• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 12
  • 2
  • Tagged with
  • 15
  • 15
  • 9
  • 9
  • 9
  • 5
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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 restoration of scrub invaded chalk grassland : a comparison of scrub clearance techniques (manual clearance and livestock browsing)

Oliver, Pauline January 2004 (has links)
The best way of dealing with the restoration of chalk grassland encroached by scrub is unclear and the subject of many debates. The traditional method is to clear the scrub primarily by manual methods of cutting the scrub and after clearance the land is left to regenerate naturally. More recently the development of using livestock to browse and gradually reduce the scrub is thought to be an alternative. However the effectiveness of either of these methods (Manual clearance or Livestock browsing) is questioned by many and some believe that once scrub has encroached, the soils beneath this will become too enriched to be able to support a chalk grassland flora. This thesis aimed to provide a better understanding by undertaking a five year investigative trial of the two restoration methods and comparing and examining the ability of these to successfully restore a chalk grassland habitat. To undertake this both methods were trailed on scrub invaded chalk grassland and changes in vascular plants and invertebrates were monitored throughout trial period. Areas of nonintervention scrub were also included to act as controls. Successful restoration was assessed by comparing the results from the trials with measurable vascular plant restoration targets that were identified and set from known chalk grasslands in favourable condition. Soil fertility within the trial area was also examined to determine if the soils were considered to fertile to support a chalk grassland flora and costs and practicalities of using ether method were recorded throughout enabling these to be taken into account. The results showed that differences in both the species richness and composition of vascular plants and spider and beetles invertebrate species occurred. Soil fertility was found to suitable to support chalk grassland plants and vascular plants species were identified as moving away from those associated with scrub into those associated with chalk grasslands. It was observed however that on the areas trailed using Manual clearance, an initial flush of ruderal species occurred after clearance, it was therefore concluded that for Manual clearance to be successful continued restoration management is required if these species are to be controlled. It was also observed that the areas trailed using Manual clearance were moving towards successful restoration quicker those trailed using Livestock browsing thus indicating that the rate of change is more gradual using Livestock browsing. This rate of change was also found to occur within the invertebrate beetles and spider communities. Species richness within the spider communities however decreased on the areas manually cleared. Costs of using the restoration methods showed that the use of Livestock browsing was five times more costly that using Manual clearance. However it was found that majority of Livestock browsing costs incurred through welfare and husbandry of the stock. Restoration using Manual clearance also involved using livestock once scrub had been cleared however the costs of these were born by a local grazier and thus did not show as a cost of restoration. It was concluded that if a grazier is not found then these costs would be incurred. Overall it is concluded that both Livestock browsing and Manual clearance have the ability to successfully restore a chalk grassland community but that this must be viewed as a long term objective. Restoration management is critical to continue after clearance until restoration targets have been met.
2

Factors determining location and species composition of wet grasslands in Southwest England /

Soest, Francien van. January 2005 (has links)
Univ., Diss.--Plymouth, 2002.
3

Community-level effects of fragmentation of the afromontane grassland in the escarpment region of Mpumalanga, South Africa

Kamffer, Dewald. January 2004 (has links)
Thesis (M.S.)--University of Pretoria, 2004. / Title from PDF t.p. (viewed Mar. 10, 2005). Includes bibliographical references.
4

Biodiversity of ants (Hymenoptera: Formicidae) in restored grasslands of different ages

Phipps, Sarah J. January 2006 (has links)
Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 27, 2007) Includes bibliographical references.
5

A vegetation survey and mapping of the woodbush granite grassland in the Limpopo Province, South Africa

Matjie, Mapula Rose January 2019 (has links)
Thesis (M. Sc. (Botany)) -- University of Limpopo, 2019 / The Woodbush Granite Grassland (WGG) is the most threatened vegetation type in Limpopo Province of South Africa. However, it has a high conservation value, because few examples of this vegetation type remain in southern Africa. Unfortunately, a large part of it is not formally conserved, making this the vegetation type most urgently in need of conservation. The study aimed at mapping transformation of the WGG, identifying species of conservation importance, and providing a management plan required for maintenance of the WGG. The objectives of the study included compiling a transformation map for the WGG, which also involved describing the remaining patches of the WGG that are in a natural or near-natural state. It also provides information on species of conservation importance, medicinal plants and threats to the WGG. On the four main study sites (Iron Crown Grassland, Haenertsburg Grassland, Ebenezer Dam Nature Reserve Grassland, and Ebenezer Dam Perimeter Grassland), quadratic plots were randomly set with a size of 25 x 25 m, and subplots of 1 x 1 m. Vegetation mapping was done during summer and winter. At each plot data was collected on all plant species occurring within the quadrat. A cover score was assigned to each plant species. A modified Braun-Blanquet data collection sheet was employed to obtain baseline data. For transformation mapping GeoTerra Image (GTI), land cover data were extracted for the WGG, using the modelled boundary as a mask, with 5 categories of transformation defined. Of the surveyed sites, the Ebenezer Dam Nature Reserve Grassland has the highest number of species, while the Haenertsburg Grassland contained the most endemic species of conservation importance. Rare species such as the Aloe zebrina, which does not occur in any formally protected area, and medicinal plants such as Athrixia phylicoides, occur on the WGG. All sites have importance with regard to WGG conservation. Identified threats include the spread of alien invasive plants, uncontrolled collection of medicinal plants, urban development, and poorly timed anthropogenic fire. vi The WGG underwent transformation to other land classes. Grassland clearing for plantations and cultivation were the main causal factors behind the observed WGG losses, with a total of 55.25% transformed. Transformation by afforestation is considered irreversible. It is concluded that the WGG is of conservation importance, and that some of it has been transformed to exotic timber plantations. The grassland is under various threats; therefore it is recommended that: (1) The proposed management plan provided in this study be adopted, (2) further research on the WGG be done on medicinal plants, (3) phytosociological and floristic studies be conducted and, (4) the effects of fire and alien invasive plant species on the grassland be investigated.
6

Comparison of IKONOS derived vegetation index and LiDar derived canopy height model for grassland management

Parker, Gary. Dong, Pinliang, January 2009 (has links)
Thesis (M.S.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.
7

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.
8

An investigation into the problems of ineffective control of invasive plants in selected areas of South Africa : a case study of Campuloclinium macrocephalum (pompom weed)

Mashiloane, William Tlokotse 09 1900 (has links)
Interference of natural environment by invasive plants is a global concern. In South Africa and in particular Gauteng Province, interference of natural land by invasive plants that originated from other countries has been an endemic problem. These invasive plants pose a threat to biodiversity as a result of its wild and wide dispersion rate where it spreads into neighbouring Provinces such as Mpumalanga, Limpopo, North West and the Free State. Pompom weed is aggressive to control and can spread by means of both wind and water. This research project investigates problems associated with ineffective control of invasive plants in general and pompom weed in particular. State organs, Non Governmental Organisations (NGOs) and farming communities were identified as relevant respondents in this study. Three hundred (300) validated questionnaires were distributed to these stakeholders and 286 were adequately completed and received. These were analysed and the data interpreted. Results obtained showed that lack of coordination and teamwork from all stakeholders are responsible for ineffective control of invasive plants in the country. The use of biological control was recommended for the control and eradication of the invasive plants. / Environmental Sciences / M.A. (Environmental Management)
9

Remote sensing of leaf area index in Savannah grass using inversion of radiative transfer model on Landsat 8 imagery: case study Mpumalanga, South Africa

Masemola, Cecilia Ramakgahlele 03 1900 (has links)
Savannahs regulate an agro-ecosystem crucial for the production of domestic livestock, one of the main sources of income worldwide as well as in South African rural communities. Nevertheless, globally these ecosystem functions are threatened by intense human exploitation, inappropriate land use and environmental changes. Leaf area index (LAI) defined as one half the total green leaf area per unit ground surface area, is an inventory of the plant green leaves that defines the actual size of the interface between the vegetation and the atmosphere. Thus, LAI spatial data could serve as an indicator of rangeland productivity. Consequently, the accurate and rapid estimation of LAI is a key requirement for farmers and policy makers to devise sustainable management strategies for rangeland resources. In this study, the main focus was to assess the utility and the accuracy of the PROSAILH radiative transfer model (RTM) to estimate LAI in the South African rangeland on the recently launched Landsat 8 sensor data. The Landsat 8 sensor has been a promising sensor for estimating grassland LAI as compared to its predecessors Landsat 5 to 7 sensors because of its increased radiometric resolution. For this purpose, two PROSAIL inversion methods and semi- empirical methods such as Normalized difference vegetation index (NDVI) were utilized to estimate LAI. The results showed that physically based approaches surpassed empirical approach with highest accuracy yielded by artificial neural network (ANN) inversion approach (RMSE=0.138), in contrast to the Look-Up Table (LUT) approach (RMSE=0.265). In conclusion, the results of this study proved that PROSAIL RTM approach on Landsat 8 data could be utilized to accurately estimate LAI at regional scale which could aid in rapid assessment and monitoring of the rangeland resources. / Environmental Sciences / M. Sc. (Environmental Science)
10

The mesofilter concept and biodiversity conservation in Afro-montane grasslands

Crous, Casparus Johannes 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Conservation planners use many traditional biodiversity conservation tools to help alleviate the global biodiversity crisis. However, ongoing biodiversity loss has stimulated the development of new and improved methods for conserving biodiversity. One such new conservation tool is the mesofilter approach. Mesofilters are biotic or abiotic ecosystem elements which are critical to the well-being of many species, and therefore could help to explain spatial heterogeneity in species across a landscape. It is also complementary to more traditionally used concepts such as coarse- and fine-filter conservation concepts. Applying the mesofilter approach in protected area, conservancy, or land-sparing design and management, could optimise biodiversity conservation in a rapidly developing world. For example, the timber industry has been pro-active in its approach to lessen biodiversity loss, by optimising design and management of the plantation matrix through ecological networks. Here, I explore the use of mesofilters within highly threatened remnant Afro-montane grasslands in KwaZulu-Natal, South Africa, to optimise biodiversity conservation planning for such landscapes. As per anecdotal evidence, I used rockiness in the landscape as a possible driver of species richness and species assemblage variability at the meso-scale, using a multi-taxon and multi-trophic approach. In this montane landscape, I also examined the effect of elevation on spatial heterogeneity of taxa. I further examined the functional responses of taxa to rockiness in the landscape. Rockiness in the landscape significantly influenced the species richness and assemblage structure of three key grassland taxa: flora, butterflies, and grasshoppers. I showed that for plants, this response was due to growth forms such as geophytes and perennial grasses that were more closely associated with rockiness, and therefore the main contributors to observed differences in the dispersion patterns of flora. Grasshoppers were not necessarily responding to higher rock exposure per se, but rather towards the environmental conditions created by rockiness within the landscape, such as lower vegetation density. For butterflies, certain behavioural traits, such as resting, territorial behaviour and/or mate-locating behaviour, were more typical in areas of higher rock exposure. This suggested that rocks are a definite habitat resource to certain butterflies. Overall, this finding where an abiotic surrogate is representative of key taxa in an ecosystem is interesting, as cross-taxon surrogacy has been shown to be stronger than surrogates based on environmental data. Furthermore, taxa responded functionally to rockiness in the landscape. This thesis therefore supports the idea that environmental surrogates are indeed useful for biodiversity conservation planning. Furthermore, ecosystems can potentially have many attributes or features that would be of conservation interest, and delineating a set of mesofilters is a useful way of expressing particular attributes to be used in wildlife conservation evaluation. The concept of the mesofilter as a practical biodiversity conservation tool is therefore validated here. I also argue the importance of habitat heterogeneity for biodiversity conservation planning in this montane grassland landscape. The potential for optimising the design of landscape configurations such as ecological networks, through information obtained from the mesofilter, is emphasised. We can safely add another tool in the biodiversity conservation toolbox of this Afro-montane grassland ecosystem. / AFRIKAANSE OPSOMMING: Bewaringbeplanners gebruik tans baie tradisionele biodiversiteit-bewarings metodes om die huidige biodiversiteits krisis te help verlig. Tog, die huidige voortdurende verliese in biodiversiteit wêreldwyd, vra na nuwer en verbeterde metodes van biodiversiteit-bewaring. Een so ‘n nuwe bewaring metode, is die mesofilter. Mesofilters is biotiese of abiotiese ekosisteem elemente wat kritiek is tot die welstand van spesies, en daarom veral waardevol is om variasie in spesies verspreiding in ‘n landskap te help verduidelik. Daarby is die mesofilter konsep ook komplementêr tot meer tradisioneel gebruike bewaringskonsepte, soos fyn-filter en breë-filter konsepte. Deur die mesofilter benadering toe te pas in die ontwerp en bestuur van beskermde areas, bewaareas, of land-spaar initiatiewe, kan ons biodiversiteitbewaring in ‘n vining ontwikkelende wêreld optimaliseer. Byvoorbeeld, die bosbou industrie is pro-aktief in hul benadering om biodiversiteit verliese te verminder, deur optimalisering van die ontwerp en bestuur van ekologiese netwerke in die plantasiematriks. In hierdie tesis, ondersoek ek die gebruik van mesofilters in hoogs bedreigde oorblyfels Afrikaberg grasvelde in KwaZulu-Natal, Suid-Afrika, om die bewaringsbeplanning van dié gebiede te optimaliseer. Vanaf anekdotiese bewyse, het ek spesifiek gebruik gemaak van klipperigheid in die landskap as ‘n moontlike drywer van spesies-rykheid en spesies-samestelling variasie by ‘n meso-skaal, deur ‘n multi-takson en multi-trofiese benadering. In hierdie berglandskap, het ek ook die effek van hoogte bo seevlak op ruimtelike verspreiding van taksa bestudeer. Verder het ek ook gekyk na die funksionele reaksie van taksa tot klipperigheid in die landskap. Klipperigheid in die landskap het ‘n beduidende invloed gehad op spesies-rykheid en spesiessamestelling van drie sleutel grasveld taksa: plante, skoenlappers, en springkane. Ek wys dat vir plante, hierdie reaksie as gevolg was van spesifieke plantgroeivorme, soos bolplante en meerjarige grasse, se noue verband met klipperigheid, en daarom, dat hierdie groepe die hoof bydraers is tot gesiene variasie in plantspesies verspreiding in die landskap. Vir springkane, was hierdie reaksie nie noodwendig omdat hulle die klippe self gebruik het nie, maar meer as gevolg van die omgewingskondisies geskep deur verhoogde klipperigheid in die landskap, soos laer plantegroei digtheid. Vir skoenlappers, was hierdie reaksie tot klippe as gevolg van sekere gedragskaraktereienskappe, soos rus op klippe, gebied beskerming en/of paarmaat soektog, wat tipies meer gesien was in klipperige omgewings. Dit dui daarop dat klippe ‘n definitiewe habitat hulpbron is vir sekere skoenlappers. Oor die algemeen is hierdie bevinding, waar abiotiese surrogate verteenwoordig is van drie sleutel taksa in ‘n ekosisteem, baie interessant, siende dat tussen-takson surrogate soms gesien word as sterker as surrogate gebaseer op omgewingsdata. Verder, taksa het funksioneel gereageer teenoor die klippe in die landskap. Hierdie tesis ondersteun dus die idee dat omgewingssurrogate wel nuttig is vir biodiversiteit-bewaring beplanning. Ekosisteme mag vele potensiele elemente van bewarings belang bevat, maar om sulke elemente as ‘n stel mesofilters te klassifiseer, is ‘n nuttige manier om spesifieke elemente te gebruik in natuurbewarings evaluasie initiatiewe. Gevolglik word die konsep van die mesofilter as ‘n praktiese biodiversiteit-bewaring gereedskapstuk hier bevestig. Ek beredeneer ook die belangrikheid van habitat heterogeniteit vir biodiversiteit-bewaring van hierdie berggrasveld landskap. Die potensiaal vir optimalisering van ontwerp en bestuur van landskap konfigurasies, soos ekologiese netwerke, word beklemtoon. Ons kan met veiligheid nog ‘n gereedskapstuk plaas in die biodiversiteitbewarings gereedskapkis van hierdie Afrikaberg grasveld ekosisteem.

Page generated in 0.1418 seconds