Dissertations / Theses on the topic 'Ecological disturbance'
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Peterson, Garry D. "Contagious disturbance and ecological resilience." [Florida] : State University System of Florida, 1999. http://etd.fcla.edu/etd/uf/1999/amg2055/peterson%5Fg.pdf.
Full textTitle from first page of PDF file. Document formatted into pages; contains ix, 261 p.; also includes graphics. Vita. Includes bibliographical references (p. 248-260).
Roderick, Mary J. "Ecological Restoration and Urban Planning: Integrating to end distURBANce." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1242941905.
Full textRoderick, Mary. "Ecological restoration and urban planning integrating to end distURBANce /." Cincinnati, Ohio : University of Cincinnati, 2009. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1242941905.
Full textAdvisor: Menelaos Triantafillou. Title from electronic thesis title page (viewed Aug. 18, 2009). Includes abstract. Keywords: Ecological Restoration; Urban Planning; Integration; Landscape Ecology. Includes bibliographical references.
Michalski, Fernanda. "Ecological consequences of habitat fragmentation and disturbance in Amazonian forests." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432441.
Full textTomblin, David Christian. "Ecological niche responses of small mammals to gypsy moth disturbance." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06302009-040517/.
Full textUnderwood, Emma Clare. "Consequences of ecological disturbance on ground dwelling invertebrates : implications for conservation /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
Full textO'Connor, Christopher Daniel. "Spatial and temporal dynamics of disturbance interactions along an ecological gradient." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311565.
Full textSchmitt, Susanne F. "Disturbance and succession on the Krakatau Islands, Indonesia." Thesis, University of Oxford, 1997. http://ora.ox.ac.uk/objects/uuid:a2b3257d-0a00-4286-a38a-01e3016da708.
Full textPankey, Joel Robert. "Centaurea in the Columbia basin ecoregion : disturbance, invasion, and competition." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Spring2009/j_pankey_042109.pdf.
Full textYang, Jian. "Spatially explicit and stochastic forest landscape model of fire disturbance and succession." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4174.
Full textThe 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 (November 14, 2006) Vita. Includes bibliographical references.
Pearson, Neil. "Ecological genetics of Arabidopsis thaliana from reservoir populations in low-disturbance habitats." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/61699/.
Full textJoubert, Lize. "Disturbance factors related to conservation of biodiversity in large-scale ecological networks." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86261.
Full textENGLISH 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.
Vasques, Ana Rita Pessoa de Figueiredo. "Assessment of higher plant species suitability for ecological restoration following major disturbance." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12101.
Full textO presente trabalho é constituído por uma revisão bibliográfica e uma série de estudos científicos experimentais visando a melhoria do conhecimento da ecologia de germinação e resposta ao estresse hídrico em arbustos autóctones. Estes estudos pretendem contribuir para o conhecimento da ecologia de espécies autóctones na fase de germinação e estabelecimento inicial das plântulas através da comparação da resposta de sementes de diferentes proveniências. Os primeiros três capítulos focam-se no estudo dos efeitos de pré-tratamentos na germinação de espécies arbustivas com diferentes estratégias de regeneração e dormência da semente, enquanto os dois últimos capítulos incidem sobre o efeito de diferentes condições de disponibilidade de água na germinação e estabelecimento inicial de plântulas com potencial para restauro ecológico. Este estudo procura abordar aspetos importantes para o estudo e validação do uso de espécies alvo para o restauro ecológico em zonas Mediterrânicas, contribuindo deste modo para a melhoria do conhecimento da ecologia destas espécies. A germinação foi estimulada por pré-tratamentos de calor em quatro das cinco espécies cuja época de dispersão da semente na primavera-verão. As sementes provenientes do sul tenderam a germinar melhor, sendo ao mesmo tempo mais pequenas. Por outro lado, a germinação em espécies cuja dispersão da semente ocorre no outono-inverno variou de acordo com o tipo de dormência da semente. A germinação foi em geral favorecida pela estratificação a frio na espécie apresentando dormência fisiológica mas foi negativamente afetada na espécie que não apresenta dormência. Esta resposta não foi, no entanto, inequívoca pois foi dependente da proveniência estudada. O efeito da estratificação a frio teve em geral um efeito mais positivo ou menos negativo nas sementes provenientes do norte em comparação com as outras proveniências. O stress-osmótico teve um efeito negativo consistente na germinação de Pistacia lentiscus e outro fator que também afetou significativamente a germinação foi a variabilidade intra-populacional entre plantas mãe. As duas proveniências apresentaram diferentes graus de associação entre a germinação e/ou caracteres morfológicos da semente ou planta mãe. Quanto à fase de estabelecimento inicial, o baixo conteúdo em água teve um claro efeito negativo no investimento relativo em biomassa acima do solo e um efeito positivo no investimento relativo em biomassa abaixo do solo em Arbutus unedo. Esta resposta não foi inequívoca, uma vez que as proveniências diferiram em adaptações morfológicas ao baixo conteúdo em água. As plântulas da proveniência mais húmida revelaram uma taxa de crescimento relativo superior mas, ao mesmo tempo, uma fraca adaptação às condições de baixa disponibilidade de água, quando comparadas com as outras proveniências. Ao contrário, as plântulas da proveniência seca com verão mais quente apresentaram semelhantes diâmetro do colo da raiz, peso seco de folhas e performance fisiológica sob os dois regimes de irrigação. Os resultados obtidos revelam diferenças significativas na germinação e desenvolvimento inicial entre as distintas proveniências que poderão estar relacionadas com adaptações ao clima dos locais de origem. Os desenvolvimentos futuros do estudo dos mecanismos subjacentes às adaptações observadas poderiam contribuir para a melhoria das previsões de sucesso do estabelecimento inicial em diferentes populações de plantas, permitindo aumentar a confiança e efetividade de custos nas decisões relacionadas com ações de restauro ecológico em cenários de alterações climáticas.
The present work is composed by a conceptual scheme based on a literature review plus a series of experimental scientific studies. These studies aim at improving the knowledge base of germination ecology and response to water stress in autochthonous shrub species through the comparison of different provenances. The first three chapters focus on the study of the role of pretreatments in the germination of shrub species with different regeneration and seed dormancy strategies while the two last chapters focus on the study of the effect of contrasting water availabilities in the germination and early establishment of species with restoration potential. This study intends to address important aspects for the study and validation of the use of target species for ecological restoration actions in Mediterranean areas, thereby contributing to the improvement of the knowledge of the ecology of these species. Germination in four out of the five species whose seeds are dispersed in spring-summer was enhanced by heat pre-treatments. The seeds from southern provenances tended to germinate better, being at the same time smaller. On the other hand, germination response in autumn-winter seed dispersed species varied according to the type of seed dormancy. Germination was, in general, enhanced by cold stratification in the species presenting physiological dormancy but negatively affected in the species with no dormancy. This response was, however, not unequivocal and depended on the role of provenance. The effect of cold stratification had, in general a more positive or less negative effect in the germination of the northern seeds when comparing to the other provenances. Osmotic-stress had a consistent negative effect on germination of Pistacia lentiscus and another factor that significantly influenced germination was intrapopulation variability between mother-plant. The two provenances presented distinct degrees of association between germination and seed or mother plant morphological traits. As to the early establishment phase, low water content had a clear negative effect on Arbutus unedo seedlings’ aboveground biomass and a positive effect on belowground biomass relative investment. This response was not unequivocal, since provenances differed in morphological adaptations to low water content. Seedlings from the wettest provenance revealed a higher relative growth rate under high water content but a poor adaptation to limited water availability when compared to the other two provenances. By contrast, seedlings from the dry provenance with the hottest summer had similar root collar diameter, leaf dry weight and physiological performance under both watering regimes. The present results revealed significant differences in germination and early development response among different provenances that could be related with adaptations to the climate of the seed source. Further studies on the mechanisms underlying the observed adaptations could contribute to the improvement of early establishment success predictions in different plant populations, allowing more reliable and cost-effective management ecological restoration-related decisions under climate change scenarios.
Thomas, Jonathan Armstrong White Joseph Daniel. "Modeling canopy foliar traits and disturbance interactions in central Texas woodlands." Waco, Tex. : Baylor University, 2009. http://hdl.handle.net/2104/5337.
Full textFox, Helen Elizabeth. "The role of anthropogenic disturbance in the creation of a socio-ecological landscape." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1008061.
Full textHyodo, Makoto. "Ecological Evaluation of Shifting Habitat History for Riverbed Management." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/202698.
Full textPearson, Audrey F. "Natural disturbance patterns in a coastal temperate rain forest watershed, Clayoquot Sound, British Columbia /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5513.
Full textRempel, Laura L. "Physical and ecological organization in a large, gravel-bed river and response to disturbance." Thesis, University of British Columbia, 2004. http://hdl.handle.net/2429/37993.
Full textArts, Faculty of
Geography, Department of
Graduate
Urquiza-Haas, Tania. "Regional-scale ecological responses to natural and anthropogenic disturbance in the Yucatan Peninsula, Mexico." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433796.
Full textAssal, Timothy J. "The ecological legacies of drought, fire, and insect disturbance in western North American forests." Thesis, Colorado State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=3746145.
Full textTemperate forest ecosystems are subject to various disturbances including insect agents, drought and fire, which can have profound effects on the structure of the ecosystem for many years after the event. Impacts of disturbance can vary widely, therefore an understanding of the legacies of an event are critical in the interpretation of contemporary forest patterns and those of the near future. The primary objective of this dissertation was to investigate the ecological legacies of drought, beetle outbreak and ensuing wildfire in two different ecosystems. A secondary objective of my research, data development, was motivated by a lack of available data which precluded ecological investigation of each disturbance.
I studied the effects of drought on deciduous and coniferous forest along a forest-shrubland ecotone in the southern portion of the Wyoming Basin Ecoregion. The results show that forests in the region have experienced high levels of cumulative drought related mortality over the last decade. Negative trends were not consistent across forest type or distributed randomly across the study area. The patterns of long-term trends highlight areas of forest that are resistant, persistent or vulnerable to severe drought.
In the second thread of my dissertation, I used multiple lines of evidence to retrospectively characterize a landscape scale mountain pine beetle disturbance from the 1970s in Glacier National Park. The lack of spatially explicit data on this disturbance was a major data gap since wildfire had removed some of the evidence from the landscape. I used this information to assess the influence of beetle severity on the burn severity of subsequent wildfires in the decades after the outbreak. Although many factors contribute to burn severity, my results indicate that beetle severity can positively influence burn severity of wildfire. This is likely due to the change in forest structure in the decades after the outbreak and not as a direct result of tree mortality from the outbreak. The long-term perspective of this study suggests that ecological legacies of high severity disturbance may continue to influence subsequent disturbance for many years after the initial event. This work also provides insight on future disturbance interactions associated with the recent mountain pine beetle outbreak that has impacted tens of millions of hectares in western North America over the last two decades.
Flenner, Ida. "Forest lakes affected by forestry - how resilient are dragonfly communities to logging in Central Sweden?" Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-797.
Full textThe main cause of environmental disturbance in the Fennoscandian boreal forests today is forestry. Natural disturbances are important to maintain diversity, but anthropogenic disturbance, such as forestry, differs in many ways from the natural ones. Forestry is a big industry in Sweden and only a small remnant of old-growth forest is left. Several studies have shown an initial decrease in e.g. dragonfly diversity a few years after logging, followed by an increase up to numbers comparable with the original species number. In this study I examined whether the new, quite diverse, species composition is similar to the one present before the logging or if some species are disappearing and are replaced with other, maybe opportunistic species. Other factors such as ongoing changes in climate also will be considered. A resampling of 34 (and an additional 4) lakes that also were sampled in 1996-97 was done during summer of 2006. Analyses of data from the two sampling occasions were done. I found that even if the diversity is just temporarily affected (or not affected at all), it is not always the same species involved. This means that the diversity in a single lake can appear to be high, but the total diversity in Sweden, or Scandinavia, is declining. I also found some interesting new species for the area, such as Nehalennia speciosa, Sympecma fusca and Aeshna mixta.
Dwyer, Ross Gordon. "Ecological and anthropogenic constraints on waterbirds of the Forth Estuary : population and behavioural responses to disturbance." Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/117159.
Full textSanford, Monte Paul. "Using insect responses to anthropogenic disturbance to improve land management and conservation planning decisions." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3289458.
Full textRippey, Jean Michele. "Emotional Disturbance as an Educational Disability: Implications for Social Workers." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/174.
Full textBerglund, Linda. "Disturbance, nutrient availability and plant growth in phenol-rich plant communities /." Umeå : Dept. of Forest Vegetation Ecology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s327.pdf.
Full textSundberg, Sebastian. "The ecological significance of sexual reproduction in peat mosses (Sphagnum)." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-526.
Full textPeat mosses (Sphagnum) are widely distributed and are a major component of mire vegetation and peat throughout the boreal and temperate regions. Most boreal Sphagnum species regularly produce sporophytes, but the ecological role of the spore has been questioned. This study shows that the spores can form a spore bank and have the ability to germinate and contribute to moss establishment whenever suitable conditions occur. The results suggest that spore production is important for explaining the wide distribution and omnipresence of Sphagnum in nutrient-poor wetlands. The results further imply that initial recruitment from spores predominates in Sphagnum after disturbance or formation of suitable habitats.
A series of experiments showed that addition of phosphorus-containing substrates, such as fresh plant litter or moose dung, resulted in spore establishment on bare, moist peat. A field experiment indicated establishment rates of about 1% of sown, germinable spores on peat with added substrates. Plant litter on moist soil, without a closed cover of bryophytes, is an important safe site for the establishment of Sphagnum spores. The results fit the observed pattern of colonisation by Sphagnum beneath Eriophorum vaginatum tussocks in mires severely disturbed by peat extraction. Successful long-distance dispersal was indicated by the occurrence of several regionally new or rare Sphagnum species in disturbed mires.
Spore number per sporophyte ranged among Sphagnum species from 18 500 to 240 000, with a trade-off between spore number and spore size. Annual spore production was estimated at 15 million spores per square metre on two investigated mires. Sporophyte production showed a large interannual variation. Sporophyte production was positively related to the amount of precipitation the preceding summer. This was probably because a high water level promoted gametangium formation. Spore dispersal occurred in July and August. The earlier timing of spore dispersal in the more drought-sensitive, hollow-inhabiting sphagna should reduce the risk of sporophytes drying out prematurely during summer droughts.
Spores kept refrigerated up to 13 years retained high germinability. A field experiment showed that Sphagnum can form a persistent spore bank, with a potential longevity of several decades.
Ojima, Miriam Nozomi. "APPLICATION OF ECOLOGICAL THEORIES TO THE GUT MICROBIOME AND BIFIDOBACTERIAL COMMUNITIES." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263793.
Full textWright, Nevil Ian. "Ecological impacts of Highveld gerbils (Tatera Brantsii) on a rehabilitated ash disposal site / Nevil Ian Wright." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1246.
Full textThesis (M.Sc. (Zoology))--North-West University, Potchefstroom Campus, 2007.
Allen, Bruce Peter. "Vegetation dynamics and response to disturbance, in floodplain forest ecosystems with a focus on lianas." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1179427491.
Full textJohnston, Christine Ninette. "Ecological and Behavioral Impacts of Snag Density on Cavity-Nesting Birds in the Oak Savanna." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1180531111.
Full textMaxwell, Jordan Daniel. "Impacts of Novel Fire and Herbivory Regimes on Snow-WaterResources and Resilience of Aspen Forests." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8267.
Full textMinor, Jesse, Donald Falk, and Greg Barron-Gafford. "Fire Severity and Regeneration Strategy Influence Shrub Patch Size and Structure Following Disturbance." MDPI, 2017. http://hdl.handle.net/10150/624330.
Full textSteele, Melita Zoë. "Natural resource harvesting and disturbance in communal lands: assessing the roles of local ecological knowledge, dependency and market access." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1004604.
Full textDupont, Jennifer Maria. "Ecological dynamics of livebottom ledges and artificial reefs on the inner central West Florida Shelf." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002841.
Full textVan, Ham Laura. "Natural recovery of human induced disturbance in an alpine/arctic tundra environment and recommendations for reclamation, Plateau Mountain Ecological Reserve." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/MQ42309.pdf.
Full textASANTE, MELDOMI ASABEA. "EFFECT OF URBAN RIPARIAN DEVELOPMENT ON BIODIVERSITY; USING BIRDS AND VEGETATION AS ECOLOGICAL INDICATORS IN COOPER CREEK LOCATED IN SOUTHWEST OHIO." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1146157392.
Full textMcKinney, Tracie. "Social and Ecological Impact of Anthropogenic Disturbance on the Sympatric White-faced Capuchin (Cebus capucinus) and Mantled Howler Monkey (Alouatta palliata)." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267816356.
Full textDolphin, Claire A. "Post Disturbance Coral Populations: Patterns in Live Cover and Colony Size Classes from Transect Studies in Two Oceans." NSUWorks, 2014. http://nsuworks.nova.edu/occ_stuetd/12.
Full textShaw, Althoff Peggy S. "Indicators of disturbance and recovery of a tallgrass prairie ecosystem following military vehicle traffic." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/460.
Full textAlves, Paula Rute Pereira Matono. "Fish assemblages as biological indicators of ecological quality in portuguese rivers." Doctoral thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/16172.
Full textCoulston, John Wesley Riitters Kurt Smith Gretchen Cole. "Large-scale analysis of sustainable forest management indicators assessments of air pollution, forest disturbance, and biodiviersity [sic] /." Connect to this title online, 2004. http://www.lib.ncsu.edu/theses/available/etd-03282004-103433/.
Full textLovseth, John Timothy. "THE PROLOGUE TO MANAGEMENT: THE EFFECTS OF HISTORICAL ANTHROPOGENIC ACTIVITIES ON FOREST ECOSYSTEMS AND CURRENT MANAGEMENT OPPORTUNITIES IN SOUTHWESTERN ILLINOIS." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/dissertations/1623.
Full textSanders, Shareen. "Increased Drought and Fire Intensity Regimes Reduce the Ecological Resilience of Mediterranean Forests in the South-West Australian Floristic Region." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-419206.
Full textMichelsen-Correa, Stephani. "Geomorphic response to restoration and disturbance: Grazing, fire, and flooding on the Middle Fork John Day River, OR." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11290.
Full textSalmon habitat restoration is ongoing at a Nature Conservancy preserve on the Middle Fork John Day River in the Columbia River Basin in north-central Oregon. The site has a long history of disturbance including dredge mining upstream, channelization, grazing, logging, fire, and floods. Using historic aerial photos, habitat unit surveys, and cross sectional profiles, this thesis shows how the channel morphology, particularly habitat unit diversity, has changed since 1939, just before placer mining began. Results show that the dominant influence on present day channel morphology is channelization from the 1930's. Other changes including dredge mining in the late 1930's to early 1940's, cessation of cattle grazing in 1991, and a fire followed by a flood in the winter of 1996-1997, had less impact because of the straightened, stabilized channel morphology.
Committee in charge: Patricia McDowell, Chairperson; W. Andrew Marcus, Member
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Waller, Penelope Anne. "Towards ecological restoration strategies for Peninsula Shale Renosterveld: testing the effects of disturbance-intervention treatments on seed germination on Devil's Peak, Cape Town." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/6606.
Full textNowicki, Robert J. "Effects of Catastrophic Seagrass Loss and Predation Risk on the Ecological Structure and Resilience of a Model Seagrass Ecosystem." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2994.
Full textLehndal, Lina. "Ecological and Evolutionary Consequences of Herbivory in the Perennial Herb Lythrum salicaria." Doctoral thesis, Uppsala universitet, Växtekologi och evolution, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-247088.
Full textHowey, Christopher A. F. "The Ecological Effects of Prescribed Fire on the Black Racer (Coluber constrictor)." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1392390834.
Full textCardoso, João Pedro Monteiro. "Wolf breeding sites in human grounds: insights on habitat features and sources of disturbance to support conservation measures." Master's thesis, Universidade de Évora, 2022. http://hdl.handle.net/10174/31369.
Full textAndersson, Mathias H. "Offshore wind farms - ecological effects of noise and habitat alteration on fish." Doctoral thesis, Stockholms universitet, Zoologiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-54049.
Full textAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3, 4 and 5: Manuscripts.