Harms produced by nuclear energy include the accident risks of population displacement, deaths, cancers, genetic, teratogenetic (affecting embryo and foetus) and psycho-social effects; increased radiation exposure to workers, locals and future generations from nuclear plants, uranium mines and waste storage facilities; thermal and toxic tailings pollution from nuclear plants and uranium mines; and other unknown long-term effects of increasing levels of background radiation. Historically, most greens have opposed nuclear energy alongside nuclear weapons. Recently, however, significant green spokespeople have combined with industry and governments in emphasising the need for nuclear energy in response to climate change. Based upon my experiences in the struggle against the Hinkley C nuclear power plant in Somerset, UK, this thesis contests the dominant framings of the debate. I suggest that arguments for nuclear energy are made possible by reductive understandings of the issue making it difficult to apprehend the significance of harms reinforced by nuclear energy. Taking an ecological approach I show how dominant discourses presuppose a hierarchical separation of science/politics, reinforced by and reinforcing the separation of nature/culture. These hierarchical separations depoliticise and naturalise harms produced by both nuclear energy and dominant forms of social organisation. As a result, these harms are difficult to communicate and contest as relevant to the discussion of our common futures. In this thesis I argue that we might more effectively convey the significance of these harms if we articulate them as injustices. Building upon the theory and practice of justice and liberation struggles I develop a heuristic framework for articulating injustices based around three intersecting images of politics as distribution, recognition and representation. I suggest articulating injustices of nuclear energy as i) the deprivation of basic necessities due to unequal distributions of burdens as well as goods; ii) the disrespect for ecological integrity due to desire for control of inevitable unpredictability in interaction; and iii) the denial of multiple authorities through monopolisation of rational speech and action and disengaged forms of knowledge production. Expressing harms of nuclear energy by way of this three-fold articulation of injustices politicises nuclear energy, climate change, and the dominant forms of social organisation, opening these up to political contestation to more effectively take ‘all affected’ into account before we reconsider how we might live together.

Digital technologies have for many years been acclaimed as tools that hold the power to transform learning, yet educational research has so far failed to demonstrate the transformative effects of these digital technologies on learning outcomes (Cuban, 2001; Price and Kirkwood, 2011). Some research has even gone so far as to question this underlying assumption regarding digital technologies ability to transform education, suggesting that they do not in fact have any inherently positive benefits for learning, and that perceived benefits are actually artefacts produced by other factors (Means et al, 2009). Several potential causes have been proposed for the slow progress in educational technology, including lack of time for staff development, unsuitability of technologies, and cultural barriers within institutions (Laurillard, 2012a). A fourth potential cause may lie with the lack of theory to explain technologies themselves (Oliver, 2013). Different theoretical perspectives have been proposed as a way to enhance our understanding of technologies, with one potential candidate being the theory of affordances. The theory of affordances has been used extensively within many fields, including educational technology, but remains a divisive and often under-defined term (Hammond, 2010). This thesis argues that this may in part be due to its distortion through adoption in multiple disciplines, and its popular description as the ‘action possibilities’ presented by an object or scenario, something not present in the theory’s original conception. It is suggested that a return to the original theory of affordances as proposed by Gibson (1979), which attempted to explain how individuals derive meaning from the world around them, returns clarity to the theory. A particular focus on the underexplored aspects of intention and invariant, together with a re-appreciation of what it means to apply the theory of affordances to digital environments, to digital spaces and places, provides a way of thinking about affordance that arguably can be applied more constructively to the effective use of technology in education. A design-based research approach was taken in order to research the original concept of affordance, and its key components of intention and invariant, within learning scenarios supported by digital technologies. Design-based research is an evolving methodology, with no strict definition, but it has shown promise in both the design and the research of technology-enhanced learning environments (Wang and Hannafin, 2005). A pilot phase at secondary school level demonstrated the potential for the approach; multiple iterations at a higher education level developed and enriched these findings into a stable model for the alignment of digital technologies with a particular pedagogical scenario. Findings suggest that affordances can be used to ‘explain’ educational technology, if the concept is broadened to include the wider ecology of learning; digital technologies not only as tools, but also as places. Extending the notion of affordances from ‘action possibilities’ to ‘transaction possibilities’ gives agency to both learner and technology, and recognises the important contribution of the digital environment to the learner experience. A specific design framework is offered which uses this redefinition of affordances as a design tool to align an authentic learning scenario with the digital technologies that have the potential to support that learning scenario. A generic design methodology is proposed, based on this framework, which has the potential to align pedagogy and technology using this updated definition of affordance. To close, some thoughts on the value of the design-based research approach are discussed.

More than half of the world’s population lives in urban areas and this figure is expected to increase. The worldwide trend is in the direction of urbanization. Building sustainable cities is one of the sustainable development goals (SDGs) initiated by United Nations Sustainable Development Solutions Network. In the anthropocene of human induced climate change, what makes a city sustainable? This paper takes Beijing as the case study, uses building smart infrastructures and lowering ecological footprints as the main thread, uses a mixed research method of questionnaires, interviews and site survey, and discusses four aspects -- transportation, waste management, green spaces and energy saving buildings -- from employees’ perspectives of how to a build a sustainable city. This paper also discusses the relations between smart infrastructure and the resilience of a city, and relations between lowering ecological footprints and a green city, and draws a conclusion that a resilient and green city is a sustainable city. We can build a sustainable Beijing only through vigorously developed public transportation, well managed waste, the development of diversified green spaces, and buildings that efficiently use natural resources as energy supplies.

The term Traditional Ecological Knowledge (TEK) is generally interpreted as the knowledge held by Indigenous communities about their environment and the cultural frameworks in which such knowledge is transmitted. There is no universally accepted definition of TEK and interpretations can vary between Western and Indigenous lenses. TEK as an academic field has gained a vast literature base; however, there is a dearth of literature in the wildlife field that expresses TEK through an Indigenous lens. There has been growing attention on TEK in the wildlife profession, warranting further exploration of how Indigenous and Western scientific paradigms may be used together in natural resources conservation. Herein, I present my doctoral research, where I focused on a culturally sensitive approach in the pursuit of TEK studies. I conducted interdisciplinary research with the Yurok Tribe of northwestern California in two parts: (1) a human dimensions study where I interviewed Yurok people regarding TEK and their relationship with wildlife and (2) a wildlife survey on Yurok ancestral lands where I used genetic analyses of scats as a noninvasive method for determining species presence and diet. In addition, I developed a synthesis document regarding historical aspects of Indian Country in the United States and philosophical contexts of TEK as science to facilitate dialogue regarding cultural sensitivity in wildlife research with a TEK component. During an internship with the National Park Service (NPS), I developed a guidance document to provide resources regarding TEK in wildlife conservation and a case study detailing how I navigated my doctoral research. My dissertation consists of five manuscripts, each formatted for a specific journal or the NPS.

No description available.

Earth mean surface temperature has increased by 1 °C since the industrial revolution, and this has already had considerable effects on animal and plant species. Ecological responses to the warming climate – often facilitated via phenotypic plasticity – are ubiquitous. However, even though evolution can occur rapidly there are only few examples of genetic adaptation to climate change. In my thesis, I used a near-natural system to study if and how organisms have adapted to 30 years of warming, and how this has affected competitive species interactions. I investigated Baltic Sea populations of the aquatic snails Galba truncatula and Theodoxus fluviatilis, which had been subjected to cooling water discharge from power plants, resulting in water temperatures 4 to 10 °C higher than in the surrounding sea. G. truncatula had high upper thermal limits and large acclimation potential. This plasticity may have helped the species to survive under the new conditions, allowing evolution through natural selection to take place. I found that the populations of the two thermal origins had diverged in SNP markers associated with warmer temperature, whereas divergence in selectively neutral markers was mainly related to geographical distance. Adaptation occurred from standing genetic variation, emphasizing the importance of genetic diversity and population size in enabling the persistence of populations. Changes in thermal sensitivity of growth and survival were subtle yet significant, and complied with theoretical models of thermal adaptation in ectotherms. At the community level, pre-adaptation to warmer conditions aided the native T. fluviatilis when competing with the alien Potamopyrgus antipodarum. However, interspecific competition limited the snails most in those traits favored under warming, highlighting the challenge of adapting to different selecting forces during global change. The persistence of species and populations under climate change depends on several factors - plasticity allowing for initial survival, evolvability in allowing the genetic changes, and species interactions affecting the new ecological niches. The results of my thesis indicate that persistence under climate change is possible when these factors align, but the relative roles of ecology and plasticity may explain why there are so few observed instances of evolution in response to climate change.

Thesis (MPhil (Religion and Culture) (Practical Theology and Missiology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Green spirituality as found in popular media such as films can be used to develop an ecological ethic in theological reflection and praxis and serve as a platform in a multi-sectoral and multi-pronged response to the ecological crisis. By examining the films Avatar, Emerald Forest, Dances with Wolves, The Day the Earth Stood Still, and the animated films of Hayao Miyazaki, ecological and spiritual themes can be drawn from the text and applied as contemporary examples of 'green spirituality'. In the first chapter I articulate and describe the research problem, whether green spirituality is found in popular media and if so, could it be used to develop an ecological ethic in theological reflection and praxis. This discussion includes the aims of the study and the description of the research methodology used in the study, as well as the delimitations of the study. In the second chapter I define some of the key terms: spirituality, green spirituality, ecological crisis, ecological ethic, and present a brief overview of the theoretical concepts, ecofeminism, and deep ecology, within whose context this study takes place. This chapter will include the literature survey that informs this study. In the third chapter I present the data, namely the green spirituality found in media such as the films Avatar, Emerald Forest, Dances with Wolves, The Day the Earth Stood Still, and the films of Hayao Miyazaki. The films are summarised and evaluated according to the green spirituality and ecological themes presented. Four signifiers are identified to be present in the films: visual, cognitive, spiritual and communal. In the fourth chapter I present my interpretation of the data, as informed by scholarly sources, and also describe the relevance of the data in the faith traditions and the positions taken by faith traditions with regards to the ecological crisis. I also present some practical suggestions for responses in theological praxis. In chapter five I present my conclusion. / AFRIKAANSE OPSOMMING: 'Groen spiritualiteit', soos gevind in populêre media soos films kan gebruik word om 'n ekologiese etiek in teologiese refleksie en praxis te ontwikkel en kan dien as 'n platform in 'n multi-sektorale en multi-fokus reaksie op die ekologiese krisis. Deur die films Avatar, Emerald Forest, Dances with Wolves, The Day the Earth Stood Still, en die films van Hayao Miyazaki te ondersoek, kan ekologiese en spirituele temas onderskei word en toegepas word as kontemporêre voorbeelde van 'groen spiritualiteit'. In die eerste hoofstuk noem en beskryf ek die navorsingsprobleem, naamlik die moontlikheid om groen spiritualiteit wat te vinde is in die populêre media soos films, te gebruik om 'n ekologiese etiek te ontwikkel in teologiese refleksie en praxis. Hierdie bespreking sluit die doelwitte en beperkings van die studie in en beskryf die navorsingsmetodologie wat gebruik word. In die tweede hoofstuk gee ek 'n paar definisies van sleutel begrippe: spiritualiteit, groen spiritualiteit, ekologiese krisis, ekologiese etiek, sowel as 'n kort oorsig van die teoretiese konsepte soos ekofeminisme en 'deep ecology' waarin die studie omraam. Hier sluit ek in wat ek verstaan onder die sleutel konsepte om die studie te definieër binne die raamwerk van die navorsing. Hierdie hoofstuk sluit die literatuur oorsig in. In die derde hoofstuk gee ek die data, naamlik die groen spiritualiteit gevind in populêre media soos die films Avatar, Emerald Forest, Dances with Wolves, The Day the Earth Stood Still, en die films van Hayao Miyazaki. Die films word opgesom en ge-evalueer volgens die groen spiritualiteit en ekologiese temas teenwoordig. In die vierde hoofstuk beskryf ek my interpretasie van die data, soos voorgestel ook deur geleerde bronne en die geloofstradisies. Ek maak ook 'n paar praktiese voorstelle in teologiese praxis. In hoofstuk vyf gee ek my gevolgtrekking.

Thesis (PhD (Biochemistry))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In the last decade a need arose to find a theoretical framework capable of gaining a quantitative understanding of ecosystems. Control analysis was proposed as a suitable candidate for the analysis of ecosystems with various theoretical applications being developed, i.e. trophic control analysis (TCA) and ecological control analysis (ECA). We set out to test the latter approach through experimental means by applying techniques akin to enzyme kinetics of biochemistry on a simple ecosystem between Saccharomyces cerevisiae and Gluconobacter oxydans. However, this exercise was far more complex than we originally expected due to the extra metabolic activities presented by both organisms. Nevertheless, we derived suitable kinetic equations to describe the metabolic behaviour of both organisms, with regards to the activities of interest to us, from pure culture experiments. We developed new techniques to determine ethanol and oxygen sensitivity of G. oxydans based on its obligately aerobic nature. These parameters were then used to build a simple kinetic model and a more complex model incorporating oxygen limited metabolism we observed at higher cell densities of G. oxydans. Our models could predict both situations satisfactorily for pure cultures and especially the more complex model could describe the lack of linearity observed between metabolic activity and cell density at higher cell densities of G. oxydans. Mixed populations of S. cerevisiae and G. oxydans reached quasi-steady states in terms of ethanol concentration and acetate flux, which was a positive indication for the application of control analysis on the ecosystem. However, the theoretical models based on parameters derived from pure culture experiments did not predict mixed culture steady states accurately. Careful analysis showed that these parameters were mostly under-estimated for G. oxydans and overestimated for S. cerevisiae. Hence, we calculated the kinetic parameters for mixed population assays directly from the experimental data obtained from mixed cultures. We could calculate the control coefficients directly from the experimental data of mixed population studies and compare it with those from theoretical models based on 3 different parameter sets. Our analysis showed that the yeast had all the control over the acetate flux while control over the steady-state ethanol was shared. The strength of our approach lies in designing our experiments with a control analysis approach in mind, but we have also shown that even for simple ecosystems this approach is non-trivial. Despite the various experimental challenges, this approach was very rewarding due to the extra information obtained especially regarding control structure with regards to the steady-state ethanol concentration. / AFRIKAANSE OPSOMMING: In die afgelope dekade het daar ’n behoefte ontstaan na ‘n teoretiese raamwerk om tot ‘n kwantitatiewe begrip van ekosisteme te kom. As kandidaat vir so tipe raamwerk is kontrole analise voorgestel gepaardgaande met die ontwikkeling van verskeie teoretiese toepassings, i.e. trofiese kontrole analise en ekologiese kontrole analise. In hierdie tesis het ons laasgenoemde aanslag eksperimenteel ondersoek op ‘n eenvoudige ekosisteem, tussen Saccharomyces cerevisiae en Gluconobacter oxydans, deur gebruik te maak van tegnieke vanuit ensiemkinetika van biochemie. Hierdie strategie was egter baie meer kompleks as wat oorspronklik verwag is as gevolg van verdere metabolise aktiwiteite aanwesig in beide organismes. Ons het egter steeds daarin geslaag om kinetiese vergelykings af te lei, vanuit suiwer kulture, wat die metaboliese gedrag van beide organismes beskryf vir die aktiwiteite van belang vir ons studie. Ons het nuwe tegnieke, gebaseer op die aerobiese natuur van G. oxydans, ontwikkel om die sensitiwiteit van G. oxydans vir etanol en suurstof te bepaal. Hierdie parameters is gebruik om eers ’n eenvoudige model en toe ‘n meer gevorderde model, wat die suurstof-beperkte metabolisme van G. oxydans by hoër biomassa te beskryf, op te stel. Beide modelle was baie effektief in die voorspelling van die situasies waarvoor hulle ontwikkel is vir die suiwer kulture waar veral die meer gevorderde model die gebrek aan ‘n linieêre verband tussen die metabolisme van G. oxydans en biomassa by hoër biomassa kon beskryf. ’n Bemoedigende aanduiding dat kontrole analise toegepas kon word op die ekosisteem was dat mengkulture van S. cerevisiae en G. oxydans het quasi-bestendige toestande bereik het in terme van etanol konsentrasies en asetaat-fluksie. Die teoretiese modelle gebaseer op die parameters afgelei vanaf suiwer kulture kon egter nie die bestendige toestande in mengkulture akkuraat voorspel nie. Nadere ondersoek het aangedui dat die parameters meesal onderskat is vir G. oxydans en oorskat is vir S. cerevisiae. Gevolglik het ons die kinetiese parameters vir mengkulture direk van eksperimentele data van die mengkulture bereken. Verder kon ons die kontrole koeffisiente ook direk vanaf die eksperimentele data van mengkulture bereken en vergelyk met dié bereken vanuit die teoretiese modelle gebaseer op drie verskillende paremeter-stelle. Ons analise het gewys dat die gis alle beheer op die asetaat-fluksie uitoefen en dat die beheer oor die etanol-konsnetrasie gedeel is tussen die twee organismes. Die krag van ons aanslag lê daarin dat die eksperimente ontwerp is met ‘n kontrole analise in gedagte, maar ons het ook bewys dat hierdie aanslag selfs vir eenvoudige ekosisteme nie triviaal is nie. Ten spyte van die eksperimentele uitdagings, was die aanslag baie waardevol as gevolg van die ekstra inligting verkry met spesifieke klem op die kontrole-struktuur met betrekking tot die etanol konsentrasie by bestendige toestand.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Globally, habitat transformation causes biodiversity loss, with the transformed matrix often affecting the disturbance regime in remnant natural patches. In South Africa, significant parts of the Indian Ocean coastal belt and grassland biomes have been transformed into commercial forestry plantations of alien trees, which are detrimental to local biodiversity. Consequently, large scale ecological networks (ENs) of remnant natural vegetation, maintained areas (e.g. firebreaks) and special landscape features (e.g. rocky outcrops and wetlands) have been implemented among forestry compartments to offset the negative effect of this land use on biodiversity. Different grassland areas, which constitute a major portion of ENs, were managed in different ways, as governed by their primary purpose (e.g. fire protection or conservation). The overall aim of this study was to determine how grassland floral and grasshopper herbivore communities responded to different disturbances (mowing, burning and grazing), and how we can adjust management of the major disturbances to effectively conserve these major components of biodiversity in ENs. Sampling was carried out in the commercial forestry ENs in the lower-elevation Zululand area and adjacent reserve area iSimangaliso Wetland Park, as well as in the forestry ENs in the higher-lying Midlands and adjacent iMpendle Nature Reserve. Both the reserves or protected areas (PAs) acted as reference sites, while other sites were chosen to represent the predominant disturbances in ENs at each locality: mowing, annual vs. longer-rotation burning, time since last fire, and domestic cattle grazing. In the Zululand subtropical grassland (chapter 2), I explored the effect of frequent mowing on firebreaks, and the effect of patch size and isolation on plant communities in non-firebreak natural areas of the EN. Frequent mowing resulted in plant species loss and a shift in species composition of firebreaks. Furthermore, small, isolated patches in the EN far away from the PA border had lower plant species richness and greater species turnover than wide, interconnected corridors near the PA border, which, in turn, was similar to reference sites in the PA. As plant species were lost from frequently-mown firebreaks and small, isolated patches in the EN, I recommend that this management practice should be confined to demarcated areas (e.g. forestry compartment edges and firebreaks) and that creation of wide, interconnected corridors should be prioritized when designing ENs. In higher elevation Afromontane grassland (chapter 3), I investigated the effect of annual burning on plant communities in firebreaks by comparing them to less frequently burned grassland in the EN and PA, respectively. Grazing by domestic cattle was taken as an embedded factor for firebreak and less frequently burned sites in the EN. There were three firebreak types: annually-burned with heavy cattle grazing (plantation firebreaks), annually-burned with light cattle grazing (peripheral firebreaks), and annual burning without cattle grazing (PA firebreaks). Burned reference grassland in the EN and PA hosted plant communities that were similar in species richness, composition and turnover. This was also the case for lightly-grazed peripheral EN firebreaks and PA firebreaks. However, species composition and turnover of plantation EN firebreaks with heavy cattle grazing differed from that in the other two firebreak types. Although not significant (P<0.1), plantation EN firebreaks had less plant species than reference burned grassland in the EN, and all firebreak types had less plant species, lower species turnover and different species composition when compared to reference burned grassland in the PA. Annual burning of firebreaks, with and without cattle grazing, caused a significant shift in plant species composition and a reduction in plant species turnover. When annual burning was combined with heavy cattle grazing, plant species were lost, as was the case in plantation EN firebreaks. Therefore, I recommend that this management practice should be confined to firebreaks, and that cattle access to firebreaks should be strictly controlled. In Chapter 4, I considered the effect of cattle grazing (presence vs. absence, as well as intensity) on Afromontane grassland against the natural backdrop of variation caused by time since last fire in grassland with longer fire-return intervals (excluding all firebreaks). Lowest plant species richness and turnover occurred in unburned (i.e. burned >12 months prior to sampling), ungrazed grassland in the PA. Burning and grazing both caused a change in plant species composition that went hand in hand with an increase in plant species richness and turnover. However, burning (burned vs. unburned) only affected plant communities in ungrazed grassland in the PA. Similarly, the presence of large mammalian grazers (EN vs. PA) only affected plant communities in unburned grassland. Unburned plant communities grazed by domestic cattle in the EN were similar to those in the PA grazed by indigenous black wildebeest, indicating that cattle grazing simulates, at least to some degree, the effect of indigenous ungulate grazing. Nevertheless, heavily-grazed grassland had less plant species than moderately-grazed grassland in the EN. I recommend that burning and grazing should continue in grassland ENs, as these natural disturbances are necessary to maintain diverse and dynamic ecosystems. Nevertheless, managers should instigate cattle grazing with caution, as high intensity grazing can be detrimental to conservation efforts. In Chapter 5, I examined the effect of annual burning, cattle grazing (presence vs. absence) and time since last fire on grasshopper assemblages in Afromontane grassland. In general, grasshoppers benefitted from disturbance, and were remarkably resilient to different disturbance regimes. Grasshopper species richness and their abundance were both greatest in annually-burned firebreaks with light cattle grazing, and lowest in moribund grassland in the PA which had not been burned for several years. Yet, time since last fire only affected grasshopper communities in the absence of large grazers (in the PA). None of the individual disturbances had an effect on the grasshopper assemblage. Rather, these insects responded to the combined effect of annual burning with cattle grazing. Sites were similar in grasshopper species richness, composition and abundance whenever either annual burning or cattle were absent, which suggests that these two disturbances drive changes in the grasshopper assemblage in these grasslands. Although grasshoppers benefited from annual burning with light cattle grazing, I would not recommend this disturbance regime outside firebreaks. Rather, management of other grassland areas in the EN should adapt longer fire-return intervals with a rotational cattle grazing system, so that undisturbed habitat is provided for other sensitive taxa. In conclusion, grassland plants and grasshoppers benefited from some form of disturbance, but were lost from small, isolated patches in the EN, as well as from areas with high disturbance frequency and intensity. Simulation of natural disturbances (moderate levels of fire and grazing) in wide, interconnected corridors is necessary for maintaining diverse and dynamic grassland ecosystem in ENs among commercial forestry plantations. / AFRIKAANSE OPSOMMING: Omskepping van natuurlike habitat na lande of plantasies veroorsaak biodiversiteitsverlies wêreldwyd. Boonop het sulke veranderinge dikwels 'n effek op die versteurings binne-in oorblywende kolle natuurlike plantegroei wat verreikende gevolge kan hê. Groot gedeeltes van die Suid-Afrikaanse grasveldbioom is omskep in bosbou plantasies wat bestaan uit uitheemse bome wat 'n baie groot nadelige effek op plaaslike biodiversiteit het. Daarom is grootskaalse ekologiese netwerke (EN’e), wat bestaan uit oorblywende kolle natuurlike plantegroei, brandbane en spesiale habitattipes in die landskap (bv. rotsriwwe en vleilande), tussen bosbouplantasies geïmplimenteer met die doel om die negatiewe effek van plantasies op plaaslike biodiversiteit te verlig. Bestuur van grasvelde, wat 'n groot gedeel van EN’e uitmaak, wissel dikwels en hang af van hulle primêre doel (bv. beskerming van plantasies teen wegholveldbrande of natuurbewaring). Die doel van hierdie projek was om vas te stel hoe plant- en springkaangemeenskappe in grasvelde reageer op verskillende versteurings (grassny, brand en beweiding), en die optimale bestuur van die versteurings om die biodiversiteit in grasvelde beter te bewaar. Steekproewe is geneem in EN’e tussen bosbouplantasies in die laagliggende Zululand en langsliggende wêrelderfenisgebied, iSimangaliso Wetland Park, asook in die hoërliggende Midlands en langsliggende iMpendle Natuurreservaat (NR). NR’e het as verwysing gedien waarteen die effek van grassny, frekwensie van brande, tydsverloop vanaf die laaste brand, en beweiding deur beeste, wat tipiese versteuringe in EN’e is, gemeet is. In hoofstuk 2 het ek vasgestel wat die effek van grassnyfrekwensie op plantgemeenskappe in brandbane is, en hoe plantgemeenskappe in subtropiese grasveld in die res van die EN reageer op die grootte en strukturele isolasie van oorblywende kolle natuurlike plantegroei. 'n Hoë grassnyfrekwensie het 'n verandering in die spesiesamestelling van plantgemeenskappe in brandbane veroorsaak wat gepaard gegaan het met spesiesverlies. Terselfdertyd was daar minder plant spesies in klein, geïsoleerde kolle natuurlike plantegroei as wat daar in wyer, aaneenskakelende gange nader aan die natuurreservaatgrens was. Laasgenoemde het plantgemeenskappe bevat wat baie soortgelyk aan die in die natuurreservaat was. Daarom stel ek voor dat die skep van wye, aaneengeskakelde natuurlike habitat prioriteit moet geniet wanneer nuwe EN’e ontwerp word, en dat gras slegs gereeld gesny moet word in spesifieke, afgebakende areas (bv. brandbane). Die rede hiervoor is dat hierdie bestuurspraktyk nie bevorderlik was vir die bewaring van plantdiversiteit in EN’e nie. In hoofstuk 3 het ek gekyk hoe die plantgemeenskappe in brandbane daarop reageer om elke jaar gebrand te word deur hulle te vergelyk met Afrikaberg grasveld in die EN en NR wat minder gereeld gebrand word. Beweiding deur beeste is gesien as 'n integrale deel van die EN. Ek het onderskei tussen plantasiebrandbane met swaar beweiding, randbrandbane met ligte beweiding en brandbane in die NR sonder beweiding. Die plantspesiesamestelling van brandbane, met ligte of geen beweiding nie, het verskil van grasvelde wat minder gereeld gebrand word. Tog is die hoeveelheid plantspesies nie geraak nie. Alhoewel die plantgemeenskappe in ligbeweide brandbane soos die in onbeweide brandbane in die NR was, het die plantspesiesamestelling van beide verskille getoon wanneer hulle vergelyk is met plantasiebrandbane wat swaarder deur beeste bewei is. Plantspesierykheid in plantasiebrandbane was boonop heelwat laer as wat in NR grasvelde gevind is, en daar was heelwat meer kaal grond in plantasiebrandbane as in enige van die ander areas. Oor die algemeen het plantspesiesrykheid van brandbane nie daaronder gely om elke jaar gebrand te word nie, maar kwesbare plantgemeenskappe in brandbane het wel daaronder gely om swaar bewei te word. Daarom stel ek voor dat jaarlikse brande tot brandbane beperk word en dat beeste se toegang tot brandbane streng beheer word. In die hoofstuk 4 ondersoek ek die effek van beweiding deur beeste (teenwoordigheid teenoor afwesigheid, sowel as beweidingsintensiteit) op die plantspesiesrykheid en samestelling van gebrande en ongebrande Afrikaberg grasvelde wat minder gereeld gebrand word. Die minste plant spesies is aangeteken in ongebrande, onbeweide grasveld in die NR. Brande en beweiding het albei 'n effek op plantspesiesamestelling gehad wat gepaard gegaan het met 'n toename in plantspesiesrykheid. Plantgemeenskappe in grasvelde wat onlangs (<12 maande voor die steekproef geneem is) gebrand is, het slegs van die in ongebrande grasvelde verskil wanneer nie een van die twee areas bewei is nie. Op 'n soortgelyke trant het die teenwoordigheid van beeste (EN teenoor NR) slegs n effek gehad in ongebrande grasvelde. Ongebrande plantgemeenskappe in die EN wat deur beeste bewei is, was baie soos die in die NR wat deur swartwildebeeste bewei is. Dit dui daarop dat beeste die effek van inheemse wildsoorte tot 'n mate naboots. Des nieteenstaande die bogenoemde, het swaar-beweide grasvelde minder plantspesies gehad as grasvelde wat slegs matig bewei is. Ek stel voor dat brande en beweiding deel moet vorm van die bestuur van grasvelde in EN’e, want hierdie natuurlike versteuringe dra by tot 'n diverse, dinamiese grasveldekosisteem. Tog moet bestuurders versigtig wees wanneer hulle die plaaslike gemeenskap se beeste in EN’e toelaat, want swaar beweiding kan bewaringsinisiatiewe in die wiele ry. In hoofstuk 5 het ek die klem na springkane verskuif, en die effek van jaarlikse brande, beweiding deur beeste (teenwoordigheid teenoor afwesigheid) en tydsverloop sedert laaste brand op hierdie sensitiewe insekte in Afrikaberg grasvelde ondersoek. Alhoewel springkaangemeenskappe baat gevind het by versteuringe, het hulle nie beduidend gereageer op enige van die indiwiduele versteuringe nie. Die digste sprinkaan bevolking met die hoogste spesies diversiteit is aangeteken in brandbane in die EN wat liggies deur beeste bewei is. Darenteen is die laagste bevolking en spesies diversiteit aangeteken in grasvelde in die NR wat groot hoeveelhede dooie plantmateriaal bevat wat aandui dat hierdie grasvelde nie onlangs gebrand het nie. Springkaangemeenskappe in gebrande grasvelde het slegs van ongebrande grasvelde verskil wanneer nie een van die twee bewei is nie. Die sleutelkombinasie van versteuringe wat die rykheid en samestelling van springkaangemeenskape bepaal het, was 'n hoë brandfrekwensie (soos in brandbane) en beweiding deur beeste. Wanneer een van hierdie versteuringe afwesig was, was springkaangemeenskappe tussen verskillende areas dieselfde. Alhoewel springkaangemeenskappe daarby baat gevind het wanneer brandbane elke jaar gebrand en deur beeste bewei is, kan ek nie hierdie bestuurspraktyk vir die res van die EN aanbeveel nie. Grasvelde in die res van die EN behoort eerder minder gereeld (elke 2-4 jaar) gebrand en met 'n rotasiestelsel bewei word. Sodoende sal brandbane voorsien in die behoeftes van springkane, en die res van die EN in die behoeftes van sensitiewe taksa wat onversteurde habitat benodig om te floreer. My slotsom is dat versteuringe nodig is om die volle diversiteit van plante en springkane en die dinamika binne-in grasvelde te bewaar. Tog verdwyn daar plantspesies uit areas met 'n hoë versteuringsintensiteit of frekwensie en klein, geïsoleerde kolle natuurlike plantegroei in die EN. Daarom beveel ek aan dat natuurlike versteuringe (brande en beweiding) matig toegepas moet word in wye, aaneengeskakelde gange in die EN. Hierdie benadering tot natuurbewaring kan biodiversiteit tussen bosbouplantasies beveilig teen verdere verlies.

<p>Dans ce travail, les préférences alimentaires pour les espèces végétales consommées par les lombriciens peuplant certains îlots des pelouses de l’avenue Roosevelt ont été étudiées. L’analyse des contenus digestifs et des fèces des vers a montré que les plantes identifiées dans les pelouses ne sont pas toutes consommées.<br> Mesurée par l’indice d’Ivlev, la sélectivité des items végétaux est variable en fonction de l’espèce de ver, de la classe d’âge et de la saison. Lorsque les dicotylédones sont en plein développement au printemps et en été, les choix des vers sont surtout manifestés pour les monocotylédones. En automne et en hiver, les monocotylédones prédominent et, les dicotylédones se retrouvant dans la litière, font l’objet de préférences marquées qui induisent des rejets relatifs de monocotylédones. Bien que Lolium perenne soit la plante la plus consommée, Bellis perennis est la dicotylédone la plus appréciée, Trifolium repens et Poa trivialis étant les plantes généralement rejetées.<br> L’indice d’Ivlev n’ayant permis de connaître que les rangs de préférences des différentes espèces végétales, les analyses ont été complétées par des tests du χ² qui ont montré que la consommation des plantes par les vers ne se fait pas au hasard. <p>Les épigés Satchellius mammalis et Lumbricus rubellus sont les espèces qui présentent le taux le plus élevé de matière organique figurée (respectivement 27 % et 26 % [19 % chez les jeunes Lumbricus spp]) dans leurs contenus digestifs. Chez les anéciques Aporrectodea longa et Lumbricus terrestris, ces taux sont très faibles (respectivement 6 % [2 fois plus chez les jeunes vers] et 11 %). Les endogés (Aporrectodea caliginosa, A. icterica et A. rosea) présentent des taux variant respectivement de 21 % [9 % chez les jeunes vers] à 8 % et 11 %. <p>L’axe de la taille des particules consommées n’a pas permis une ségrégation des niches (d’après notre étude, la taille des vers n’affecte pas celle des particules ingérées), mais l’axe de la nature des particules consommées est plus discriminant. Dans la niche tridimensionnelle (taille et nature des particules ingérées, notre étude, et les cycles annuels d’activité [Tiho, 2001]), le seul recouvrement fort qui se maintienne est celui de la niche de L. rubellus sur celle de L. terrestris. Un recouvrement marginal (α = 0,66) est observé, celui de la niche de A. longa sur celle de L. terrestris. Ceci révèle une compétition interspécifique entre ces trois espèces ayant des régimes alimentaires très proches. <p> <p>In this study, preferences for plants consumed by earthworms inhabiting certain islets of the Roosevelt avenue lawns have been studied. Examination of gut contents and faeces showed that not all of the plants identified in the lawns are consumed.<br> Measured by the Ivlev’s electivity index, the selectivity of plants is variable according to the earthworm species, its size class and the season. When the dicotyledons are developing in spring and in summer, the choices of the earthworms are particularly observed for the monocotyledons. In autumn and winter, the monocotyledons are developing and the dicotyledons in the litter are highly chosen, leading the relative reject of the monocotyledons.<br> Although Lolium perenne is the most consumed plant, Bellis perennis is the most appreciated dicotyledon, Trifolium repens and Poa trivialis being generally rejected.<br> As the Ivlev’s index of preference has only permit to know the rank of preference of the different plants, the analysis was completed by the χ² tests which demonstrated that the consumption of plants by earthworms is not done randomly. <p>The epigées Satchellius mammalis and Lumbricus rubellus are the species which present the highest rate of organic matter (respectively 27 % and 26 % [19 % for the immatures Lumbricus spp] in their gut contents.<br> For the anéciques Aporrectodea longa and Lumbricus terrestris, these rates are very low (respectively 6 % [twice more for the immatures worms] and 11 %).<br> The endogées (Aporrectodea caliginosa, Aporrectodea icterica and Aporrectodea rosea) present rates varying respectively from 21 % [9 % for the young worms] to 8 % and 11 %. <p>The axis of the particles size ingested did not permit the niches segregation (in our study, the earthworms size does not affect the size of the particles ingested), but the axis of the nature of the particles ingested is more discriminant. In the three-dimensional niche (size and nature of particles ingested [our study] and the annuals cycles of activity [Tiho, 2001]), the young worms not being considered, only one high overlap is maintained, that of L. rubellus niche on that of L. terrestris. A marginal overlap (α = 0.66) is observed, that of A. longa niche on that of L. terrestris. Having a similar trophic resource (consumption of litter), an interspecific competition must exist between these three species for the access to the food.