Dissertations / Theses on the topic 'Landscape processes'
To see the other types of publications on this topic, follow the link: Landscape processes.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Landscape processes.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Boesing, Andrea Larissa. "Landscape processes underpinning bird persistence and avian-mediated pest control in fragmented landscapes." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-16032017-134918/.
Full textAbstract:
The influence of habitat loss on biodiversity is related to a set of non-linear processes, which strongly affect isolation and connectivity and determine both extinction and colonization rates. Landscape changes due anthropogenic disturbances are driving not only species loss per se, but also loss of functions performed by those species, which could have important impacts on the provision of ecosystem services and ecosystem function. The objective of this dissertation is to move beyond our current understanding about landscape processes underpinning bird persistence and avian-mediated pest control in fragmented landscapes. In chapter 1, we systematically review the empirical evidence of landscape structure effects on avian-mediated pest control in agricultural systems worldwide in order to point out the main landscape processes underpinning ecosystem service provision and gaps in knowledge where research efforts should be focused. We have found 226 bird species that provide pest regulation worldwide, and a substantial proportion of those are native habitat-dependent species in tropical systems. Moreover, more heterogeneous landscapes, increased habitat amount, and decreased isolation among patches are positively associated with increased avian-mediated pest control rates. Then, using bird data collected in fragmented landscapes in the Brazilian Atlantic forest, in chapter 2 we test for community-level extinction thresholds across a range of biodiversity indices (taxonomic, functional, and phylogenetic diversity) in order to evaluate how much habitat is need to maintain sustainable ecosystem functioning and ecosystem resilience, and how matrix composition might affect these thresholds. In general, we have found that more permeable matrices are able to postpone species loss in fragmented landscapes. However, since habitat loss reaches 20% of habitat remaining, all aspects of biodiversity are compromised. Finally, in chapter 3 we investigate the cross-habitat spillover process - one of the main processes regulating avian-mediated pest control in tropical regions. Matrix composition is a key factor in facilitating species movement into matrices, as 24% of the species pool can spill over into coffee plantations, while spillover into pasture is nearly non-existent. Moreover, the interaction between forest cover and edge density is an important predictor of spillover when habitat amount is low. Our results suggest that landscape configuration and matrix composition should be considered when planning agricultural landscapes in order to ensure long-term persistence of biodiversity and ecosystem services provisionO efeito da perda de habitat sobre a biodiversidade está ligado a um conjunto de processos não-lineares que fortemente afetam a conectividade e o isolamento da paisagem, e determinam taxas de extinção e colonização. Mudanças na estrutura da paisagem desencadeadas por distúrbios antropogênicos levam não somente à perda de espécies per se, mas também a perda de funções que estas espécies desempenham no ecossistema, com importantes implicações em termos de funcionalidade e provisão de serviços ecossistêmicos. O objetivo geral desta tese é elucidar os processos, que ocorrem no nível da paisagem, que modulam a persistência de aves e, consequentemente, as funções destas aves na provisão do controle de pragas em paisagens fragmentadas. No primeiro capítulo da tese, nós revisamos sistematicamente as evidências empíricas dos efeitos da estrutura da paisagem sobre o controle de pragas provido por aves em sistemas agrícolas ao redor do mundo, identificando os processos, no nível da paisagem, subjacentes a este controle e as lacunas de conhecimento onde futuros esforços devem ser concentrados. Identificamos 226 espécies de aves provendo controle de pragas em sistemas agrícolas, sendo que uma porção substancial destas espécies em sistemas tropicais são dependentes de habitats nativos. Em geral, paisagens mais heterogêneas, com elevada cobertura de habitat nativo e menor isolamento entre fragmentos estão positivamente relacionados com elevadas taxas de controle de pragas provido por aves. Por conseguinte, no segundo capítulo, usamos dados de aves em paisagens fragmentadas emersas em diferentes contextos de matriz agrícola na Mata Atlântica brasileira, para testar limiares de extinção ao nível de comunidade. Foram usadas diferentes métricas de diversidade biológica (taxonômica, funcional e filogenética), com o intuito de avaliar o quanto de habitat é necessário para garantir o funcionamento e resiliência do ecossistema. Nós encontramos que matrizes mais permeáveis são capazes de postergar a perda de espécies em paisagens fragmentadas, no entanto, quando a perda de habitat alcança o limiar crítico de 20%, todos os aspectos da biodiversidade estão comprometidos, independentemente do tipo de matriz. Por fim, no capítulo 3, nós investigamos o processo de \'transbordamento\' (i.e. spillover), um dos principais processos reguladores da provisão do serviço de controle de pragas pela biota dependente de habitats nativos. Nós demonstramos que a composição da matriz é um fator determinante facilitando o movimento de espécies para as matrizes agrícolas, sendo que 24% do pool de espécies consegue utilizar matrizes de cafezal, enquanto este movimento é quase inexistente em matrizes de pastagem. Ademais, em paisagens com pouca cobertura florestal, a interação entre cobertura florestal e densidade de borda é um importante preditivo do spillover. Nossos resultados sugerem que a configuração da paisagem e a composição da matriz devem ser consideradas no planejamento de paisagens agrícolas para garantir a persistência em longo prazo da biodiversidade e a provisão de serviços ecossistêmicos
2
Westerberg, Lars. "Population processes in heterogenous landscapes /." Linköping : Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/tek897s.pdf.
Full text
3
Tsou, Ching-Ying. "Landscape Evolution by Fluvial Processes and Gravitational Slope Processes in Tectonically Active Mountains in Taiwan." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188494.
Full text
4
Greenwald, Katherine Rose. "Habitat fragmentation, functional landscape connectivity, and metapopulation processes in amphibians." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243366608.
Full text
5
Greenwald, Katherine R. "Habitat fragmentation, functional landscape connectivity, and metapopulation processes in amphibians." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243366608.
Full text
6
Marstellar, Tina L. "Investigating sediment source to sink processes in a post-orogenic landscape." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47549.
Full textAbstract:
In order to understand the life cycle of a mountain range, it is crucial to identify and quantify the processes that influence the rate of denudation, sediment flux through the landscape, and the resulting changes in relief over long time scales in tectonically-inactive regions. Geologic history and the quartz-rich lithologies make the southern Appalachian Mountains an ideal location for terrestrial cosmogenic nuclide (TCN) measurements aimed at studying erosion and denudation processes in an evolving post-orogenic landscape. We used in situ-produced TCN measurements of Beryllium-10 (10Be) to determine the denudation rate in ten catchments along the southern Appalachians. The locations selected are all within the east-draining Blue Ridge escarpment in North Carolina and Georgia. In five of the ten catchments we sampled two grain sizes, gravel and sand. In the remaining five catchments we sampled one grain size, sand. Our analysis provided erosion rates of 15 to 26 mm Ky-1 for the 0.025 to 0.050 cm sand samples and 12 to 20 mm Ky-1 for 3 to 8 cm gravel samples. We analyzed these TCN measurements in the context of several basin metrics, including slope and relief, derived from a digital elevation model (DEM). Our results provide evidence that most surficial basin metrics are not good predictors of denudation rates at a global scale, but can aid in predictions at a regional level. This finding supports the dynamic equilibrium hypothesis of landscape evolution and casts doubt on the possibility to estimate basin-wide denudation rates and watershed sediment supply at a global scale from simple metrics of basin morphology.
7
Chilton, Kristin Danielle. "Investigating the Effects of Lithology on Landscape Evolution Processes across Scales." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104740.
Full textAbstract:
Geomorphologists have long observed the influence of lithology on landscape form and evolution. However, the specific mechanisms by which this is accomplished are not well characterized. Here, I investigate the role of lithology in landscape evolution processes across spatial and temporal scales and geomorphic domains, to progress our understanding of the basic controls on the processes which shape Earth's surface. These investigations were carried out within the Valley and Ridge province of the Appalachian Mountains, where contrasts in strength of underlying lithologies (juxtaposed by Alleghanian deformation) exert a clear, dominant control on the fabric of the landscape, providing an excellent opportunity to study the influence of lithology on a variety of landscape evolution processes.
First, I assess the geomorphic function of boulders found on hillslopes and channels in the Valley and Ridge province of the Appalachians, which are sourced from resistant lithologies capping ridgelines. High-resolution UAV surveys and field mapping of boulder distributions and characteristics reveal that boulders are abundant on hillslopes and highly concentrated in channels, often trap sediment upslope, and appear to be long-lived. These observations suggest that boulders act as armor for hillslopes and channels, shielding weaker underlying units from erosion and inhibiting fluvial incision, and therefore play an important role in preserving topography in the Valley and Ridge landscape, highlighting a specific mechanism by which lithology exerts an influence on topography in this setting. Second, I investigate the relative importance of rock strength and discontinuity spacing in setting fluvial bedrock erodibility by comparing knickpoint and non-knickpoint bedrock, which correspond to end-member erodibility cases, and assess how lithology impacts knickpoint expression. Detailed field surveys of 21 lithologic knickpoints, surrounding non-knickpoint reaches, and corresponding bedrock properties reveal three key outcomes: 1) discontinuity spacing is a stronger predictor of knickpoint occurrence, and therefore more significant in setting bedrock erodibility in this setting, confirming quantitatively the hypothesis that discontinuities exert a dominant control on fluvial erodibility, 2) knickpoint expression is a function of the unique combination of characteristics within a given stratigraphic interval, and therefore highly complex and specific to local conditions, implying that knickpoint morphology should be interpreted with extreme caution, and 3) because all 21 study knickpoints occur within the same unit, inter-unit heterogeneity must be accounted for before lithologic influence on channel profile convexities can be ruled out, rather than comparing to geologic map contacts. These findings represent an important contribution towards a more functional understanding of the influence of lithology on fluvial bedrock incision processes.Doctor of Philosophy
It has long been observed that underlying geology has a strong impact on the shape of the surrounding landscape and influences the erosional processes that act within that landscape. However, though the importance of rock type in shaping landscapes is recognized, the specific mechanisms by which this is accomplished are not well understood. The work presented here investigates the role of rock type and rock properties in landscape evolution processes in both hillslope and river environments within the Valley and Ridge Province of the Appalachian Mountains. This setting is ideally suited for investigating the role of rock type on landscape evolution processes because of the wide variation in rock types present in this setting, which exert a strong influence on local topography (e.g., strong rocks form ridges while weak rocks underlie valleys). First, I mapped the distribution of large boulders on local Valley and Ridge slopes and mountain streams to assess the potential for these boulders to play a role in preserving local topography. Results show that boulders are sourced from resistant rock types found along ridgelines, and are abundant on hillslopes and highly concentrated in channels. Boulders also trap sediment upslope and appear to remain in place for long periods of time. These observations suggest boulders play an important role in slowing erosion of weaker rock types underlying hillslopes and channels, and therefore aid in preserving topography in this setting. Second, I conducted detailed surveys of local small-scale waterfalls and surrounding flat river reaches and compared properties of the bedrock between these locations to better understand how bedrock properties influence erodibility. In this setting, waterfalls often signify strong underlying bedrock relative to the rock beneath flat river reaches, so comparing bedrock properties between these areas should give insight into how properties like rock strength and bed thickness impact how erodible the bedrock is. Results show that bed thickness is the most important variable impacting bedrock erodibility in this setting, and that waterfall appearance is a product of the unique combination of bedrock properties within a given area. These results are important for improving our ability to model natural landscapes and erosional processes, and for developing a more complete understanding for the relationships between rock type and river morphology.
8
Reuter, Hannes Isaak [Verfasser]. "Spatial crop and soil landscape processes under special consideration of relief information in a loess landscape / Hannes Isaak Reuter." Hannover : Technische Informationsbibliothek (TIB), 2016. http://d-nb.info/1095502832/34.
Full text
9
Capell, René. "Modelling dominant runoff processes using tracers and landscape organisation in larger catchments." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=186120.
Full textAbstract:
This work has contributed to the understanding of dominant runoff generation at the large catchment scale and to the understanding of the relationships between landscape properties and hydrological behaviour. The developed models were used to estimate the climate change impact on the hydrology in the study catchment. A multivariate geochemical tracer survey was carried out in North Esk catchment in north east Scotland. A generic typology was developed using multivariate statistical methods to characterise the hydrochemical tracer response. Upland headwater runoff was dominant downstream in winter and provided significant flows during base flow periods in summer. These insights were complemented by a conjunctive analysis of long-term river flow data and a one year stable isotope survey. Integrative metrics of transit times, hydrometric responses, and catchment characteristics were explored for relationships at the large catchment scale. The evaluation that the associated soils and bedrocks, themselves controlling the flow path distribution, have a strong influence on the integrated hydrological catchment response. The empirically-based understanding of dominant runoff generation processes in the North Esk uplands and lowlands were used in a stepwise rainfall-runoff model development. Tracers were directly incorporated to reduce structural and parameter uncertainty. The integration of tracers helped reduce parameter uncertainty. These tracer-aided models increased confidence for using them to explore the effects of environmental change. Climate change impacts in the catchment where explored by forcing the models with projected climate change forcing from the UK Climate Projections 2009. The results revealed landscape-specific changes in the hydrological response with increased summer drought risk in the lowlands and diminishing snow influence and increased winter floods in the uplands. The spatial integration mediated the extremes observed in the subcatchments.
10
Cavazzi, Stefano. "Spatial scale analysis of landscape processes for digital soil mapping in Ireland." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8591.
Full textAbstract:
Soil is one of the most precious resources on Earth because of its role in storing and recycling water and nutrients essential for life, providing a variety of ecosystem services. This vulnerable resource is at risk from degradation by erosion, salinity, contamination and other effects of mismanagement. Information from soil is therefore crucial for its sustainable management. While the demand for soil information is growing, the quantity of data collected in the field is reducing due to financial constraints. Digital Soil Mapping (DSM) supports the creation of geographically referenced soil databases generated by using field observations or legacy data coupled, through quantitative relationships, with environmental covariates. This enables the creation of soil maps at unexplored locations at reduced costs. The selection of an optimal scale for environmental covariates is still an unsolved issue affecting the accuracy of DSM. The overall aim of this research was to explore the effect of spatial scale alterations of environmental covariates in DSM. Three main targets were identified: assessing the impact of spatial scale alterations on classifying soil taxonomic units; investigating existing approaches from related scientific fields for the detection of scale patterns and finally enabling practitioners to find a suitable scale for environmental covariates by developing a new methodology for spatial scale analysis in DSM. Three study areas, covered by detailed reconnaissance soil survey, were identified in the Republic of Ireland. Their different pedological and geomorphological characteristics allowed to test scale behaviours across the spectrum of conditions present in the Irish landscape. The investigation started by examining the effects of scale alteration of the finest resolution environmental covariate, the Digital Elevation Model (DEM), on the classification of soil taxonomic units. Empirical approaches from related scientific fields were subsequently selected from the literature, applied to the study areas and compared with the experimental methodology. Wavelet analysis was also employed to decompose the DEMs into a series of independent components at varying scales and then used in DSM analysis of soil taxonomic units. Finally, a new multiscale methodology was developed and evaluated against the previously presented experimental results. The results obtained by the experimental methodology have proved the significant role of scale alterations in the classification accuracy of soil taxonomic units, challenging the common practice of using the finest available resolution of DEM in DSM analysis. The set of eight empirical approaches selected in the literature have been proved to have a detrimental effect on the selection of an optimal DEM scale for DSM applications. Wavelet analysis was shown effective in removing DEM sources of variation, increasing DSM model performance by spatially decomposing the DEM. Finally, my main contribution to knowledge has been developing a new multiscale methodology for DSM applications by combining a DEM segmentation technique performed by k-means clustering of local variograms parameters calculated in a moving window with an experimental methodology altering DEM scales. The newly developed multiscale methodology offers a way to significantly improve classification accuracy of soil taxonomic units in DSM. In conclusion, this research has shown that spatial scale analysis of environmental covariates significantly enhances the practice of DSM, improving overall classification accuracy of soil taxonomic units. The newly developed multiscale methodology can be successfully integrated in current DSM analysis of soil taxonomic units performed with data mining techniques, so advancing the practice of soil mapping. The future of DSM, as it successfully progresses from the early pioneering years into an established discipline, will have to include scale and in particular multiscale investigations in its methodology. DSM will have to move from a methodology of spatial data with scale to a spatial scale methodology. It is now time to consider scale as a key soil and modelling attribute in DSM.
11
Yang, Jian. "Spatially explicit and stochastic forest landscape model of fire disturbance and succession." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4174.
Full textAbstract:
Thesis (Ph. D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (November 14, 2006) Vita. Includes bibliographical references.
12
Stoy, Padraic Fitzgerald. "A review of landscape influences on riparian zone processes in mountainous headwater catchments." Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/stoy/StoyP1212.pdf.
Full textAbstract:
Understanding the drivers of riparian zone hydrology is crucial for informed management of water quality, especially in headwater catchments. This study reviews landscape influences on riparian zone processes in mountainous headwater catchments, and combines recent findings and management techniques into a conceptual analysis of riparian zone hydrology and nutrient export. A case study synthesizing recently published work in Tenderfoot Creek Experimental Forest (TCEF) is developed outlining riparian zone hydrology, riparian buffering, and nutrient export. We demonstrate that a major influence on the hydrology and nutrient export in mountainous catchments can be landscape structure, and use this finding as a framework to develop a conceptual approach to riparian zones in mountainous areas. The conceptual analysis is intended to inform management through the identification of riparian areas that are important for stream water quality depending on hydrologic drivers in the catchment. Understanding the variability of riparian zone hydrology and subsequent water quality impacts will allow for more focused and informed management decisions for riparian areas.
13
Tranel, Lisa Marie. "Evaluation of Coupled Erosional Processes and Landscape Evolution in the Teton Range, Wyoming." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/38693.
Full textAbstract:
The evolution of mountain landscapes is controlled by complex interactions between large-scale tectonic, surficial and climate conditions. Dominant processes are attributed to creating characteristic features of the landscape, but topographic features are the cumulative result of coupled surficial processes, each locally effective in a different climate or elevation regime. The focus of erosion by glacial, fluvial, or mass wasting processes is highly sensitive to small changes in boundary conditions, therefore spatial and temporal variability can be high when observed over short time scales. This work evaluated methods for dissecting the history of complex alpine landscapes to understand the role of individual processes influenced by changing climate and underlying bedrock. It also investigated how individual and combined mechanisms of surficial processes influenced the evolution of topography in the Teton Range in Wyoming. Detrital apatite (U-Th)/He thermochronology and cosmogenic radionuclide erosion rates were applied to determine spatial and temporal variability of erosion in the central catchments of the range. Spatial variability existed between the glacial and fluvial systems, indicating that sediment erosion and deposition by these processes was controlled by short-term variability in climate conditions. Effective glacial incision also controlled other processes, specifically enhancing rock fall activity and inhibiting fluvial incision. Short-term erosion rates were highly variable and were controlled by stochastic processes, particularly hillslope failures in response to slope oversteepening due to glacial incision and orientation and spacing of bedrock fractures. Erosion rates averaged over 10 ky time scales were comparable to long-term exhumation rates measured in the Teton Range. The similarity of spatial erosion patterns to predicted uniform erosion and the balance between intermediate and long-term erosion rates suggests the landscape of the Teton Range is approaching steady-state, but frequent stochastic processes, short-term erosional variability and coupled processes maintain rugged topographic relief.Ph. D.
14
Larsen, Laurel Griggs. "Hydroecological feedback processes governing self-organization of the Everglades ridge and slough landscape." 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:3303846.
Full textAbstract:
Thesis (Ph.D.)--University of Colorado at Boulder, 2008.Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1530. Adviser: John P. Crimaldi. Includes supplementary digital materials.
15
Oldknow, C. J. "Late Quaternary landscape evolution in the Great Karoo, South Africa : processes and drivers." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3002474/.
Full textAbstract:
The Great Karoo spans the north-central part of South Africa at a major climatic boundary. The characteristics, spatial patterns and drivers of river channel response to Late Quaternary climate changes in the Sneeuberg, South Africa remain unclear due to the discontinuous alluvial stratigraphic record and the lack of dated palaeoclimatic archives. Dendritic channel networks in the upper Sundays River are deeply incised exposing terrace fills of varying thickness (2-6 m), extent (1 - > 10km) and pedogenic overprinting. Channels exhibit 'stepped' long profiles where resistant rock strata (dolerite, sandstone) cross valley floors, but are now partially or completely breached. DGPS surveys, sediment logging, mineral magnetic measurements and radiometric dating (OSL and 14C) were used to determine the source, age structure and depositional process of valley fills and ascribe intensity of pedogenic overprinting. A conceptual model of terrace development in relation to changing conditions of connectivity was tested. First order streams were desensitised to late Quaternary base level changes downstream due to the blocking effect of two barriers, with localised autogenic 'cut and fill'. Contrastingly, the continuity of 4 fill terraces over incised barriers in 2nd-4th order tributaries indicate relatively high sensitivity to post-LGM climatic change. However, deposition of alluvium (T2) inset within periglacial deposits (T1) was partly a complex response to re-connection of the channel network with deep upland colluvial stores resulting in the valleys becoming choked with sediment. This caused a rise in groundwater and formation of extensive (> 10 km2) rootmats on valley floors, restricting depth of subsequent channel entrenchment (T3/T4). This study presents one of the first attempts in South Africa to test and explain terrace genesis and correlation using existing conceptual models for sediment connectivity. The relative roles of periglaciation and fluvial activity are shown to be key influences on dynamics of Quaternary sedimentation, pedogenesis and erosion and help to explain how sediments can be preserved over long periods (104 years) in catchments subject to base level fall.
16
Lodal, Genevieve M. "Greening the suburbs exploring the connections between suburban development and natural processes /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 118 p, 2008. http://proquest.umi.com/pqdweb?did=1597633601&sid=8&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
17
Deshpande, Amol Mukund. "Design Process to Integrate Natural and Human Systems." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9679.
Full textAbstract:
After more than a century, there are very few examples of excellent interdisciplinary work in landscape architecture, like the "Emerald Necklace" designed by Frederick Law Olmsted or Landschaftspark Duisburg-Nord by Peter Latz. Most of the projects still have only one purpose: they are either reserved for conservation as are the great national parks, or are planned for recreation or development that ignores natural systems.
"Most...landscape designers are still inspired by and primarily focused on aesthetics; society's other major objectives are secondary for them" (Richard Forman 2002, p: 85).
In 1993, American Society of Landscape Architects defined sustainable development as, "development that meets the needs of the present without compromising the future." Thus designers need to understand how natural and human systems work and design for the protection of our environmental as an integral part of any development.
Landscape architects can achieve this by borrowing principles of legendary works like the "Emerald Necklace" and combining those with new technology to meet changing cultural and ecological needs. This thesis asserts that sustainable development should be achieved by reconciling human systems and its effects on the surrounding environment by using and revealing natural systems to spread consciousness and earn attention and care for our environment.
Suitability analysis by Ian McHarg, Bioregionalism by Clair Reiniger, Regenerative design process by Lyle, and Framework for ecological design by Prof. Carl Steinitz are various design processes to create developments, which can respond to both natural and human needs.
The thesis project, Riverside Park and Biomedical Complex in the South Jefferson Redevelopment Area in Roanoke, VA, explores how a design process, consisted of framework for ecological design and principals of eco-revelatory design, can help to plan a sustainable development, which uses and reveals natural systems to reconciling human systems and its effects on the surrounding environment. The project demonstrates how a multidisciplinary approach towards landscape design can help to create a multifunctional design that meets the, ecological and cultural, needs of the present without compromising the future.Master of Landscape Architecture
18
Renwick, Anna R. "Abundance thresholds and ecological processes in a fragmented landscape field voles, parasites and predators /." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=61553.
Full text
19
Pedley, Katherine Louise. "Modelling Submarine Landscape Evolution in Response to Subduction Processes, Northern Hikurangi Margin, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/4648.
Full textAbstract:
The steep forearc slope along the northern sector of the obliquely convergent Hikurangi subduction zone is characteristic of non-accretionary and tectonically eroding continental margins, with reduced sediment supply in the trench relative to further south, and the presence of seamount relief on the Hikurangi Plateau. These seamounts influence the subduction process and the structurally-driven geomorphic development of the over-riding margin of the Australian Plate frontal wedge.
The Poverty Indentation represents an unusual, especially challenging and therefore exciting location to investigate the tectonic and eustatic effects on this sedimentary system because of: (i) the geometry and obliquity of the subducting seamounts; (ii) the influence of multiple repeated seamount impacts; (iii) the effects of structurally-driven over-steeping and associated widespread occurrence of gravitational collapse and mass movements; and (iv) the development of a large canyon system down the axis of the indentation. High quality bathymetric and backscatter images of the Poverty Indentation submarine re-entrant across the northern part of the Hikurangi margin were obtained by scientists from the National Institute of Water and Atmospheric Research (NIWA) (Lewis, 2001) using a SIMRAD EM300 multibeam swath-mapping system, hull-mounted on NIWA’s research vessel Tangaroa. The entire accretionary slope of the re-entrant was mapped, at depths ranging from 100 to 3500 metres. The level of seafloor morphologic resolution is comparable with some of the most detailed Digital Elevation Maps (DEM) onshore. The detailed digital swath images are complemented by the availability of excellent high-quality processed multi-channel seismic reflection data, single channel high-resolution 3.5 kHz seismic reflection data, as well as core samples. Combined, these data support this study of the complex interactions of tectonic deformation with slope sedimentary processes and slope submarine geomorphic evolution at a convergent margin.
The origin of the Poverty Indentation, on the inboard trench-slope at the transition from the northern to central sectors of the Hikurangi margin, is attributed to multiple seamount impacts over the last c. 2 Myr period. This has been accompanied by canyon incision, thrust fault propagation into the trench fill, and numerous large-scale gravitational collapse structures with multiple debris flow and avalanche deposits ranging in down-slope length from a few hundred metres to more than 40 km. The indentation is directly offshore of the Waipaoa River which is currently estimated to have a high sediment yield into the marine system. The indentation is recognised as the “Sink” for sediments derived from the Waipaoa River catchment, one of two target river systems chosen for the US National Science Foundation (NSF)-funded MARGINS “Source-to-Sink” initiative. The Poverty Canyon stretches 70 km from the continental shelf edge directly offshore from the Waipaoa to the trench floor, incising into the axis of the indentation. The sediment delivered to the margin from the Waipaoa catchment and elsewhere during sea-level high-stands, including the Holocene, has remained largely trapped in a large depocentre on the Poverty shelf, while during low-stand cycles, sediment bypassed the shelf to develop a prograding clinoform sequence out onto the upper slope. The formation of the indentation and the development of the upper branches of the Poverty Canyon system have led to the progressive removal of a substantial part of this prograding wedge by mass movements and gully incision. Sediment has also accumulated in the head of the Poverty Canyon and episodic mass flows contribute significantly to continued modification of the indentation by driving canyon incision and triggering instability in the adjacent slopes.
Prograding clinoforms lying seaward of active faults beneath the shelf, and overlying a buried inactive thrust system beneath the upper slope, reveal a history of deformation accompanied by the creation of accommodation space. There is some more recent activity on shelf faults (i.e. Lachlan Fault) and at the transition into the lower margin, but reduced (~2 %) or no evidence of recent deformation for the majority of the upper to mid-slope. This is in contrast to current activity (approximately 24 to 47% shortening) across the lower slope and frontal wedge regions of the indentation. The middle to lower Poverty Canyon represents a structural transition zone within the indentation coincident with the indentation axis. The lower to mid-slope south of the canyon conforms more closely to a classic accretionary slope deformation style with a series of east-facing thrust-propagated asymmetric anticlines separated by early-stage slope basins. North of the canyon system, sediment starvation and seamount impact has resulted in frontal tectonic erosion associated with the development of an over-steepened lower to mid-slope margin, fault reactivation and structural inversion and over-printing.
Evidence points to at least three main seamount subduction events within the Poverty Indentation, each with different margin responses:
i) older substantial seamount impact that drove the first-order perturbation in the margin, since approximately ~1-2 Ma
ii) subducted seamount(s) now beneath Pantin and Paritu Ridge complexes, initially impacting on the margin approximately ~0.5 Ma, and
iii) incipient seamount subduction of the Puke Seamount at the current deformation front.
The overall geometry and geomorphology of the wider indentation appears to conform to the geometry accompanying the structure observed in sandbox models after the seamount has passed completely through the deformation front. The main morphological features correlating with sandbox models include: i) the axial re-entrant down which the Poverty Canyon now incises; ii) the re-establishment of an accretionary wedge to the south of the indentation axis, accompanied by out-stepping, deformation front propagation into the trench fill sequence, particularly towards the mouth of the canyon; iii) the linear north margin of the indentation with respect to the more arcuate shape of the southern accretionary wedge; and, iv) the set of faults cutting obliquely across the deformation front near the mouth of the canyon. Many of the observed structural and geomorphic features of the Poverty Indentation also correlate well both with other sediment-rich convergent margins where seamount subduction is prevalent particularly the Nankai and Sumatra margins, and the sediment-starved Costa Rican margin. While submarine canyon systems are certainly present on other convergent margins undergoing seamount subduction there appears to be no other documented shelf to trench extending canyon system developing in the axis of such a re-entrant, as is dominating the Poverty Indentation.
Ongoing modification of the Indentation appears to be driven by: i) continued smaller seamount impacts at the deformation front, and currently subducting beneath the mid-lower slope, ii) low and high sea-level stands accompanied by variations on sediment flux from the continental shelf, iii) over-steepening of the deformation front and mass movement, particularly from the shelf edge and upper slope.
20
Geronilla, Kristina. "Re-presenting the Waterfront: revealing the intersection of human and natural processes." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35894.
Full textAbstract:
Water and waterfronts are appealing to almost any person, as a visitor or designer. This study challenges the author's design processes and understanding of the landscape as the sculpted meeting ground, intersecting human and natural physical processes. It progresses from assumptions through collaborated ideas of others in a literature review through case studies of various waterfront situations and finally to the design project of the Jones Point waterfront in Alexandria, Virginia. Here the intermingled aspects from cultural activities over time and local, physical movement of land by water are assessed to be revealed and enhanced for the visitor's benefit, use, and connection with place. For it is the author's belief that the landscape and space can be sculpted, experienced, and imagined for the purpose of connecting us to a larger framework of living systems on this planet and beyond. The design extends the city to the waterfront and vice versa with an understanding of both physical processes and cultural choices to the point of being unable to distinguish action from reaction.Master of Landscape Architecture
21
Rau, Austin. "Environmental processes of H3N2 influenza genetics and hospitalizations in Minnesota 2012-2013." Thesis, University of Iowa, 2018. https://ir.uiowa.edu/etd/6252.
Full textAbstract:
Influenza causes thousands of illnesses and deaths annually in the United States. In part, this is a product of rapid changes in influenza genetics, resulting in different variants than a previous season. Influenza virus traverses landscapes by infecting susceptible hosts, thus allowing seasonal influenza to move great distances due to the mobility of humans who occupy diverse natural, social, and built environments. Using H3N2 influenza viral sequences from Minnesota in the 2012-2013 influenza season we explored relationships between the diversity of influenza genetics and the environments in which humans live.
Landscape genetic methods were used to test for relationships between genetic diversity of influenza viruses with different concepts of distance separating the viruses in time and space. Additional analyses were used to identify relationships between influenza genetic evolution and socio-environmental characteristics of Minnesota zip code tabulation areas (ZCTAs) where those viruses were isolated. Influenza hospitalization data in Minnesota ZCTAs was also analyzed with spatial and statistical methods to compare differences and similarities between environmental features driving influenza genetic evolution and influenza morbidity.
Findings indicated a complex genetic landscape with few significant correlations between genetic distance and other distance concepts. Elderly populations and populations without health insurance were found to be drivers of H3 hospitalizations. The synthesis of information from theses analyses can be used to inform our overall understanding of influenza diffusion and will allow for more targeted and effective public health prevention strategies.
22
Bullivant, Lucy Georgina. "From masterplanning to adaptive planning : understanding the contemporary tools and processes for civic urban order." Thesis, London Metropolitan University, 2014. http://repository.londonmet.ac.uk/1108/.
Full textAbstract:
My research is an examination of the scope of contemporary urban design and planning tools and processes which can act as alternative qualitative methodologies for the renewal of urban conditions at multiple scales through adaptive methods embracing change, stresses and shocks affecting societies and the city as a growing epicentre of human inhabitation and complex systems. With growing urbanisation, the question of what constitutes liveable urbanism across urban territories is a critical one. Addressing the lack of unified and culturally aware analysis of the evolution in urban design and planning practice being applied in various contexts across the developed and developing world, I have, through my own international research programme over more than 15 years, traced their potentials for incubating renewal through a collection of published outputs, each with their own approach: a book, essays for the media and for exhibition catalogues and a webzine. Through examination I have learned about the capacities of tools and processes to break with silo thinking and damaging legacies of the past, and to adapt, or to forge new instrumentalities in ways that are context-responsive and situational. My focus has been on studying largely ongoing, phased projects, so this is a work in progress. This self-appointed intellectual mandate for comparative urbanism has required a form of evaluation that includes consideration of the use and mis-use of history and old rules, operational narratives and contestory factors, enquiry into assumptions made, responsibilities claimed, and objectives combining issues of determination (of plans, by their clients) and self-determination (of communities). I have striven to show how the recognition of planning baggage and the emptying out of its tactics, is, in diverse ways, creating space for alternative behaviors in the form of new, potentially more socially equitable and responsive patterns of operation, engaging and reusing resources. I have learned that new hybrid processes of top down and bottom up planning, and interest in engaging with multi-modal approaches with their relative novelty and unprecedented forms of complexity, represent major challenges to long-held beliefs about planning’s role in society and the typical relationships between planner and those planned for. They foster a sense of the symbiotic relationships, interdependencies, alliances and self-determination cities need to generate their futures in socially equitable and resilient ways. My body of research will help inform and contribute methodologies and concepts to future outputs on related themes concerning urban design and planning’s role and identity, including issues of Urbanista.org, my webzine. The wider implications of my research are also that institutions involved in land use of all kinds accordingly need to carry a responsibility to adopt a higher commitment to the value of and need for adaptive instruments of civic urban order.
23
Rehak, Katrin. "Pliocene-Pleistocene landscape evolution in south-central Chile : interactions between tectonic, geomorphic, and climatic processes." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1979/.
Full textAbstract:
Landscapes evolve in a complex interplay between climate and tectonics. Thus, the geomorphic characteristics of a landscape can only be understood if both, climatic and tectonic signals of past and ongoing processes can be identified. In order to evaluate the impact of both forcing factors it is crucial to quantify the evolution of geomorphic markers in natural environments.
The Cenozoic Andes are an ideal setting to evaluate tectonic and climatic aspects of landscape evolution at different time and length scales in different natural compartments. The Andean Cordillera constitutes the type subduction orogen and is associated with the subduction of the oceanic Nazca Plate beneath the South American continent since at least 200 million years. In Chile and the adjacent regions this convergent margin is characterized by active tectonics, volcanism, and mountain building. Importantly, along the coast of Chile megathrust earthquakes occur frequently and influence landscape evolution. In fact, the largest earthquake ever recorded occurred in south-central Chile in 1960 and comprised a rupture zone of ~ 1000 km length. However, on longer time scales beyond historic documentation of seismicity it is not well known, how such seismotectonic segments have behaved and how they influence the geomorphic evolution of the coastal realms. With several semi-independent morphotectonic segments, recurrent megathrust earthquakes, and a plethora of geomorphic features indicating sustained tectonism, the margin of Chile is thus a key area to study relationships between surface processes and tectonics.
In this study, I combined geomorphology, geochronology, sedimentology, and morphometry to quantify the Pliocene-Pleistocene landscape evolution of the tectonically active south-central Chile forearc. Thereby, I provide (1) new results about the influence of seismotectonic forearc segmentation on the geomorphic evolution and (2) new insights in the interaction between climate and tectonics with respect to the morphology of the Chilean forearc region.
In particular, I show that the forearc is characterized by three long-term segments that are not correlated with short-lived earthquake-rupture zones that may. These segments are the Nahuelbuta, Toltén, and Bueno segments, each recording a distinct geomorphic and tectonic evolution. The Nahuelbuta and Bueno segments are undergoing active tectonic uplift. The long-term behavior of these two segments is manifested in form of two doubly plunging, growing antiforms that constitute an integral part of the Coastal Cordillera and record the uplift of marine and river terraces. In addition, these uplifting areas have caused major changes in flow directions or rivers. In contrast, the Toltén segment, situated between the two other segments, appears to be quasi-stable.
In order to further quantify uplift and incision in the actively deforming Nahuelbuta segment, I dated an erosion surface and fluvial terraces in the Coastal Cordillera with cosmogenic 10Be and 26Al and optically stimulated luminescence, respectively. According to my results, late Pleistocene uplift rates corresponding to 0.88 mm a-1 are faster than surface-uplift rates averaging over the last 5 Ma, which are in the range of 0.21 mm a-1. This discrepancy suggests that surface uplift is highly variable in time and space and might preferably concentrate along reverse faults as indicated by a late Pleistocene flow reversal.
In addition, the results of exposure dating with cosmogenic 10Be and 26Al indicate that the morphotectonic segmentation of this region of the forearc has been established in Pliocene time, coeval with the initiation of uplift of the Coastal Cordillera about 5 Ma ago, inferred to be related to a shift in subduction mode from erosion to accretion.
Finally, I dated volcanic clasts obtained from alluvial surfaces in the Central Depression, a low-relief sector separating the Coastal from the Main Cordillera, with stable cosmogenic 3He and 21Ne, in order to reveal the controls of sediment accumulation in the forearc. My results document that these gently sloping surfaces have been deposited 150 to 300 ka ago. This deposition may be related to changes in the erosional regime during glacial episodes.
Taken together, the data indicates that the overall geomorphic expression of the forearc is of post-Miocene age and may be intimately related to a climatic overprint of the tectonic system. This climatic forcing is also reflected in the topography and local relief of the Central and Southern Andes that vary considerably along the margin, determined by the dominant surface process that in turn is eventually controlled by climate. However, relief also partly reflects surface processes that have taken place under past climatic conditions. This emphasizes that due care has to be exercised when interpreting landscapes as mirrors of modern climates.Landschaften entwickeln sich im komplexen Zusammenspiel von Klima und Tektonik. Demzufolge können sie nur verstanden werden, wenn sowohl klimatische als auch tektonische Signale vergangener und rezenter Prozesse identifiziert werden. Um den Einfluss beider Faktoren zu bewerten, ist es deshalb wichtig, die Evolution geomorphologischer Marker in der Natur zu quantifizieren. Die känozoischen Anden sind eine ideale Region, um tektonische und klimatische Aspekte der Landschaftsentwicklung auf verschiedenen Zeit- und Längenskalen zu erforschen. Sie sind das Modell-Subduktionsorogen, assoziiert mit der Subduktion der ozeanischen Nazca-Platte unter den südamerikanischen Kontinent seit ca. 200 Mio Jahren. In Chile ist dieser konvergente Plattenrand geprägt von aktiver Tektonik, Vulkanismus und Gebirgsbildung. Bedeutenderweise ereignen sich entlang der Küste häufig Megaerdbeben, die die Landschaftsentwicklung stark beeinflussen. Tatsächlich ereignete sich das größte jemals aufgezeichnete Erdbeben mit einer Bruchzone von ca. 1000 km Länge 1960 im südlichen Zentralchile. Nichtsdestotrotz ist auf längeren Zeitskalen über historische Dokumentationen hinaus nicht bekannt, wie sich solche seismotektonischen Segmente verhalten und wie sie die geomorphologische Entwicklung der Küstengebiete beeinflussen. Mit semi-unabhängigen morphotektonischen Segmenten, wiederkehrenden Megaerdbeben und einer Fülle geomorphologischer Marker, die aktive Tektonik anzeigen, ist somit der Plattenrand von Chile ein Schlüsselgebiet für das Studium von Zusammenhängen zwischen Oberflächenprozessen und Tektonik. In dieser Arbeit kombiniere ich Geomorphologie, Geochronologie, Sedimentologie und Morphometrie, um die plio-pleistozäne Landschaftsentwicklung des tektonisch aktiven süd-zentralchilenischen Forearcs zu quantifizieren. Mit dieser Analyse liefere ich (1) neue Ergebnisse über den Einfluss seismotektonischer Forearc-Segmentierung auf die geomorphologischen Entwicklung und (2) neue Erkenntnisse über die Interaktion zwischen Klima und Tektonik bezüglich der Gestaltung des chilenischen Forearcs. Ich zeige, dass der Forearc in drei langlebige morphotektonische Segmente gegliedert ist, die nicht mit kurzlebigen Erdbebenbruchzonen korrelieren. Die Segmente heißen Nahuelbuta, Toltén und Bueno Segment, wovon jedes eine andere geomorphologische und tektonische Entwicklung durchläuft. Die Nahuelbuta und Bueno Segmente unterliegen aktiver tektonischer Hebung. Das langfristige Verhalten dieser beiden Segmente manifestiert sich in zwei beidseitig abtauchenden, wachsenden Antiklinalen, die integraler Bestandteil des Küstengebirges sind und die Hebung von marinen und fluvialen Terrassen aufzeichnen. Die Hebung verursachte weitreichende Veränderungen in den Fließrichtungen des Gewässernetzes. Im Gegensatz dazu ist das Toltén Segment, das sich zwischen den beiden anderen Segmenten befindet, quasi-stabil. Um die Hebung und Einschneidung in dem tektonisch aktiven Nahuelbuta Segment zu quantifizieren, habe ich eine Erosionsfläche und fluviale Terrassen in dem Küstengebirge mit kosmogenem 10Be und 26Al bzw. optisch stimulierter Lumineszenz datiert. Meinen Ergebnissen zufolge sind die spätpleistozänen Hebungsraten, die ca. 0,88 mm a-1 betragen, höher als die Oberflächenhebungsraten, die über die letzten 5 Mio Jahre mitteln und ca. 0,21 mm a-1 betragen. Diese Diskrepanz deutet an, dass die Hebung der Oberfläche räumlich und zeitlich sehr stark variiert und sich präferiert an Aufschiebungen konzentriert. Zusätzlich zeigen die Ergebnisse der Expositionsdatierung mit kosmogenem 10Be und 26Al, dass die morphotektonische Segmentierung im Pliozän etabliert wurde, zeitgleich mit dem Beginn der Hebung des Küstengebirges vor ca. 5 Mio Jahren infolge eines Wechsels des Subduktionsmodus von Erosion zu Akkretion. Schließlich habe ich vulkanische Klasten, die aus alluvialen Flächen im Längstal stammen, mit den stabilen kosmogenen Nukliden 3He und 21Ne datiert, um Aufschluss über die Faktoren zu erhalten, die die Sedimentablagerung im Forearc bestimmen. Meine Ergebnisse weisen darauf hin, dass diese flach einfallenden Oberflächen, die vor 150.000 bis 300.000 Jahren abgelagert wurden, in Zusammenhang mit Änderungen des Erosionsregimes in glazialen Episoden entstanden sind. Zusammenfassend zeigen die Daten, dass der heutige geomorphologische Ausdruck des Forearcs post-Miozän und eng mit einer klimatischen Überprägung des tektonischen Systems verknüpft ist. Der klimatische Einfluss spiegelt sich ebenfalls in der Topographie und dem lokalen Relief der Zentral- und Südanden wider. Beide Parameter variieren stark entlang des Plattenrandes, bestimmt durch den jeweils dominierenden Oberflächenprozess, der wiederum letztendlich vom vorherrschenden Klima abhängt. Allerdings reflektiert das Relief teilweise Oberflächenprozesse, die unter vergangenen Klimaten aktiv waren. Das betont die äußerst große Vorsicht, die nötig ist, wenn Landschaften als Spiegel des aktuellen Klimas interpretiert werden.
24
Duffy, Brittany A. "Trees in the Agricultural Matrix: Reforestation Processes in a Tropical Dry Landscape in Chinandega, Nicaragua." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2608.
Full textAbstract:
Tree management practices in the tropical dry forest region of Nicaragua were examined to determine opportunities and factors influencing tree-planting initiatives and forest recovery within the agricultural matrix. A 217.11 ha tree inventory and 44 social surveys were conducted in three rural communities. The inventory found 88 species, 66.68% were native, and 70 valued for multiple uses. Farmers’ reasons for maintaining trees varied, emphasizing live fencing, wood, and fruit. The landscape also contains a tree plantation and a riparian forest, and the origins and management of these tree cover components of the landscape are also considered. Tree planting interventions should supplement extant stakeholder motivation with technical training and basic materials only as explicitly requested by participants, rather than imposing costly or inappropriate project preferences. Initiatives should also focus on smallholders and on multi-use native species suggested by stakeholders in order to maximize the economic, social and environmental benefits provided.
25
Palmtag, Juri. "Landscape partitioning and burial processes of soil organic carbon in contrasting areas of continuous permafrost." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-136383.
Full textAbstract:
Recent studies have shown that permafrost soils in the northern circumpolar region store almost twice as much carbon as the atmosphere. Since soil organic carbon (SOC) pools have large regional and landscape-level variability, detailed SOC inventories from across the northern permafrost region are needed to assess potential remobilization of SOC with permafrost degradation and to quantify the permafrost carbon-climate feedback on global warming. This thesis provides high-resolution data on SOC storage in five study areas located in undersampled regions of the continuous permafrost zone (Zackenberg in NE Greenland; Shalaurovo and Cherskiy in NE Siberia; Ary-Mas and Logata in Taymyr Peninsula). The emphasis throughout the five different study areas is put on SOC partitioning within the landscape and soil horizon levels as well as on soil forming processes under periglacial conditions. Our results indicate large differences in mean SOC 0–100 cm storage among study areas, ranging from 4.8 to 30.0 kg C m-2, highlighting the need to consider numerous factors as topography, geomorphology, land cover, soil texture, soil moisture, etc. in the assessment of landscape-level and regional SOC stock estimates. In the high arctic mountainous area of Zackenberg, the mean SOC storage is low due to the high proportion of bare grounds. The geomorphology based upscaling resulted in a c. 40% lower estimate compared to a land cover based upscaling (4.8 vs 8.3 kg C m-2, respectively). A landform approach provides a better tool for identifying hotspots of SOC burial in the landscape, which in this area corresponds to alluvial fan deposits in the foothills of the mountains. SOC burial by cryoturbation was much more limited and largely restricted to soils in the lower central valley. In the lowland permafrost study areas of Russia the mean SOC 0–100 cm storage ranged from 14.8 to 30.0 kg C m-2. Cryoturbation is the main burial process of SOC, storing on average c. 30% of the total landscape SOC 0–100 cm in deeper C-enriched pockets in all study areas. In Taymyr Peninsula, the mean SOC storage between the Ary-Mas and Logata study areas differed by c. 40% (14.8 vs 20.8 kg C m-2, respectively). We ascribe this mainly to the finer soil texture in the latter study area. Grain size analyses show that cryoturbation is most prominent in silt loam soils with high coarse silt to very fine sand fractions. However, in profiles and samples not affected by C-enrichment, C concentrations and densities were higher in silt loam soils with higher clay to medium silt fractions.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
26
Tudor, Emily Paige. "The Patterns and Processes of Insect Pollinator Re-assembly across a Post-mining Restoration Landscape." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/83667.
Full textAbstract:
This thesis presents an integration of in situ field studies and ex situ laboratory experiments to provide a deeper insight into the patterns and processes underpinning the reassembly of insect pollinator communities in post-mining Jarrah Forest restoration. Overall, this research highlighted the value of early successional patches and suggests that the habitat selection of some endemic insect pollinators is driven largely by their thermal tolerance, energetic requirements, and ecophysiology.
27
Marshall, Jill. "Lithologic, Climatic, and Biotic vs. Abiotic Controls on Erosion and Landscape Evolution." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/19291.
Full textAbstract:
The triumvirate of tectonics, lithology, and climate control landscape evolution. This study quantifies how lithologic variation and climate-mediated changes in ecosystems perturb steady state processes in the unglaciated, soil-mantled Oregon Coast Range (OCR). I first demonstrate that minor grain-scale differences in rock properties in a seemingly uniform sandstone control differences in rock strength, biotic bedrock-to-soil production efficacy, and erosion rates and influence relief at the watershed scale. I then build on sedimentology, paleoecology, and isotopic-derived paleoerosion data I collected from a new 50 ka sediment archive at Little Lake, OR to explore climate controls on soil production and erosion rates 21 ka across the OCR and spanning 50 ky within a single watershed. In Chapter III, I combine a mechanistic frost weathering model with a regional Last Glacial Maximum (LGM) climate reconstruction and paleovegetation data to demonstrate that accelerated frost-driven erosion was pervasive across the OCR during the LGM. My findings provide a new framework to quantify how the late Pleistocene affects modern erosion and soil formation rates in unglaciated environments and implies that most landscapes reside in a transient state. In Chapter IV, I document climate-mediated ecosystem influence on erosion rates over 3 climatic intervals. 10Be-derived erosion rates increase 3x (from 0.6 mm/yr to 0.21 mm/yr) as the OCR transitioned from the open forest-dominated marine isotope stage (MIS) climate interval (50-26 ka) into the periglacial subalpine MIS 2 glacial interval (26-13 ka). Measured erosion rates fell by more than half as the subalpine ecosystem gave way to the modern MIS 1 closed canopy Douglas-fir forest. Coupling paleovegetation-derived climate information with core observations I model frost weathering intensity from ~ 43 ka to 21 ka and establish a correspondence with increasing frost weathering intensity and increasing 10Be-derived erosion rates. Utilizing a transient mixing depth and erosion rate model, I am able to broadly replicate measured erosion rates at Little Lake through time. My findings contradict previous work that suggests climate has only weak control on erosion rates.
This dissertation includes previously published and unpublished co-authored material.
28
Baber, Matthew James. "Understanding anuran community dynamics in temporary wetlands: the interaction and importance of landscape and biotic processes." FIU Digital Commons, 2001. http://digitalcommons.fiu.edu/etd/1357.
Full textAbstract:
The major objective of this study was to determine the relative importance of landscape factors, local abiotic factors, and biotic interactions in influencing tadpole community structure in temporary wetlands. I also examined the influence of agricultural activities in South-central Florida by comparing tadpole communities in native prairie wetlands (a relatively unmodified habitat) at the Kissimmee Prairie Sanctuary (KPS) to tadpole communities in three agriculturally modified habitats found at MacArthur Agro- Ecology Research Center (MAERC). Environmental characteristics were measured in 24 isolated wetlands, and tadpoles were sampled using throw-traps and dipnets during the 1999 wet season (June - October). Landscape characteristics were expected to predominately influence all aspects of community structure because anurans associated with temporary wetland systems are likely to exist as metapopulations. Both landscape characteristics (wetland proximity to nearest woodland and the amount of woodland surrounding the wetland) and biotic interactions (fish predation) had the largest influence on tadpole community structure. Predatory fish influenced tadpole communities more than expected due to the ubiquity of wetlands, lack of topographic relief, and dispersal abilities of several fish species. Differences in tadpole community structure among habitat types were attributed to differences in woodland attributes and susceptibility to fish colonization. Furthermore, agricultural modification of prairie habitats in South-central Florida may benefit amphibian communities, particularly woodland-dwelling species that are unable to coexist with predatory fish. From a conservation standpoint, temporary wetlands proximal to woodland areas and isolated from permanent water sources appear to be most important to amphibians. In addition, the high tadpole densities attained in these wetlands suggest that these wetlands serve as biological hotspots within the landscape, and their benefits extend into the adjacent terrestrial matrix. Further research efforts are needed to quantify the biological productivity of these systems and determine spatial dynamics of anurans in surrounding terrestrial habitats.
29
Wilseman, Jennifer A. "A Comparison of Design Processes Between Sustainable SITES Certified and Noncertified Urban Open Space Projects." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5444.
Full textAbstract:
In response to the World Commission on Environment and Development’s Brundtland Report (1987) and other documents that have brought the need to address environmental, economic, and social issues to the forefront of the awareness of the public, the Sustainable SITES Initiative was modeled after LEED certification and was formed to establish a rating system and comprehensive framework of guidelines for development. It is a collaborative effort between the ASLA, the Lady Bird Johnson Wildflower Center, and the United States Botanic Garden. In June 2015, the Green Building Certification, Inc. of the United States Green Building Council acquired SITES and will oversee future certifications. SITES was formed to address the need for a coordinated response between all landscape design professionals, and to work in addition to and synergistically with LEED certification.
This study investigates the new sustainability rating system while exploring the professional marketplace and the design processes of three landscape architecture firms. The purpose of this study is to answer the question, “How do the design processes differ between SITES certified and noncertified urban open space projects in the Puget Sound area?”. There are currently 47 landscape projects across the United States that have been certified by the SITES pilot program rating system.
This is an exploratory study that examines the processes of three landscape architecture firms, with two projects within each firm: one sustainably certified through SITES, one is not certified, for a total of six case studies. By analyzing and documenting the presence and nature of patterns, similarities and differences, this study aims to strengthen the objective of SITES certification for the purpose of recognition and to validate existing sustainable landscape architectural practices.
This study pinpoints the components of sustainable landscape architectural and highlights landscape architecture’s commitment to sustainable development. Landscape architecture has a rich history of incorporating sustainable practices into their work. With this new rating system, landscape projects can gain recognition for sustainable practice through marketing projects as SITES certified, as the LEED certification program exemplifies. This study can also inform future collaborations with LEED certifications. SITES currently works synergistically with LEED certification on several components, but increased collaboration will be mutually beneficial. The SITES certification process is very involved and time-consuming, and with valuable feedback from Landscape Architects, expedited certification can be possible.
30
Xie, Yujing, and 谢玉静. "Habitat loss and fragmentation under urbanization: the spatio-temporal dynamics of causes, processes andconsequences at landscape level." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50662302.
Full textAbstract:
Landscape modification, especially those human-dominated changes, has been widely considered as one of the key drivers inducing the degradation of environment and ecosystem. The consequent habitat loss and fragmentation, which are closely related to ecological process, have attracted much scholarly attention. However, very few studies have systematically examined their causes and consequences at the landscape level. Integrating human activities into consideration in a holistic way remains poorly understood in particular. This thesis reports a systematic study of habitat loss and fragmentation under urbanization. This research distinguishes itself from previous works in its investigation of the spatio-temporal dynamics of causes and consequences of habitat loss and fragmentation, and its endeavor to disentangle habitat fragmentation from simple habitat loss in terms of their processes and effects.
The Shenzhen River cross-border watershed, shared by Hong Kong Special Administrative Region and Shenzhen, is used as a case to illustrate how these ideas can work in practice. The study period spans from 1988 to 2008.The main contents of the study include analysis of the processes and causes of habitat loss and fragmentation, and dynamic consequences on water quality and ecosystem services for biodiversity conservation at spatial and temporal scales. Various methods are employed, mainly including conventional and newly developed landscape metrics (such as the Urbanization Isolation Effect (UIE) and Habitat Isolation Degree (HID)), a spatial statistical approach based on the Geographically Weighted Regression (GWR) model, spatio-temporal analyses and cross-border comparison.
Major findings of the research are highlighted as follows. First, habitat loss and fragmentation show great spatial heterogeneity as well as temporal variation due to extensive and rapid urban sprawl in the study area. Second, by adopting the GWR model, it is found that human-related factors have played a significant role in determining not only the “amount” but also the “location” of habitat loss. Third, by using two new landscape metrics, namely the UIE and HID, both the extent (urban sprawl) and intensity (population density) of urbanization are suggested to have significant influences in habitat isolation. Fourth, water quality in the watershed is recognized to be closely correlated with habitat loss and fragmentation, and the correlations show major discrepancies between the Hong Kong and the Shenzhen sides. Moreover, by proposing a compound indicator (NP/MPS) for measuring habitat fragmentation (independent of simple habitat loss), it is found that habitat loss has exerted a bigger influence on water quality degradation than habitat fragmentation. Fifth, by integrating habitat connectivity into the evaluation of ecosystem services for biodiversity conservation, both the habitat size and connectivity are recognized to be important in explaining the degradation of ecosystem services value. Habitat size has played a dominant role in the overall change of ecosystem services value, whereas the role of connectivity (fragmentation) is more critical when the “stepping stones” sites are lost.
The study provides a new framework to examine the habitat loss and fragmentation under urbanization at the landscape level. The efforts show great effectiveness in providing sound and useful information for future landscape planning, biodiversity conservation and watershed management.published_or_final_version
Geography
Doctoral
Doctor of Philosophy
31
Bookhagen, Bodo. "Late quaternary climate changes and landscape evolution in the Northwest Himalaya geomorphologic processes in the Indian summer monsoon domain /." Phd thesis, [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974115487.
Full text
32
Quénéhervé, Geraldine Suzanne [Verfasser]. "Assessment of Landscape Processes, Forms and Features in the Lake Manyara Region, East African Rift Valley / Geraldine Suzanne Quénéhervé." Tübingen : Universitätsbibliothek Tübingen, 2018. http://d-nb.info/1227771762/34.
Full text
33
McGuire, Luke. "Modeling the Evolution of Rill Networks, Debris Fans, and Cinder Cones: Connections between Sediment Transport Processes and Landscape Development." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293538.
Full textAbstract:
Landscapes evolve through a number of processes in response to a wide range of forcing mechanisms. Many of the processes that drive landscape evolution occur at the interface between fluid and sediment. Sediment transport leads to changes in topography that, in turn, influence fluid flow. Feedback mechanisms between topography and fluid flow can lead to the formation of patterns, such as sand ripples, dune fields, parallel channel networks, and periodically spaced valleys. In many cases, the development and evolution of patterns within landscapes are heavily influenced by environmental conditions. Therefore, given relationships between landform features and the underlying processes, present-day landscapes have the potential to be used to infer a record of climatic conditions over the course of their development. An inability to make direct observations over geologically relevant timescales makes it difficult to study the processes that influence landscape evolution. Mathematical models provide a means of quantitatively linking natural patterns and landscape features with physical processes. Patterns in landscapes also provide a simple means of testing quantitative representations of geomorphic processes. In this work, we develop landscape evolution models to study the development of debris-flow-dominated hillslopes, rill networks, and cinder cones. Through a combination of theoretical modeling, analysis of experimental data, and remote sensing data, we attempt to better understand each of these three systems. While each system is interesting in isolation, these and similar studies add to our knowledge of the mathematical representations of processes that are used more generally within the study of landscape evolution.
34
Greenleaf, Holly Lee. "From Maintenance To Stewardship: Green Stormwater Infrastructure Capacity In Vermont Towns & Design And Participatory Processes To Provide Cultural Ecosystem Services." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1010.
Full textAbstract:
The impervious surfaces of built landscapes create stormwater runoff that causes water quantity and quality problems downstream, upsetting natural hydrology and harming aquatic ecosystems. Green stormwater infrastructure (GSI) includes practices that reduce the amount of stormwater runoff and the pollutants it carries utilizing plants, soils, and other materials to capture, store, reuse, infiltrate, evapotranspire, and filter stormwater. GSI helps to restore developed landscapes, mimicking natural hydrologic processes and providing important water treatment functions as well as beneficial green spaces in urban areas. However, there are many challenges associated with the implementation and maintenance of GSI in our communities and cultures.
This research explores the human side of implementing GSI, investigating current maintenance capacities in rural and urban settings, and exploring multifunctional benefits of GSI to provide both biophysical and cultural ecosystem services (CES). Research goals include characterizing the current state of GSI implementation and maintenance in municipalities in the State of Vermont (USA) and eliciting lessons that can inform GSI design practices and policies. Multifunctional GSI design objectives that provide and enhance CES are described, revealing opportunities to instill values and a sense of stewardship for the health wellbeing of people and ecosystems.
The first chapter provides relevant topical background to set the stage for the latter two chapters. The second chapter analyzes results from a survey of municipal officials in Vermont that occurred as part of NSF-EPSCoR-funded Basin Resilience to Extreme Events project research on stormwater management. The survey included questions about GSI and maintenance practices in place and perceptions of visual appeal and ability to maintain bioretention systems shown in landscape visualizations. Results show that visual appeal and perceived maintainability of vegetated bioretention practices do not appear to be significant barriers to adoption and operation, but stormwater policy and funding are shown to be both significant barriers and solutions to implementing and maintaining GSI in Vermont municipalities. Additionally, urban and rural towns provide very different contexts for implementing and maintaining GSI in Vermont and characteristics of development patterns and maintenance capacity should be considered in policy, regulations, outreach, and education.
The third chapter offers a literature review, guided by a CES framework, of design elements that can be included in GSI to create multifunctional urban green spaces. CES categories of aesthetic, recreation, education, sense of place, social capital, and stewardship benefits framed a set of design elements, principles, practices, and documented benefits to guide multifunctional design of GSI. Findings include the importance of participatory processes to elicit diverse landscape values, visible water pathways, biodiversity, spaces for creative use, accessibility, interaction with water, interpretive signage, and artful and biophilic design features to enhance feelings of preference, pleasure, relaxation, learning, connection, and inclusion. The health and wellbeing of water and people must be integrated into the design of GSI for cities to be ecologically functional and culturally meaningful to their populations.
35
Godinho, Sérgio Rui Borreicho Coelho. "Remote sensing and geographical modelling to assess montado change patterns: causes, impacts and biogeophysical process." Doctoral thesis, Universidade de Évora, 2015. http://hdl.handle.net/10174/17738.
Full textAbstract:
The magnitude of montado change patterns over times, as well as their causes and effects on natural process, remains poorly understood. A comprehensive analysis of these spatio-temporal processes using an integrated and multidisciplinary approach was implemented in this doctoral thesis to better understand the main causes and impacts of montado landscape changes. The main goal of this doctoral thesis was to analyse the montado landscape dynamics by using cartographic information and remote sensing-derived data for assessing change patterns, its causes and impacts on biogeophysical processes. The central topic of this thesis was to study the usefulness and effectiveness of Earth Observation Satellites (EOS) in providing accurate and comparable montado land cover information to support detailed long-term landscape change analysis. To achieve such goal four specific research objectives were addressed: (i) determine the recent spatio-temporal patterns of montado changes in southern Portugal; and identifying the effects of selected environmental, land management, and spatial factors in these changes; (ii) explore the capability of EOS and advanced image classification techniques for producing accurate montado land cover maps; (iii) assess the effectiveness of existing remote sensing-based approaches for estimating the percentage of montado tree canopy cover at the pixel level; and (iv) develop an effective remote sensing-based methodological approach to understand the effects of montado canopy cover decrease in local land surface biogeophysical process dynamics. From the investigations conducted, a decline trend of montado ecosystem was clearly identified through the estimated montado area and tree canopy cover regression. Furthermore, the demonstrated usefulness and effectiveness of EOS was one of the most important outputs of this thesis towards a broader long-term montado change analysis which may also include the assessment of its effects on local biogeophysical processes; Detecção Remota e modelação geográfica para avaliar os padrões de alteração do montado: causas, impactes e processos biogeofisicos
Resumo:
A magnitude dos padrões de alteração do montado ao longo do tempo, bem como as suas causas e efeitos nos processos naturais, continua pouco estudada. Uma análise compreensiva destes processos espacio-temporais usando uma abordagem integradora e multidisciplinar foi implementada nesta tese de doutoramento para melhor conhecer as grandes causas e impactes das alterações da paisagem de montado. O grande objectivo desta tese de doutoramento foi analisar as dinâmicas do montado através da utilização de informação cartográfica e dados derivados de detecção remota para avaliar os padrões de alteração, as suas causas e impactes nos processos biogeofisicos. O tópico central desta tese foi estudar a utilidade e a eficácia dos Satélites de Observação da Terra (SOT) em providenciarem informação comparável e precisa da cobertura espacial do montado que permitam análises mais detalhadas sobre as alterações deste sistema numa prespectiva de longo termo. Para atingir este propósito quatro objectivos específicos de investigação foram tidos em conta: (i) determinar os padrões de alteração espacio-temporais recentes da paisagem de montado no sul de Portugal; (ii) explorar as capacidades dos SOT e de técnicas avançadas de classificação de imagem para produzir mapas de ocupação do montado com elevada exactidão. (iii) analisar a eficácia de abordagens de detecção remota existentes para estimar a percentagem de cobertura das copas das árvores do montado à escala do pixel; e (iv) desenvolver uma abordagem metodológica com recurso a técnicas de detecção remota para compreender os efeitos da perda de cobertura das copas do montado na dinâmica dos processos biogeofísicos à escala local. Com base na investigação levada a cabo, identificou-se a tendência clara de declínio do ecossistema montado através das estimativas da regressão na área ocupada por montado bem como da redução da percentagem de cobertura por copas. Para além disso, a demonstração da utilidade e eficácia dos SOT para apoiar uma análise mais abrangente das alterações do montado, bem como os seus efeitos nos processos biogeofísicos locais, foi um dos resultados mais importantes desta tese.
36
Bridge, S. R. J. "The landscape scale spatial distribution of vegetation gradients in a mixedwood boreal forest, linking ecological patterns to geomorphic processes across scales." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20820.pdf.
Full text
37
Udy, Kristy [Verfasser], Teja [Akademischer Betreuer] Tscharntke, Christoph [Gutachter] Scherber, and Kreft [Gutachter] Holger. "Scaling of Animal Communities: From Local and Landscape to Global Processes / Kristy Udy ; Gutachter: Christoph Scherber, Kreft Holger ; Betreuer: Teja Tscharntke." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1149959266/34.
Full text
38
Lechmere-Oertel, Richard Geoffrey. "The effects of goat browsing on ecosystem patterns and processes in succulent thicket, South Africa." Thesis, University of Port Elizabeth, 2003. http://hdl.handle.net/10948/309.
Full textAbstract:
Transformation in the arid succulent thicket of the Eastern Cape of South Africa in response to unsustainable livestock production has been widespread, with less than 10 percent remaining intact. Transformation in succulent thicket has resulted in large areas of dense thicket (comprising a two-phase mosaic of perennial-vegetated patches separated by animal paths and bare patches) being replaced with a ‘pseudo-savanna’ of remnant canopy trees with a structurally simple field layer of ephemeral and short- lived perennial grasses and forbs. There is an extensive literature describing the transformation of succulent thicket, with many speculative statements about the underlying mechanisms of transformation. The central focus of this study was to improve our mechanistic understanding of transformation in succulent thicket using field experiments. Hopefully these results will set another foundation upon which future management of succulent thicket can be improved and large-scale restoration initiated. This study comprises four themes that are linked to the concept of landscape function. The central premise of landscape function is that functional landscapes have mechanisms that capture and retain scarce resources. Conversely, as landscapes become increasingly dysfunctional, so these mechanisms become disrupted. In succulent thicket, dysfunctio n appears to be linked to the reduced ability to harvest water, cycle carbon and a loss of organic carbon. In this thesis I examined some of the key processes that influence water and organic carbon fluxes: perennial vegetation cover, soil fertility, litter fall and decomposition, and runoff and soil erosion. The experimental design that was used for all this work was a factorial ANOVA based on replicated fenceline contrasts that reflect differences in long-term management history. The main objectives of this thesis were to: quantify the patterns of transformation in an arid form of succulent thicket, including changes in the biomass, cover and structure of the dominant vegetation guilds; test the stability of the transformed succulent thicket ecosystem to show whether it is a new stable state or an intermediate stage in a trajectory towards a highly desertified state where only the ephemeral grasses and forbs persist; describe and compare soil fertility across transformation contrasts, concentrating on changes in the spatial patterns of soil resources and the ability of the soil to harvest precipitation; to compare litter fall and decomposition of leaf material from the dominant plants in intact and transformed succulent thicket; to quantify and compare run-off and erosion from run-off plots in intact and transformed succulent thicket. Transformation and stability I quantified the changes in plant diversity, physiognomy and biomass that occur across transformation contrasts. Thicket transformation results in a significant loss of plant diversity and functional types. There is also a significant reduction in the biomass (c. 80 t.ha-1) and structural complexity of the vegetation, both vertically and horizontally. These results were interpreted in terms of their implications for ecosystem functioning and stability. To test the stability of the transformed succulent thicket I used aerial photographs and ground-truthing to track the survivorship of canopy trees over 60 years in pseudo-savanna landscapes. I also measured seedling establishment in different habitats. I show that the pseudo-savanna is not a stable state owing to ongoing adult mortality and no recruitment of canopy trees. Soil fertility and water status I hypothesised that the above-ground changes in ve getation would be accompanied by similar trends in the pattern and levels of soil nutrient resources and the ability of the landscape to harvest precipitation. I compared soil fertility (organic carbon, available nitrogen and phosphorus), texture, matric potential, and surface micro-topography in the two main micro- habitats on either side of the replicated fenceline contrasts. The results show that intact spekboom thicket has a distinct spatial pattern of soil fertility where nutrients and organic carbon are concentrated under the patches of perennial shrubs, compared to under canopy trees and open spaces. Transformation results in a significant homogenisation out of this pattern and an overall reduction in the fertility of the landscape. The proportion of the landscape surface that would promote infiltration of water decreases from 60 – 0.6 percent. Soil moisture retention (matric potential) also decreases with transformation. I interpreted these patterns in terms of the ability of the landscape to harvest and release water after rainfall events. Litter fall and decomposition Surface litter and soil organic matter are critical components to wooded ecosystems; contributing to several ecosystem functions. The rates of litter fall and decomposition are ratelimiting steps in nutrient cycling and incorporation of organic matter into the soil. The ecological mechanisms behind the collapse of succulent thicket in the face of domestic herbivory are not fully understood, but are believed to include the breakdown of several ecosystem processes, including litter fall and decomposition. I quantified the changes in litter fall and litter decomposition of four of the dominant perennial woody plants (Euclea undulata, Pappea capensis, Portulacaria afra and Rhus longispina) across the replicated fenceline. Litter fall was measured over 14 months using mesh traps. Decomposition was measured over 15 months using a combination of litterbags and unprotected leaf packs. I also quantified soil microclimate during the experimental period; hypothesising that transformation would lead to soil conditions less amenable for biotic activity. Litter fall in succulent thicket was very high for a semi-arid system, comparing more to temperate forests. The leaf-succulent P. afra contributed the largest single component of the total litter production at a landscape scale. The effect of transformation on litter fall was species specific. Deep-rooted or drought-adapted species showed no change in litter yield with transformation; shallow-rooted species showed a significant decrease. There were few significant differences in decomposition rates across the transformation gradient and between litter types. Portulacaria afra litter had the steepest rate of mass loss, and was most affected by transformation. The more recalcitrant (high C:N ratio) leaves of P. capensis remained largely unaffected by transformation. These results indicate the critical role of the perennial vegetation in incorporating organic carbon into the soil. Transformation of succulent thicket leads to a disruption of the flow of carbon into the soil, reinforcing the cycle of transformation through reduced fertility. Rehabilitation of this ecosystem will require the active establishment of species, such as P. afra, that will restart the flow of carbon into the soil. Run-off & Erosion The landscape function model predicts that functional semi-arid shrublands efficiently conserve limiting resources such as water and water-bourn sediments (soil and organic matter). As these rangelands become transformed through unsustainable livestock production, so their ability to conserve resources decreases. The primary determinant of landscape function and conservation of resources appears to be the proportional cover of perennial vegetation. I hypothesised that the switch from a two-phase mosaic dominated by perennial succulent and woody shrubs to a single phase system dominated by an ephemeral field layer would be accompanied by disruption of the mechanisms that conserve resources. Specifically, I tested the hypothesis that transformation of succulent thicket increases runoff volume, sediment concentration of runoff, soil erosion and loss of organic matter at a patch scale (c. 100 m2). Runoff and water-borne sediment were measured from runoff plots established across replicated fenceline contrasts. Data were collected from eight extreme weather events over two years. There were no significant differences between runoff and erosion across the transformation contrast, as each extreme weather event was unique in terms of its runoff response. The transformed runoff plots alone also gave inconsistent results, largely due to differences in the cover of ephemeral forbs and weakly perennial grasses. Runoff and erosion were not predictable from the data across the transformation gradient due to complex interactions between the nature of the above-ground vegetation, soil micro-topography and land use history. The results highlighted the need for longer-term catchment experiments to generate a predictive understanding of the effect of transformation on runoff and erosion in succulent thicket.
39
Nyktas, Panagiotis. "Dynamic feedbacks between landform, landscape processes and vegetation patterns : a modelling framework to predict the distribution of plant species in Lefka Ori, Crete, Greece." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590674.
Full textAbstract:
The aim of the thesis has been to describe and model landforms and active landscape processes and include model feedbacks and climatic parameters into plant species distribution models. The study area has been an ecologically important mountainous area, the Lefka Ori of Crete. Starting point has been a number of previous studies underlying that climatic and geoenvironmental factors are among the most significant controlling the spatial distribution of rare and endemic species. The limitations of past studies that this study tried to address were (a) some of these factors are complex (e.g. landscape instability, mass movement), (b) they do not refer to the landscape scale (e.g. erosion-deposition, water redistribution) or (c) data are not available (i.e. climatic). To achieve these aims: (i) Object Based Image Analysis was used to create a geological map of the area, (i i) a set of land surface parameters were created from elevation data, (iii) a semi-automated method was developed to map the landforms of potential ecological Significance, (iv) available climatic data were reviewed and satellite imagery was utilized to address the climatic component through snow cover persistence patterns, (v) a field experiment was set up for the description of active landscape processes, (vi) dynamic landscape process were modeled for water redistribution, erosionsedimentation, landscape (in)stability and mass movement patterns. In the course of the study 75 vegetation plots were sampled and merged with another 80 from past stud ies leading to the formulation of statistical models (GLMs) for 59 species. The resu lts show that geology, elevation and snow cover persistence patterns explain most of the variability for most species thus were more frequently included in the predictive models. This signifies the climatic and geological control over species distribution. For four species of conservation importance model results were presented in detail leading to probabilistic distribution maps.
40
Zapata-Rios, Xavier. "The Influence of Climate and Landscape on Hydrological Processes, Vegetation Dynamics, Biogeochemistry and the Transfer of Effective Energy and Mass to the Critical Zone." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/555944.
Full textAbstract:
The Critical Zone (CZ) is the surficial layer of the planet that sustains life on Earth and extends from the base of the weathered bedrock to the top of the vegetation canopy. Its structure influences water fluxes, biogeochemistry and vegetation. In this dissertation, I explore the relationships between climate, water fluxes, vegetation dynamics, biogeochemistry, and effective energy and mass transfer fluxes (EEMT) in a semi-arid critical zone. This research was carried out in the upper Jemez River Basin in northern New Mexico across gradients of climate and elevation. The main research objectives were to (i) quantify relations among inputs of mass and energy (EEMT), hydrological and biogeochemical processes within the CZ, (ii) determine water fluxes and vegetation dynamics in high elevation mountain catchments with different terrain aspect and solar radiation, and (iii) study temporal variability of climate and its influence on the CZ water availability, forest productivity and energy and mass fluxes. The key findings of this study include (i) significant correlations between EEMT, water transit times (WTT) and mineral weathering products around Redondo Peak. Significant correlations were observed between dissolved weathering products (Na⁺ and DIC) and maximum EEMT. Similarly, ³H concentrations measured at the springs were significantly correlated with maximum EEMT; (ii) terrain aspect strongly controls energy, water distribution, and vegetation productivity in high elevation ecosystems in catchments draining different aspects of Redondo Peak. The predominantly north facing catchment, when compared to the other two eastern catchments, receives less solar radiation, exhibits less forest cover and smaller biomass, has more surface runoff and smaller vegetation water consumption. Furthermore, the north facing catchment showed smaller NDVI values and shorter growing season length as a consequence of energy limitation, and (iii) from 1984 to 2012 a decreasing trend in water availability, increased vegetation water use, a reduction in both forest productivity and EEMT was observed at the upper Jemez River Basin. These changes point towards a hotter, drier and less productive ecosystem which may alter critical zone processes in high elevation semi-arid systems.
41
Tonelli, Mattia. "Effects of different pastures management on dung beetle communities in a sub-mountainous landscape of central Italy: a multicomponent biodiversity and ecological process analysis." Doctoral thesis, Universidad de Alicante, 2017. http://hdl.handle.net/10045/65761.
Full textAbstract:
Los escarabajos coprófagos (Coleoptera: Scarabaeoidea) son un grupo de insectos muy importante en términos de diversidad y biomasa en los pastos de la cuenca del Mediterráneo. A pesar de su importancia ecológica, los escarabajos coprófagos están amenazados por varios factores, entre los cuales se destacan los cambios en el manejo de la ganadería tradicional. El objetivo general de esta tesis fue evaluar los efectos del abandono de la ganadería, su extensificación y uso histórico de productos médico veterinarios sobre las comunidades de escarabajos coprófagos usando medidas de biodiversidad y cuantificando la capacidad de remoción de estiércol en un paisaje sub-montano de la provincia de Pesaro-Urbino (Italia). En este trabajo se colectaron un total de 156 936 individuos, pertenecientes a 58 especies de escarabajos coprófagos. Los resultados de este trabajo sugieren que el uso histórico de productos médico veterinarios tiene un impacto negativo y ubiquitario sobre todas las especies de la comunidad de estudio, llevando a un empobrecimiento de los ensambles y a una pérdida de abundancia y biomasa. No obstante se ha registrado el mantenimiento de la estructura de la comunidad. Estos resultados son corroborados igualmente cuando nos enfocamos en la diversidad funcional. En efecto, el uso histórico de productos médico veterinarios lleva a una pérdida en el número de roles funcionales dentro de la comunidad, sin embargo las abundancias se encuentran repartidas equitativamente dentro de cada nicho funcional. Todos estos efectos sobre la comunidad de escarabajos coprófagos debido al uso de productos médico veterinarios, al final quedan reflejados en una pérdida del 70% en la capacidad de remoción de estiércol, comparados con áreas donde estos productos no son aplicados. La extensificación de la ganadería está representada por áreas que tienen una intensidad de pastoreo muy baja, las cuales pueden ser consideradas como la primera etapa hacia el abandono completo. En este sentido, los resultados de este trabajo demuestran como una simple reducción de la carga ganadera lleva a efectos negativos sobre las comunidades de escarabajos coprófagos, registrando una disminución en la diversidad alpha y en el número de especies indicadoras. Esta disminución en la cantidad de recurso trófico tiene implicaciones sobre la composición de la comunidad, favoreciendo especies oportunistas cuya biología le permite evitar la competencia, como por ejemplo; especies cleptoparásitas o especies cuyas larvas tienen un comportamiento saprófago. Este “efecto filtro” (filter effect) debido a la disminución de la cantidad trófica, está confirmado por los resultados de diversidad funcional, en los cuales se registró una disminución en el número de nichos funcionales y una fuerte redundancia por la presencia de nichos funcionales muy similares entre ellos. Los efectos sobre la comunidad de escarabajos coprófagos en los sitios con baja carga ganadera reflejan finalmente una pérdida en la capacidad de enterramiento del estiércol del 30-40% respecto a las comunidades en áreas con una mayor carga ganadera. Los resultados de este trabajo muestran que en las áreas con abandono total de la ganadería se observó una disminución en el número de especies, en la abundancia y biomasa total, en el número de especies indicadoras, en la abundancia de las especies de gran tamaño y en las especies que no tienen un comportamiento de nidificación durante el periodo reproductivo. Sin embargo, el mantenimiento de una comunidad bien estructurada, subraya la importancia de dos factores locales: el excremento de la fauna silvestre y la mayor complejidad del hábitat debido a un proceso de invasión de árboles en el pasto. Este último factor es probablemente responsable de la presencia de especies indicadoras típicas de hábitats más cerrados como los bosques o matorrales. En cuanto a los resultados de diversidad funcional, estos confirman la interpretación del “efecto filtro” debido a la disminución en la cantidad de recurso trófico. En efecto, estos resultados muestran una unicidad funcional significativa en esta comunidad como consecuencia del fuerte cambio composicional que el abandono de la ganadería ha implicado, a pesar de una disminución en el número de nichos funcionales y en el mantenimiento de una buena estructura funcional. Así mismo, se registró una disminución en la capacidad de enterramiento del estiércol entre 27% y 47% respecto a las áreas con baja carga ganadera y con carga moderada por todos estos cambios cuali y cuantitativos en la comunidad de escarabajos coprófagos de los sitios abandonados. Se propone la ganadería ecológica como forma correcta de gestión de los pastos, la cual permitiría mantener un nivel de carga moderado, así como el control en uso de compuestos médico veterinarios.
42
Löbel, Swantje. "Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes." Doctoral thesis, Uppsala universitet, Ekologisk botanik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-106847.
Full textAbstract:
The aim of this thesis was to increase knowledge about metapopulation and metacommunity processes in patchy, dynamic landscapes, using epiphytic bryophytes as a model system. Host trees and deciduous forest stands in the coniferous landscape are patchy, temporal and undergo changes in habitat quality during succession. Epiphytes must track this dynamic habitat network for their long-term survival. Community patterns at different spatial scales were explored and linked to regional metapopulation processes and local population dynamics. Spatial structuring in species richness both at a local and regional scale indicated stronger dispersal limitation but lower sensitivity to habitat quality in species with large asexual than in species with small sexual diaspores. In sexually dispersed species, a strong rescue effect was indicated by a bimodal frequency distribution of the species and by increasing local abundance with increasing patch connectivity. Present connectivity to other deciduous forest patches had positive effects on richness of asexually dispersed species, whereas richness of sexually dispersed species was instead related to the landscape connectivity 30 years ago. A study of local growth and reproduction suggested that this is caused by delayed sexual, but not asexual, reproduction. Habitat conditions affected the production of sporophytes, but not of asexual diaspores. No differences in either growth rates or competitive abilities among species with different dispersal and life-history strategies were found. In vitro experiments showed that establishment is higher from large asexual diaspores than from small sexual. Establishment of all diaspore types was limited by pH. There were indications of trade-offs between high germination and protonemal growth rates, desiccation tolerance and a rapid development of shoots from protonema. The results indicated that the epiphyte metacommunity is structured by two main trade-offs: dispersal distance (diaspore size) versus age at first reproduction, and dispersal distance versus sensitivity to habitat quality. Trade-offs in species traits may have evolved as a consequence of conflicting selection pressures imposed by habitat turnover, connectivity and irregular water supply rather than by species interactions. Syndromes of interrelated species traits imply that fairly small changes in habitat conditions can lead to distinct changes in metacommunity diversity: the results indicate that increasing distances among patches cause most harm to asexually dispersed species, whereas cuttings of forests of high age and quality as well as increasing patch dynamics are most harmful to sexually dispersed species.Senarelagd disputation från: 2009-09-26, Lindahlsalen, EBC, Villavägen 9, 75236 Uppsala, Uppsala, 10:00
43
Nakamura, Alline Alves. "Em percurso." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/27/27159/tde-21032017-101901/.
Full textAbstract:
Em percurso se constitue de imagens, sobretudo fotografias, feitas entre 2008 e 2016, nos trajetos e percursos de algumas cidades por onde passei. Somam-se ao conjunto as fotos realizadas em espaços privados e nas ruas por onde faço minhas andanças. Parto de minha experiência em registrar as paisagens, lugares e espaços durante os meus deslocamentos, principalmente entre as cidades de Atibaia-SP e a capital paulista, através das janelas de veículos particulares e transportes coletivos. As recordações das viagens em família e de ter feito desenhos em pequenos cadernos na década passada, dentro dos ônibus ou de memória, estruturam a minha compreensão visual atualmente. A câmera fotográfica torna-se um instrumento de desenho. Após a captura das fotografias, os procedimentos de tratamento, edição e impressão fazem parte do processo de construção das imagens. Os relatos escritos em breves notas sobre algumas vivências trazem informações que podem colaborar na percepção do que é visto. Ao mesmo tempo, as palavras têm sua autonomia, assim como as imagens.Em percurso (En route) is made of images, mainly photographs, shot between the years of 2008 and 2016, along the paths and routes of some cities I\'ve been to. Some other pictures, depicting private spaces and streets that I walk on, have also been added to the set. I depart at my experience in registering landscapes, places and spaces as I go from one place to another, especially from the city of Atibaia-SP to the capital of the State, through the windows of private cars or public transportation. The memories of family trips and of drawings made in small notebooks in the last decade, inside buses or out of my memory, organize my current visual understanding. The photography camera becomes a drawing device. After shooting, the treatment procedures, editing and printing are part of the process of building images. The short written notes about some experiences offer information that may contribute to the perception of what is seen. At the same time, the words are autonomous as well as the images are.
44
Yang, Perry 1968. "Ecological interactions of natural processes and new urban form : a landscape ecological analysis fo the change of urban and natural patterns in eastern-Taipei metropolitan fringes." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/70735.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2001.Includes bibliographical references (leaves 81-85).
The ecological effect of urban form has been an important issue in 20" century planning history. The inadequate relationships between development patterns of modern cities and their natural surroundings had been discussed in Geddes's Cities in Evolution, McHarg's Design with Nature, Lynch's Good City Form, Forman's "ecologically optimum spatial form" in Land Mosaics, and Mitchell's "fine-grain urban pattern" in City of Bits and Etopia (Geddes, 1915; Lynch, 1961, 1981; McHarg, 1969; Forman, 1995; Mitchell, 1995, 1999). However, these normative theories have almost never been tested by empirical studies and quantitative analysis. The thesis is about ecological effects of a twenty-year period urbanization in the fringe area of eastern Taipei metropolis. Using the technology of GIS and the principles of landscape ecology, some quantitative and spatial analyses are applied here to verify the complicated non-linear relationship between city form, forest patch shape and hydrological effects in the case study of eastern Taipei. Some landscape ecological indices like forest patch numbers, corridor connectivity, compactness of city form, landscape fragmentation and landscape heterogeneity are measured across different spatial scales and over twenty years period. Some correlations between the landscape indices and the hydrological change are verified. The following are the main findings of the study: 1. The empirical study provides an operational approach to large-scale metropolitan spatial analysis. The integration of GIS technologies and landscape ecological analysis shows the potential for the future development of a GIS based ecological design and planning tool. 2. A holistic framework is proposed for the purpose of integrating consideration of urban development, landscape change and hydrological processes. The evidence shows that there exist some correlations among the three processes. 3. Some landscape ecological indices are highly correlated with hydrological effects, including the number of 10 hectare or larger forest patches, the compactness index K and the fractal dimension D of city form, and the evenness index E of the landscape heterogeneity. 4. The data show a 10 year "time lag" phenomenon between urban development and hydrological effect in eastern Taipei. The differences of the runoff effect between 1980s and 1990s support the hypothesis that there exists a threshold point or limitation of the natural system. When the magnitude of urban development goes beyond that limitation, the original hydrological system became "irreversible" or "less reversible". 5. The evidence of the threshold point indicates that the strategic timing point and spatial points could become the basis for design and planning intervention. Using scenarios planning procedure, a sustainable urban environment could be achieved gradually by applying landscape ecological principles.
by Perry Pei-ju Yang.
S.M.
45
Larsson, Emy. "The Landscape between Bureaucracy and Political Strategy : A Qualitative Case Study of the Policy Process in Swedish Security and Defence Policy." Thesis, Försvarshögskolan, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-9682.
Full textAbstract:
The Swedish Defence bill of 2015 demonstrated a rapid change in policy objectives, consequently moving away from an expeditionary force and converging into a territorial defence force. Previous research has attributed and explained the quick shift to the geostrategic unbalance that followed after the illegal annexation of Crimea in 2014. Yet, major policy changes are often years in the making, indicating that there must be additional explanations to the rapid shift. By applying a modified version of John Kingdon’s (2011) Multiple Streams Framework on the case of Sweden changing its security and defence policy, this thesis examines the policy process that preceded the official policy decision. The thesis provides further explanation to why the rapid policy change occurred by utilising qualitative content analysis. The analysis shows that the new policy was adopted due to several factors: one being the attention brought to several problems pertaining to the previous policy, another one was found in the timing between focusing events and the on-going work process of the Swedish defence commission, and lastly, strong actors within the policy field were in favour of a change in policy. The thesis concludes that the presence of several factors within the processes of politics, policy and problems enabled the rapid policy change.
46
Nettley, Amy Jessica. "Visualising change in the Tamar Valley : participatory processes for generating 3D visual tools to communicate sea-level rise." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/15030.
Full textAbstract:
This thesis introduces and analyses a unique approach which involved iteratively engaging with stakeholders to generate a film about sea-level rise at a heritage site. The project used fine-scale remote sensing techniques, including airborne and terrestrial laser scanning (TLS), to produce spatially accurate and realistic 3D digital visualisations of projected sea level rise at Cotehele Quay, a site on the River Tamar in Cornwall which is owned and managed by the National Trust. Area residents and stakeholders were involved in a series of focus groups which provided guidance on the integration of the spatial models into a short film. This thesis makes an original contribution to knowledge about how non-scientific audiences understand and interpret visual realism and spatial accuracy when engaged with the process of developing such a tool. Ultimately, the thesis proposes a new kind of visual realism based on this knowledge, known as ‘participatory realism’. The main output of this research was a film, ‘Changing Tides at Cotehele Quay’, which is presently being used by the National Trust as part of their wider communication toolkit. In addition to reflecting on the production of the film, the thesis makes the argument that at present TLS is not being proactively used to engage wider audiences. The research explored how TLS and other spatial data can be used in settings which are more public-facing; the thesis analyses the results of this innovative practice and interrogates the way in which people interacted and responded in the course of their participation.
47
Franklin, Hannah Mayford. "Understanding Variation in Water Quality using a Riverscape Perspective." Thesis, University of Canterbury. Biological Sciences, 2010. http://hdl.handle.net/10092/5197.
Full textAbstract:
With the increasing degradation of rivers worldwide, an understanding of spatial and temporal patterns in freshwater quality is important. Water quality is highly variable in space and time, yet this is largely overlooked at the scale of stream catchments. I employed a landscape ecology approach to examine the spatial patterning of water quality in complex, impacted stream networks on the Canterbury Plains of the South Island of New Zealand, with the goal of understanding how land-use effects proliferate through stream systems.
In particular, I used “snapshot” sampling events in conjunction with spatial modelling and longitudinal profiles to investigate the ways in which spatial and environmental factors influence the variability of water quality in stream networks. Spatial eigenfunction analyses showed that distance measures, which took into account variable connectivity by flow and distance along the stream between sites, explained more spatial variance in water quality than traditional distance metrics. Small upstream reaches were more spatially and temporally variable than main stems (under summer base-flow conditions). The extent of spatial variation in water quality differed between stream networks, potentially depending on linkages to groundwater and the surrounding landscape. My results indicated that the water quality of headwater streams can have a disproportionate influence over water quality throughout an entire network.
I investigated spatio-temporal patterns in water quality more intensively in one stream network, the Cam River, in which I found consistent spatial pattern through time. The relative balance between nutrient inputs (pollution and groundwater) and in-stream conditions influenced the spatial pattern of water quality, as well as that of several ecosystem processes which I measured simultaneously. The spatially intensive and explicit approach has allowed identification of key factors controlling water quality and ecosystem processes throughout the Cam River. This research highlights the importance of taking a spatially explicit approach when studying stream water quality and that such an approach could be insightful and will contribute to solving current stream management problems.
48
Schmiedel, Inga Verfasser], Heike [Akademischer Betreuer] Culmsee, Erwin [Akademischer Betreuer] Bergmeier, Christoph [Akademischer Betreuer] Leuschner, Renate [Akademischer Betreuer] Bürger-Arndt, Susanne [Akademischer Betreuer] [Bögeholz, Hermann [Akademischer Betreuer] Behling, and Markus [Akademischer Betreuer] Hauck. "Vascular plant species richness at the landscape scale: Patterns and processes / Inga Schmiedel. Gutachter: Erwin Bergmeier ; Christoph Leuschner ; Renate Bürger-Arndt ; Susanne Bögeholz ; Hermann Behling ; Markus Hauck. Betreuer: Heike Culmsee." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1072550598/34.
Full text
49
Nelson, Jason M. "The Roles of Natural and Semi-Natural Habitat in the Provisioning of Biodiversity and Ecosystem Services of Beneficial Insects in Agricultural Landscapes." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1344485293.
Full text
50
Bacles, Cecile Fanny Emilie. "Effects of chronic habitat fragmentation on population genetic processes in temperate tree species : the example of rowan and ash in a deforested landscape and implications for native woodland restoration in southern Scotland." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/10749.
Full textAbstract:
In southern Scotland, human-mediated deforestation for pasture since the Neolithic has dramatically altered the landscape. We intensively surveyed a single catchment (Moffat Dale) for severely fragmented populations of Sorbus aucuparia L., an insect pollinated bird dispersed species, and Fraxinus excelsior L., which is wind pollinated and wind dispersed. These remnants are being considered for seed collection in a native woodland restoration programme currently being implemented. Quantifying genetic variation at isozyme and chloroplast DNA markers in S. aucuparia remnants revealed that high levels of genetic diversity are maintained. However, genetic differentiation among remnants was detected for both types of marker and the estimated ratio of pollen flow to seed flow between fragments is close to one (r=1.36) suggesting reduced historical pollen-mediated gene flow but efficient seed dispersal. Similarly, F. excelsior remnants maintain high levels of genetic diversity at nuclear microsatellite markers and low interpopulation differentiation (q=0.080). Using the neighbourhood model, it was estimated from open-pollinated progeny arrays that contemporary pollen flow is extensive and that effective pollen dispersal distance with in the catchment averages 328 m. A detailed paternity analysis conducted on progeny arrays confirmed these results. Although pollen flow is an important component of realised gene flow, a parentage analysis showed that it is not predominant as 56.6% of the seedlings that recently established in Moffat Dale immigrated into the catchment. S. aucuparia and F. excelsior remnants in a severely deforested landscape are part of the wide reproductive network. Genetic diversity within remnants and gene exchange among them have been maintained by efficient long distance seed and pollen-mediated dispersal, making them an appropriate seed source for planting stock.