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Dissertations / Theses on the topic 'Spatial Ecosystems'
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1
Zillio, Tommaso. "Spatial Dynamics of Ecosystems." Doctoral thesis, SISSA, 2005. http://hdl.handle.net/20.500.11767/4081.
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Sandin, Leonard. "Spatial and temporal variability of stream benthic macroinvertebrates : implications for environmental assessment /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-6056-5.pdf.
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Gill, Wendy Jane. "The spatial characterisation of transitional areas between plant communities : a case study from upland Britain." Thesis, University of Plymouth, 1996. http://hdl.handle.net/10026.1/2196.
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The concept of the ecotone was formalised by Clements (1 905) as a boundary zone between plant communities. Little research exists on the ecological importance or the geographical variability of these zones. Two types of boundaries are acknowledged: the ecotone and the ecocline. The ecotone is a sharp boundary; the ecocline a gradual boundary. The term 'transitional area' is proposed here to more accurately describe these areas as this research demonstrates that a complex continuum exists between the two end points. Additionally, mosaics often complicate the nature of the transition and may form a boundary type in their own right. Upland plant communities represent important semi-natural habitats within the British Isles. Effective management depends on an understanding of their structure and function. This research is primarily concerned with the description of structure (spatial pattern and variability in floristic composition) but explanation of these patterns is only possible through an understanding of function (vegetation dynamics). Pilot studies determined an appropriate methodology for studying transitional areas. The approach progressed from a linear transect to a two-dimensional rectangular transect. The pilot studies also evaluated a range of methods for data analysis. Extended field sampling followed which included 23 sites in 4 locations: Dartmoor, Snowdonia, North York Moors and Barra, Western Isles of Scotland. Data analysis exposed the complexities of the transitional areas sampled but 'noise' often obscured the true characteristics. To overcome this a Species Ratio Index Model was devised to identify the strength of signal for each boundary. The final characterisation of transitional areas is based on three main components: ecotone, ecocline and mosaics, each displaying varying amplitude. Of the sites sampled, few boundaries revealed single characteristics and the majority were far more complex than their observed patterns implied. On the basis of this characterisation a classification is proposed which incorporates both natural and anthropogenic factors. The classification represents an important contribution to the understanding of boundary types. This study reinforces the significance of boundaries in the landscape. The potential for future research is great, particularly through the development of a predictive model for management purposes.
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Alibegovic, Goran. "Spatial and Temporal Characterisation of Ecosystems in Landscapes Surrounding Granite Outcrops." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/2087.
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This study develops and implements a methodology to map granite outcrops over the Southwest Western Australian Floristic Region using biannual Landsat TM imagery based on seasonal vegetation change. Ecosystem greenspots are mapped using a weighted seasonal summation of long term MODIS imagery to identify locations that may act as habitat refuges under climate change. Phenological characteristics on granite outcrop aprons are compared to non-apron areas to quantify habitat differences and responses to recent climate change.
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Koukoulas, Sotirios. "Analysing the spatial structure of semi natural deciduous woodlands through high resolution airborne imagery and Geographical Information Systems." Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272583.
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Leach, Taylor Hepburn. "Cause and Consequences of Spatial Dynamics of Planktonic Organisms in Lake Ecosystems." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1479747973843758.
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Thompson, Melissa L. "Evaluating the use of high spatial resolution imagery in characterizing sagebrush ecosystems." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594496621&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Edwards, Grant R. "The creation and maintenance of spatial heterogeneity in plant communities : the role of plant-animal interactions." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239335.
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Engelhard, Sarah Laure. "Marine Spatial Connectivity in Theory and Conservation." Thesis, Griffith University, 2017. http://hdl.handle.net/10072/365470.
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Globally, ecosystems are experiencing increasing pressure from anthropogenic stressors. Human population growth is responsible for overexploitation of natural resources, pollution, land alteration and climate change. A change in landscape connectivity, may not only reduce the habitable space for species, but may also affect their movement and population dynamics. These changes potentially reduce the
resilience of ecosystems against other stressors. Reserves are a common method to protect areas from overexploitation and habitat destruction and help to safeguard ecosystem functioning. Reserve size, location and configuration influence the effect of reserves and the optimal design of protected areas is a field of ongoing research. Connectivity is a guiding principle in protected area planning but the explicit
incorporation of connections remains a challenge. Reasons can be found in the scarcity of quantitative data on connectivity and a lack of agreement on connectivity measures. Currently, connections in marine landscapes are less studied than on land. The aim of this thesis was to examine the relationship between connectivity and ecosystem processes, and to test methods for modelling and incorporating quantitative
data on connectivity in the design of marine protected areas.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Grifffith School of Environment
Science, Environment, Engineering and Technology
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DENARO, Giovanni. "Stochastic models for phytoplankton dynamics in marine ecosystems." Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/91323.
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In this thesis, the stochastic advection-reaction-diffusion models are analyzed to obtain the vertical stationary spatial distributions of the main groups of picophytoplankton, which account about for 80% of total chlorophyll on average in Mediterranean Sea. In Chapter 1 we give a short presentation of the experimental and phytoplanktonic data collected during different oceanographic surveys in Mediterranean Sea. In Chapter 2 we introduce the deterministic and stochastic approaches (one-population model) adopted to describe the picoeukaryotes dynamics in Sicily Channel. Moreover, numerical results for the biomass concentration are compared with experimental data by using chi-squared goodness-of-fit test. In Chapter 3 we modify the previous one-population model to study the population dynamics of two picophytoplankton groups, i.e. picoeukaryotes and picoprokaryotes (Prochlorococcus). The agreement between theoretical results and experimental findings is checked by using two comparative methods: chi-squared goodness-of-fit test and Kolmogorov-Smirnov (K-S) test. In Chapter 4 we introduce a deterministic model used to perform the spatio-temporal analysis of five picophytoplankton species sampled in a site of the Tyrrhenian Sea: numerical results are compared with experimental data acquired during different oceanographic surveys in the period from 24 November 2006 to 9 June 2007. The models investigated in the chapters 2, 3 and 4, show that real distributions are well reproduced by theoretical profiles. Specifically, position, shape and magnitude of the theoretical deep chlorophyll maximum exhibit a good agreement with the experimental values. Finally, conclusions and future prospects of this thesis are discussed.
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HARRISON, Sofie, and sofieh@student ecu edu au. "The influence of seabird-derived nutrients on island ecosystems in the oligotrophic marine waters of south-western Australia." Edith Cowan University. Computing, Health And Science: School Of Natural Sciences, 2006. http://adt.ecu.edu.au/adt-public/adt-ECU2007.0010.html.
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Nutrient inputs from productive marine environments have been shown to directly and indirectly subsidise primary producers and consumers in terrestrial ecosystems (e.g. Polis and Hurd 1995; 1996; Anderson and Polis 1998; 1999). But does this theory hold true on islands surrounded by oligotrophic waters, which account for a significant proportion of the marine environment? The aim of the present study was to examine the applicability of the spatial subsidisation hypotheses proposed by Polis and his co-authors to an oligotrophic system in south-western region of Western Australia. These aims were achieved by comparing soil and plant nutrients, and the nitrogen stable isotope signatures of soil, plants, detritus and invertebrates in areas with (islands) and without (mainland sites) inputs from seabirds. In addition, the responses of plant nutrients and vegetation assemblages to guano additions were examined in a controlled field experiment.
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López, Muñoz Ignacio Francisco. "Optimal spatial arrangements of three ecosystems: microalgae pond, anaerobic digester and aerobic wastewater treatment plant." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/139852.
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Ingeniero Civil en BiotecnologíaIngeniero Civil Químico
Actualmente existen diversos problemas medioambientales, dos de ellos corresponden a la futura crisis energética, debido al agotamiento de los combustibles fósiles, y a la existencia de aguas residuales con altas concentraciones de nitrógeno y carbono. Un microorganismo llamado microalga podría ser una potencial solución a estos problemas, ya que éstos consumen nitrógeno y carbono para acumular lípidos en su medio intracelular, el cual posteriormente es procesado para producir biocombustibles. Sin embargo, la producción de energía a partir de microlagas es aún muy cara, es por eso que se debe optimizar este proceso, en este trabajo se abordará la estrategia de optimización a través del acoplamiento de ecosistemas, los cuales corresponden a: Piscina de microalgas (PM), digestor anaeróbico (DA) y una planta de tratamiento de aguas (PTA). El objetivo general de esta investigación es encontrar el arreglo espacial óptimo entre ellos. Se diseñaron y calibraron modelos matemáticos simples para el ecosistema PM y PTA. La calibración se llevó a cabo usando las curvas de nitrógeno y de demanda química de oxígeno (DQO) en paralelo, con una suma de errores de 22.5% para el PM y de 38.5% para el PTA. Los parámetros obtenidos son comparables a los encontrados en la literatura. Los ecosistemas fueron acoplados a través de sus flujos de DQO y de nitrógeno, y las siguientes funciones objetivo fueron definidas: 1) Maximizar el metano producido 2) Maximizar la energía total producida y 3) Maximizar las ganacias obtenidas gracias al valor del metano y de la biomasa producida. Además, fueron consideradas restricciones medioambientales, tales como la concentración de nitrógeno y la DQO en la salida del sistema. Si lo que se maximiza es el metano, se obtienen 99.96 [mol]. El reactor anaeróbico es el más grande y recibe la alimentación más alta, el CH4 generado corresponde al 72.4% del máximo teórico. En este caso, el arreglo espacial no puede ser presentado como una cadena de etapas porque el diagrama de flujos obtenido es uno circular y por lo tanto el orden entre cada ecosistema es irrelevante para el proceso. Si la ganacia y la energía total producida son maximizadas, se obtuvo 343.6 US$ y 115.53 [kWh], respectivamente. El ecosistema de tratamiento de aguas recibe la alimentación más alta, el cual produce el mayor beneficio económicos y la mayor producción de energía. El metano producido es un 21% del máximo teórico. En ambos casos, el arraglo espacial obtenido son iguales, debido a la presencia de mínimos locales y a la similtud de las funciones objetivo. Además, es posible concluir que el primer paso del proceso debiese ser el ecosistema PTA, luego el DA y finalmente el PM. Así, se pudo cumplir el objetivo general de este trabajo. Finalmente, la metodología usada es capaz de cumplir los objetivos planteados, incluso es posible escalar el problema agregando otros ecosistemas o usarla en otras aplicaciones." "In recent years several environmental problems have come about, two of them are an energy crisis as a result of fossil fuel exhaust and the waste water created with high nitrogen and carbon concentrations. A potential solution of the aforementioned problems is contained in the properties of microalgae, which is a microorganism that can accumulate lipids in its intracellular medium. These lipids can be processed and converted into biofuel by allowing microalgae to consume nitrogen and an organic source from the medium. However, energy production from microalgae is too expensive in comparison with fossil fuel and thus there is a need to optimize this process. The strategy of optimizing by coupling ecosystems will be carried out in this work. The ecosystems that will be coupled are: Microalgae pond (MP), anaerobic digester (AD) and wastewater treatment plant (WWT). The general objective of this research is to find the optimal spatial arrangement among them through mathematical modelling. Simple mathematical models were designed and calibrated to MP and WWT ecosystem. Calibrations were carried out using nitrogen and chemical oxygen demand (COD) curves in parallel with a sum error of 22.5% in MP and 38.5% in WWT. Obtained parameters are similar to ones found in previous literature. Ecosystem were coupled through COD and nitrogen flows and the following objectives functions were defined: 1) Maximize methane produced 2) Maximize total energy produced and 3) Maximize profit due to the value of methane and microalgae biomass produced. Environmental constraints were considered, such as nitrogen and COD because they are in the output. When the methane produced was maximized it reached 99.96 [mol]. The anaerobic reactor has the biggest size, it receives the highest input flow, and CH4 generated is the 72.4% of maximum theoretical methane production. This result determined that the spatial arrangement can not be summarized by a chain of processes since the flowsheet obtained is a circular one and thus the order is irrelevant for the process. When profit and total energy produced are maximized, it was obtained 343.6 US$ and 115.53 [kWh]$ respectively. Waste water ecosystem received the biggest input flow, which produced the majority of amount of revenues and energy. Methane produced is equal to 21% of maximum theoretical. In both cases, the spatial arrangements obtained are equals due to the presence of local minima and the similarity in the objective function. These calculations allow to conclude the best order of the ecosystems: WWT, AD, and finally MP. Finally the methodology is enough to reach the objectives of this work, even it is possible to scale the system adding more than one ecosystem or using this methodology in other fields.
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Hedberg, Nils. "Sea cages, seaweeds and seascapes : Causes and consequences of spatial links between aquaculture and ecosystems." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-141009.
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Aquaculture is of growing importance in the global seafood production. The environmental impact of aquaculture will largely depend on the type of environment in which the aquaculture system is placed. Sometimes, due to the abiotic or biotic conditions of the seascape, certain aquaculture systems tend to be placed within or near specific ecosystems, a phenomenon that in this thesis is referred to as aquaculture system - ecosystem links. The exposed ecosystems can be more or less sensitive to the system specific impacts. Some links are known to be widespread and especially hazardous for the subjected ecosystem such as the one between the shrimp aquaculture and the mangrove forest ecosystem. The aim of this thesis was to identify and investigate causes and consequences of other spatial links between aquaculture and ecosystems in the tropical seascape. Two different aquaculture system - ecosystem links were identified by using high resolution satellite maps and coastal habitat maps; the link between sea cage aquaculture and coral reefs, and the one between seaweed farms and seagrass beds. This was followed by interviews with the sea cage- and seaweed farmers to find the drivers behind the farm site selection. Many seaweed farmers actively choose to establish their farms on sea grass beds but sea cage farmers did not consider coral reefs when choosing location for their farms. The investigated environmental consequences of the spatial link between sea cage aquaculture and coral reefs were considerable both on the local coral reef structure, and coral associated bacterial community. Furthermore, coral reef associated fish are used as seedlings and feed on the farms, which likely alter the coral food web and lower the ecosystem resilience. Unregulated use of last resort antibiotics in both fish- and lobster farms were also found to be a wide spread practice within the sea cage aquaculture system, suggesting a high risk for development of antibiotic resistant bacteria. The effects of seaweed farms on seagrass beds were not studied in this thesis but have earlier been shown to be rather substantial within the borders of the farm but less so outside the farm. Further, a nomenclature is presented to facilitate the discussion about production system - ecosystem links, which may also be used to be able to incorporate the landscape level within eco-certifying schemes or environmental risk assessments. Finally - increased awareness of the mechanisms that link specific aquaculture to specific habitats, would improve management practices and increase sustainability of an important and still growing food producing sector - the marine aquaculture.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.
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Henry, Mary Catherine. "Characterizing fire-related spatial patterns in fire-prone ecosystems using optical and microwave remote sensing." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280006.
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The use of active and passive remote sensing systems for relating forest spatial patterns to fire history was tested over one of the Arizona Sky Islands. Using Landsat Thematic Mapper (TM), Shuttle Imaging Radar (SIR-C), and data fusion I examined the relationship between landscape metrics and a range of fire history characteristics. Each data type (TM, SIR-C, and fused) was processed in the following manner: each band, channel, or derived feature was simplified to a thematic layer and landscape statistics were calculated for plots with known fire history. These landscape metrics were then correlated with fire history characteristics, including number of fire-free years in a given time period, mean fire-free interval, and time since fire. Results from all three case studies showed significant relationships between fire history and forest spatial patterns. Data fusion performed as well or better than Landsat TM alone, and better than SIR-C alone. These comparisons were based on number and strength of significant correlations each method achieved. The landscape metric that was most consistent and obtained the greatest number of significant correlations was Shannon's Diversity Index. Results also agreed with field-based research that has linked higher fire frequency to increased landscape diversity and patchiness. An additional finding was that the fused data seem to detect fire-related spatial patterns over a range of scales.
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Zhao, Chang. "Quantifying and mapping the supply of and demand for urban ecosystem services." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6350.
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The ecosystem services (ES) concept is meant to facilitate consideration of the value of nature in conservation and landscape management processes by translating ecosystem functions into human benefits. Incorporating the ES concept into policy and decision-making has proven difficult due to challenges in identifying, measuring, and locating services and in predicting the impacts of decisions upon them. ES mapping offers a key solution to increase our understanding of the spatial patterns of ES supply and demand and the spatial relationships between them, but may be challenging to implement given a lack of spatial data related to ES or existence of such data at coarse resolution that may not facilitate accurate ES quantification, mapping and modeling. This issue is particularly acute in urban settings where landscapes are highly heterogeneous and fragmented. This research seeks to improve our understanding of urban ES supply, demand and the relationships between them, as well as the impacts of spatial scale, input data quality and method choice on ES mapping in urban landscapes. The dissertation is composed of three studies. In the first study, I introduce a spatially-explicit framework for quantifying and mapping ES supply and demand using carbon storage and sequestration services as an example. This framework assesses supply based on biophysical conditions and demand based on socioeconomic characteristics, allowing for more integrative ES assessments in urban areas. In the second study, I evaluate the sensitivity of ES maps to input spatial data resolution and method choice (ecosystem component-based and land-cover proxy-based methods) in a heterogeneous urban landscape using biomass carbon storage as an example. I find that ES map accuracy is highly dependent on analytical scales and input data representativeness. ES estimates based on ecosystem-component data are more accurate than those based on land-cover proxies. The accuracy of land-cover proxy-based maps, however, can be increased by using high-resolution land-cover maps. The third study aims to increase understanding of ES supply, demand, and supply-demand balance in urban contexts. To this end, I create a high-thematic-resolution land-cover dataset and combine it with the InVEST pollination model to assess the capacity of urban ecosystems to supply pollination services to satisfy the demands of urban agriculture. I find using land-cover dataset at a higher thematic resolution enhances the accuracy of pollination estimates, highlighting the importance of considering scale and land-use dependencies in urban ES mapping. Combined, these studies advance our knowledge of ES supply, demand and the relationships between them, and provide new insight into the impacts of input data spatial and thematic resolution and method choice on the accuracy of urban ES maps.
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Henri, Dominic Charles. "From individuals to ecosystems : a study of the temporal and spatial variation in ecological network structure." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15726.
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Ecological network theory has developed from studies of static, binary trophic relationships to the analysis of quantitative, dynamic communities consisting of multiple link-types. Particularly, work has focused on the dynamic nature of ecological networks, which maintains stability in complex communities. However, there are few in situ network-level studies of the determinants of temporal and spatial variation in community structure. This thesis utilises data from a 10-year study of a host-parasitoid network and a collaborative study in an applied ecological setting to identify individual level factors important to network structure. The work aims towards an empirical, predictive framework linking adaptive foraging behaviour to ecological network structure. The results show that condition-dependent foraging behaviours structure host-parasitoid networks. The realised niches of the studied parasitoid species were generally biased towards larger host species and condition-dependent sex ratio allocation increased the likelihood that females would eclose from relatively larger hosts and males from relatively smaller hosts, which resulted in sex ratios deviating from Hamiltonian (50:50) predictions. Further, both of these aspects of behaviour are plastic, where parasitoid behaviour responded to environmental heterogeneity. Particularly, host preference behaviour conformed to an egg-/time-limitation framework, where the size dependency of the behaviour is greater when individuals have a greater likelihood of being egg-limited. Both the size-dependency and the plasticity of these behaviours differed significantly between secondary parasitoid species. This species identity effect interacted with landscape heterogeneity, which may explain some inter- and intra-specific variation in network structure. With respect to applied ecology, the results show that the benefits of natural vegetation for pest control are dependent upon the dispersal capabilities and the diet breadth of the pest and its natural enemies. The findings are evaluated towards a predictive framework for understanding the effects of future climate change on community structure and stability. We consider this framework in terms of applied ecology, particularly pest control ecosystem services provided by natural vegetation in an agricultural environment. The synergistic nature of the multiple determinants of network structure found in this thesis suggest that future studies should focus on the whole network, which is not necessarily the sum of its parts.
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Millington, Heidi Kathryn. "Spatial Analysis of the Impacts of Urbanisation on the Health of Ephemeral Streams in Southeast Queensland." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/367358.
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Aquatic ecosystems are vulnerable to threats from human activity. Numerous studies have shown that urban freshwater stream ecosystems are especially vulnerable to the intensity and complexity of stream health stressors associated with activities in the surrounding urban landscape. Scientists, government organisations and local volunteer groups are well aware of the deteriorating health of urban streams and are working towards understanding and managing the sources of stress on stream health. Improving the health of urban streams has the potential to provide local benefits such as biodiversity protection, enhanced ecosystem health, water purification, access to green space, scenic amenity and improved land values. While several important stressors have been identified in the Urban Stream Syndrome (elevated sediments, nutrients and contaminants, increased hydrologic flashiness and altered riparian and biotic assemblages) further research is required on the most important stressors and the mechanisms by which they impact stream health, especially in systems within dry climates where urban streams experience low flow conditions and flashy natural hydrology. Catchment-scale impervious surface has been identified in previous studies as a major driver of altered urban stream hydrology leading to degraded stream health. However, especially in drier climates, other aspects such as water quality and ecological processes associated with longitudinal and lateral connectivity have been identified as potentially more important stressors on urban stream health.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Marshall, Laura. "Statistical developments for understanding anthropogenic impacts on marine ecosystems." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3172.
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Over the past decades technological developments have both changed and increased human in influence on the marine environment. We now have greater potential than ever before to introduce disturbance and deplete marine resources. Two of the issues currently under public scrutiny are the exploitation of fish stocks worldwide and levels of anthropogenic noise in the marine environment. The aim of this thesis is to investigate and develop novel analyses and simulations to provide additional insight into some of the challenges facing the marine ecosystem today. These methodologies will improve the management of these risks to marine ecosystems. This thesis first addresses the issue of competition between humans and grey seals (Halichoerus grypus) for marine resources, providing compelling evidence that a substantial proportion of the sandeels consumed by grey seals in the North Sea are in fact H. lanceolatus, which is not commercially exploited, rather than the commercially important A. marinus. In addition, we present quantitative results regarding sources of bias when estimating the total biomass of sandeels consumed by grey seals. Secondly, we investigate spatially adaptive 2-dimensional smoothing to improve the prediction of both the presence and density of marine species, information that is often key in the management of marine ecosystems. Particularly, we demonstrate the benefits of such methods in the prediction of sandeel occurrence. Lastly this thesis provides a quantitative assessment of the protocols for real-time monitoring of marine mammal presence, which require that acoustic operations cease when an animal is detected within a certain distance (i.e. the "monitoring zone") of the sound source. We assess monitoring zones of different sizes with regards to their effectiveness in reducing the risks of temporary and permanent damage to the animals' hearing, and demonstrate that a monitoring zone of 2 km is generally recommendable.
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Neal, Andrew. "Soil Moisture Controls on Spatial and Temporal Patterns of Carbon Dioxide Fluxes in Drylands." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/241932.
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Dryland ecosystems provide a unique opportunity to study the effects of water limitation on ecosystem activity. The sensitivity of these systems to small inputs of moisture is well-documented, but the expression of water limitation in terms of carbon dioxide flux between the ecosystem and atmosphere remains unclear. Applying a simple conceptual approach to soil moisture dynamics, patterns in carbon flux become clear. Release of carbon dioxide via respiration is primarily driven by moisture in the shallow soil, and differences in respiration rates among plant functional types are only evident after controlling for soil moisture. Alternatively, carbon uptake by a semiarid shrubs ecosystem is largely driven by the availability of deep soil moisture. This link to deep soil moisture improves spatial scaling of gross and net carbon uptake using remote sensing data. Lateral redistribution of moisture on the landscape connects readily observed physical features, namely topography, to ecosystem function, but redistribution is generally not considered in carbon models. A simple runoff scheme coupled to a conceptual model for carbon flux demonstrates the high degree of spatial heterogeneity in carbon dioxide flux resulting from moisture redistribution. The importance of redistribution in carbon modeling is highlighted by interannual variability in modeled carbon fluxes under different rainfall characteristics (event size, event duration, interstorm duration). The links between hydrology and ecology across spatial scales become clearer when topographically-based moisture distribution is used as an organizing variable. In all, this research identifies new avenues for research where moisture dynamics are of central interest in dryland ecohydrology.
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Harrison, Sofie A. "The influence of seabird-derived nutrients on island ecosystems in the oligotrophic marine waters of south-western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2006. https://ro.ecu.edu.au/theses/68.
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Nutrient inputs from productive marine environments have been shown to directly and indirectly subsidise primary producers and consumers in terrestrial ecosystems (e.g. Polis and Hurd 1995; 1996; Anderson and Polis 1998; 1999). But does this theory hold true on islands surrounded by oligotrophic waters, which account for a significant proportion of the marine environment? The aim of the present study was to examine the applicability of the spatial subsidisation hypotheses proposed by Polis and his co-authors to an oligotrophic system in south-western region of Western Australia. These aims were achieved by comparing soil and plant nutrients, and the nitrogen stable isotope signatures of soil, plants, detritus and invertebrates in areas with (islands) and without (mainland sites) inputs from seabirds. In addition, the responses of plant nutrients and vegetation assemblages to guano additions were examined in a controlled field experiment.
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Sigovini, Marco <1980>. "Multiscale dynamics of zoobenthic communities and relationships with environmental factors in the Lagoon of Venice." Doctoral thesis, Università Ca' Foscari Venezia, 2011. http://hdl.handle.net/10579/1092.
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The thesis focuses on the macrozoobenthic community in the Lagoon of Venice. Main aspects investigated include: spatial and interannual variability of the community structure; the role of environmental factors in structuring benthic communities; spatial scales of variability of the community, also in relationship to variability scales of environmental factors. A three-year data set was analyzed. High interannual variability and spatial heterogeneity was verified. Multivariate structure and univariate descriptors were considerably related to environmental factors. A gradient from sea landwards in species richness and community composition was evidenced and related to the composite ecocline, mainly to seawater renewal and salinity. More complex spatial patterns were recognized. Univariate descriptors and multivariate structures follow different scales of variability. The results have implications for quality assessment of transitional ecosystems.La tesi analizza la comunità macrozoobentonica della Laguna di Venezia. Sono stati principalmente indagati: la variabilità spaziale e interannuale della struttura della comunità; il ruolo dei fattori ambientali; le scale spaziali di variabilità della comunità, in relazione alla scala di variabilità dei fattori ambientali. Il data set analizzato è relativo a tre anni. E' stata verificata un'elevata variabilità interannuale ed eterogeneità spaziale. Descrittori di struttura multivariata e univariate sono risultati notevolmente correlati ai fattori ambientali. E' stato evidenziato un gradiente da mare verso terra in merito al numero di specie e alla composizione della comunità, in relazione ad un ecocline composito, e principalmente a ricambio idrico e salinità. Sono emersi pattern spaziali più complessi. Descrittori univariati e strutture multivariate seguono diverse scale di variabilità. I risultati hanno implicazioni per la valutazione della qualità degli ecosistemi di transizione.
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Hogland, John Scott MacKenzie Mark D. "Creating spatial probability distributions for longleaf pine ecosystems across east Mississippi, Alabama, the Panhandle of Florida, and west Georgia." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Thesis/HOGLAND_JOHN_19.pdf.
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Pilote, Martin. "Trends in the Exchange of CO2 and CH4 between the Atmosphere and Eastern Canadian Subarctic and Arctic Ecosystems." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33426.
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Significant warming of Arctic and northern regions is ongoing and may greatly alter the carbon cycle of these regions. During the International Polar Year, an extensive study was carried out in the Eastern Canadian subarctic and Arctic in order to characterize CO2 and CH4 exchanges from these potentially sensitive ecosystems. The main objectives of this study were to identify the land cover and environmental factors leading to greatest CO2 and CH4 emissions in a highly heterogeneous subarctic landscape, to quantify interannual variability in the net ecosystem exchange of CO2 (NEE) in subarctic forest tundra and investigate the weather conditions that increase net uptake of CO2, and finally, to evaluate the general trends of mid-summer NEE along a latitudinal gradient spanning from 55° to the 72° north. At the landscape level, CO2 and CH4 exchanges showed large variability. Although CH4 emissions were greatest in wetlands, their areal coverage is small in the Kuujuarapik area and limited the influence of these CH4 sources. At the ecosystem level, large-scale atmospheric processes controlled growing season length and cumulative growing degree days which greatly influenced annual and seasonal NEE trends. The subarctic forest tundra near Kuujuarapik was a net source of CO2 in all 3 study years but the source strength was least with the greatest growing degree days while the length of the snow-free period appeared to be less important. Across a latitudinal gradient covering subarctic forest tundra to Arctic tundra, variations in summer NEE could be linked to surface organic carbon content with higher net CO2 uptake at sites with greater soil organic carbon. Warmer days tended to correlate with smaller daily net CO2 uptake (or greater net CO2 losses) but overall, warmer growing seasons reduced the net losses of CO2 on an annual basis. Carbon fluxes in Eastern Canadian subarctic and Arctic regions are highly variable in space and time but these observations help establish a baseline for future examinations of how these carbon exchanges may change with further warming.
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Haberstroh, Charlotte Juliane. "Geographical Information Systems (GIS) Applied to Urban Nutrient Management: Data Scarce Case Studies from Belize and Florida." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6620.
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Nutrient inputs into the environment greatly impact urban ecosystems. Appropriate management strategies are needed to limit eutrophication of surface water bodies and contamination of groundwater. In many existing urban environments, retrofits or complete upgrades are needed for stormwater and/or wastewater infrastructure to manage nutrients. However, sustainable urban nutrient management requires comprehensive baseline data that is often not available. A Framework for Urban Nutrient (FUN) Management for Geographic Information Systems (GIS) was developed to specifically address those areas with limited data access. Using spatial analysis in GIS, it links water quality, land use, and socio-demographics, thereby reducing data collection and field-based surveying efforts. It also presents preliminary results in a visually accessible format, potentially improving how data is shared and discussed amongst diverse stakeholders. This framework was applied to two case studies, one in Orange County Florida and one in Placencia, Belize.
A stormwater pond index (SPI) was developed to evaluate 961 residential wet ponds in Orange County, Florida where data was available for land use and socio-demographic parameters, but limited for water quality. The SPI consisted of three categories (recreation, aesthetics, education) with a total of 13 indicators and provided a way to score the cultural and ecosystem services of 41 ponds based on available data. Using only three indicators (presence of a fence, Dissolved Oxygen (DO) < 4 mg/l, and water depth < 3 ft), 371 out of 961 stormwater ponds were assessed. Additional criteria based on socio-demographic information (distance to a school, population density, median household income under $50,000, percentage of population below the poverty line, and distance to parks) identified seven wet ponds as optimum for potential intervention to benefit residents and urban nutrient management purposes.
For the second case study, a water quality analysis and impact assessment was performed for the Placencia peninsula and lagoon in Belize. This study had access to water quality data, but limited land use data and very limited socio-demographic data. Since May 2014, water quality samples have been taken from 56 locations and analyzed monthly. For this study, Dissolved Oxygen (DO), Nitrate (NO3--N), Ammonia (NH3), Chemical Oxygen Demand (COD), and 5-Day Biochemical Oxygen Demand (BOD5), Escherichia coli (E. coli), and Enterococci were selected to assess spatial and temporal variation of water quality in the groundwater on the peninsula as well as the surface water in lagoon, estuaries and along the coast. A spline interpolation of DO, Nitrate, BOD5, and COD for June 2016 indicated the concentration distribution of those parameters and areas of special concern. A spatial analysis was conducted that showed that Nitrate and Enterococci exceeded the effluent limits of Belize very frequently in the complete study area while the other parameters contributed to the identification of key areas of concern. As a high variability of concentrations over time was observed, a temporal analysis was conducted identifying a link between the water quality data and two temporal impact factors, rainfall and tourism. The two case studies showed the broad and flexible application of the FUN management for GIS and the great advantages the use of GIS offers to reduce costs and resources use.
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Vilmi, A. (Annika). "Assessing freshwater biodiversity:insights from different spatial contexts, taxonomic groups and response metrics." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526216669.
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Abstract Freshwater ecosystems are severely threatened by a variety of anthropogenic stressors. In order to keep track with at least part of the changes, it is important to efficiently assess and monitor freshwater biological diversity. Biological assessment programs are developed to detect human-induced changes in the ecological state of aquatic systems. These programs typically rely on the assumption that environmental conditions are the sole drivers of biological communities occupying a site and, thus, these local communities would correctly inform about environmental conditions. Recently, this background principle of current bioassessment methods has faced some criticism, stemming from the idea that community structuring is a more complex process than just a mere result of local environmental conditions. In this thesis, I studied the natural and anthropogenic drivers of freshwater biodiversity. I was particularly interested if the various biodiversity metrics studied showed any spatial patterns and if so, for which reasons these patterns might occur. To obtain a comprehensive picture of spatial patterns in biodiversity, I studied multiple spatial contexts, biological groups and indices. I found that environmental conditions were not the only drivers of freshwater biodiversity. Instead, different spatial patterns, likely stemming from dispersal processes, were surprisingly powerful drivers of aquatic communities and index values derived from them. The spatial context (i.e. spatial extent and connectivity) of the aquatic study systems likely played a major role in structuring biodiversity. I also found that the distinct biological groups and indices studied were partly related to different predictor variables. The findings of this thesis are of importance to the development of new bioassessment methods. The results of this thesis also suggest that the spatial context of the study setting should be acknowledged when interpreting results based on current bioassessment methodsTiivistelmä Makeanveden ekosysteemit ovat hyvin alttiita ihmistoiminnalle. Ekosysteemissä mahdollisesti tapahtuvien muutosten havaitseminen vaatii tehokkaita vesistöjen ekologisen tilan ja luonnon monimuotoisuuden arviointi- ja seurantamenetelmiä. Näiden menetelmien toimintaperiaatteen yleisenä tausta-ajatuksena on, että biologiset yhteisöt määräytyvät paikallisten ympäristöolojen mukaan. Tietyn paikan yhteisön oletetaan siis heijastavan kyseisen paikan ympäristön tilaa. Viime aikoina tausta-ajatus paikallisten ympäristöolojen merkityksestä ainoana eliöyhteisöjä muovaavana tekijänä on kuitenkin kohdannut kritiikkiä. Kriitikot painottavat, että biologisten yhteisöjen rakenteeseen vaikuttavat monet muutkin asiat kuin paikalliset ympäristöolosuhteet ja niissä tapahtuvat ihmisperäiset muutokset. Väitöskirjassani tutkin sisävesien luonnon monimuotoisuuteen vaikuttavia tekijöitä. Olin erityisen kiinnostunut siitä, näkyykö tutkituissa biologisissa parametreissa maantieteellisessä tilassa ilmeneviä spatiaalisia säännönmukaisuuksia. Saadakseni mahdollisimman laaja-alaisen käsityksen luonnon monimuotoisuudessa esiintyvistä spatiaalisista säännönmukaisuuksista, tutkin useaa spatiaalista kontekstia, eliöryhmää ja indeksiä. Tutkimuksessa selvisi, että paikalliset ympäristöolosuhteet eivät ole ainoita luonnon monimuotoisuuteen vaikuttavia tekijöitä. Erilaiset spatiaaliset säännönmukaisuudet, todennäköisesti eliöiden levittäytymiseen liittyvien seikkojen aiheuttamina, olivat yllättävän yleisiä makeiden vesien eliöyhteisöjen rakenteessa ja niihin perustuvien indeksien arvoissa. Tutkimussysteemien spatiaalinen konteksti (alueen laajuus ja paikkojen väliset spatiaaliset suhteet) selvästi vaikutti luonnon monimuotoisuutta kuvastavien indeksien arvojen vaihteluun. Lisäksi selvisi, että eri eliöryhmät ja indeksit olivat useimmiten liitoksissa hyvin erilaisiin selittäviin muuttujiin, osoittaen, että nämä mittarit kuvastavat eri asioita. Väitöskirjassa esitetyt havainnot on tärkeää huomioida vesistöjen ekologisen tilan ja luonnon monimuotoisuuden arviointi- ja seurantamenetelmiä kehitettäessä. Spatiaalisen kontekstin merkitys olisi hyvä huomioida myös nykyisten arviointi- ja seurantamenetelmien tuottamien tulosten tulkinnassa
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Jörgensen, Tove Lund. "Coral Reef Habitats and Fish Connectivity : Implications for coastal management and fishery." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-125595.
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Coral reefs have one of the highest levels of biodiversity of all ecosystems in the world and are important for both human livelihood and food security throughout many tropical countries. However, due to increased anthropogenic pressure on marine ecosystems, especially during the last couple of decades, coral reefs have become critically over-fished, and many reefs are now in a degraded state and are facing additional future threats due to further over-exploitation, chemical pollution, sedimentation, and effects of climate change. The main aim of this PhD thesis was to understand effects of anthropogenic disturbances on tropical coastal ecosystems and fish connectivity for coastal management purposes. Therefore, linkages between anthropogenic disturbance and corals were investigated (Paper I), as well as interactions between coral reef habitat and associated fish assemblage (Paper II). Furthermore, connectivity between coral reefs and other tropical coastal ecosystems was explored (Paper III), as well as fish migration to reproduction sites (Paper IV), and evaluations of spatial ecology methods (Paper V). The result showed that coral reefs that are already exposed to disturbances, such as freshwater and nutrient run-offs, may be more sensitive to climate change, in terms of increased sea surface temperatures (Paper I). In addition, there were also clear linkages between coral reef quality, in terms of coral coverage, and fish assemblages, which displayed high spatial variability and suggesting patchy recovery after the 1997/1998 bleaching and subsequent coral mass mortality event (Paper II). This highlights the importance of understanding effects of disturbances on corals, especially in terms of synergistic effects between increased water temperatures and other coastal stressors such as decreased salinity and increased nutrients; and the indirect effects of habitat degradation on the fish community. Linkages between fish and different coastal habitats were further explored. The results showed that coral reefs were strongly connected with mangrove and seagrass beds, through ontogenetic migration of fish (Paper III). Migrations to spawning sites of groupers were related to lunar activities when thousands of fish gather for reproduction purposes during new moon, which increases the risk of over-exploitation (Paper IV). The results emphasises the importance of protecting key areas such as nursing grounds and reproduction sites. Furthermore, acoustic telemetry has become an increasingly common method in studies of fish movement, and the results showed that efficiency of acoustic arrays may increase depending on deployment strategies and habitat characteristics (Paper V). In conclusion, the results from this PhD thesis emphasises the importance of protecting coral reef habitats, as well as identifying related susceptible tropical coastal areas, such as nursing grounds and reproduction sites. Indeed, a better scientific understanding of coral reef ecology and indirect and direct effects on fish assemblages are needed for efficient and accurate coastal management decisions.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.
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Dunn, Shanna K. "Analyzing Spatial Patterns in Reefscape Ecology Via Remote Sensing, Benthic Habitat Mapping, and Morphometrics." NSUWorks, 2009. http://nsuworks.nova.edu/occ_stuetd/234.
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A growing number of scientists are investigating applications of landscape ecology principles to marine studies, yet few coral reef scientists have examined spatial patterns across entire reefscapes with a holistic ecosystem-based view. This study was an effort to better understand reefscape ecology by quantitatively assessing spatial structures and habitat arrangements using remote sensing and geographic information systems (GIS).
Quantifying recurring patterns in reef systems has implications for improving the efficiency of mapping efforts and lowering costs associated with collecting field data and acquiring satellite imagery. If a representative example of a reef is mapped with high accuracy, the data derived from habitat configurations could be extrapolated over a larger region to aid management decisions and focus conservation efforts.
The aim of this project was to measure repeating spatial patterns at multiple scales (10s m2 to 10s km2) and to explain the environmental mechanisms which have formed the observed patterns. Because power laws have been recognized in size-frequency distributions of reef habitat patches, this study further investigated whether the property exists for expansive reefs with diverse geologic histories.
Intra- and inter-reef patch relationships were studied at three sites: Andavadoaka (Madagascar), Vieques (Puerto Rico), and Saipan (Commonwealth of the Northern Mariana Islands). In situ ecological information, including benthic species composition and abundance, as well as substrate type, was collected with georeferenced video transects. LiDAR (Light Detection and Ranging) surveys were assembled into digital elevation models (DEMs), while vessel-based acoustic surveys were utilized to empirically tune bathymetry models where LiDAR data were unavailable. A GIS for each site was compiled by overlying groundtruth data, classifications, DEMs, and satellite images. Benthic cover classes were then digitized and analyzed based on a suite of metrics (e.g. patch complexity, principle axes ratio, and neighborhood transitions).
Results from metric analyses were extremely comparable between sites suggesting that spatial prediction of habitat arrangements is very plausible. Further implications discussed include developing an automated habitat mapping technique and improving conservation planning and delimitation of marine protected areas.
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Picazo, Mota Félix. "Diversity patterns in freshwate ecosystems : new insights using water beetles at different spatial scales = Patrones de diversidad en ecosistemas acuáticos continentales : nuevas aportaciones usando coleópteros a diferentes escaleas espaciales." Doctoral thesis, Universidad de Murcia, 2016. http://hdl.handle.net/10803/369839.
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El objetivo general de esta tesis es profundizar en el conocimiento que se tiene sobre los patrones de diversidad que las comunidades biológicas muestran en ecosistemas acuáticos continentales, la comprensión de los principales factores que los determinan y su variación a diferentes escalas espaciales, prestando especial atención a las particularidades y oportunidades de estudio derivadas del carácter lótico o lenítico de los hábitats. Para ello se ha trabajado un amplio rango de enfoques (taxonómico, funcional y ecológico), a distintas escalas espaciales (desde comunidades locales del sureste ibérico hasta inventarios completos de diferentes regiones con entidad biogeográfica del Paleártico occidental), y utilizando coleópteros como indicadores de biodiversidad acuática, de forma que, en última instancia, toda esta información resulte útil para ser implementada en futuras políticas de conservación de la naturaleza. En los capítulos 1 y 2 se estudia la contribución que los cuerpos de agua estancada realizan a la diversidad regional de coleópteros acuáticos, tanto en su conjunto como para cada uno de los tipos de hábitat establecidos. El primer capítulo se centra únicamente en la composición de las comunidades, mientras que el segundo trata, además, el modo en que éstas se estructuran. En ellos se constata la importancia que estos ambientes tienen no sólo para los especialistas leníticos, sino también para un amplio espectro de especies facultativas. También se destaca el papel de las pozas naturales en términos de riqueza total de especies y de las lagunas endorreicas próximas a ambientes salinos en términos de riqueza de endemismos. En el capítulo 2 se identifica la conductividad como la variable que mejor explica las diferencias en la composición de las faunas, mientras que el grado de perturbación de origen antrópico es el principal responsable del patrón de anidamiento detectado. Al analizar los sitios dulces y salinos de manera independiente, ambas variables juegan papeles diferentes tanto en la composición como en la estructura. El nivel de perturbación se muestra de nuevo la variable que mejor explica el patrón de anidamiento para agua dulce, mientras que en sitios salinos lo es la conductividad. En el capítulo 3 se introduce un enfoque funcional, y se demuestra que la riqueza de especies de las distintas familias de coleópteros acuáticos está significativamente relacionada con su diversidad de rasgos, tanto biológicos como ecológicos. No obstante, hubo familias que presentaron mayor o menor diversidad de rasgos biológicos de la que cabría esperar en función de su diversidad taxonómica. Los resultados apuntan hacia un predominio de procesos de filtrado del hábitat en arroyos de cabecera mientras que factores de tipo biótico, por ejemplo competencia entre especies, serían más relevantes en hábitats a priori menos estresados como los ambientes leníticos. Como resultado del estudio taxonómico detallado de las comunidades acuáticas realizado en los capítulos anteriores, en el capítulo 4 se describe una nueva especie para la ciencia: Stictonectes abellani. La información se completa con la estimación de la distribución potencial y las preferencias ambientales de las 3 especies del género endémicas de la península Ibérica. Finalmente, en el capítulo 5 se constata, a una escala espacial más amplia, la existencia de patrones latitudinales de diversidad alfa y gamma diferentes para especialistas lóticos y leníticos, así como un descenso de diversidad beta con la latitud para ambos grupos de taxones. Estos hallazgos confirman el papel clave que la capacidad de dispersión, enmarcada en los cambios climáticos del Pleistoceno, juega en la configuración de los patrones de diversidad observados en el Paleártico occidental, y que en última instancia tiene su origen en la distinta estabilidad (a largo plazo) que presentan ambos tipos de hábitat.The main goal of this thesis is to increase the existing knowledge about diversity patterns displayed by biological communities in freshwater ecosystems, the understanding on the main factors underlying them and their performance at different spatial scales, especially focusing on the particularities derived from the lotic-lentic divide. For that purpose, different approaches (taxonomic, functional and ecological), at different spatial scales (from local assemblages of Iberian southeast to whole inventories of different biogeographic regions in the Western Palaearctic), and using beetles as surrogates of aquatic biodiversity, so that, all this information can be finally useful to be implemented in future nature conservation policies. Chapters 1 and 2 deal with the contribution of standing water bodies to regional diversity of water beetles, both for the whole set of localities and for each of the habitat types established. The former is focused exclusively on the local assemblage composition, whereas the latter also tackles the way in which they are structured. Both chapters confirm the importance that these systems have not only for lentic specialist but also for a wide spectrum of facultative species. The role of natural pools in terms of total richness and endorheic lagoons close to saline habitats in terms on endemic richness is highlighted as well. Chapter 2 shows that conductivity is the most explanatory variable for differences in assemblage composition, whereas the degree of anthropogenic impact is the main responsible for the nestedness pattern detected. When fresh and saline water bodies were analyzed independently the two mentioned variables played different roles both in the assemblage composition and structure. The degree of anthropogenic stress was again the most explanatory variable for the nestedness pattern showed by the fresh water sites, whereas for saline sites was conductivity. Chapter 3 includes a functional approach and demonstrates that the species richness of the different water beetle families is significantly related to their biological and ecological trait diversities. However, there were families which displayed higher or lower biological trait diversity than expected in relation to their taxonomic diversity. These results point to the predominance of habitat filtering processes in headwater streams whereas biotic factors, such as interspecific competition, would be more relevant in a priori less stressed habitats as some lentic systems are. As a result of the detailed taxonomic study of the water beetle assemblages carried out in the previous chapters, in chapter 4 a new species for science is described: Stictonectes abellani. Such information is completed with the estimation of the potential distribution and the environmental preferences of the 3 Iberian endemic species of the genus. Finally, chapter 5 evidences, in a wider spatial scale, the existence of contrasting latitudinal patterns of alpha and gamma diversity for lotic and lentic specialist, as well as the decrease of beta diversity as latitude increases for both groups of species. Such findings prove the key role that dispersal ability, framed in the Pleistocene climate changes, plays in shaping the diversity patterns observed in the Western Palaearctic, which is finally originated by the contrasting long-term stability displayed by both kinds of habitats.
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Guttal, Vishwesha. "Applications of nonequilibrium statistical physics to ecological systems." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209696541.
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Ruiz, Winston Franz Rios. "Biogeografia de bactérias da filosfera de Maytenus robusta na Mata Atlântica." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-14022011-084227/.
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A biogeografia estuda a distribuição dos organismos em relação ao espaço e ao tempo, favorecendo a compreensão dos mecanismos que geram e mantém a diversidade, especiação, extinção e dispersão das espécies. Dentre as florestas tropicais, a Mata Atlântica constitui um mosaico vegetal de grande diversidade, onde a filosfera representa um dos habitats mais comuns para os microrganismos. O objetivo do presente trabalho foi avaliar a estrutura e diversidade da comunidade bacteriana da filosfera de Maytenus robusta no Parque Estadual Carlos Botelho, Parque Estadual Ilha do Cardoso e Estação Ecológica de Assis, no estado de São Paulo, Brasil. As folhas foram coletadas em duas épocas do ano, seca e chuvosa. A estrutura da comunidade bacteriana foi avaliada através de PCR-DGGE da região V3 do gene rRNA 16S e a diversidade por sequenciamento da região V1-V3 do mesmo gene. A similaridade entre a estrutura de comunidades de Bacteria foi determinada com base na presença ou ausência das bandas detectadas no gel após PCR-DGGE. O agrupamento hierárquico gerado com o coeficiente de Jaccard e o método UPGMA mostrou a existência de comunidades bacterianas distintas na filosfera de M. robusta nas áreas amostradas. A existência de padrões biogeográficos foi determinada através de análises de regressão, usando os dados de similaridade da estrutura das comunidades bacterianas e os de distância geográfica entre as árvores amostradas. A correlação negativa observada nas avaliações fornece evidências para suportar a hipótese de que a similaridade entre as comunidades bacterianas da filosfera de plantas da mesma espécie diminui com o aumento da distância entre as árvores, dentro de um mesmo bioma. A avaliação espaço temporal da composição da comunidade bacteriana, realizada pela análise NMDS, demonstrou que houve efeito espacial mas no temporal na estrutura das comunidades bacterianas da filosfera de M. robusta. A afiliação taxonômica de 1.470 sequências de clones do gene rRNA 16S de Bacteria, obtidas da filosfera de M. Robusta, nas diferentes áreas e épocas, e a comparação múltipla das bibliotecas, mostraram que as comunidades bacterianas na filosfera foram distintas umas das outras, sendo os filos Proteobacteria e Acidobacteria os mais frequentes. Somente 1% das Unidades Taxonômicas Operacionais foram comuns entre os indivíduos avaliados. Com base nos resultados obtidos, pode-se inferir que, em cada bioma, plantas da mesma espécie possuem comunidades bacterianas únicas, sugerindo a existência de endemismo, altos níveis de especiação e baixa dispersão das comunidades bacterianas nas áreas avaliadas.Biogeography studies the distribution of organisms in relation to space and time, favoring the understanding of the mechanisms that generate and keep the diversity, speciation, extinction and dispersion of species. Among the tropical forests, the Atlantic Forest constitutes a highly diverse vegetation mosaic, in which the phyllosphere represents one of the most common habitats for microorganisms. The goal of this work was to evaluate the structure and diversity of the bacterial community from the phyllosphere of Maytenus robusta in the Carlos Botelho State Park, Ilha do Cardoso State Park and Assis Ecologic Station, São Paulo state, Brazil. The leaves were collected in two different seasons of the year, dry season and rainy season. The structure of the bacterial community was evaluated through PCR-DGGE of the 16S rRNA gene V3 region, and the diversity by sequencing of the V1-V3 region of the same gene. The similarities between the structures of the bacterial community were determined based on the presence or absence of bands detected in the gels after PCR-DGGE. The hierarchical clustering generated using the Jaccard coefficient and the UPGMA method showed the existence of distinct bacterial communities in the M. robusta phyllosphere of the sampled areas. The existence of biogeographic patterns was determined through regression analyses, using the community structure similarity data geographic distance among the sampled trees. The negative correlation observed in most of the cases provides evidence to support the hypothesis that the similarity between the bacterial communities from phyllosphere of plants of the same species decreases as the distance among trees increased, within the same biome. The spacial-temporal evaluation of the structure of the bacterial communities, performed by the NMDS analyses, showed the occurrence of spacial but not temporal effects on the structure of the bacterial communities of M. robusta phyllosphere. The taxonomic affiliation of 1,470 bacterial 16S rRNA gene clones obtained from the M. robusta phyllosphere, in different areas and seasons, as well as the multiple comparisons of libraries showed that the bacterial communities in the phyllosphere were distinct from each other, and that Proteobacteria and Acidobacteria phyla were the most frequent. Only 1% of the bacterial Operational Taxonomic Units were common among the individuals evaluated. Based on the results obtained it is possible to conclude that, in each biome, plants of same species have unique bacterial communities, suggesting the existence of endemism, high levels of speciation and low dispersal of bacterial communities in the evaluated areas.
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Stempfhuber, Barbara Hildegard Josefine [Verfasser], Michael [Akademischer Betreuer] [Gutachter] Schloter, and Johannes [Gutachter] Kollmann. "Drivers for the performance of nitrifying organisms and their temporal and spatial interaction in grassland and forest ecosystems / Barbara Hildegard Josefine Stempfhuber ; Gutachter: Johannes Kollmann, Michael Schloter ; Betreuer: Michael Schloter." München : Universitätsbibliothek der TU München, 2016. http://d-nb.info/1113749148/34.
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Laan, Jan Dingemans van der. "Spatio-temporal patterns in ecosystems : a bioinformatic approach = Patronen in ruimte en tijd in ecosystemen /." Utrecht : Universiteit, Fac. Biologie, 1994. http://www.gbv.de/dms/bs/toc/189735392.pdf.
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Cosme, Maximilien. "Modélisation qualitative à événements discrets des dynamiques d'écosystèmes." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONG013.
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Les écosystèmes se déploient dans le temps au rythme des événements successifs qui modifient ses composants. Ces événements, qu'ils soient aléatoires ou non, sont les phénomènes par lesquels les écosystèmes s'assemblent et se désassemblent. Chaque séquence d'états – ou trajectoire – est une histoire possible de l'écosystème. Mais si ces événements, ou leur ordre, avait été différent, l'état futur aurait pu l'être également. Or, l'ordre des événements, du fait des limites de notre connaissance, est souvent incertain. Lorsque cette incertitude est grande, il est donc raisonnable de concevoir la dynamique de l'écosystème comme un ensemble de trajectoires possibles. Si l'ensemble des trajectoires possibles était connu, il pourrait notamment se révéler utile pour savoir si un état souhaitable est atteignable, et si oui, par quel(s) chemin(s). Dans cette thèse, nous proposons une approche de modélisation nommée EDEN (pour Ecological Discrete-Event Networks) permettant de répondre à cette question. Elle se présente sous la forme d'un formalisme dont les variables sont qualitatives et dont les valeurs sont modifiées par des règles "si-alors" représentant les événements de l'écosystème. Celles-ci sont tirées une à une, de façon non-déterministe et sans aucune probabilité. Cette approche non-déterministe et non-probabiliste a donc été qualifiée de possibiliste. Les dynamiques se présentent alors sous la forme d'un graphe états-transitions dont on peut vérifier l'existence de propriétés dynamiques (comme le fait qu'une espèce puisse persister).Dans un premier temps, une brève histoire de la modélisation en écologie des écosystèmes est présentée, avec une attention particulière aux approches de modélisation qualitatives, dont l'approche EDEN fait partie. Prenant appui sur les limites des approches existantes pour répondre à certaines questions, nous proposons l'approche EDEN et justifions la pertinence de ses propriétés par des exemples simples.Dans un second temps, l'approche EDEN est illustrée sur des écosystèmes semi-arides d'Afrique de l'Est et de l'Ouest dans le but de savoir si certains états d'intérêt sont atteignables (comme le maintien de la végétation en savane, ou de la fertilité dans un agroécosystème). Pour ce faire, nous présentons et utilisons des outils jusqu'ici peu utilisés en écologie, comme les summary graphs et les logiques temporelles. Pour un scénario donné, ces outils rendent possible de définir (1) les transitions possibles entre les états d'intérêt, (2) les conditions dans lesquelles elles peuvent advenir et (3) les événements responsables de ces transitions. En Afrique de l'Est, l'approche EDEN a permis de déterminer les effets à long terme sur la végétation et les activités humaines d'une réduction/accroissement de la disponibilité en eau de surface, indiquant une forte influence indirecte de cette dernière sur la végétation ligneuse. En Afrique de l'Ouest, en utilisant EDEN, il a été possible de déterminer les conditions permettant à de petits producteurs du sud-ouest du Burkina Faso de développer un agropastoralisme persistant, ainsi que les événements nécessaires pour atteindre un tel état.Nous discutons enfin des apports de l'ensemble des modèles EDEN à divers champs de l'écologie, ainsi que des améliorations possibles et des ponts à dresser entre l'écologie, la biologie des systèmes et l'informatique théoriqueEcosystems unfold over time in response to successive events that modify their components. These events, whether random or not, are the phenomena by which ecosystems assemble and disassemble. Each sequence of states - or trajectory - is a possible history of the ecosystem. Yet, if these events, or their order, had been different, the future state could have been different. However, the order of events, due to the limits of our knowledge, is often uncertain. When this uncertainty is important, it is therefore reasonable to conceive the dynamics of the ecosystem as a set of possible trajectories. If the set of possible trajectories were known, it could be useful to know if a desirable state is attainable, and if so, by which path(s).In this thesis, we propose a modelling approach named EDEN (for Ecological Discrete-Event Networks) to answer this question. It is presented in the form of a formalism whose variables are qualitative and whose values are modified by "if-then" rules representing the events of the ecosystem. These rules are executed one by one, in a non-deterministic way and without any probability. This non-deterministic and non-probabilistic approach has therefore been called possibilistic. The dynamics are then presented in the form of a state-transition graph whose dynamic properties (such as the fact that a species can persist) can be verified.First, a brief history of dynamical modelling in ecosystem ecology is presented, with a particular focus on qualitative modelling approaches, to which EDEN belongs to. Based on the limitations of existing approaches to answer certain questions, we propose the EDEN approach and justify the relevance of its properties with simple examples.Then, the EDEN approach is illustrated on semi-arid ecosystems in East and West Africa in order to know if certain states of interest are reachable (such as the maintenance of vegetation in savanna, or soil fertility in an agroecosystem). To do this, we present and use tools that have not been used much in ecology until now, such as summary graphs and temporal logics. For a given scenario, these tools enable to define (1) the possible transitions between the states of interest, (2) the conditions under which they can occur and (3) the events responsible for these transitions. In East Africa, the EDEN approach was able to determine the long-term effects on vegetation and human activities of reduced/increased surface water availability, indicating a strong indirect influence of the latter on woody vegetation. In West Africa, using EDEN, it was possible to determine the conditions that allowed small-scale producers in southwestern Burkina Faso to develop persistent agropastoralism, as well as the events necessary to achieve such a state.Finally, we discuss the contributions of the EDEN set of models to various fields of ecology, as well as possible improvements and bridges to be built between ecology, systems biology and theoretical computer science
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Barros, Ceres. "Etude de la stabilité des écosystèmes à plusieurs échelles spatiales et trophiques." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV013/document.
Full textAbstract:
Dans un contexte de changement global qui continue de menacer les espèces et l’intégrité des écosystèmes à travers le monde, l’étude de la stabilité des écosystèmes n’a jamais été aussi importante. Jusqu’à aujourd’hui, la plupart des études sur la stabilité des écosystèmes se sont centrées sur des écosystèmes simples et des perturbations individuelles, en focalisant généralement sur le comportement de propriétés écosystémiques particulières, comme les indices de productivité et de diversité. Cependant, les écosystèmes sont soumis simultanément à de multiples perturbations. De plus, à grande échelle spatiale, différents écosystèmes se succèdent, chacun répondant différemment à une perturbation donnée. L’étude de la stabilité des écosystèmes doit donc progresser vers des approches plus intégratives qui seront informatives à des échelles pertinentes pour la gestion des écosystèmes. Cette thèse est un pas en avant dans cette direction. Ici, j’ai utilisé plusieurs approches pour évaluer la façon dont de multiples facteurs de changement global, tels que les changements climatiques graduels et extrêmes et les changements d’usage du sol, affectent la stabilité des écosystèmes à grande échelle spatiale, du point de vue d’un seul niveau trophique à un point de vue multitrophique.Je commence par souligner l’importance de considérer les interactions entre les changements climatiques graduels et extrêmes, en conjonction avec les changements de l’usage du sol, pour la gestion de paysages hétérogènes, comme les Alpes européennes. En utilisant un modèle de végétation dynamique et spatialement explicite, je montre qu’une augmentation de la fréquence et de l’intensité de la sécheresse pourrait drastiquement changer les tendances d’embroussaillement des habitats ouverts alpins et subalpins qui sont généralement prévues par les projections ne prenant pas en compte ces évènements extrêmes dans le futur. J’ai ensuite étudié si la sécheresse et le réchauffement climatique progressif amenaient les communautés végétales à souffrir des transitions différentes, en utilisant une approche innovatrice dans laquelle les états des communautés sont décrits d’une façon multidimensionnelle. Je montre que bien que les effets de la sécheresse sur la structure des forêts et des pâturages ne devraient pas trop affecter les trajectoires à long terme causées seulement par le réchauffement climatique graduel, ils devraient rendre les communautés forestières plus instables que les prairies dans le futur. Cependant, l’analyse des réponses de la végétation reste limitée à un seul niveau trophique. Vu que les réseaux trophiques représentent les flux d’énergie dans un écosystème, l’étude de leur stabilité aux perturbations devrait fournir des informations plus précises sur la stabilité globale de l’écosystème. Donc, j’ai aussi étudié la stabilité des réseaux trophiques dans les aires protégées européennes face à des scénarios futurs d’usage du sol et de climat. Mes résultats montrent que ces réseaux trophiques peuvent être très sensibles aux changements climatiques, même s’ils ne sont soumis à aucun changement d’usage du sol. Notamment, je montre que la prise en compte des phénomènes de dispersion des espèces aura un impact important sur la robustesse des réseaux, et je souligne l’importance de leur prise en compte pour la gestion des écosystèmes.Dans ma thèse, je démontre que les concepts de stabilité de l’écosystème peuvent et doivent être appliqués à des échelles pertinentes pour la gestion des écosystèmes, tout en adoptant la nature multidimensionnelle des écosystèmesAs global change threatens ecosystems worldwide with biodiversity loss, studying ecosystem stability has never been so important. Most ecosystem stability studies have heretofore focused on single ecosystems and disturbances, usually following the behaviour of particular ecosystem properties, such as productivity and diversity indices. However, ecosystems are subjected to multiple disturbances simultaneously and at large spatial scales different ecosystems co-occur, each responding specifically to any given disturbance. Hence, the study of ecosystem stability needs to move towards approaches that can be informative at broad scales that are relevant for ecosystem management. This thesis is a step forward in this direction. Here, I used several approaches to assess how multiple global change drivers, such as climate change, extreme whether events, and land-use changes, affect ecosystem stability at landscape and larger spatial scales, and from single to multi-trophic level perspectives.I begin by highlighting the importance of considering the interactions between gradual and extreme climate changes, in conjunction with land-use changes, for the management of highly diverse landscapes, such as the European Alps. Using a spatially explicit dynamic vegetation model, I show that increasing drought frequency and intensity will likely change the trends of treeline movement expected under future gradual climate warming scenarios. I then investigated whether drought and gradual climate warming caused plant communities to shift in different ways, using n-dimensional hypervolumes to describe community states in multidimensional space. Drought effects on forest and grassland structure did not greatly change the long-term trajectories caused by gradual climate warming alone, but showed that forest communities became more unstable than grasslands in the future. However, focusing on vegetation dynamics remains limited to a single trophic level. Because trophic networks represent energy flows in an ecosystem, studying their stability to disturbances should provide more accurate information on overall ecosystem stability. Hence, I also investigated trophic network stability in European protected areas to future scenarios of land-use and climate changes. My results show that these trophic networks may be highly sensitive to climate changes, even if no land-use changes occur. Importantly, I show that considering different dispersal limitations will greatly impact network robustness, and stress the importance of accounting for these processes in ecosystem management.In my thesis, I demonstrate that ecosystem stability concepts can and should be applied at scales that are relevant for management, while embracing the multidimensional nature of ecosystems
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Laan, Jan D. van der. "Spatio-temporal patterns in ecosystems : a bioinformatic approach = Patronen in ruimte en tijd in ecosystemen een bioinformatische benadering /." [S.l. : s.n.], 1994. http://www.gbv.de/dms/bs/toc/189735392.pdf.
Full text
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Turc, Hubert-Alexandre. "Contribution à l'étude de la définition et de la conception d'un écosystème clos artificiel simplifié à partir de l'opération d'oxydation par voie humide." Châtenay-Malabry, Ecole centrale de Paris, 1997. http://www.theses.fr/1997ECAP0531.
Full textAbstract:
La vie d'équipages au cours de missions spatiales de longues durées sera rendue possible en développant des systèmes autorégénérants, dits systèmes de support de vie. Ces dispositifs combinent des procédés physico-chimiques et biologiques, mimant les fonctions d'un écosystème naturel, ou la vie d'êtres humains sera assurée par le recyclage total de la matière organique via des chaines trophiques artificielles. La production primaire sera assurée par des organismes photosynthétiques, régénérant l'oxygène atmosphérique, et produisant une ration alimentaire équilibrée. Le fonctionnement d'un système de support de vie n'est rendu possible qu'en convertissant efficacement l'ensemble des déchets en des formes exploitables par les organismes en présence. La clef de voute d'un système de support de vie réside donc dans l'association harmonieuse d'un procédé de production primaire et d'un procédé de traitement de déchets. Nous avons donc réalisé expérimentalement sous la forme d'un montage baptisé ECLAS (Ecosystème CLos Artificiel Simplifie) cette première étape de la conception d'un système de support de vie. Un pilote d'oxydation hydrothermale a été développé, minéralisant en continu la matière organique, ainsi qu'un module de production de végétaux supérieurs en conditions artificielles. Ces deux modules ont été couplés du point de vue des flux de gaz et des matières condensées, par des dispositifs spécifiques, afin de conduire à un fonctionnement de type permanent, ou s'équilibrent la production et la consommation des espèces chimiques majoritaires. L'ensemble a été instrumenté en conséquence. Un outil adéquat de simulation numérique traitant des problèmes mixtes de transferts de matières continus et discontinus a été développé. Les premiers résultats du couplage expérimental, pour un régime de fonctionnement discontinu sur une période de un mois, ont pu alors conduire à une première extrapolation numérique d'un fonctionnement permanent.
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Wallhead, Philip John. "Accounting for unpredictable spatial variability in plankton ecosystem models." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/63762/.
Full textAbstract:
Limitations on our ability to predict fine-scale spatial variability in plankton ecosystems can seriously compromise our ability to predict coarse-scale behaviour. Spatial variability which is deterministically unpredictable may distort parameter estimates when the ecosystem model is fitted to (or assimilates) ocean data, may compromise model validation, and may produce mean-field ecosystem behaviour discrepant with that predicted by the model. New statistical methods are investigated to mitigate these effects and thus improve understanding and prediction of coarse-scale behaviour e.g. in response to climate change. First, the standard model fitting technique is generalised to allow model-data ‘phase errors’ in the form of time lags, as has been observed to approximate mesoscale plankton variability in the open ocean. The resulting ‘variable lag fit’ is shown to enable ‘Lagrangian’ parameter recovery with artificial ecosystem data. A second approach employs spatiotemporal averaging, fitting a ‘weak prior’ box model to suitably-averaged data from Georges Bank (as an example), allowing liberal biological parameter adjustments to account for mean effects of unresolved variability. A novel skill assessment technique is used to show that the extrapolative skill of the box model fails to improve on a strictly empirical model. Third, plankton models where horizontal variability is resolved ‘implicitly’ are investigated as an alternative to coarse or higher explicit resolution. A simple simulation study suggests that the mean effects of fine-scale variability on coarse-scale plankton dynamics can be serious, and that ‘spatial moment closure’ and similar statistical modelling techniques may be profitably applied to account for them.
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Rackliffe, Daniel Riley. "Spatial Heterogeneity of Ecosystem Metabolism in a Shallow Wetland." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5757.
Full textAbstract:
Spatial heterogeneity in ecosystem metabolism may play a critical role in determining ecosystem functions. Variation in ecosystem metabolism between macrophyte patches in shallow wetlands at the extremes of freshwater habitats has not been investigated. We estimated ecosystem metabolism in mesocosms containing different macrophytes using 24-hour oxygen curves to test our hypotheses: (1) net aquatic production (NAP) during spring and summer would be similar among algal patches (metaphyton and Chara), (2) NAP in algal patches would be greater than patches dominated by the vascular plant Potamogeton foliosus, (3) heterotrophy and anaerobiosis would be greatest in patches dominated by Lemna, and (4) the pond would be autotrophic in the spring and fall but heterotrophic in the summer. We found that different patches generated differences in NAP but not always as we predicted. NAP was different among algal patches in the spring and summer, and only metaphyton was more heterotrophic than P. foliosus. In the summer Chara and Lemna patches were heterotrophic and metaphyton became autotrophic. As predicted, the pond was net autotrophic in the spring and heterotrophic in the summer with an absence of patchiness in fall attributed to the dominance of Lemna. This research suggests the importance of macrophyte patchiness in wetlands in determining patterns of ecosystem metabolism despite challenges in measuring 24 hour oxygen curves (e.g. oxygen supersaturation). Consequently, macrophyte traits may be important in determining spatial heterogeneity of ecosystem metabolism in shallow ponds.
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Kabaya, Kei. "Essays on Spatially Diverse Values of and Preferences in Ecosystem Services." Kyoto University, 2019. http://hdl.handle.net/2433/242700.
Full textAbstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第21823号
農博第2336号
新制||農||1067(附属図書館)
学位論文||H31||N5195(農学部図書室)
京都大学大学院農学研究科生物資源経済学専攻
(主査)教授 栗山 浩一, 教授 伊藤 順一, 教授 梅津 千恵子
学位規則第4条第1項該当
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Ferrari, Marika. "Spatial assessment of multiple ecosystem services in an Alpine region." Doctoral thesis, Università degli studi di Trento, 2014. https://hdl.handle.net/11572/367721.
Full textAbstract:
Ecosystem Services (ESs) are the goods and services supplied by ecosystems. In order to fully understand their contribution to human wellbeing, there is a need to identify them, assess their supply, recognise areas where they appear together repeatedly and analyse the
interactions that may exist among them. Most of these tasks are also specifically required by the European Biodiversity Strategy for 2020, which asks Member States, by 2014, to identify key ESs and to spatially assess their supply and demand (European Commission, 2011).
Nevertheless, these are difficult tasks and to date they have been only partly performed: existing studies in fact have typically focused on a small sub-set of ESs and made use of information that poorly reflects the actual variability of the ESs distribution across a region.
The present research aims to fill these gaps, by developing methods involving a wide set of ESs and providing a detailed ESs assessment, based on spatial and statistical analyses. The methods have been tested on an Alpine region of Italy, Trentino. The Alps present a
heterogeneous landscape, resulting from the combination of natural and urbanized environments, that allows the supply of a wide range of ESs. The research has four specific objectives. The first objective focuses on the selection and the representation over specific spatial units of the real supply of multiple ESs. Operatively, 51
experts from the local administrative offices and research institutes have been involved in the selection of the most important ESs and spatial indicators for the case study. The experts identified 25 ESs and 57 representative spatial indicators (1 to 5 indicators for each service), and provided data for indicators mapping. To consider the heterogeneity of the ESs supply across the region, indicators were mapped over 20 different spatial units, including: land cover classes, cadastral parcels, fishing zones and catchments.The second objective is to develop and test a statistical method for identifying key indicators that are spatially-explicit and able to measure the biophysical, socio-cultural and economic values of ESs (both in terms of stock and flow). Spearman pairwise correlation analysis was performed among the indicators of the same service in order to identify the highly correlated ones, hence deemed to provide redundant information. Key indicators were selected among the lowly correlated ones. 35 indicators were selected for the case study (out of the 57 initial
indicators). The analysis showed that there is a minimum number of key indicators for each ES. Accordingly, three general rules were identified for the selection: (i) if the supply of an ES is regulated, both its biophysical-stock and biophysical-flow indicators must be selected, (ii) if multiple stock (flow) biophysical indicators for a single ES are mapped over different spatial units, all stock (flow) indicators must be maintained, (iii) socio-cultural or economic indicators are always selected as key indicators. The third objective is to develop and test a statistical method for defining bundles of ESs, as
sets of spatially correlated services. Principal Component Analysis was used to summarize the information of the 35 indicators, while hierarchical clustering was applied to identify 11 ESs clusters. Clusters were turned into bundles by analyzing the spatial variability of the services due to biophysical (e.g. morphological conditions) and human (e.g. land use) factors. The
results of the analysis show that in Trentino multiple ESs can be grouped in a few number of bundles with a complex shape. In particular, areas with poor ESs supply are grouped in one single bundle and the largest bundle follows the spatial distribution of a single land cover class: i.e. forest.The fourth objective is to develop a method to study interactions among ESs, by combining
statistical and spatial analyses. In fact, the supply of a given ES is correlated with the supply of other ESs and it is affected by multiple external factors. Correlations may be positive when an increase in the supply of one service corresponds to higher supplies of other services (i.e. synergies), or negative when an increase in the supply of one service corresponds to lower supplies of other services (i.e. tradeoffs). The degree of interactions among 35 key indicators is determined by performing a Spearman pairwise correlation analysis. The latter enabled to identify six patterns of ESs interactions, one pattern of tradeoffs and five of synergies. The analysis showed that the local land use management has not compromised the capacity of
ecosystems to provide regulating services while supplying the provisioning ones. The external factors causing the variability of the services across the region were identified and explained by means of spatial and Spearman correlation analyses among the ESs principal components.
Principal components were turned into drivers of change by analyzing the spatial variability of the ESs due to biophysical (e.g. forest density) and human (e.g. land use) factors. Land use management was found as the external factor that causes the greatest variability of the ESs distribution across the region. Within forest areas, forest management activities that involve
loss of vegetation were found as the main drivers of ESs change. This research aimed to consider a wide set of ESs and information able to reflect the actual variability of the services distribution across a region. It proposed a scientifically sound methodology to deal with the main issues of the ESs spatial assessment, that may reveal
efficiently applicable in other geographical areas where ESs are heterogeneously supplied.
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Ferrari, Marika. "Spatial assessment of multiple ecosystem services in an Alpine region." Doctoral thesis, University of Trento, 2014. http://eprints-phd.biblio.unitn.it/2758/1/PhDThesis_MarikaFerrari.pdf.
Full textAbstract:
Ecosystem Services (ESs) are the goods and services supplied by ecosystems. In order to fully understand their contribution to human wellbeing, there is a need to identify them, assess their supply, recognise areas where they appear together repeatedly and analyse the
interactions that may exist among them. Most of these tasks are also specifically required by the European Biodiversity Strategy for 2020, which asks Member States, by 2014, to identify key ESs and to spatially assess their supply and demand (European Commission, 2011).
Nevertheless, these are difficult tasks and to date they have been only partly performed: existing studies in fact have typically focused on a small sub-set of ESs and made use of information that poorly reflects the actual variability of the ESs distribution across a region.
The present research aims to fill these gaps, by developing methods involving a wide set of ESs and providing a detailed ESs assessment, based on spatial and statistical analyses. The methods have been tested on an Alpine region of Italy, Trentino. The Alps present a
heterogeneous landscape, resulting from the combination of natural and urbanized environments, that allows the supply of a wide range of ESs. The research has four specific objectives. The first objective focuses on the selection and the representation over specific spatial units of the real supply of multiple ESs. Operatively, 51
experts from the local administrative offices and research institutes have been involved in the selection of the most important ESs and spatial indicators for the case study. The experts identified 25 ESs and 57 representative spatial indicators (1 to 5 indicators for each service), and provided data for indicators mapping. To consider the heterogeneity of the ESs supply across the region, indicators were mapped over 20 different spatial units, including: land cover classes, cadastral parcels, fishing zones and catchments.The second objective is to develop and test a statistical method for identifying key indicators that are spatially-explicit and able to measure the biophysical, socio-cultural and economic values of ESs (both in terms of stock and flow). Spearman pairwise correlation analysis was performed among the indicators of the same service in order to identify the highly correlated ones, hence deemed to provide redundant information. Key indicators were selected among the lowly correlated ones. 35 indicators were selected for the case study (out of the 57 initial
indicators). The analysis showed that there is a minimum number of key indicators for each ES. Accordingly, three general rules were identified for the selection: (i) if the supply of an ES is regulated, both its biophysical-stock and biophysical-flow indicators must be selected, (ii) if multiple stock (flow) biophysical indicators for a single ES are mapped over different spatial units, all stock (flow) indicators must be maintained, (iii) socio-cultural or economic indicators are always selected as key indicators. The third objective is to develop and test a statistical method for defining bundles of ESs, as
sets of spatially correlated services. Principal Component Analysis was used to summarize the information of the 35 indicators, while hierarchical clustering was applied to identify 11 ESs clusters. Clusters were turned into bundles by analyzing the spatial variability of the services due to biophysical (e.g. morphological conditions) and human (e.g. land use) factors. The
results of the analysis show that in Trentino multiple ESs can be grouped in a few number of bundles with a complex shape. In particular, areas with poor ESs supply are grouped in one single bundle and the largest bundle follows the spatial distribution of a single land cover class: i.e. forest.The fourth objective is to develop a method to study interactions among ESs, by combining
statistical and spatial analyses. In fact, the supply of a given ES is correlated with the supply of other ESs and it is affected by multiple external factors. Correlations may be positive when an increase in the supply of one service corresponds to higher supplies of other services (i.e. synergies), or negative when an increase in the supply of one service corresponds to lower supplies of other services (i.e. tradeoffs). The degree of interactions among 35 key indicators is determined by performing a Spearman pairwise correlation analysis. The latter enabled to identify six patterns of ESs interactions, one pattern of tradeoffs and five of synergies. The analysis showed that the local land use management has not compromised the capacity of
ecosystems to provide regulating services while supplying the provisioning ones. The external factors causing the variability of the services across the region were identified and explained by means of spatial and Spearman correlation analyses among the ESs principal components.
Principal components were turned into drivers of change by analyzing the spatial variability of the ESs due to biophysical (e.g. forest density) and human (e.g. land use) factors. Land use management was found as the external factor that causes the greatest variability of the ESs distribution across the region. Within forest areas, forest management activities that involve
loss of vegetation were found as the main drivers of ESs change. This research aimed to consider a wide set of ESs and information able to reflect the actual variability of the services distribution across a region. It proposed a scientifically sound methodology to deal with the main issues of the ESs spatial assessment, that may reveal
efficiently applicable in other geographical areas where ESs are heterogeneously supplied.
42
Carter, Christopher Michael. "Spatial and temporal dynamics of phytoplankton communities in a coastal ecosystem." Thesis, University of Canterbury. Zoology, 2004. http://hdl.handle.net/10092/4807.
Full textAbstract:
The phytoplankton community dynamics and the processes influencing phytoplankton community structure were investigated in Beatrix Bay, Pelorus Sound, New Zealand. The particular focus was on bottom-up resource acquisition driving phytoplankton dynamics in this coastal ecosystem. Sampling for water column structure, nutrient concentration, and phytoplankton community composition was done over two years in conjunction with experiments that manipulated nutrient concentration and light levels, to test how these affected phytoplankton community dynamics seasonally.
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Tardieu, Léa. "Integrating ecosystem services in the evaluation of transport infrastructure projects." Thesis, Montpellier, SupAgro, 2014. http://www.theses.fr/2014NSAM0024.
Full textAbstract:
L'objectif de cet article est d'introduire la prise en compte des Services Écosystémiques (SE), c'est-à-dire les bénéfices que la société retire du fonctionnement des écosystèmes, dans le cadre des procédures d'évaluation des projets d'infrastructures de transport terrestres. La prise en compte des SE dans les outils d'évaluation de projet, l'étude d'impact environnemental et le bilan socio-économique, peut sensiblement améliorer les décisions publiques. Pour montrer cela, nous commençons par mettre en lumière les différents défis associés à l'intégration des SE dans les décisions en matière d'implantation d'infrastructures de transport. L'intégration ne peut être faite que si l'estimation des SE, en termes de changements d'offre, de demande et de valeurs associées à ces changements, est faite de manière spatialement explicite. Nous illustrons ce point, dans un premier temps, à travers l'étude de la perte d'un service : la régulation du climat global engendrée par la construction d'une ligne grande vitesse dans l'ouest de la France. Puis, nous approfondissons la question de la combinaison de la perte directe et de la perte indirecte de services due aux impacts de l'infrastructure sur la connectivité des entités spatiales. Pour les deux types d'impacts nous intégrons des seuils potentiels sur la fourniture de services en proposant une méthode de prise en compte des effets sur des écosystèmes particulièrement sensibles.Nous appliquons cette méthode au même cas de projet d'infrastructure et comparons différentes options de tracé afin de donner un exemple de la manière dont les choix pourraient être améliorées en cartographiant les pertes directe et indirecte de SE. Enfin, nous tentons de montrer l'intérêt de la prise en compte des SE dans l'étude d'impact et le bilan socio-économique de manière à mesurer l'information supplémentaire donnée par une telle intégration. Une attention particulière est portée au caractère applicable de l'analyse aux cadres réglementaires actuels entourant ces deux outils. Nous montrons que ce type d'analyse peut éclairer et orienter différentes étapes d'un projet d'infrastructure: des études préliminaires, à l'étude du tracé final. Dans le cas des études d'impact, l'intégration de ces considérations peut permettre de mesurer la perte de services engendrée par chaque tracé d'infrastructure et d'intégrer ces pertes en tant que nouveau critère de choix de tracé. Concernant le bilan socio-économique, la perte de services exprimée en termes monétaires peut permettre de donner une indication quant à la perte sociale engendrée par le tracé final en matière de capital naturel. Plus spécifiquement ce type d'étude peut permettre une meilleure identification des mesures d'insertions les plus appropriées, en élargissant le types d'impacts pris en compte et en donnant des indications quantitatives des coûts engendrées par les différentes options d'implémentation. Ceci peut permettre aux parties prenantes du projet de mieux appréhender les différents effets engendrés par le projet, à une plus grande échelle, leur permettant de sortir des strictes frontières du projet et des contrôles règlementairesThe purpose of this thesis is to broaden the assessment process of terrestrial transport infrastructure into the field of Ecosystem Services (ES), i.e., the benefits people derive from ecosystems. Taking into account ES in an ex-ante assessment of public infrastructure projects can be of critical importance for the improvement of transportation decision-making tools, such as environmental impact assessment and cost-benefit analysis. To achieve this, we first review the major challenges to integrate the ES approach into transport infrastructure decisions. This inclusion is only possible if changes in ES, involved by the project, are explained in a spatially explicit way. We illustrate this point, in a first step, by assessing the loss of a global climate regulation service due to the soil sealing caused by a infrastructure construction, using the example of a high-speed rail in Western France.We further deepen the issue of combining direct loss of ES with indirect loss due to impacts of the infrastructure on landscape connectivity. For both direct and indirect effects we also integrate potential threshold effects on ES loss. We compare implementation options, for the same case of infrastructure project, to provide an example of how choices can be improved by mapping ES loss associated with a combination of direct and indirect impacts. Finally, we provide a test of the usefulness of the ES consideration into environmental impact assessment and cost benefit analysis in order to assess the additional information it may bring. Attention is paid to the applicable character of methods to the real legal framework within which they must be conduced. We show that this type of analysis can enlighten and provide guidance at different stages of transport project: from preliminary studies to the study of the final implementation option. For environmental impact assessment, the integration of an ES based approach opens the possibility of measuring a loss in ES supply (and its economic value) providing a means of selecting among different route option for the infrastructure. For cost-benefit analysis, since the ES loss induced by the selected route option is expressed in monetary terms, it can be integrated as a standard social cost in the analysis, permitting a more efficient control of natural capital loss. More specifically, this type of analysis can help designing appropriate environmental measures by expanding the types of impacts assessed, and provide a quantitative assessment of the cost related to the final chosen option. Then, it may help project stakeholders to apprehend the effects on a broader (ecosystem) scale instead of staying confined into project boundaries and regulatory check-lists
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Bauer, Dana Marie. "Cost-effective land development with a spatially-realistic ecosystem constraint /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3206243.
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David, Gwendoline. "Spatio-temporal structuring of microbial communities in freshwater ecosystems." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL049.
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Les microorganismes constituent la forme de vie la plus abondante et diverse sur Terre et ils présentent une grande diversité phylogénétique et métabolique. Ils sont donc impliqués dans les cycles biogéochimiques et les réseaux trophiques, ce qui en fait des acteurs clés du fonctionnement des écosystèmes. Pour décrypter l'écologie des microorganismes, il est essentiel de prendre en compte les échelles spatiales, temporelles et taxonomiques. Bien que des paramètres abiotiques et biotiques aient été identifiés comme influençant la composition des communautés microbiennes dans les écosystèmes aquatiques (e.g. la température, la prédation), des études complémentaires sont nécessaires pour mieux comprendre la structure des communautés microbiennes. Cependant, l'étude des interactions biotiques entre microorganismes est difficile en raison de leur petite taille, de la grande diversité et du peu d’individus cultivés. Cette thèse de doctorat vise à décrire la diversité microbienne au sein de deux types d'écosystèmes d'eau douce encore peu étudiés, et à identifier les facteurs qui déterminent la composition de leurs communautés microbiennes. La première partie de cette thèse vise à décrire la distribution spatiale (horizontale et verticale) des protistes planctoniques du lac Baïkal (Sibérie, Russie). Nous nous sommes intéressés à des échantillons collectés en été 2017 le long d'un transect de ~600 km couvrant les trois bassins du lac, de la surface aux profondeurs (~1500 m) et du littoral au pélagique. Les trois autres parties présentent une étude de huit ans de la composition et de la dynamique temporelle des communautés microbiennes des trois domaines du vivant, à la surface de cinq petits écosystèmes d'eau douce (sud-ouest de Paris, France). Les échantillons ont été collectés à deux fréquences, mensuelle (2011-2013) et saisonnière (2011-2019). Les communautés planctoniques ont été caractérisées par le séquençage des gènes ARNr 16S et 18S. Dans tous les écosystèmes, les communautés microbiennes sont très diverses, couvrant tous les super-groupes eucaryotes et procaryotes connus. Elles incluent des lignées typiquement marines (e.g. diplonémide, MAST), ce qui suggère que la frontière entre le marin et l'eau douce pourrait être plus fine que prévu. Des taxons encore peu connus ont aussi été détectés, tels que des bactéries du Candidate Phyla Radiation. Des analyses multivariées ont montré que seule une faible fraction de la variance des communautés peut être expliquée par les paramètres abiotiques étudiés. Pour les variations spatiales, nous avons constaté une faible variabilité des communautés du lac Baïkal dans les différents bassins, mais avec une forte stratification le long de la colonne d'eau. La profondeur, qui traduit les variations environnementales (e.g. la lumière) dans la colonne d'eau, semble influencer significativement les communautés. Les petits écosystèmes abritent différentes communautés microbiennes malgré leur proximité géographique. Pour les variations temporelles, deux dynamiques ont été identifiées. À l'échelle intra-annuelle, les communautés sont caractérisées par une forte saisonnalité. Cependant, moins de 2% des unités taxonomiques opérationnelles présentent une récurrence saisonnière. Cela suggère que les écosystèmes ont un fonctionnement saisonnier, malgré des dynamiques individuelles imprévisibles. À l'échelle interannuelle, les communautés microbiennes sont de plus en plus différentes au cours des huit années, indiquant des changements continus dans leur composition. Enfin, l’inférence des interactions microbiennes grâce aux réseaux de cooccurrence reflète les variations spatio-temporelles précédemment observées. En effet, les communautés sont plus complexes à la surface du lac Baïkal qu'en profondeur. De plus, les petits écosystèmes partagent des topologies similaires pour chaque saison. Cela souligne l'importance des interactions écologiques chez les communautés microbiennes, dans l'espace et le tempsMicroorganisms are the most abundant and diverse forms of life on Earth and are characterized by high phylogenetic and metabolic diversities. They are thus involved in biogeochemical cycles and trophic webs, which make them key players in ecosystem functioning. To decipher the ecology of microorganisms, it is crucial to include spatial, temporal and taxonomic scales. Although several abiotic and biotic parameters have been identified as drivers of microbial community composition in aquatic ecosystems (e.g. temperature, orthophosphate concentration, predation, symbiosis), more investigations are needed to better understand how microbial community structure is shaped. However, investigating biotic interactions involving microbes is challenging because of microbial features (e.g. small size, high diversity, low cultivation efficiency). This PhD thesis aims at describing the microbial diversity inside two overlooked types of freshwater ecosystems and at identifying the factors driving microbial community composition. The first section of this thesis aims at comprehensively describing the spatial distribution (horizontal and vertical) of planktonic microbial eukaryotes in Lake Baikal (Siberia, Russia). We focus on samples collected in summer 2017 along a transect of ~600 km across the three basins of the lake, from the surface to the deepest areas (~1500 m) and from littoral to open waters. The three other sections present an eight-year investigation of the composition and temporal dynamics of microbial communities belonging to the three domains of life at the surface of five small freshwater ecosystems (located in the South West of Paris, France). Samples were collected at two different frequencies, monthly (2011-2013) and seasonally (2011-2019). The composition of planktonic communities was assessed by the sequencing of the phylogenetic marker genes 16S and 18S rRNA. In all the ecosystems studied, the microbial communities were diverse, covering all eukaryotic and prokaryotic supergroups. Moreover, they included typically marine lineages, especially in Lake Baikal, (e.g. diplonemid, MAST) which suggested that the frontiers between marine and freshwater systems may be thinner than previously thought. They also included taxa that remain enigmatic, such as bacteria of the Candidate Phyla Radiation. Multivariate analysis showed that only a low fraction of the variance can be explained by the measured physico-chemical parameters. In terms of spatial variations, there was a weak variability of communities in Lake Baikal in summer across sampling basins, but a strong stratification along the water column. Depth, which is a proxy and a summary of the variations of the environmental conditions (e.g. light) along the water column, appeared to be a major driver of community composition. The small freshwater ecosystems harbored different microbial communities despite their geographic proximity. In terms of temporal variations, two types of patterns were detected. At the intra-annual scale, global communities were characterized by a strong seasonality. However, at the Operational Taxonomic Unit level, less than 2% of the community were characterized by recurrent seasonal patterns. This suggests that ecosystems have a yearly seasonal functioning, despite the presence of some unpredictable microbial dynamics. At the inter-annual scale, microbial communities experienced an increase of dissimilarities over the eight years, indicating turnovers in community composition. Finally, the structure of the communities studied through co-occurrence network inference reflected the spatio-temporal variations previously observed. Indeed, communities were more connected at the surface of Lake Baikal compared to the bottom. Moreover, ecosystems shared similar structural properties at each season. This underlines the importance of ecological interactions in the composition of microbial community over space and time
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Solé-Senan, Xavier Oriol. "Plant diversity and ecosystem services in agricultural landscapes along different spatial scales." Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/406287.
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Aquesta tesi té com a objectiu escatir fins quin punt les diversitats d'espècies i funcional de les comunitats de flora arvense canvien a escala de camp i de paisatge. A escala de camp, l'estudi s'ha focalitzat en l'anàlisi de l'efecte de la intensificació agrícola, depenent de la posició dins del camp i en funció del nivell de pertorbació en cada hàbitat que forma part del tradicional paisatge en mosaic en els ambients mediterranis. A escala de paisatge, hem analitzat els canvis en la diversitat al llarg de gradients d'heterogeneïtat en el paisatge, tenint en compte d'una banda l'heterogeneïtat composicional i per l'altra l'heterogeneïtat configuracional. L'aproximació basada en atributs biològics ens ha permès dirigir l'estudi a analitzar de quina manera afecten els canvis a la composició florística d'aquestes comunitats a la provisió dels serveis ecosistèmics que els agroecosistemes aporten a altres organismes.La presente tesis tiene como objetivo dilucidar hasta qué punto la riqueza en especies y la diversidad funcional de las comunidades de flora arvense cambian a escala de campo y de paisaje. A escala de campo, el estudio se ha enfocado en el análisis del efecto de la intensificación agrícola, en cuanto a la posición en el campo y al nivel de perturbación en cada hábitat en la diversidad y funcionalidad de las comunidades de flora arvense. A escala de paisaje, hemos analizado los cambios en la diversidad a lo largo de gradientes de heterogeneidad en el paisaje, teniendo en cuenta por un lado la heterogeneidad composicional y por el otro la heterogeneidad configuracional. La aproximación basada en atributos biológicos nos ha permitido enfocar el estudio en cómo afectan los cambios en la composición florística de dichas comunidades a la provisión de los servicios ecosistémicos que los agroecosistemas aportan a otros organismos.
This thesis is aimed at disentangling the extent at which species richness and functional diversity of plant species from arable communities change at field and landscape scale. At field scale, the study was focused on the effects of agricultural intensification regarding field position and the level of disturbance at which such habitat is subjected on the diversity and functionality of arable plants community. At landscape scale, we assessed the diversity changes along gradients of landscape heterogeneity, taking into account on the one hand the surrounding compositional landscape heterogeneity and on the other hand the configurational landscape heterogeneity. The trait-based approach conducted allows us to focus on how shifts in species composition in such arable plant communities are expected to affect the delivery of the ecosystem services that these agroecosystems provide to other organisms.
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Harris, Linda Rozanne. "An ecosystem-based spatial conservation plan for the South African sandy beaches." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1007920.
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An ecosytem-based spatial conservation plan for the South African sandy beaches. Sandy beaches are valuable ecosystems. They support a collection of species that is unique, comprising many endemic species, and provide a number of key ecosystem goods and services, including scenic vistas for human recreation, nesting sites for turtles and birds, and important areas for biogeochemical recycling, water filtration and purification. However, sandy beaches have not been well understood or appreciated as ecosystems, and consequently have a legacy of poor coastal management. In many instances this has lead to a "tyranny of small decisions", where multiple, seemingly insignificant management decisions and actions have resulted in complete transformation and degradation of the shoreline in several places. In addition to inappropriate management strategies, beaches are also poorly represented in conservation areas. Further, where they are recognised as being "conserved" in marine protected areas, this often is a false sense of protection because the far more sensitive dune portion of the littoral active zone is invariably not included in the reserve. In short, there is a need for a new way to approach sandy beach conservation and management that includes the system (dunes, intertidal beaches and surf zones) as a whole. On one hand, the approach should make provision for use of the abundant natural resources and opportunities associated with sandy shores in ways that are sustainable and contribute to biodiversity stewardship - through ecosystem-based management and marine spatial planning. But, on the other hand, it must simultaneously contribute to securing a sufficient amount of the key ecological attributes of beaches (habitats, biodiversity and processes) in a network of reserves, to ensure that the ecosystem, natural resources, and services all persist in perpetuity - through systematic conservation planning. The aim of this Thesis is to integrate these into a single approach, which I call ecosystem-based spatial conservation planning for sandy beaches, using the South African sandy shores as a case study. To achieve this broad aim, the Thesis is divided into three parts. Part 1 deals with establishing baseline information by quantifying spatial patterns in sandy beach habitats (Chapter 1), biodiversity, key assemblages and processes, and outstanding physical features (Chapter 2). First, mapping sandy beach habitats is a challenge given the vast, linear extent of shorelines and significant resources required to complete the project. Therefore, a novel approach was derived using statistical techniques (conditional inference trees) to identify physical features of beaches that can be observed on Google Earth (or similar) imagery, and that can provide good predictions of beach morphodynamic (habitat) types. Based on the results of this analysis, sandy beaches (and all other coastal habitat types) were mapped digitally in ArcGIS. Second, spatial patterns in sandy beach biodiversity (vertebrates, macrofauna, microflora and foredune plants) were mapped by compiling existing data on the distributions of key species that have been well studied or mapped previously (vertebrates and foredune plants), and by niche modelling (macrofauna and microflora). For the latter, data from all previous sandy-beach sampling events in South Africa were compiled from published and unpublished sources, and supplemented with additional sampling of 23 beaches along the national shoreline, targeting macrofauna and phytoplankton. Altogether, the macrofauna database comprised data from 135 sites and 186 sampling events, and the microflora (phytoplankton and microphytobenthos) database comprised data from 73 sites and 510 samples. The probabilistic distribution of each "resident" species (present at 10 or more sites) was modelled in MaxEnt version 3.3.3k, probability thresholds were determined statistically (to convert the data into predicted presence-absence), and displayed as a digital map. A composite biodiversity map was compiled, and key trends in species richness and endemism along the national shoreline were quantified. To supplement biodiversity proper, additional valued-features of sandy beaches were mapped, including: important assemblages; unique habitat features; and sites associated with key ecological processes. Part 2 considers threats to sandy beaches in the context of deriving an appropriate management strategy that seeks to provide for use of the coast, but in a way that has least overall impact to the ecosystem. A method for assessing cumulative threats to sandy beaches is adapted from an existing framework (Chapter 4). This entailed compiling a list of threats to beaches, and scoring these (out of 10) in terms of the severity of their respective impacts to beaches, and how long it would take the ecosystem to recover should the threat be removed. The scoring was based on the collective expert opinion of the scientific community working on sandy beaches, at a workshop during the VIth International Sandy Beach Symposium 2012. To standardize the scores and ensure broad applicability, a base case scenario of a pristine beach was established, and maximum theoretical scores were provided for this context. The method for integrating these scores into a spatial, cumulative threat assessment was then determined. In Chapter 5, the maximum theoretical scores (from Chapter 4) were down-scaled to suit the current threat regime to the South African sandy beaches, and the cumulative threat assessment methodology was applied. From this analysis, the most threatened beaches in South Africa, and the most important threats were highlighted. A decision-support tool for managers was derived from the site-specific cumulative threat-impact scores, based first on the degree of permanent habitat transformation, and second on the cumulative impact of other stressors where the impacts these stressors have could potentially be mitigated or ameliorated. Part 3 concerns conservation of beaches explicitly. It addresses how much of which valued features of beaches is required to ensure their long-term persistence, and the design of a network of beaches in South Africa that are of ecological importance and should be set aside as reserves. Conservation targets are set in Chapter 6, using species-area curves to determine a baseline percentage-area required to protect sandy beach habitats, which is modified using heuristic principles based on habitat rarity and threat status (from a recent national assessment). A fixed target was applied to all species, also modified by heuristic principles, and another fixed target was applied to key assemblages and processes.
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Ojike, Uzoma. "Combining tools and techniques for embedding an ecosystem approach in spatial planning." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11196.
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Despite the attention garnered by sustainability in the last three decades and the advances in its tools and techniques, we are no closer to attaining sustainability now than we were at the start. This elusiveness has been attributed to the lack of a clearly defined global method for evaluating sustainability and poor integration into sector, national and international policies and decision-making, amongst others. A clear limitation observed in most concepts/methods is their inability to integrate effectively ecological, economic and social sustainability during assessment. Rather, there is a tendency to assess them separately and integrate them after the assessment. This process often leaves loopholes in sustainability assessment as there are trade-offs created that often favour economic sustainability but more rarely favour environmental, or even social, sustainability. In order to address this limitation, the Millennium Ecosystem Assessment (MEA) in 2005 recognized that the complex interactions between these ecological, economic and social processes have to be understood and established a universal valuation concept known as ecosystem services which can be used in sustainability assessment and Spatial Planning. Ecosystem services are the benefits or services created by the ecosystem which are essential for the daily functioning of humans and economies. This research explores how best to achieve integration of the Ecosystem Approach within environmental/sustainability assessment. It adopts a mixed method approach that combines the use of existing qualitative techniques, Network Analysis and stakeholder engagement, and quantitative techniques, Geographical Information Systems, within a regeneration case study at local level (Dartford in North Kent, United Kingdom). The thesis makes recommendations for better integration of an Ecosystem Approach in Spatial Planning and decision making and the ways in which assessment tools and techniques can be best combined.
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Zhang, Jing. "Bayesian spatial analysis with application to the Missouri Ozark Forest ecosystem project." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/6062.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 3, 2009) Vita. Includes bibliographical references.
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Nolander, Carl. "Spatial and Economic Values of Ecosystem Services : The Case of Sweden's Forests." Licentiate thesis, Luleå tekniska universitet, Samhällsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67918.
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The objective of this licentiate thesis is to determine the value of ecosystem services and their relative importance, and to develop methods to weight these benefits against the market value of timber and other uses for forests. These issues are addressed in two papers with a focus on spatial modeling of ecosystem services and the method of benefit transfer. The aim is to contribute to the research regarding the optimal social use of forests for Sweden in particular and the future of forestry in general, particularly when it comes to ecosystem services and the tradeoff between demands for different forest products. The first article is a review study of previous studies estimating monetary valuations of ecosystem services of forests during the past 20 years. The review has a particular focus on spatial modeling of ecosystem services and the underlying characteristics that influence the value of an ecosystem service. In total, 118 studies are included in the review, and themajority of these studies do not model the spatial distribution of the ecosystem services and assume it identical across the area that is being studied, but the share of spatially explicit studies is increasing in the last ten years. The review finds that carbon sequestration, recreation, and ecosystem services related to the prevention of natural hazards,e.g. floods and avalanches, are the forest based ecosystem services that consistently are valued highly in the reviewed studies. There is however, significant variation in the values reported for similar ecosystem services. The second article is focused estimates the value of recreation and carbon sequestration in Swedish forests, using the benefit transfer approach and a spatially explicit perspective. The distribution for the services is mapped for the whole country, and the monetary value applied to the services is based on comparisons between the results of previous studies. The aim of the article is to develop the use of spatial mapping on larger scales than has been done previously, and add to the limited number of ecosystem service valuations for the Nordic countries by providing a fully populated spatial mapping of two of the more important ecosystem services of Sweden. In general, values found for the two ecosystem services are almost as high as timber values, but the values and their distribution varies highly across the landscape. Both ecosystem services are found to have higher values in southern Sweden and close to cities.