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Dissertations / Theses on the topic 'Anthropogenic disturbances'

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Published: 4 June 2021
Last updated: 20 February 2023

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1

Eklöf, Johan S. "Anthropogenic Disturbances and Shifts in Tropical Seagrass Ecosystems." Doctoral thesis, Stockholm University, Department of Systems Ecology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7285.

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Seagrasses constitute the basis for diverse and productive ecosystems worldwide. In East Africa, they provide important ecosystem services (e.g. fisheries) but are potentially threatened by increasing resource use and lack of enforced management regulations. The major aim of this PhD thesis was to investigate effects of anthropogenic distur-bances, primarily seaweed farming and coastal fishery, in East African seagrass beds. Seaweed farming, often depicted as a sustainable form of aquaculture, had short- and long-term effects on seagrass growth and abundance that cascaded up through the food web to the level of fishery catches. The coastal fishery, a major subsistence activity in the region, can by removing urchin predators indirectly increase densities of the sea urchin Tripneustes gratilla, which has overgrazed seagrasses in several areas. A study using simulated grazing showed that high magnitude leaf removal – typical of grazing urchins – affected seagrasses more than low magnitude removal, typical of fish grazing. Different responses in two co-occurring seagrass species furthermore indicate that high seagrass diversity in tropical seagrass beds could buffer overgrazing effects in the long run. Finally, a literature synthesis suggests that anthropogenic disturbances could drive shifts in seagrass ecosystems to an array of alternative regimes dominated by other or-ganisms (macroalgae, bivalves, burrowing shrimp, polychaetes, etc.). The formation of novel feedback mechanisms makes these regimes resilient to disturbances like seagrass recovery and transplantation projects. Overall, this suggests that resource use activities linked to seagrasses can have large-scale implications if the scale exceeds critical levels. This emphasizes the need for holistic and adaptive management at the seascape level, specifically involving improved techniques for seaweed farming and fisheries, protection of keystone species, and ecosystem-based management approaches.

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Eklöf, Johan S. "Anthropogenic disturbances and shifts in tropical seagrass ecosystems /." Stockholm : Department of Systems Ecology, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7285.

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3

PAPAZACHARIOU, VASILIKI. "Coral Fungia fungites- associated microbial communities and their shifts upon anthropogenic disturbances." Thesis, Uppsala universitet, Limnologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-377137.

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One of the main focus of coral reef ecology has been to shed light on the importance of all microbial members of coral holobiont and how their interactions contribute to the coral’s resilience. However, knowledge is lacking about the composition of microbial communities inhabiting the surface mucus layer of corals including Fungia fungites, a species that lives under stressful conditions close to fish farms in Vietnam. I investigated the prokaryotic communities that are thriving in Fungia fungites surface mucus layer (SML) in the wild and how they were affected upon antibiotics and nitrogen stress using 16S rRNA gene-based techniques. Firstly, I observed a significant alteration in the composition of microbial communities due to antibiotics effect, with exposed communities featuring lower richness and α-diversity in contrast to the controls. Further, mucosal microbial communities were found to be mostly dominated by Proteobacteria (especially of the classes of Alphaproteobacteria and Gammaproteobacteria) and less by Bacteroidetes (Flavobacteriia). Results from this study suggest a developed antibiotic resistance of Alteromonadales and Campylobacterales indicated by their increased abundance upon antibiotics effect. Moving forward, future studies should focus on exploring also the contribution of non-prokaryotic microbial members of Fungia fungites holobiont and how antibiotic resistance can potentially influence coral’s health. The results support that Fungia fungites SML microbial communities are strongly affected by antibiotics exposure and call for future research to focus on the function of these microbial communities and how they can contribute to the coral’s resilience.
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Abdelnour, Alex Gabriel. "Assessing ecosystem response to natural and anthropogenic disturbances using an eco-hydrological model." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42899.

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The impact of natural and anthropogenic disturbances on catchment hydrological and biogeochemical dynamics are difficult or impossible to capture through experimentation or observation alone. Process-based simulation models can address this need by providing a framework for synthesizing data describing catchment responses to climate, harvest, fire, and other disturbances. However, existing models are either too simple to capture important process-level hydrological and biogeochemical controls on ecosystem responses to disturbance, or are too computationally expensive to simulate the local dynamics over large watershed areas, or require a high level of expertise to implement. To this end, a spatially distributed, physically based, eco-hydrological model (VELMA: Visualizing Ecosystems for Land Management Assessments) that is both computationally efficient and relatively easy to implement is developed. VELMA is a state-of-the-art model with real-time visualization tools that shows temporal and spatial patterns of state and flux variables, and is used to address the effects of changes in climate, land-use, and other interacting stressors on multiple ecosystem services such as timber production, carbon sequestration, regulation of water quality and quantity and reduction of greenhouse gases at scales relevant to formulating management decisions. In this study, VELMA was applied to the H.J. Andrews Experimental forest, an intensively studied watershed with observed daily temperature, precipitation, streamflow, and nutrient losses data. VELMA was first used to explore the factors that controls catchment response to forest harvest. Specifically, elucidate how forest harvest factors such as harvest location and amount control watershed hydrological and biogeochemical fluxes. Thereafter, VELMA was used to reconstruct and analyze the impact of two significant disturbance events − a stand replacing fire and a 100% clearcut − on vegetation and soil carbon and nitrogen dynamics. Finally, VELMA was used to explore the potential impact of climate change on catchment hydrological regime, site productivity and carbon and nitrogen dynamics at high spatial resolution relevant to formulating management decision. The main insights from this study include: (1) streamflow, nutrient losses to the stream, and gaseous carbon and nitrogen losses to the atmosphere are strongly sensitive to the location of harvest as a result of the spatial variation in soil water content, plant nitrogen uptake, soil organic carbon decomposition, nitrification, and denitrification within the watershed, (2) forested riparian buffers reduce water and nutrient losses to the stream through plant transpiration, plant nitrogen uptake, soil storage, and soil microbial decomposition, (3) following fire and harvest, losses of N from the terrestrial system to the stream are tightly constrained by the hydrological cycle and driven mainly by wet-season rain events large enough to generate hydrologic connectivity and flushing of nutrients along hillslopes, (4) climate change strongly impacts the hydrological regime in the Pacific Northwest as a result of less snowpack, earlier snowmelt, higher winter streamflow, lower summer streamflow, and soil moisture deficit, and (5) climate change increases plant and soil biomass accumulation as a result of longer growing season and higher soil organic decomposition, reduce water quality by increasing the amount of nutrients that reach the stream, and transforms the ecosystem into a net source of carbon to the atmosphere.
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Neigh, Christopher Sean R. "Identifying and understanding North American carbon cycle perturbations from natural and anthropogenic disturbances." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8172.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Geography. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Chandrasekara, W. U. "The effects of anthropogenic disturbances on the macrobenthic fauna of saltmarshes and their recovery." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320394.

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Tolkkinen, M. (Mikko). "Biodiversity and ecosystem functioning in boreal streams:the effects of anthropogenic disturbances and naturally stressful environments." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526209043.

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Abstract The effect of biodiversity loss and change on the functioning of ecosystems is one of the key questions in ecological research. For stream ecosystems, compelling evidence indicates that species diversity may enhance ecosystem functions. However, ecosystem functions are often regulated by the same environmental factors that also shape diversity; thus, a major challenge for ecologists is to separate the effects of biodiversity loss on the ecosystem functions from the direct effects of human induced disturbance. In this doctoral thesis, I studied how decomposer communities and ecosystem functions respond to human disturbances (nutrient enrichment, acidification) and a natural stressor (naturally low water pH). I also studied how human disturbances and natural stressors affect the phylogenetic structure of stream fungal communities. I showed that human disturbance had a strong impact on species dominance patterns by reducing species evenness. Species dominance patterns also explained the variation in decomposition rates. Changes in abiotic variables also had a direct effect on leaf decomposition rates. In the naturally acidic sites, human impact (land drainage) further decreased water pH and increased metal concentrations, thereby reducing leaf decomposition rates, whereas high nutrient concentrations enhanced leaf decomposition. Naturally low pH had no effect on decomposition rates. Decomposer community similarity was higher in drainage-impacted sites, but only in naturally acidic, not in circumneutral, streams. Human induced disturbance also modified the phylogenetic similarity of fungal decomposer communities, with communities in disturbed sites consisting of more closely related species when compared to those in circumneutral reference sites. Leaf litter decomposition showed greater temporal variation in human disturbed sites than in reference sites, whereas fungal community variability was similar in disturbed and reference sites. Thus, temporally replicated monitoring may be needed for a reliable assessment of human disturbance in streams. My thesis emphasizes that using both functional and taxonomic measures allows a more comprehensive assessment of biological responses to human disturbance
Tiivistelmä Biodiversiteetin väheneminen ja siitä seuraava ekosysteemin toiminnan heikkeneminen on eräs keskeisimmistä ekologisista kysymyksistä. Ekosysteemin toiminnot ovat kuitenkin monesti yhteydessä ympäristöolosuhteisiin, joten on vaikea erottaa vähentyneen biodiversiteetin ja ympäristöolojen suhteellista merkitystä ekosysteemien toimintoihin. Tässä väitöskirjatyössäni tutkin, kuinka virtavesien hajottajayhteisöt ja ekosysteemin toiminnot (lehtikarikkeen hajotus) muuttuvat valuma-alueen ihmistoimintojen myötä. Tutkin myös, kuinka luontainen stressi (matala pH) vaikuttaa yhteisöihin ja ekosysteemin toimintoihin. Tarkastelen myös akvaattisten sienten fylogeneettistä rakennetta ihmistoiminnan muuttamissa vesiympäristöissä. Osoitan tutkimuksissani, että ihmistoiminnoilla on vaikutuksia hajottajayhteisöiden kokonaisrunsauden jakautumiseen lajien kesken. Muutamien runsaiden lajien dominoimissa yhteisöissä lehtikarikkeen hajoaminen on tehokkaampaa kuin yhteisöissä, joissa lajien runsauserot ovat pienempiä. Myös ympäristöoloilla on vaikutus lehtikarikkeen hajotukseen. Luontaisesti happamissa puroissa metsäojituksen seurauksena lisääntynyt veden metallipitoisuus ja alhainen pH vähentävät hajotuksen määrää. Toisaalta joen korkea ravinnepitoisuus lisää hajotusta. Lehtikarikkeen hajotus vaihtelee enemmän vuosien välillä ihmistoimintojen muuttamissa virtavesissä kuin luonnontilaisissa vesissä. Toisaalta sieniyhteisöt pysyvät koostumukseltaan samankaltaisina vuosien välillä ihmistoiminnan muuttamissa paikoissa ja referenssipaikoissa. Tämä työ osoittaa, että toiminnallisten ja yhteisöihin perustuvien indikaattorien yhteiskäyttö antaa kokonaisvaltaisimman kuvan ihmistoimintojen vaikutuksesta virtavesien ekosysteemeihin
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Grubh, Archis R. "Effects of anthropogenic disturbances and biotic interactions on stream biota in gulf coastal plain streams." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1155753270.

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Pellecchia, Antonella. "Experimental analysis of the effects of extreme events of mechanical disturbance on rocky shore algal and invertebrate assemblages in the Bagnoli-Coroglio post-industrial area and in reference sites in the Gulf of Naples." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17977/.

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Among the various natural and anthropogenic threats to coastal systems, industrial activities and their heritage of local contamination play a key role, especially where new disturbances are superimposed to extant degraded conditions. This may affect the functioning of assemblages, including their ability to recover, in unpredictable ways. Organisms subject to chronic contamination may respond better to a present discrete disturbance compared to organisms from reference areas not affected by the same contamination due to their adaptation to harsh conditions. By contrast, the same organisms may be more sensitive to the new disturbance if chronic contamination kept them close to their tolerance limit. This study tested such alternatives by comparing the patterns of recovery from the experimental removal of all erect organisms of lowshore benthic assemblages between the post-industrial site of Bagnoli-Coroglio (Gulf of Naples) and reference sites located outside it. Recovery was assessed over six months. Response variables included mean values and temporal trajectories of assemblage structure, richness of taxa and abundance of conspicuous taxa. The examined assemblages showed great recovery ability that was comparable between the post-industrial site and reference sites. Discussed potential explanations include: (i) intertidal organisms would quickly recover irrespective of background contamination as an adaptation to the naturally harsh and variable environmental conditions of their living habitat; (ii) reference sites would be subject to environmental stress comparable to that of Bagnoli-Coroglio being located in the highly urbanized Gulf of Naples; (iii) large variability between- and withinsites may have masked any impacts of experimental disturbance and their differences between the post-industrial site and the reference sites; (iv) historical contamination would be limited to subtidal sediments, without propagating to adjacent rocky habitats.
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Vleminckx, Jason. "The influence of soil factors and anthropogenic disturbances on tree species assemblages in central African forests." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209100.

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La diversité végétale exceptionnelle des forêts tropicales a toujours suscité une part d’incompréhension chez les scientifiques qui tentent de comprendre les processus à l’origine de cette diversité, ainsi que les mécanismes expliquant les changements spatiaux de composition spécifique. Une des clés de ce dernier mystère résiderait dans l’influence de la différentiation des niches écologiques, mais aussi de la dispersion limitée des graines et d’événements stochastiques (purement aléatoires et non prévisibles). La niche d’une espèce contraint celle-ci à s’établir dans un habitat présentant des gammes de conditions bien délimitées en termes de propriétés du sol (disponibilité en nutriments et toxicité de certains éléments) et d’intensité lumineuse. Par exemple, certaines espèces sont plus tolérantes à l’ombrage (espèces « sciaphiles ») que d’autres qui ne peuvent s’établir que dans des trouées forestières offrant suffisamment de lumière (espèces « héliophiles »). En Afrique centrale, les communautés d’arbres sont aujourd’hui en grande partie composées de ces espèces dites « héliophiles », alors que les ouvertures forestières naturelles sont rares. Il est fortement suspecté que la dominance de ces espèces soient la conséquence de trouées générées par l’homme qui, jusqu’au début de la période coloniale (vers 1900), occupait de vastes surfaces de forêt où il pratiquait l’agriculture sur brûlis. Cependant, peu d’études ont jusqu’à présent déterminé dans quelle mesure ces pratiques agricoles ont influencé la composition spécifique des forêts à l’échelle régionale comme à l’échelle locale.

L’objectif du présent travail est de faire la lumière sur l’impact de ces perturbations humaines mais aussi plus généralement sur l’influence relative de la niche écologique des espèces d’arbres par rapport à d’autres facteurs (dispersion limitée et facteurs stochastiques) sur leur distribution spatiale. Pour cela nous avons utilisé des données botaniques et environnementales provenant d’inventaires réalisés dans une forêt tropicale située en République Démocratique du Congo (quatre transects parallèles mesurant chacun 500 à 600 m de long), ainsi que des données similaires complémentées d’inventaires anthracologiques (estimation de la quantité de charbons de bois dans le sol, utilisée comme indicateur de feux passés d’origine anthropique) récoltées dans trois régions du sud du Cameroun (208 parcelles de 0,2 ha chacune).

Les données récoltées nous ont permis de mettre en évidence un impact significatif des propriétés physico-chimiques du sol sur la composition en espèces d’arbres. Plus précisément, nous avons pu constater une différence floristique marquée entre deux habitats très contrastés (sol sableux vs. sol argileux, Rép. Dém. Du Congo), et cela à une échelle spatiale locale (< 1 km²) où l’on pensait que de l’influence des facteurs stochastiques et de dispersion limitée étaient prépondérante. Mes analyses ont également démontré que cette différence était plus marquée pour les arbres de la canopée que pour les arbres des strates inférieures (« sous-canopée »), ce qui est sans doute lié au fait que de nombreux individus de la sous-canopée sont composés de juvéniles régénérant la canopée, parmi lesquels de nombreux arbres subissent une exclusion compétitive en cours (brouillant ainsi les signaux d’association espèce-habitat).

À une échelle spatiale beaucoup plus large cette fois (de 5 à 100 km, inventaires du Sud Cameroun), nous avons démontré que la diversité floristique était également influencée de manière significative par l’hétérogénéité spatiale de propriétés abiotiques du sol, notamment par les concentrations en (i) certains nutriments essentiels pouvant présenter des valeurs potentiellement limitantes (K, Mg, Ca et P) ainsi qu’en en (ii) élements pouvant être présents en quantités toxiques (Al et Mn). Cependant, alors que le signal environmental a été clairement détecté à l’échelle communautaire, seule les abondances d’une minorité d’espèces (< 15%) ont répondu significativement à la variation des conditions de sol. En outre, le nombre de réponses significatives a augmenté avec l’échelle d’observation ainsi qu’avec le degré d’hétérogénéité environnementale et/ou floristique. Pour mettre en évidence cet effet du sol, nous avons introduit une nouvelle approche permettant de tester la fraction d’une analyse de partition de variance correspondant à la part de variation floristique expliquée par l’effet de conditions édaphiques spatialement structurées (co-variation entre effets spatiaux et édaphiques), en combinant l’analyse de partition de variance avec des vecteurs propres de Moran (« Moran’s eigenvector maps ») et des translations toroïdales. Bien que cette méthode nous ait permis de déterminer si la fraction en question était significative, nous avons également mis en doute son interprétation habituelle suggérant que cette fraction représente une structure floristique directement induite par des structures spatiales de conditions de sol. Grâce à des simulations de populations végétales liées à des propriétés environnementales, nous avons mis en évidence que la valeur de la fraction étudiée ne semble finalement pas influencée par le degré de structuration spatiale des conditions environnementales, remettant donc en question l’utilité de l’analyse de partition de variance pour inférer des effets de processus écologiques sous-jacents sur la distribution spatiale des espèces d’arbres.

Enfin, les données floristiques et anthracologiques du Sud Cameroun ne nous ont pas permis de démontrer statistiquement l’hypothèse que les perturbations humaines passées sont en partie responsables de la dominance actuelle des espèces héliophiles. L’absence de corrélation significative entre l’abondance relative de ces espèces et la quantité de charbons de bois dans le sol peut s’expliquer par le fait que la majorité de ces charbons (60%) étaient trop vieux (1500 à 3000 ans) pour refléter des perturbations ayant influencé la diversité végétale présente.

Les conclusions générales de ma thèse de doctorat soutiennent que la niche écologique des espèces d’arbres des forêts tropicales africaines contribue de manière significative à déterminer leur assemblage dans l’espace, mais aussi que ces effets de niche dépendent fortement du contexte environnemental étudié ainsi que de l’échelle spatiale d’observation. Ce travail lève donc en partie un voile sur l’écologie des écosystèmes forestiers d’Afrique centrale qui restent largement méconnus par rapport à ceux d’Asie du Sud-Est et des régions néotropicales.


Doctorat en sciences, Spécialisation biologie végétale
info:eu-repo/semantics/nonPublished

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Paterson, Andrew M. "Assessing the impact of anthropogenic disturbances on water quality in Canadian Shield lakes, a paleolimnological perspective." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ56094.pdf.

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Pucko, Carolyn Ann. "The Impacts of Multiple Anthropogenic Disturbances on the Montane Forests of the Green Mountains, Vermont, USA." ScholarWorks @ UVM, 2014. http://scholarworks.uvm.edu/graddis/315.

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How and why species’ ranges shift has long been a focus of ecology but is now becoming increasingly important given the current rate of climatic and environmental change. In response to global warming, species will need to migrate northward or upward to stay within their climatic tolerances. The ability of species to migrate will determine their fate and affect the community compositions of the future. However, to more accurately predict the future extent of species, we must identify and understand their responses to past and current climatic and environmental changes. The first place change is expected to occur is within ecotones where the ranges of many species converge and individuals exist at the limits of their environmental tolerances. In montane regions, these boundaries are compressed, creating a situation in which even relatively small changes in conditions can lead to shifts in the elevational ranges of species. In this dissertation, I examine the responses of forests in the Green Mountains of Vermont to recent climatic and environmental change in an attempt to understand how future climate change will affect their location and composition. I focus on the Boreal-Deciduous Ecotone (BDE), where the high elevation spruce-fir forests converge with the lower elevation northern hardwoods. In addition to investigating adult trees within the BDE, I also examine the responses of understory herbs and tree seedlings to changes in environmental and climatic factors. Factors considered in these investigations include temperature, soil environment, light environment, invasive species, competition, disturbance and many others. I will examine the complex range of responses in forest species that results from prolonged exposure to these forces alone and in combination. I have attempted to identify the responses of forest species to environmental changes by resurveying historic vegetation plots (Chapter 2), experimentally manipulating the growing environment of tree seedlings (Chapter 3) and performing dendrochronological analyses on tree rings (Chapter 4). Through my resurvey of historic vegetation plots, I determined the degree to which understory species have shifted as individuals or as groups. I also identified a set of novel understory communities that have developed since the 1960's in response to recent climate change, acid deposition and invasive species (Chapter 2). By transplanting and artificially warming tree seedlings, I identified factors responsible for limiting the growth and survival of northern hardwood species above the BDE. Temperature was the primary factor limiting sugar maple (Acer saccharum) at high elevations, while yellow birch (Betula alleghaniensis) was limited almost exclusively by light (Chapter 3). Dendrochronological studies of sugar maples indicated that prolonged exposure to acidified soils has only recently caused growth declines and has altered their relationship to climate (Chapter 4). Together, these studies have produced a cohesive picture of how northeastern montane forests have responded to recent climate change and other anthropogenic impacts. These findings can be used to help predict future species' ranges and identify species that may not be capable of migrating fast enough on their own to keep pace with changes in climatic conditions.
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Sanford, 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.

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Kovacs, John Michael. "Multiple approaches for assessing mangrove use and mangrove change following anthropogenic and natural disturbances, a case study of the Mexican Pacific." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ58143.pdf.

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Schaaf, Wolfgang. "Development of element cycling in forest ecosystems after anthropogenic disturbances : case studies at long-term atmospheric polluted and post-mining sites /." Cottbus : Brandenburgische Techn. Univ, 2004. http://www.gbv.de/dms/bs/toc/488098432.pdf.

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Larsson, Josefine. "Genetic Aspects of Environmental Disturbances in Marine Ecosystems : Studies of the Blue Mussel in the Baltic Sea." Doctoral thesis, Södertörns högskola, Miljövetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-33697.

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Anthropogenic environmental changes can serve as drivers for evolutionary responses in wild populations. To predict the long-term impact of anthropogenic changes on populations, it is crucial to understand the genetic effects caused by these disturbances. The Baltic Sea is considered to be one of the world’s most contaminated seas, and the increase of anthropogenic chemical pollution is a major threat to its ecosystems. This thesis assesses the impact of harbors and sewage treatment plants on physiological traits and genetic structure of resident populations of blue mussels at replicated sites in the Baltic Sea. The initial evaluation of the overall genetic pattern in blue mussel populations in the Swedish West Coast, the Baltic Proper and the Bothnian Sea found genetic differentiation between the three water basins and a low genetic differentiation within each basin, especially within the Baltic Proper. Despite the low genetic differentiation among blue mussels within the Baltic Proper, a parallel genetic differentiation associated with sewage treatment plant effluents was found in this basin. This included genomic regions with a high degree of differentiation between reference sites and sites affected by sewage plants effluent. This genetic differentiation is suggested to be due to post-dispersal selection acting in each generation. In contrast, no parallel genetic differentiation was associated with harbors. We identified five genomic regions in blue mussels, showing strong signs of selection, shared among three out of four replicated reference sites and sites affected by sewage effluents in the Baltic Proper i.e. Askö, Tvärminne and Karlskrona. An initial characterization of these genomic regions revealed functions related to immune and endocrine responses, oxidative stress and shell formation. Our results indicate that selection caused by sewage effluents involves multiple loci. The same genomic regions are found across different locations in the Baltic Proper but there are also unique genomic regions at each location. No genotoxic or histopathological effects were found among blue mussels from sewage effluent-affected areas but a higher frequency of histological abnormalities in the digestive gland were observed in mussels from harbors.
Evolutionära anpassningar till miljöstörningar i marina ekosystem: genetisk ekotoxikologi i Östersjön
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Guttmann, E. B. "Continuity and change in arable land management in the Northern Isles : evidence from anthropogenic soils." Thesis, University of Stirling, 2001. http://hdl.handle.net/1893/3551.

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Human activity can affect the soil in ways which are traceable long after the land has been given over to other uses, and past land management practices can be reconstructed by investigation of these relict characteristics. In some regions the addition of fertilising materials to the arable soils has created artificially deepened anthropogenic topsoils which can be over 1m thick. Such relict soils are found all over the world, and are widespread in north-western Europe. This work focuses on the anthropogenic soils in the Northern Isles, which were formed from the Neolithic period up until the 20th century. Three multi-period sites were investigated using thin section micromorphology, organic/inorganic phosphate analysis, soil magnetism, particle size distribution, loss on ignition and soil pH. Current views of anthropogenic soil formation, based on pedological investigation and historical documentary sources, are that they are formed as a result of the addition of domestic animal manures and turf used as animal bedding to arable areas. This project sets out to test the hypothesis that in fact anthropogenic soils are the result of a wide range of formation processes which took place over extended periods of time. The hypothesis has been tested by analysing soils and associated middens of different dates, which have been sealed and protected by blown sand deposits. The results have shown that in the Neolithic period arable soils were created by cultivating the settlement's midden heaps as well as by adding midden material to the surrounding soils. In the Bronze Age human manure, ash and domestic waste were spread onto the fields around the settlements to create arable topsoils up to 35cm thick. In the Iron Age arable agriculture was intensified by selective use of organic manures on one of the sites investigated, but organic waste material was not used as efficiently as it was in later periods, and on both sites it was allowed to accumulate within the settlements. In the Norse period, when the intensive system used in historical times appears to have originated, organic waste may have been used more efficiently. These changes appear to reflect a greater organisation of land resources and manuring strategies and increased demand for arable production over time.
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18

Jud, Zachary R. "Anthropogenic Disturbances in Estuarine Ecosystems: The Effects of Altered Freshwater Inflow, Introduction of Invasive Species, and Habitat Alteration in the Loxahatchee River, FL." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1197.

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With the majority of Earth’s population living in coastal areas, estuarine ecosystems have been particularly affected by anthropogenic disturbances. My dissertation research focused on three interrelated types of human disturbance that affect estuaries: Anthropogenic alteration of freshwater inflow, the introduction of invasive species, and habitat alteration. Using the LoxahatcheeRiver(Jupiter, FL) as a model system, my goal was to understand how these disturbances affect estuarine organisms, particularly fishes. One of the most ecologically harmful disturbances affecting estuaries is anthropogenic alteration of freshwater inflow (and resulting changes in salinity patterns). To identify effects of freshwater inflow on the behavior of an ecologically and economically important fish (common snook Centropomus undecimalis), I conducted a 19-month acoustic telemetry study. Common snook were more abundant and made more frequent upstream migrations during the wet season, but freshwater inflow did not appear to be the proximate cause for these behaviors. Increased estuarine salinity resulting from anthropogenic flow alteration may have facilitated the second type of disturbance that I address in this dissertation; the invasion of non-native Indo-Pacific lionfish into estuarine habitats. During the course of my dissertation research, I documented the first ever estuarine invasion by non-native lionfish. Using mark-recapture, I identified high site fidelity in lionfish, a trait that may aid future control efforts. The extremely low minimum salinity tolerance that I identified in lionfish appears to have allowed the species to colonize far upriver in estuaries with anthropogenically modified salinity patterns. Anthropogenic salinity alteration has also led to a severe degradation of oyster reef habitats in theLoxahatcheeRiver. As a foundation species, oysters provide food, shelter, and nursery habitat for a wide variety of estuarine organisms, including many ecologically and economically important fishes. Increasingly, degraded oyster reef habitats have been the focus of restoration efforts. I identified a relatively rapid (< 2 years) convergence between restored and natural oyster reef communities, and documented the importance of vertical relief in restoration success. My dissertation research is critical for the management and conservation of coastal rivers inFlorida, while more broadly informing restoration and management decisions in many other estuarine and coastal ecosystems.
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19

Dahl, Martin. "Natural and human-induced carbon storage variability in seagrass meadows." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-148400.

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Seagrasses are considered highly important CO2 sinks, with the capacity to store substantial quantities of organic carbon in the living biomass and sediments, and thereby acting as a buffer against climate change. In this thesis, I have studied carbon storage variability in temperate and tropical seagrass habitats and identified factors influencing this variation. In addition, as seagrass areas are decreasing worldwide, I have assessed effects of different anthropogenic disturbances on carbon sequestration processes. The result from this thesis showed that there was a large variation in carbon storage within and among temperate, tropical and subtropical regions. The highest organic carbon stocks were found in temperate Zostera marina meadows, which also showed a larger carbon storage variability than the subtropical and tropical seagrass habitats. The tropical and subtropical seagrass meadows had inorganic carbon pools exceeding the organic carbon accumulation, which could potentially weakens the carbon sink function. The variability in organic carbon stocks was generally strongly related to the sediment characteristics of the seagrass habitats. In Z. marina meadows, the strength of the carbon sink function was mainly driven by the settings of the local environment, which in turn indicates that depositional areas will likely have higher organic carbon stocks than more exposed meadows, while in the tropics seagrass biomass was also influencing sedimentary carbon levels. Furthermore, locations with large areas of seagrass were associated with higher carbon storage in tropical and subtropical regions, which could be related to increased accumulation of both autochthonous and allochthonous carbon. In an in situ experiment, impacts on carbon sequestration processes from two types of disturbances (with two levels of intensity) were tested by simulating reduced water quality (by shading) and high grazing pressure (through removal of shoot biomass). At high disturbance intensity, reductions in the net community production and seagrass biomass carbon were observed, which negatively affected carbon sequestration and could impact the sedimentary organic carbon stocks over time. In the treatments with simulated grazing, erosion was also seen, likely due to an increase in near-bed hydrodynamics. When experimentally testing effects of increased current flow on organic carbon suspension in Z. marina sediment, a ten-fold release of organic carbon with higher current flow velocities was measured, which resulted in an increase in the proportion of suspended organic carbon by three times in relation to other sediment particles. Therefore, periods with enhanced hydrodynamic activity could result in a removal of organic carbon and thereby likely reduce the seagrass meadows’ capacity to store carbon. The findings of this thesis add to the emerging picture that there is a large natural variability in seagrasses’ capacity to store carbon, and highlight how human-induced disturbances could negatively affect the carbon sink function in seagrass meadows.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.

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20

Tierney, Lauren. "An Agent-Based Model of Wildlife Migratory Patterns in Human-Disturbed Landscapes." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/19266.

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In recent years, human decision-making has led to significant landscape impacts in the western United States. Specifically, migratory wildlife populations have increasingly been impacted by rural urban development and energy resource development. This research presents the application of agent-based modeling to explore how such impacts influence the characteristics of migratory animal movement, focusing on mule deer (Odocoileus hemionus) in Western Wyoming. This study utilizes complex adaptive systems and agent-based modeling frameworks to increase understanding of migratory patterns in a changing landscape and explores thresholds of interference to migration patterns due to increased habitat degradation and fragmentation. The agent-based model utilizes GPS-collar data to examine how individual processes lead to population-level patterns of movement and adaptation. The assessment incorporates elements from both human and natural systems to explore potential future scenarios for human development in the natural landscape and incorporates adaptive behaviors, as well as animal-movement ecology, in changing landscapes.
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21

Adams, Jennifer Karen. "Multiproxy reconstructions of recent environmental change : understanding the ecological response of shallow lakes within the Selenga River basin, southeast Siberia, to anthropogenic and natural disturbances." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10040922/.

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Floodplain delta wetlands are highly productive and critical ecosystems between terrestrial uplands and large, aquatic systems. The largest inland freshwater floodplain delta in the world is the Selenga Delta. The Selenga Delta serves a crucial function between UNESCO World Heritage Site Lake Baikal, and the lake’s primary inflow, the Selenga River, and its tributaries. The Selenga River flows approximately 950 km through northern Mongolia and southern Siberia prior to reaching the Selenga Delta, and within the Selenga River basin, numerous anthropogenic activities, including industry, urban settlements, agriculture, and mining, have the potential to cause ecological damage to the Selenga River and its tributaries. The aims of this thesis were to assess the extent of current and historical contamination in Selenga River basin shallow lakes, investigate the primary environmental drivers of variability in ecological structure and function of shallow lakes within the basin, and understand the ecological responses and sensitivity to disturbance. Multiproxy palaeolimnological investigstions of three shallow lakes with the Selenga River basin (two from within the Selenga Delta and one from a more heavily industrialized region), were chosen to undertake a multiproxy palaeolimnological approach to addressing these aims. Investigations on shallow lakes across the Selenga Delta revealed that variability and composition of contemporary ecological communities are determined by degree of connectivity, trophic interactions, and physical landscape parameters such as lake surface area and depth. The greatest period of contamination of shallow lakes (by trace metals and persistent organic pollutants) occurred in the mid-20th century, closely linked with periods of economic development in Russia. However the main drivers of ecological variability since the 19th century have been natural and anthropogenically-induced changes in hydrological regimes, and nutrient pollution, which resulted in significant ecological shifts across multiple trophic levels in shallow lakes.
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22

Salgado-Herrera, Miriam. "Characterization of Bacteria Community and Evaluation of Anthropogenic and Natural Disturbances in Surface Waters Quality of Sabana River in the Luquillo Experimental Forest in Puerto Rico." Thesis, Universidad del Turabo (Puerto Rico), 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10285300.

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Characterization of bacteria community and evaluation of anthropogenic and natural disturbances in surface waters quality of Sabana River in the Luquillo Experimental Forest in Puerto Rico. This doctoral dissertation research focused on the bacterial characterization, and evaluation of anthropogenic, and natural disturbances in the surface waters quality of the Sabana River in the Luquillo Experimental Forest in Puerto Rico. Monthly samples were taken at seven stations along the river during one year, and physicochemical factors such as temperature, pH, conductivity, DO and salinity were measured to explore their effect in the bacterial community. The effect of recreation was evaluated at El Puente, and at La Paila in the Sabana River, and at Puente Roto in the Mameyes River, from August 4 to September 8, 2012. Samples were collected up-river (before), on-site, and down-river (after) primary contact recreation activity. The number of bathers, and the temperature of the water were recorded. Also, four monthly sampling events were conducted under low flow conditions between May 2015 and August 2015, at two sites in the Sabana River impacted by non-point sources. Terminal restriction fragment length polymorphism (T-RFLP), pyrosequencing, and Colilert and Enterolert Test-System, were used for the bacterial community characterization. It was found that number of phylotypes of the bacterial community increases from upriver to downriver as anthropogenic disturbances proliferate along the river, and that bacteria are adapted or acclimated to in situ temperature, dissolved oxygen, conductivity, salinity and pH, therefore, show little variation in time and space. Pyrosequncing revealed that a total of 12 bacteria classes, 27 orders, 33 families, 82 genera and 186 species were found in the Sabana River. There is an increase in families and species through the three stations, with the largest amounts observed downriver at station # 7. Vogesella spp. was the most abundant specie at the three stations, with 59% at station # 1, 67% at station # 4, and 53% at station # 7. A significant positive and strong correlation was found between the amount of E. coli and the number of bathers at MPRS (R = 0.919; p-value = 0.027), which means that a high number of bathers coincides with a high concentration of E.coli.

Also, there is a significant positive and strong correlation between the concentration of Enterococci and the number of bathers at Pai.S (R is 0.908; p-value = 0.033). There were not significant differences between the bacterial community up-river, on site and down river of the two non-point sources.

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23

Phyu, Phyu Lwin. "Land-use changes caused by livelihood transitions and their impact on tropical lower montane forest in Shan State, Myanmar." Kyoto University, 2018. http://hdl.handle.net/2433/231019.

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24

Corriveau, Brit Madelaine. "The effects of natural and anthropogenic disturbances on the structure and composition of early-successional plant communities in the Interior Cedar-Hemlock (ICH) zone of southern British Columbia." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2285.

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Wildfire is the primary natural disturbance in Interior Cedar-Hemlock (ICH) forests, and since the mid-20th century, forest harvesting (clearcutting, in this case) has become the primary anthropogenic disturbance type. Forest management in British Columbia is currently governed by a paradigm that maintains that biological diversity can be preserved by utilizing forest harvesting regimes that closely mimic "natural" disturbance regimes, but a question remains as to how closely these regimes mimic wildfire disturbances. More specifically, how do clearcutting and wildfires compare in their effects on the structure and composition of early-successional ICH plant communities? This study compares vegetation structure, composition, relative abundance and diversity among 39 sites that experienced either a stand-replacing fire or a clearcut within the last 40 years. Sites of different ages and disturbance types were located within the wet cool ICHwkl and very-wet cool ICHvk I biogeoclimatic variants near Revelstoke, B.C. For each site, overstory structural characteristics (tree and snag diameters, basal area and density), overstory composition, and surface fuels (volume of coarse woody debris (CWD)) were assessed. Understory vegetation percent cover, species richness, composition and diversity were also determined. Linear regression analysis was used to examine differences in each of these variables between disturbance types, over time. The trends in structural legacies (especially snag and CWD dynamics) varied greatly between wildfire and clearcut sites. Compared to burned sites, clearcut sites exhibited patterns of accelerated succession in several characteristics (overstory tree regeneration, vegetation cover and understory species richness) due to planting treatments and pre-disturbance relicts. Understory species composition also varied between disturbances, with clearcut sites containing more shade-tolerant survivors initially. Both disturbance types had similar levels of floristic diversity during early succession. These results suggest that clearcut harvesting may not emulate stand-replacing fires in terms of impact on early ICH plant succession in any aspect but diversity. However, it is unclear if these early-successional differences will continue through time. There is a need for further research in this ecosystem, as well as any other ecosystems where emulation silviculture is applied, in order to confirm that silvicultural effects mimic those of natural disturbance regimes.
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25

Vidal, Osvaldo J. [Verfasser], and Albert [Akademischer Betreuer] Reif. "Anthropogenic disturbances affecting Southern Beech (Nothofagus pumilio) forests in Torres del Paine Biosphere Reserve, southern Chilean Patagonia = Anthropogenische Auswirkungen auf Südbüche (Nothofagus pumilio) Wälder im Torres del Paine Biosphärenreservat, südchilenischen Patagonien." Freiburg : Universität, 2012. http://d-nb.info/1122592450/34.

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26

Scherrer, Pascal, and n/a. "Monitoring Vegetation Change in the Kosciuszko Alpine Zone, Australia." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040715.125310.

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This thesis examined vegetation change over the last 43 years in Australia's largest contiguous alpine area, the Kosciuszko alpine zone in south-eastern Australia. Using historical and current data about the state of the most common vegetation community, tall alpine herbfield, this thesis addressed the questions: (1) what were the patterns of change at the species/genera and life form levels during this time period; (2) what were the patterns of recovery, if recovery occurred, from anthropogenic disturbances such as livestock grazing or trampling by tourists; (3) what impacts did natural disturbances such as drought have on the vegetation and how does it compare to anthropogenic disturbances; and (4) What are the benefits, limitations and management considerations when using long-term data for assessing vegetation changes at the species/genera, life form and community levels? The Kosciuszko alpine zone has important economic, cultural and ecological values. It is of great scientific and biological importance, maintaining an assemblage of vegetation communities found nowhere else in the world. It is one of the few alpine regions in the world with deep loamy soils, and contains endemic flora and fauna and some of the few periglacial and glacial features in Australia. The area also forms the core of the Australian mainland's most important water catchment and is a popular tourist destination, offering a range of recreational opportunities. The vegetation of the Kosciuszko alpine zone is recovering from impacts of livestock grazing and is increasingly exposed to pressures from tourism and anthropogenic climate change. At the same time, natural disturbances such as drought and fire can influence the distribution, composition and diversity of plants. Thus, there is a need for detailed environmental data on this area in order to: (1) better understand ecological relationships; (2) understand existing and potential effects of recreational and management pressures on the region; (3) provide data against which future changes can be assessed; and (4) provide better information on many features of this area, including vegetation, for interpretation, education and management. The research in this thesis utilised three types of ecological information: (1) scientific long-term datasets; (2) photographic records; and (3) a comparison of disturbed and undisturbed vegetation. This research analysed data from one of the longest ongoing monitoring programs in the Australian Alps established by Alec Costin and Dane Wimbush in 1959. Permanent plots (6 transects and 30 photoquadrats) were established at two locations that differed in the time since grazing and have been repeatedly surveyed. Plots near Mt Kosciuszko had not been grazed for 15 years and had nearly complete vegetation cover in 1959, while plots near Mt Gungartan showed extensive impacts of grazing and associated activities which only ceased in 1958. Some transect data from 1959 to 1978 have been analysed by the original researchers. The research presented in this thesis extends this monitoring program with data from additional surveys in 1990, 1999 and 2002 and applies current methods of statistical evaluation, such as ordination techniques, to the whole data set for the first time. Results indicated that the recovery from livestock grazing and the effects of drought have been the main factors affecting vegetation. Recovery from livestock grazing at the three transects at Gungartan was slow and involved: (1) increasing genera diversity; (2) increasing vegetation cover; (3) decreasing amounts of bare ground; and (4) a directional change over time in species composition. Patterns of colonisation and species succession were also documented. In 2002, 44 years after the cessation of grazing, transects near Mt Gungartan had similar vegetation cover and genera diversity to the transects near Mt Kosciuszko, but cover by exposed rock remained higher. A drought in the 1960s resulted in a temporary increase of litter and a shift in the proportional cover of life forms, as grasses died and herb cover increased at both locations. Proportions of cover for life forms reverted to pre-drought levels within a few years. The results also highlighted the spatial variability of tall alpine herbfield. The photoquadrats were surveyed in the years 1959, 1964, 1968, 1978 and 2001 and are analysed for the first time in this thesis. After comparing a range of methods, visual assessment using a 130 point grid was found to be the most suitable technique to measure vegetation cover and genera diversity. At the 18 quadrats near Mt Gungartan, there was a pattern of increasing vegetation cover as bare areas were colonised by native cudweeds and the naturalized herb Acetosella vulgaris. Revegetation from within bare areas largely occurred by herb species, while graminoids and shrub species predominately colonised bare ground by lateral expansion from the edges, eventually replacing the colonising herbs. At the 12 quadrats near Mt Kosciuszko, vegetation cover was almost complete in all years surveyed except 1968, which was at the end of a six year drought. Similar to the results from the transect study, the drought caused an increase in litter at both locations as graminoid cover declined. Initially herb cover increased, potentially as a result of decreased competition from the graminoids and a nutrient spike from decaying litter, but as the drought became more severe, herb cover also declined. Graminoid cover rapidly recovered after the drought, reaching pre-drought levels by 1978, and was at similar levels in 2001. Herb cover continued to decline after peaking in 1964. The photoquadrat study also documented the longevity and growth rates of several species indicating that many taxa may persist for several decades. It further provided insights into replacement patterns amongst life forms. In addition to assessing vegetation change following livestock grazing and drought at the long-term plots, recovery from tourism impacts was examined by comparing vegetation and soils on a closed walking track, with that of adjacent undisturbed tall alpine herbfield at a series of 22 paired quadrats. Fifteen years after the track was closed there was limited success in restoration. Over a quarter of the closed track was still bare ground with non-native species the dominant vegetation. Plant species composition differed and vegetation height, soil nutrients and soil moisture were lower on the track which had a higher compaction level than adjacent natural vegetation. The results presented in this thesis highlight that tall alpine herbfield is characterised by nearly entire vegetation cover which is dominated by graminoids, followed by herbs and shrubs in the absence of disturbance by livestock grazing, trampling or drought. The studies also showed that under quot;average" conditions, the relative cover of herbs and graminoids remained fairly stable even though there can be considerable cycling between them. Spatial variability in terms of taxa composition was high. The only common introduced species in unrehabilitated sites was Acetosella vulgaris, which was effective at colonising bare ground but was eventually replaced by other native species. However, in areas actively rehabilitated, such as on the closed track, non-native species introduced during revegetation efforts still persist with high cover 15 years after their introduction. Monitoring of vegetation change is also important at the landscape scale. This thesis provides a review of the potential use, the limitations and the benefits of aerial photography to examine vegetation change in the Kosciuszko alpine zone. Numerous aerial photography runs have been flown over the area since the 1930s for government agencies, industry and the military. Some of these records have been used to map vegetation communities and eroding areas at a point in time. Other studies compared different types and scales of photographs, highlighting in particular the benefits and potential of large scale colour aerial photography to map alpine vegetation. However, despite their potential to assess vegetation change over time, a temporal comparison of vegetation in the Kosciuszko alpine zone from aerial photographs has not been completed to this date. Historical photographs may not be easy to locate or access and difficulties with vegetation classification may restrict the practicality of using historical aerial photographs to assess vegetation change. Despite these issues, aerial photography may provide a very useful and efficient tool to assess changes over time when applied appropriately, even in alpine environments. The development of digital classification techniques, the application of statistical measures of error to both methodology and data, and the application of geographic information systems are likely to further improve the practicality of historical aerial photographs for the detection of vegetation change and assist in overcoming some of the limitations. The results presented in this thesis highlight the need for limiting disturbance, for ongoing rehabilitation of disturbed areas and for long-term monitoring in the Kosciuszko alpine zone. The results contribute to our understanding of how vegetation may change in the future and may be affected by new land use activities and climate change. This type of information, which otherwise would require the establishment of long-term studies and years of monitoring, can assist land managers of this and other important protected areas. The study highlights how the use and expansion of already existing datasets to gather ecological information can save considerable money and time, providing valuable data for current and emerging issues.
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27

Scherrer, Pascal. "Monitoring Vegetation Change in the Kosciuszko Alpine Zone, Australia." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/366283.

Full text
Abstract:
This thesis examined vegetation change over the last 43 years in Australia's largest contiguous alpine area, the Kosciuszko alpine zone in south-eastern Australia. Using historical and current data about the state of the most common vegetation community, tall alpine herbfield, this thesis addressed the questions: (1) what were the patterns of change at the species/genera and life form levels during this time period; (2) what were the patterns of recovery, if recovery occurred, from anthropogenic disturbances such as livestock grazing or trampling by tourists; (3) what impacts did natural disturbances such as drought have on the vegetation and how does it compare to anthropogenic disturbances; and (4) What are the benefits, limitations and management considerations when using long-term data for assessing vegetation changes at the species/genera, life form and community levels? The Kosciuszko alpine zone has important economic, cultural and ecological values. It is of great scientific and biological importance, maintaining an assemblage of vegetation communities found nowhere else in the world. It is one of the few alpine regions in the world with deep loamy soils, and contains endemic flora and fauna and some of the few periglacial and glacial features in Australia. The area also forms the core of the Australian mainland's most important water catchment and is a popular tourist destination, offering a range of recreational opportunities. The vegetation of the Kosciuszko alpine zone is recovering from impacts of livestock grazing and is increasingly exposed to pressures from tourism and anthropogenic climate change. At the same time, natural disturbances such as drought and fire can influence the distribution, composition and diversity of plants. Thus, there is a need for detailed environmental data on this area in order to: (1) better understand ecological relationships; (2) understand existing and potential effects of recreational and management pressures on the region; (3) provide data against which future changes can be assessed; and (4) provide better information on many features of this area, including vegetation, for interpretation, education and management. The research in this thesis utilised three types of ecological information: (1) scientific long-term datasets; (2) photographic records; and (3) a comparison of disturbed and undisturbed vegetation. This research analysed data from one of the longest ongoing monitoring programs in the Australian Alps established by Alec Costin and Dane Wimbush in 1959. Permanent plots (6 transects and 30 photoquadrats) were established at two locations that differed in the time since grazing and have been repeatedly surveyed. Plots near Mt Kosciuszko had not been grazed for 15 years and had nearly complete vegetation cover in 1959, while plots near Mt Gungartan showed extensive impacts of grazing and associated activities which only ceased in 1958. Some transect data from 1959 to 1978 have been analysed by the original researchers. The research presented in this thesis extends this monitoring program with data from additional surveys in 1990, 1999 and 2002 and applies current methods of statistical evaluation, such as ordination techniques, to the whole data set for the first time. Results indicated that the recovery from livestock grazing and the effects of drought have been the main factors affecting vegetation. Recovery from livestock grazing at the three transects at Gungartan was slow and involved: (1) increasing genera diversity; (2) increasing vegetation cover; (3) decreasing amounts of bare ground; and (4) a directional change over time in species composition. Patterns of colonisation and species succession were also documented. In 2002, 44 years after the cessation of grazing, transects near Mt Gungartan had similar vegetation cover and genera diversity to the transects near Mt Kosciuszko, but cover by exposed rock remained higher. A drought in the 1960s resulted in a temporary increase of litter and a shift in the proportional cover of life forms, as grasses died and herb cover increased at both locations. Proportions of cover for life forms reverted to pre-drought levels within a few years. The results also highlighted the spatial variability of tall alpine herbfield. The photoquadrats were surveyed in the years 1959, 1964, 1968, 1978 and 2001 and are analysed for the first time in this thesis. After comparing a range of methods, visual assessment using a 130 point grid was found to be the most suitable technique to measure vegetation cover and genera diversity. At the 18 quadrats near Mt Gungartan, there was a pattern of increasing vegetation cover as bare areas were colonised by native cudweeds and the naturalized herb Acetosella vulgaris. Revegetation from within bare areas largely occurred by herb species, while graminoids and shrub species predominately colonised bare ground by lateral expansion from the edges, eventually replacing the colonising herbs. At the 12 quadrats near Mt Kosciuszko, vegetation cover was almost complete in all years surveyed except 1968, which was at the end of a six year drought. Similar to the results from the transect study, the drought caused an increase in litter at both locations as graminoid cover declined. Initially herb cover increased, potentially as a result of decreased competition from the graminoids and a nutrient spike from decaying litter, but as the drought became more severe, herb cover also declined. Graminoid cover rapidly recovered after the drought, reaching pre-drought levels by 1978, and was at similar levels in 2001. Herb cover continued to decline after peaking in 1964. The photoquadrat study also documented the longevity and growth rates of several species indicating that many taxa may persist for several decades. It further provided insights into replacement patterns amongst life forms. In addition to assessing vegetation change following livestock grazing and drought at the long-term plots, recovery from tourism impacts was examined by comparing vegetation and soils on a closed walking track, with that of adjacent undisturbed tall alpine herbfield at a series of 22 paired quadrats. Fifteen years after the track was closed there was limited success in restoration. Over a quarter of the closed track was still bare ground with non-native species the dominant vegetation. Plant species composition differed and vegetation height, soil nutrients and soil moisture were lower on the track which had a higher compaction level than adjacent natural vegetation. The results presented in this thesis highlight that tall alpine herbfield is characterised by nearly entire vegetation cover which is dominated by graminoids, followed by herbs and shrubs in the absence of disturbance by livestock grazing, trampling or drought. The studies also showed that under quot;average" conditions, the relative cover of herbs and graminoids remained fairly stable even though there can be considerable cycling between them. Spatial variability in terms of taxa composition was high. The only common introduced species in unrehabilitated sites was Acetosella vulgaris, which was effective at colonising bare ground but was eventually replaced by other native species. However, in areas actively rehabilitated, such as on the closed track, non-native species introduced during revegetation efforts still persist with high cover 15 years after their introduction. Monitoring of vegetation change is also important at the landscape scale. This thesis provides a review of the potential use, the limitations and the benefits of aerial photography to examine vegetation change in the Kosciuszko alpine zone. Numerous aerial photography runs have been flown over the area since the 1930s for government agencies, industry and the military. Some of these records have been used to map vegetation communities and eroding areas at a point in time. Other studies compared different types and scales of photographs, highlighting in particular the benefits and potential of large scale colour aerial photography to map alpine vegetation. However, despite their potential to assess vegetation change over time, a temporal comparison of vegetation in the Kosciuszko alpine zone from aerial photographs has not been completed to this date. Historical photographs may not be easy to locate or access and difficulties with vegetation classification may restrict the practicality of using historical aerial photographs to assess vegetation change. Despite these issues, aerial photography may provide a very useful and efficient tool to assess changes over time when applied appropriately, even in alpine environments. The development of digital classification techniques, the application of statistical measures of error to both methodology and data, and the application of geographic information systems are likely to further improve the practicality of historical aerial photographs for the detection of vegetation change and assist in overcoming some of the limitations. The results presented in this thesis highlight the need for limiting disturbance, for ongoing rehabilitation of disturbed areas and for long-term monitoring in the Kosciuszko alpine zone. The results contribute to our understanding of how vegetation may change in the future and may be affected by new land use activities and climate change. This type of information, which otherwise would require the establishment of long-term studies and years of monitoring, can assist land managers of this and other important protected areas. The study highlights how the use and expansion of already existing datasets to gather ecological information can save considerable money and time, providing valuable data for current and emerging issues.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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28

Leupold, Maike [Verfasser], Miriam Akademischer Betreuer] Pfeiffer, Peter [Akademischer Betreuer] [Kukla, and Jens [Akademischer Betreuer] Zinke. "Coral-based climate reconstructions in the central and western Indian Ocean from the Holocene to the present-day : orbital forcing, internal variability and anthropogenic disturbances / Maike Leupold ; Miriam Pfeiffer, Peter Kukla, Jens Zinke." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1221697366/34.

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29

Abrahams, Mark. "Wildlife responses to anthropogenic disturbance in Amazonian forests." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/64005/.

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Legally inhabited indigenous, extractive and sustainable use tropical forest reserves, have been lauded as a solution to the intractable problem of how to assure the welfare and secure livelihoods of the world’s diverse forest-dependent people, whilst conserving the world’s most biodiverse terrestrial ecosystems. This strategy has been critiqued by human rights advocates, who assert that legally inhabited reserves paternalistically restrict the livelihood choices and development aspirations of forest-dwellers, and by conservationists, who argue that sustained human presence and resource extraction erodes tropical forest biodiversity. This thesis examines both the anthropogenic impacts on tropical forests at the regional, landscape and household scales and the livelihood challenges faced by semi-subsistence local communities in the Brazilian Amazon. A spatially explicit dataset of 633,721 rural Amazonian households and an array of anthropogenic and environmental variables were used to examine the extent and distribution of structural (deforestation) and non-structural (hunting) human disturbance adjacent to 45 cul-de-sac rivers across the Brazilian states of Amazonas and Pará. At the landscape and household scales, a total of 383 camera trap deployments, 157 quantitative interviews and 164 GPS deployments were made in the agricultural mosaics and forest areas controlled by 63 semi-subsistence communities in the Médio Juruá and Uatumã regions of Central-Western Brazilian Amazonia, in order to quantify and explicate the (i) livelihood costs incurred through the raiding of staple crops by terrestrial forest vertebrates, (ii) degree of depletion that communities exert upon the assemblage of forest vertebrates and (iii) spatial behaviour of hunting dogs and their masters during simulated hunts. Our results indicate that at the regional scale, accessibility, fluvial or otherwise, modulated the drivers, spatial distribution and amount of anthropogenic forest disturbance. Rural household density was highest in the most accessible portions of rivers and adjacent to rivers close to large urban centres. Unlike the low unipolar disturbance evident adjacent to roadless rivers, road-intersected rivers exhibited higher disturbance at multiple loci. At the household and landscape scales semi-subsistence agriculturalists lost 5.5% of their staple crop annually to crop raiders and invested significant resources in lethal and non-lethal strategies to suppress crop raiders, and to avoid losses an order of magnitude higher. Crop raiding was heightened in sparsely settled areas, compounding the economic hardship faced by communities already disadvantaged by isolation from urban centres. A select few harvest-sensitive species were either repelled or depleted by human communities. Diurnal species were detected relatively less frequently in disturbed areas close to communities, but individual species did not shift their activity patterns. Aggregate species biomass was depressed near urban areas rather than communities. Depletion was predicated upon species traits, with large-bodied large-group-living species the worst impacted. Hunting dogs travelled only ~ 13% farther than their masters. Urban hunters travel significantly farther than rural hunters. Hunting dogs were recognised to have deleterious impacts on wildlife, but were commonly used to defend against crop raiders.
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Maletzke, Benjamin Thomas. "Effects of anthropogenic disturbance on landscape ecology of cougars." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Dissertations/Spring2010/b_maletzke_0041410.pdf.

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Martin, Thomas Edward. "Avifauna and anthropogenic forest disturbance in two biodiversity hotspots." Thesis, Lancaster University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543999.

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Miller, Rebecca Jane. "The effects of anthropogenic disturbance upon African penguin colonies." University of Western Cape, 2020. http://hdl.handle.net/11394/7851.

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Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol)
African penguin (Spheniscus demersus) mainland colonies are a popular tourist attraction in the Western Cape of South Africa. The African penguin population is in decline and the species is listed as endangered on the International Union for the Conservation of Nature (IUCN) Red List. This thesis aimed to investigate the impact of ecotourism upon African penguin colonies by comparing two colonies of differing levels of tourist visitation in the Western Cape in 2017. The high visitation colony is a mainland colony where ecotourism activities take place (Stony Point), and the low visitation colony is an island colony where ecotourism does not occur (Robben Island). As well as inter-colony comparisons, nests at the high visitation colony within areas of differing exposure levels were also compared.
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Oliver, Lucie Rebecca. "Mussel assemblages as biomonitors of anthropogenic disturbance in estuarine environments." Thesis, Bangor University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438829.

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Cameron, Laura Jean. "Anthropogenic natures : Wicken Fen and histories of disturbance 1923-1943." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249030.

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Pickell, Paul Drew. "Characterizations of boreal anthropogenic disturbance regimes from multi-scalar Earth observations." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55965.

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Anthropogenic disturbance regimes are anticipated to overwhelm Earth’s ecosystems during the Anthropocene. Boreal forests are particularly at risk of significant transition due to human appropriation of renewable and non-renewable resources. Forestry and energy development in the boreal forest have three primary ecological consequences: suppression of historical disturbance regimes such as fire; emergence of novel ecosystems; and the eradication of ecological memory, which maintains ecological integrity. The objective of this dissertation is to improve our understanding of the pattern characteristics of anthropogenic disturbance regimes in order to mitigate the negative, unintended outcomes of managed boreal forests. Anthropogenic disturbance from forest harvesting and energy development was mapped for industrialized landscapes of Alberta, Canada between 1949 and 2012. A comparative analysis using spatial models of unsuppressed fires sampled across Alberta and Saskatchewan and aerially-interpreted forest inventory data revealed that the anthropogenic disturbance patterns were beyond the historical range-of-variability in terms of disturbed area, largest patch size, and undisturbed forest remnants. When the spatial data were segmented based on a recent period of intensive energy development, it was determined that energy development in Alberta was a major driver of cumulative anthropogenic disturbance patterns. Levels of undisturbed forest remnants within anthropogenic disturbances declined between 18-34% and edge density increased between 15-175% following energy development. Landscape-level patterns of forest cover changes were assessed using a time series of satellite imagery between 1985 and 2010. Forest disturbance was classified as resource extraction or fire in the Foothills of Alberta with 94% overall accuracy. The rate of resource extraction exceeded fire, accounting for 86% of annual forest disturbance, indicating that fire was suppressed in the landscape. A time series pattern analysis approach applied across Canada demonstrated that managed boreal forests were associated with rising edge density, declining core forest cover, and declining largest forest patch size. Boreal forests that had low disturbance rates were characterized by inherent forest cover pattern variation. This dissertation advanced new perspectives on conceptualizing, detecting, and characterizing patterns of anthropogenic disturbance regimes. Future work is identified primarily around the development and interpretation of landscape structure thresholds and transition indicators.
Forestry, Faculty of
Graduate
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Dafforn, Katherine Ann Biological Earth &amp Environmental Sciences Faculty of Science UNSW. "Anthropogenic modification of estuaries: disturbance and artificial structures influence marine invasions." Awarded by:University of New South Wales. Biological, Earth & Environmental Sciences, 2009. http://handle.unsw.edu.au/1959.4/44778.

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Estuarine environments are threatened by the synergistic effects of anthropogenic disturbance and bioinvasion. The construction of artificial structures (such as pilings and pontoons) provides a habitat resource in close proximity to vessel hulls that may be carrying a wide range of non-indigenous fouling species. In addition, the release and accumulation of toxicants from antifouling (AF) paints on vessel hulls creates a chemical disturbance that may reduce the invasion resistance of native communities. This thesis examines how shipping-related disturbances affect sessile communities, and in particular what role AF paints and artificial structures play in the invasion of estuaries. Using a series of field-based experiments, I found that copper and tributyltin have the potential to influence both the transport of species to a new region, via the application of AF paints on vessel hulls, and their subsequent establishment, via the accumulation of AF biocides in estuaries. Temperature, pH, salinity and turbidity were also related to species distributions. During subtidal surveys of artificial and natural structures I found more non-indigenous species (NIS) on pilings and pontoons than on rocky reef, and shallow floating structures were identified as hotspots for invaders. These findings suggest that artificial structures play an important role in the initial establishment of sessile non-indigenous species in new regions. A subset of NIS were also present on the reefs sampled during the survey and I conducted manipulative experiments to determine factors affecting the invasibility of turf and canopy-forming algal assemblages. The resident assemblage provided a barrier to most invaders, particularly when light and sedimentation levels were also high (i.e. on horizontal substrate). My results suggest that the areas of reef most susceptible to invasion are vertical rock walls and those subjected to disturbances that release space. In summary, this is the first study to relate copper and tributyltin contamination in the field to NIS distributions. My research has also highlighted the potential role of artificial structures in facilitating the establishment of NIS in estuaries and identified invasion threats to rock wall communities and disturbed reefs in estuarine systems.
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Sundin, Josefin. "Sex in Murky Waters : Anthropogenic Disturbance of Sexual Selection in Pipefish." Doctoral thesis, Uppsala universitet, Zooekologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-195861.

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Animals experience variation in their environment because of natural changes. However, due to anthropogenic disturbance, the speed and severity of these changes have recently increased. This thesis investigates how reproductive behaviours may be affected by human induced environmental change. In specific, I investigate how visual and chemical changes in the aquatic environment, caused by eutrophication, affect mating systems and sexual selection in fish. Broad-nosed- and straight-nosed pipefish, which both have been studied in detail for a long period, were used as model organisms. These two species are particularly suitable model organisms since they perform complex courtship behaviours, including the advertisement of ornaments and a nuptial dance. Further, two distinct populations were studied, one on the Swedish west coast and one in the Baltic Sea, as these two locations vary in the degree and extent of environmental disturbance, in particular turbidity. I found that changes in the visual environment had no impact on the development of female sexual ornaments in these sex-role reversed pipefishes, but it hampered adaptive mate choice. Turbidity also had a negative effect on reproductive success in the Baltic Sea population. Changes in the chemical environment in the form of increased pH reduced the probability to mate, while hypoxia did not alter mating propensity. However, hypoxic water delayed the onset of both courting and mating. Hence, human induced change in aquatic environments may alter the processes of sexual selection and population dynamics.
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Forbes, Bruce Cameron. "Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196.

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The literature of disturbance ecology reveals that, under present climatic conditions, non-native plants have little or no role in high arctic tundra revegetation. Rather, it has been suggested that indigenous flora, especially long-lived perennial graminoids, are crucial to recovery. However, few long-term data are available on past impacts within productive sedge-meadows in the High Arctic, and none which consider the non-vascular flora.
This thesis combines biogeographical and patch dynamics perspectives to focus on $ geq$21 yr of natural and assisted recovery of vegetation and soils from a wide range of dated anthropogenic surface disturbances at three Canadian Arctic sites. Empirical, experimental and archival investigations were made among climatically similar, but widely disjunct, coastal lowlands of contrasting geologies on Baffin, Devon, and Cornwallis Islands. These data encompass minerotrophic and oligotrophic wetlands in which the vascular floras show minimal differentiation yet the sampled bryofloras share only 31.8% of their total taxa. The occurrences chosen for study are representative of the most widespread, small-scale human impacts in the North, including vehicular, pedestrian, construction, and pollution disturbances.
It was determined that rutting from even a single passage of a tracked vehicle in summer resulted in significant reductions in species richness and biomass. On slopes $ geq$2$ sp circ$, these same small ruts have drained large areas of peatlands, a serious cumulative impact. Long-term effects of drainage include the local extinction of populations of Sphagnum spp. and rhizomatous vascular aquatics, and changes in the chemistry and thermal regime of drained mineral soils. Other effects include significant changes in biomass and the concentrations of macronutrients in the leaves of dominant species. These effects were magnified in peatlands drained where multi-pass vehicle movements occurred.
Species richness displayed an inverse relationship with trampling intensity and the soils of heavily trampled ground remained severely compacted after 21 years. These patches were dominated by dense swards of ruderal grasses. Nutrient concentrations in the leaves of the latter and other colonizing and surviving species tended to increase with trampling intensity. Trampled patches and archaeological sites appeared selectively grazed by several herbivores. Although humans initiated the disturbances within these patches, it is the animals which are responsible for many of the dynamics of patch change over the long-term.
Classification and ordination procedures revealed linkages between the floristic associations of trampled meadows on Baffin Island and archaeological sites on Devon and Cornwallis Islands. One critical implication is that even low levels of human impact may give rise to ruderal plant communities which are extremely persistent. These patches are poor in terms of species richness, but contribute to habitat heterogeneity at the landscape level and comprise preferred forage for local vertebrate herbivores.
Archaeological excavation and restoration revealed that at least some stores of viable seed exist in both mesic and wet tundra soils and point to the importance of initial floristic composition (sensu Egler 1954). From a long-term perspective, the data establish that mesic tundra vegetation and soils are easily disturbed and recover much more slowly than their low arctic counterparts under similar disturbance regimes.
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Fox, 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.

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The aim of this thesis is to examine the role of anthropogenic disturbance in the creation of a socio-ecological landscape. Three key questions were answered: what impact has past anthropogenic disturbance had on present vegetative characteristics; what value did this disturbed landscape have to local people; how did the local peoples' worldviews and eco-cosmologies influence how they perceived, valued and managed their landscape? Research was based in a rural, predominantly amaXhosa village in the Kat River valley, Eastern Cape, South Africa. Four major landscape components characterised the environment, namely dense forests, former grazing lands, abandoned fields and old settlements. A combination of qualitative and quantitative methods were adopted, consisting of a vegetation and soil survey and social science methods including semistructured interviews, focus groups, transect walks and participant observation. The key finding was that anthropogenic disturbance is necessary to enhance the potential of the area to support human habitation. However, anthropogenic disturbance can have positive or negative effects for both local people and the environment. An intermediate level of disturbance is a key factor leading to a resilient socio-ecological system. Various anthropogenic disturbances have had significant affects on vegetation characteristics in terms of species richness, and a change in vegetation composition and species heights. Of the three anthropogenic landscapes examined, former grazing lands were the least intensively disturbed. They were also more species rich and structurally diverse than areas that were under agricultural production or used as a settlement. Dense forests, although the least desirable landscape to local people were, together with sacred pools, sources of ecosystem renewal and played a critical role during times of disturbance. Anthropogenic disturbance has added value to local people's livelihoods; this disturbance has resulted in a patchy landscape that supplies a wide variety of resources to local people. Local people are dependent on their environment for their basic needs; this has encouraged sustainable management practices. The local AmaXhosa still retain many elements of their traditional worldview, which has many characteristics of Animism. The environment is an integral component of their belief system and certain sites and species have significant cultural value and are protected.
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Piller, Leanne M. "An intertidal monitoring program for Mobil, Port Stanvac (Sth. Australia) : anthropogenic versus natural disturbance /." Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09SM/09smp6407.pdf.

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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.

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42

Warwick-Evans, V. C. "Assessing the potential impacts of anthropogenic disturbance on seabirds : a case study from Alderney." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3001637/.

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Seabirds are threatened by multiple anthropogenic pressures in the marine environment. These pressures may be short- or long- term and impacts may be either direct or indirect and affect reproduction or survival. Marine Renewable Energy Installations (MREIs) provide a relevant, and spatially explicit, example of such pressures. However, there is currently very little empirical evidence as to how MREIs will impact seabirds. Studies have shown that potential impacts are likely to be species and device specific, temporary or long term, and both positive and negative. Current approaches to predict and assess these impacts from MREIs rely on understanding the species- specific risk of devices (e.g. by making predictions based on the ecology of the seabird), the occurrence of individual species at-sea (e.g. from boat-based surveys), and demographic studies of breeding populations (e.g. through long-term ringing studies). However, these approaches are limited in their ability to detect changes in the distribution of seabirds at-sea and at breeding colonies. They may omit the impacts on non-breeding birds, and overlook the cumulative impacts of multiple pressures on specific populations when predicting potential impacts. Alderney in the English Channel hosts internationally and nationally important seabird colonies, in addition to providing a suitable environment for the installation of tidal turbines. Additionally, the home range area of the colony of Northern gannets Morus bassanus breeding just offshore of Alderney overlaps with nine sites proposed for the development of MREIs, thus Alderney provides an ideal site for this type of study. This thesis explores simple approaches to predict and assess the impacts of proposed MREIs on seabirds, and demonstrates how the large amount of existing seabird tracking data can be used to predict the colony specific impacts of spatial change on seabirds. These approaches are developed at our Alderney study site but are broadly applicable elsewhere. Overall our results suggest that the MREIs proposed for development around Alderney and the English Channel are unlikely to cause population level impacts to the seabirds breeding on, and around, Alderney. With ever increasing human pressures on the marine environment it is vital that we identify robust approaches with which to predict and monitor the impacts of these pressures. This thesis provides simple, robust and cost-effective approaches to predict and assess the potential impacts of spatial change on seabirds, and could be easily adapted for other sites, and for alternative types of spatial change.
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Persha, Lauren. "Decentralized forest management, anthropogenic disturbance patterns and forest change in the Usambara Mountains, Tanzania." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337272.

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Thesis (Ph.D.)--Indiana University, School of Public Environmental and Affairs, 2008.
Title from PDF t.p. (viewed on Jul 28, 2009). Source: Dissertation Abstracts International, Volume: 69-12, Section: B, page: 7386. Adviser: James C. Randolph.
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Breland, Bianca Patricia. "The effects of anthropogenic disturbance on weedy characteristics of the common sunflower, Helianthus annuus." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337077.

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Pereira, Costa Raquel Filomena. "Behavioural flexibility in wild mountain gorillas and implications for its conservation: Anthropogenic impacts on species-specific behaviours." Kyoto University, 2021. http://hdl.handle.net/2433/261605.

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付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院
Kyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第22878号
理博第4644号
新制||理||1668(附属図書館)
京都大学大学院理学研究科生物科学専攻
(主査)准教授 足立 幾磨, 准教授 Michael Alan Huffman, 教授 高田 昌彦
学位規則第4条第1項該当
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Groothedde, Julia. "Mother-pup interaction and the impact of anthropogenic disturbance in wild harbour seals (Phoca vitulina)." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68157.

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This study investigated the abundance of harbour seals (Phoca vitulina) on inter-tidal sandbanks, mother-pup interactions as well as the impact of anthropogenic disturbance during breeding season. The abundance was a composite picture of harbour seals of different age and sex, and increased gradually towards peaks in June. Although the sandbank water inlet was the longest time emerged, mother-pup pairs and other seals hauled out more abundant on the other sandbanks, probably due to space availability, differences in sandbank structure and distance to human activity. Mothers and their offspring were found to be mostly inactive during haul out. Mothers initiated significantly more frequently interactions i.e. hauling out, entering water and suckling. Seals hauled out at sandbanks close to the dyke were most frequently disturbed by pedestrians. Important regarding the impact on the seals seemed to be the group size of pedestrians and the distance to the seals (on dyke or seaside of it), i.e. pedestrians seaside disturbed more seals. This applies also to the disturbance by marine activity, e.g. distance of seals to the engine boat. Jet fighters were shown to affect the highest mean number of seals per event. After anthropogenic disturbances separations of mother and offspring were not recorded, e.g. due to seals being in the water; however, the steep edges as result of the culvert at water inlet lead to a few separations. The most frequent behavioural response towards anthropogenic disturbance was commotion with a probably lower level of energy costs during the energy consuming lactation period.
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Glatzel, Stephan [Verfasser]. "The influence of anthropogenic disturbance on the greenhouse gas exchange of hydromorphic soils / Stephan Glatzel." Aachen : Shaker, 2005. http://d-nb.info/1186589582/34.

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Fontana, Giovanni <1978&gt. "Natural patterns and anthropogenic disturbance in north Adriatic marine benthic assemblages: descriptive and methodological studies." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1772/.

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Marine soft bottom systems show a high variability across multiple spatial and temporal scales. Both natural and anthropogenic sources of disturbance act together in affecting benthic sedimentary characteristics and species distribution. The description of such spatial variability is required to understand the ecological processes behind them. However, in order to have a better estimate of spatial patterns, methods that take into account the complexity of the sedimentary system are required. This PhD thesis aims to give a significant contribution both in improving the methodological approaches to the study of biological variability in soft bottom habitats and in increasing the knowledge of the effect that different process (both natural and anthropogenic) could have on the benthic communities of a large area in the North Adriatic Sea. Beta diversity is a measure of the variability in species composition, and Whittaker’s index has become the most widely used measure of beta-diversity. However, application of the Whittaker index to soft bottom assemblages of the Adriatic Sea highlighted its sensitivity to rare species (species recorded in a single sample). This over-weighting of rare species induces biased estimates of the heterogeneity, thus it becomes difficult to compare assemblages containing a high proportion of rare species. In benthic communities, the unusual large number of rare species is frequently attributed to a combination of sampling errors and insufficient sampling effort. In order to reduce the influence of rare species on the measure of beta diversity, I have developed an alternative index based on simple probabilistic considerations. It turns out that this probability index is an ordinary Michaelis-Menten transformation of Whittaker's index but behaves more favourably when species heterogeneity increases. The suggested index therefore seems appropriate when comparing patterns of complexity in marine benthic assemblages. Although the new index makes an important contribution to the study of biodiversity in sedimentary environment, it remains to be seen which processes, and at what scales, influence benthic patterns. The ability to predict the effects of ecological phenomena on benthic fauna highly depends on both spatial and temporal scales of variation. Once defined, implicitly or explicitly, these scales influence the questions asked, the methodological approaches and the interpretation of results. Problem often arise when representative samples are not taken and results are over-generalized, as can happen when results from small-scale experiments are used for resource planning and management. Such issues, although globally recognized, are far from been resolved in the North Adriatic Sea. This area is potentially affected by both natural (e.g. river inflow, eutrophication) and anthropogenic (e.g. gas extraction, fish-trawling) sources of disturbance. Although few studies in this area aimed at understanding which of these processes mainly affect macrobenthos, these have been conducted at a small spatial scale, as they were designated to examine local changes in benthic communities or particular species. However, in order to better describe all the putative processes occurring in the entire area, a high sampling effort performed at a large spatial scale is required. The sedimentary environment of the western part of the Adriatic Sea was extensively studied in this thesis. I have described, in detail, spatial patterns both in terms of sedimentary characteristics and macrobenthic organisms and have suggested putative processes (natural or of human origin) that might affect the benthic environment of the entire area. In particular I have examined the effect of off shore gas platforms on benthic diversity and tested their effect over a background of natural spatial variability. The results obtained suggest that natural processes in the North Adriatic such as river outflow and euthrophication show an inter-annual variability that might have important consequences on benthic assemblages, affecting for example their spatial pattern moving away from the coast and along a North to South gradient. Depth-related factors, such as food supply, light, temperature and salinity play an important role in explaining large scale benthic spatial variability (i.e., affecting both the abundance patterns and beta diversity). Nonetheless, more locally, effects probably related to an organic enrichment or pollution from Po river input has been observed. All these processes, together with few human-induced sources of variability (e.g. fishing disturbance), have a higher effect on macrofauna distribution than any effect related to the presence of gas platforms. The main effect of gas platforms is restricted mainly to small spatial scales and related to a change in habitat complexity due to a natural dislodgement or structure cleaning of mussels that colonize their legs. The accumulation of mussels on the sediment reasonably affects benthic infauna composition. All the components of the study presented in this thesis highlight the need to carefully consider methodological aspects related to the study of sedimentary habitats. With particular regards to the North Adriatic Sea, a multi-scale analysis along natural and anthopogenic gradients was useful for detecting the influence of all the processes affecting the sedimentary environment. In the future, applying a similar approach may lead to an unambiguous assessment of the state of the benthic community in the North Adriatic Sea. Such assessment may be useful in understanding if any anthropogenic source of disturbance has a negative effect on the marine environment, and if so, planning sustainable strategies for a proper management of the affected area.
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Glatzel, Stephan Nicolaus [Verfasser]. "The influence of anthropogenic disturbance on the greenhouse gas exchange of hydromorphic soils / Stephan Glatzel." Aachen : Shaker, 2005. http://nbn-resolving.de/urn:nbn:de:101:1-2019051909153994750530.

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Menberu, M. W. (Meseret Walle). "Hydrology of peat-dominated headwater catchments:theories and empirical analysis of the impacts of anthropogenic disturbance." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526219370.

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Abstract Peatland drainage affects about half the peatland area in Finland. Drainage changes natural peatland hydrology and affects water quality through effects on peat decomposition, mineralization, and enhanced mobilization. Runoff water from degraded peatlands transports metals and nutrients and impairs downstream water quality. Peatland restoration through drain blocking can reverse or minimize the negative effects and return degraded peatlands to their natural state over time. In this thesis, a before-after-control-impact study was applied at national scale to 44 boreal peatlands representative of a south-north boreal climate gradient, to study peatland watertable and pore water quality responses to drainage and restoration. Runoff dynamics, watertable levels, and associated characteristics were studied after peatland forestry drainage and subsequent restoration at seven sites. Analysis of watertable-related hydrological responses of 24 drained and restored sites and 19 undisturbed control sites revealed that restoration generally returned watertable levels and fluctuations at restored sites to near-undisturbed levels. This created favorable high-watertable conditions under which peatland species typically flourish. Examination of drainage/restoration effects on local geochemical conditions by studying pore water quality at the same sites revealed that, compared with undisturbed sites, forestry drainage increased dissolved organic carbon (DOC), total phosphorus (Ptot), and total nitrogen (Ntot). Nutrient concentrations continued to increase in the first year after restoration because of significant peatland disturbance, but DOC and nutrient concentrations declined to near-undisturbed levels over time. Watertable level, soil and air temperature, peatland class, and trophic level influenced pore water quality. An investigation of catchment-scale runoff processes in response to drainage and restoration revealed the complexity of runoff dynamics in peatlands. The amount of event runoff water varied between sites, but disturbed sites had higher mean runoff efficiency than undisturbed sites. Raising the watertable increased mean runoff efficiency compared with drained and undisturbed control sites, as shown by higher mean event runoff coefficient. In periods of no rainfall, low flow in all treatment conditions (disturbed, restored, undisturbed) was similar. During rainfall, the drainage networks at disturbed sites created short flow paths and water reached the outlets faster. Watertable-related storage (i.e., specific yield) at disturbed sites was significantly smaller than at other sites, but restoration raised the watertable to near-undisturbed levels into the layer of less decomposed and significantly higher specific yield. Comparing the success of restoration against peatland ecological functions revealed some improvements to restoration techniques that could improve restoration efficiency. However, better hydrological indicators of peatland disturbance are needed
Tiivistelmä Suomessa on ojitettu iso pinta-ala turvemaita. Ojituksen seurauksena turvemaiden hydrologia on muuttunut ja valumavesien laatu heikentynyt orgaanisen aineksen hajoamisen, mineralisaation ja ravinteiden liikkeellelähdön seurauksena. Valumavedet sisältävät usein metalleja ja ravinteita, jotka heikentävät alapuolisten vesistöjen laatua ja ekologista tilaa. Turvemaiden ennallistaminen ojia tukkimalla tai patoamalla voi vähentää näitä haitallisia vaikutuksia ja palauttaa suoekosysteemin luonnollisen toiminnan ajan saatossa. Tässä väitöstyössä hyödynnettiin kansallista soiden ennallistamisen monitorointiverkostoa, jossa on vedenlaadusta, valunnasta ja vesipintojen korkeudesta aineistoa ennen ja jälkeen soiden ennallistamisen sekä vastaavaa aineistoa luonnontilaisilta vertailualueilta. Tämä aineisto mahdollisti ojituksen ja ennallistamisen hydrologisten vaikutusten tutkimisen ”Ennen-Jälkeen-Kontrolli” – asetelmalla. Tutkimuksessa oli 44 tutkimuskohdetta, jotka edustivat kattavasti Suomen eri ilmastovyöhykkeitä. Näistä seitsemällä kohteella tutkittiin myös valunnan muodostumisen dynamiikkaa turvemetsätalousmailla, ennallistetuilla soilla sekä luonnontilaisilla soilla. Tutkimuksen havaittiin, että ennallistamisen seurauksena vesipintojen taso ja vaihtelu palautui (24 kohdetta) lähelle luonnon tilaa (19 kohdetta). Tulos osoittaa, että kunnostus mahdollistaa suoekosysteemille tyypillisten kasvien palautumisen. Vedenlaatuun liittyvät selvitykset sen sijaan osoittivat, että ojituilla alueilla liuennut orgaaninen hiili (DOC), kokonaisfosfori (Ptot) ja kokonaistyppi (Ntot) pitoisuudet olivat korkeita huokosvesissä. Ravinnepitoisuudet kohosivat edelleen ensimmäisenä vuotena ennallistamisen jälkeen, sillä varsinaiset ennallistamistoimet (puiden kaato, ojien tukkiminen) aiheuttivat häiriötä alueella. Tästä huolimatta DOC ja ravinnepitoisuudet laskivat lähemmäksi luonnontilaisia vertailualueita seuraavina vuosina. Aineiston perusteella, vesikorkeus, maaperän ja ilman lämpötila, suotyyppi ja suon ravinnetaso vaikuttivat veden laatuun. Valunnan vasteet valuma-alueella osoittivat monimutkaisia valunta-sadantaprosesseja turvemailla. Nuoren veden osuus valunnasta sateiden jälkeen vaihteli suuresti tutkimuskohteilla, mutta ojitetuilla/myöhemmin ennallistetuilla kohteilla oli keskimääräistä suurempi valunnan osuus kuin luonnontilaisilla vertailualueilla. Vesikorkeuden nosto ennallistuksessa lisäsi valunnan määrää verrattuna ojitettuun tilanteeseen tai luonnontilaiseen tilanteeseen. Ajanjaksoilla, ilman sadantaa, valuntaprosessit olivat hyvin samankaltaiset ojitetuilla ja myöhemmin ennallistetuilla sekä luonnontilaisilla vertailualueilla. Sateiden jälkeen ojaverkosto muodosti lyhyitä virtausreittejä ja viipymää valuma-alueella. Vesivarastoa kuvaava ominaisantoisuus oli ojitetuilla aluilla merkittävästi heikompi kuin luonnontilaisilla kohteilla. Ennallistaminen vedenkorkeutta nostamalla sen sijaan näkyi merkittävästi korkeampana ominaisantoisuutena. Tätä selittää heikommin maatunut turvekerros suon pinnalla. Työn tulokset edistävät tietoa suokunnostuksen hydrologiasta. Tuloksia voidaan käyttää arvioimaan ja suunnittelemaan soiden ennallistamisen toimenpiteitä ja vaikutuksia
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