswerk is verder ondersoek deur gebruik te maak van die SPSS-kruistabelleringsanalise. In vergelyking met boere wat nie bewaring ondersteun nie, is gevind dat die meer bewaringsgesinde boere jonger is, nie noodwendig 'n beter opvoeding het nie, en groter plase (>500 ha) besit waarop meer brokkies oorblywende Overberg Kustelike Renosterveld (>300 ha) gevind word. Grondeienaars se houding jeens Overberg Kustelike Renosterveld was grootliks negatief. Dit is as gevolg van sekere verwante plante en diere wat deur boere as probleme ervaar word, en omdat dit nie ekonomies lewensvatbaar is om renosterveld te behou nie. Die beskikbaarheidstelling van aansporingsmiddele (waarvan hulpverlening met omheinings en grondbestuur die aantreklikste was), en 'n toename in landbou-voorligting is egter praktiese en positiewe dryfvere wat bewaring kan bevorder. Daar is ook 'n behoefte vir meer opvoeding van grondeienaars oor aspekte soos die skaarsheid van Overberg Kustelike Renosterveld, sodat die verdere transformasie van oorblywende fragmente voorkom kan word. Die tweede gedeelte van die studie was daarop gemik om 'n gebruikersvriendelike indeks te ontwikkel waarmee die bewaringsgesindheid van grondeienaars teenoor die bewaring van renosterveld gemeet kan word. Deur gebruik te maak van Spearman se rangorde-korrelasies en Cronbach se Alpha is die data aan 'n herhalende item-analise onderwerp. Die resultate het 'n indeks met twee dimensies en 'n Cronbach Alpha-koëffisiënt van 0.67 gelewer. Die dimensies of komponente van bewaringsgesindheid jeens renosterveld het onder meer ingesluit: i) 'n grondeienaar se opvatting oor die moontlike voordeel van Overberg Kustelike Renosterveld en ii) sy/haar bereidwilligheid om dit bewaar. Die gemiddelde telling vir bewaringsgesindheid was 0.6 (± 0.03), wat in die algemeen 'n simpatieke houding jeens die bewaring van Overberg Kustelike Renosterveld onder grondeienaars aandui. Hiervolgens blyk dit dat alhoewel heelwat grondeienaars weens die lae landbouwaarde van renosterveld nie 'n hoë waarde op hierdie plantegroeitipe plaas nie, hulle bereidwilligheid om dit te bewaar soms verwagtinge oortref. Dit is dalk 'n moontlike verklaring vir die bogemiddelde gemiddelde bewaringsgesindheidtelling. 'n Variansie-analise het 'n noemenswaardige, positiewe korrelasie met bewaringsgesindheid ten opsigte van die volgende veranderlikes getoon: i) area van Overberg Kustelike Renosterveld; ii) die grondeienaar se moontlike lidmaatskap van 'n bewaringsgroep; iii) die teenwoordigheid van ekotoerisme-bedrywighede op die eiendom; en iv) die tydperk wat die eiendom al in besit van die grondeienaar se familie is. Die voorgestelde gebruik van die indeks is toepaslik omdat die indeks-tellings (wat vir gebruik in 'n Geografiese Inligtingstelsel databasis aangepas kan word) bewaringslui kan help met besluite random die toekenning van hulpbronne. Die aanname is dat individuele grondeienaars wie hoë tellings aangeteken het, met alle waarskynlikheid meer geredelik aan bewaringsinisiatiewe sal wil deelneem.

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