No description available.

Woody plant invasion of grasslands is prevalent worldwide, but the biogeochemical consequences of this vegetation shift remain largely unquantified. In the Rio Grande Plains, TX, grasslands and savannas dominated by C4 grasses have undergone succession over the past century to subtropical thorn woodlands dominated by C3 trees/shrubs. To elucidate mechanisms of soil organic carbon (SOC) and soil total N (STN) storage and dynamics in this ecosystem, I measured the mass and isotopic composition (δ13C, δ15N) of C and N in whole-soil and soil size/density fractions in chronosequences consisting of remnant grasslands (Time 0) and woody plant stands ranging in age from 10-130 years. Rates of SOC and STN storage averaged 10-30 g C m-2yr-1 and 1-3 g N m-2yr-1, respectively. These accumulation rates increased soil C and N pools 80-200% following woody encroachment. Soil microbial biomass (SMB-C) also increased after woody invasion. Decreasing Cmic/C org and higher qCO2 in woodlands relative to grasslands suggests that woody litter is of poorer quality than grassland litter. Greater SOC and STN following woody invasion may also be due to increased protection of organic matter by stable soil structure. Soil aggregation increased following woody encroachment; however, most of the C and N accumulated in free particulate organic matter (POM) fractions not protected within aggregates. Mean residence times (MRTs) of soil fractions were calculated based on changes in their δ13C with time after woody encroachment. Free POM had the shortest average MRTs (30 years) and silt+clay the longest (360 years). Fine POM had MRTs of about 60 years, reflecting protection by location within aggregates. δ15N values of soil fractions were positively correlated with their MRTs, suggesting that higher δ15N values reflect an increased degree of humification. Increases in SOC and STN are probably being sustained by greater inputs, slower turnover of POM (some biochemical recalcitrance), and protection of organic matter in aggregates and association with silt and clay. Grassland-to-woodland conversion during the past century has been geographically extensive in grassland ecosystems worldwide, suggesting that changes in soil C and N dynamics and storage documented here could have significance for global C and N cycles.

No description available.

<p>Land use and land cover changes significantly affect C storage in terrestrial ecosystems. Programs intended to compensate land owners for the maintenance or enhancement to C stocks are promising, but require detailed and spatially explicit C distribution estimates to monitor the effectiveness of management interventions. Savanna ecosystems are significant components of the global C cycle, however, they have not received much attention for the development of C monitoring approaches. In this dissertation I have investigated three of the aspects related to woody plant cover dynamics in semiarid savannas of central Argentina: spatio-temporal dynamics, precise field surveying and scaling from field to region with the use of freely available remotely sense data. </p><p>To examine the long term changes in woody plant cover, I first carefully extracted information from historical maps of the Caldenal savannas of central Argentina (190,000 km2) in the 1880s to generate a woody cover map that was compared to a 2000s dataset. Over the last ~120 years, woody cover increased across ~12,200 km2 (14.2 % of the area). During the same period, ~5,000 km2 of the original woody area was converted to croplands and ~7,000 km2 to pastures, about the same total land area as was affected by woody plant encroachment. A smaller area, fine scale analysis between the 1960s and the 2000s revealed that tree cover increased overall by 27%, shifting from open savannas to a mosaic of dense woodlands along with additional agricultural clearings. Statistical models indicate that woody cover dynamics in this region were affected by a combination of environmental and human factors.</p><p>To assess the consequences of woody cover dynamics on C, we also measured ecosystem C stocks along a gradient of woody plant density. I characterized changes in C stocks in live biomass (woody and herbaceous, above- and belowground), litter, and soil organic carbon (to 1.5 m depth) pools along a woody plant cover gradient (0 to 94 %). I found a significant increase in ecosystem C stocks with increasing woody cover, with mean values of 4.5, 8.4, 12.4, and 16.5 kg C m-2 for grasslands, shrublands, open and closed forests, respectively. Woody plant cover and soil silt content were the two primary factors accounting for the variability of ecosystem C. I developed simple regression models that reliably predict soil, tree and ecosystem C stocks from basic field measurements of woody plant cover and soil silt content. These models are valuable tools for broad scale estimation if linked to regional soil maps and remotely sensed data, allowing for precise and spatially explicit estimation of C stocks and change at regional scales.</p><p>Finally, I used the field survey data and high resolution panchromatic images (2.5 m resolution) to identify tree canopies and train a regional tree percent cover model using the Random Forests (RF) algorithm. I found that a model with summer and winter tasseled cap spectral indices, climate and topography performed best. Sample spatial distribution highly affected the performance of the RF models. The regression model built to predict tree C stocks from percent tree cover explained 83 % of the variability, and the spatially explicit tree C model prediction presented an root mean squared error (RMSE) of 8.2 tC/ha which represented ~30% of the mean C stock for areas with tree cover. Our analysis indicates that regionally over the last ~120 years, increases in woody plant cover have stored significant amounts of C (95.9 TgC), but not enough to compensate for in C generated by the conversions of woodlands and natural grasslands to croplands and pastures (166.7 TgC), generating a regional net loss of 70.9 TgC. C losses could be even larger in the future if, as predicted, energy crops would trigger a new land cover change phase in this region.</p> / Dissertation

De nos jours les cartes d’utilisation/occupation du sol (USOS) à une échelle régionale sont habituellement générées à partir d’images satellitales de résolution modérée (entre 10 m et 30 m). Le National Land Cover Database aux États-Unis et le programme CORINE (Coordination of information on the environment) Land Cover en Europe, tous deux fondés sur les images LANDSAT, en sont des exemples représentatifs. Cependant ces cartes deviennent rapidement obsolètes, spécialement en environnement dynamique comme les megacités et les territoires métropolitains. Pour nombre d’applications, une mise à jour de ces cartes sur une base annuelle est requise. Depuis 2007, le USGS donne accès gratuitement à des images LANDSAT ortho-rectifiées. Des images archivées (depuis 1984) et des images acquises récemment sont disponibles. Sans aucun doute, une telle disponibilité d’images stimulera la recherche sur des méthodes et techniques rapides et efficaces pour un monitoring continue des changements des USOS à partir d’images à résolution moyenne. Cette recherche visait à évaluer le potentiel de telles images satellitales de résolution moyenne pour obtenir de l’information sur les changements des USOS à une échelle régionale dans le cas de la Communauté Métropolitaine de Montréal (CMM), une métropole nord-américaine typique. Les études précédentes ont démontré que les résultats de détection automatique des changements dépendent de plusieurs facteurs tels : 1) les caractéristiques des images (résolution spatiale, bandes spectrales, etc.); 2) la méthode même utilisée pour la détection automatique des changements; et 3) la complexité du milieu étudié. Dans le cas du milieu étudié, à l’exception du centre-ville et des artères commerciales, les utilisations du sol (industriel, commercial, résidentiel, etc.) sont bien délimitées. Ainsi cette étude s’est concentrée aux autres facteurs pouvant affecter les résultats, nommément, les caractéristiques des images et les méthodes de détection des changements. Nous avons utilisé des images TM/ETM+ de LANDSAT à 30 m de résolution spatiale et avec six bandes spectrales ainsi que des images VNIR-ASTER à 15 m de résolution spatiale et avec trois bandes spectrales afin d’évaluer l’impact des caractéristiques des images sur les résultats de détection des changements. En ce qui a trait à la méthode de détection des changements, nous avons décidé de comparer deux types de techniques automatiques : (1) techniques fournissant des informations principalement sur la localisation des changements et (2)techniques fournissant des informations à la fois sur la localisation des changements et sur les types de changement (classes « de-à »). Les principales conclusions de cette recherche sont les suivantes : Les techniques de détection de changement telles les différences d’image ou l’analyse des vecteurs de changements appliqués aux images multi-temporelles LANDSAT fournissent une image exacte des lieux où un changement est survenu d’une façon rapide et efficace. Elles peuvent donc être intégrées dans un système de monitoring continu à des fins d’évaluation rapide du volume des changements. Les cartes des changements peuvent aussi servir de guide pour l’acquisition d’images de haute résolution spatiale si l’identification détaillée du type de changement est nécessaire. Les techniques de détection de changement telles l’analyse en composantes principales et la comparaison post-classification appliquées aux images multi-temporelles LANDSAT fournissent une image relativement exacte de classes “de-à” mais à un niveau thématique très général (par exemple, bâti à espace vert et vice-versa, boisés à sol nu et vice-versa, etc.). Les images ASTER-VNIR avec une meilleure résolution spatiale mais avec moins de bandes spectrales que LANDSAT n’offrent pas un niveau thématique plus détaillé (par exemple, boisés à espace commercial ou industriel). Les résultats indiquent que la recherche future sur la détection des changements en milieu urbain devrait se concentrer aux changements du couvert végétal puisque les images à résolution moyenne sont très sensibles aux changements de ce type de couvert. Les cartes indiquant la localisation et le type des changements du couvert végétal sont en soi très utiles pour des applications comme le monitoring environnemental ou l’hydrologie urbaine. Elles peuvent aussi servir comme des indicateurs des changements de l’utilisation du sol. De techniques telles l’analyse des vecteurs de changement ou les indices de végétation son employées à cette fin. / Nowadays land use/land cover maps at regional scale are commonly generated with satellite data of medium spatial resolution (between 10 m and 30m). The National Land Cover Database (NLCD) in the United States and the Coordination of Information on the Environment (CORINE) Land Cover program in Europe, both based on LANDSAT images, are two typical examples. However, these maps become rapidly obsolete, especially in highly dynamic areas such as mega cities and metropolitan areas. In many applications, such as to monitor the water quality affected by the Land use/Land cover (LULC) change, the spread of invasive species, policy making for city managers, annual updating of LULC maps is required. Since 2007, the USGS offers access to ortho-rectified LANDSAT imagery free of charge. Both archived (since 1984) and recently acquired images are available. Without doubt, such data availability will stimulate the research on fast and cost effective methods and techniques for “continuous” regional land cover/use map updating using medium resolution satellite imagery. The objective of this research was to evaluate the potential of such medium resolution satellite imagery for providing information on changes useful for the continuous updating of LULC maps at a regional scale in the case of the Montreal Metropolitan Community (MMC) area, a typical North American metropolis. Previous studies have demonstrated that many factors could affect the results of automatic change detection such as: (1) the characteristics of the images (spatial resolution, spectral bands, etc.); (2) the method itself used to automatically detect changes; and (3) the complexity of the landscape. In the study site except for the Central Business District (CBD) and some commercial streets, land uses (industrial, commercial, residential, etc.) are well delimited. Thus this study was focused on the other factors affecting change detection results, namely, the characteristics of the images and the method of change detection. We used 6 spectral bands of LANDSAT TM/ETM+ with 30 m spatial resolution and 3 spectral bands of ASTER-VNIR with 15 m spatial resolution to evaluate the impact of image characteristics on change detection. Concerning the change detection method, we decided to compare two types of automatic techniques: (1) techniques providing information principally on the location of changed areas,and (2) techniques providing information on both the location of changed areas and the type of changes ("from-to" classes). The main conclusions of this research are as follows: Change detection techniques such as image differencing or change vector analysis applied to LANDSAT multi-temporal imagery provide an accurate picture of changed areas in a fast and efficient manner. They can thus be integrated in a continuous monitoring system for a rapid evaluation of the volume of changes. The produced maps could be helpful to guide the acquisition of high spatial resolution imagery if a detailed identification of the type of changes is required. Change detection techniques such as principal component analysis and post-classification comparison applied to LANDSAT multi-temporal imagery could provide a relatively accurate picture of “from-to” classes but at a very general thematic level (for example, built-up to green space and vice-versa, forest lands to bare soil and vice-versa, etc.). ASTER images with better spatial resolution but with less spectral bands than LANDSAT images do not provide more detailed thematic information (for example forest land to commercial or industrial areas). The results indicate that future research should be focused on the detection of changes in the vegetation cover as medium resolution imagery is highly sensitive to this type of surface cover. Maps indicating the location and the type of changes in vegetation cover are in itself very useful for various applications, such as environmental monitoring or urban hydrology, and can be used as indicators on land use changes. Techniques such as change vector analysis or vegetation indices could be used to this end.

Changing land cover from prairie grasslands to intensive, primarily cereal agriculture, over the North American Great Plains since the mid-19th century, has had a hydrological and climatological impact on that ecosystem (Pielke, Sr., et al., 2011). Agriculture has introduced timed harvest seasons, irrigation, and C3 photosynthesizing crops with poorer water efficiency than the grasses it replaced. All of these changes have been linked to exacerbated drought conditions and warmer temperatures; however, few studies have quantified this relationship at the continental scale. In order to evaluate the change imposed by this shift in land use and land cover, the observation based 20th Century Reanalysis Project (20CR) was used to quantify the climatological differences in temperature and humidity between areas of natural prairie and agriculture over the 20th century. An additional analysis used the Observation Minus Reanalysis (OMR) technique to isolate the surface climate signal found in the 20CR. We find indications that changing land cover had an impact on climate. However, using observation based data returned no evidence of a statistically significant change due to the small land use and land cover change (LULCC) signal within the larger climate noise. Therefore, an idealised modelling experiment was undertaken using the Geophysical Fluid Dynamics Laboratory (GFDL) AM2-LM2 atmosphere-land model to remove these other influences. This experiment compared the results of two model simulations: one where the entirety of the prairie was preserved as grassland (GRASS), and another where the entire prairies had been converted into an agricultural area (AGRIC). Relative to GRASS, the AGRIC simulation has reduced surface albedo and root zone depth, and increased roughness length over the prairies, which collectively cause a significant summer drying. This occurs when the shallower rooting zone limited potential evapotranspiration (PET) forcing the additional energy created by turbulent mixing and a lower surface albedo to warm the air, surpassing PET and reaching drier conditions faster. While not conclusive, the results presented in this thesis represent a step towards filling the gaps in understanding land-atmosphere interactions and connecting LULCC to climate.

Remote sensing techniques are vital for early detection of several problems such as natural disasters, ecological problems and collecting information necessary for finding optimum solutions to those problems. Remotely sensed information has also important uses in predicting the future risks, urban planning, communication.Recent developments in remote sensing instrumentation offered a challenge to the mathematical and statistical methods to process the acquired information. Classification of satellite images in the context of land cover classification is the main concern of this study. Land cover classification can be performed by statistical learning methods like additive models, decision trees, neural networks, k-means methods which are already popular in unsupervised classification and clustering of image scene inverse problems. Due to the degradation and corruption of satellite images, the classification performance is limited both by the accuracy of clustering and by the extent of the classification. In this study, we are concerned with understanding the performance of the available unsupervised methods with k-means, supervised methods with Gaussian maximum likelihood which are very popular methods in land cover classification. A broader approach to the classification problem based on finding the optimal discriminants from a larger range of functions is considered also in this work. A novel method based on threshold decomposition and Boolean discriminant functions is developed as an implementable application of this approach. All methods are applied to BILSAT and Landsat satellite images using MATLAB software.

Submitted by ANDRE GONÇALVES VIEIRA (dre_goncalves@hotmail.com) on 2018-06-26T12:07:49Z No. of bitstreams: 1 Andre Goncalves Vieira.pdf: 2971952 bytes, checksum: 0be9dedd15aa5f09b36cea2fed69d752 (MD5) / Approved for entry into archive by Claudia Adriana Spindola null (claudia@fct.unesp.br) on 2018-06-26T12:23:26Z (GMT) No. of bitstreams: 1 vieira_ag_me_prud.pdf: 2971952 bytes, checksum: 0be9dedd15aa5f09b36cea2fed69d752 (MD5) / Made available in DSpace on 2018-06-26T12:23:26Z (GMT). No. of bitstreams: 1 vieira_ag_me_prud.pdf: 2971952 bytes, checksum: 0be9dedd15aa5f09b36cea2fed69d752 (MD5) Previous issue date: 2018-05-16 / O uso e a cobertura da terra sem planejamento adequado alteram as condições naturais de uma bacia hidrográfica. Essa situação pode ser observada em diversos municípios, como no caso de Presidente Prudente - SP, e em particular, na bacia hidrográfica do Córrego do Gramado, que se localiza na zona leste do município. As atividades antrópicas desenvolvidas na bacia hidrográfica do Córrego do Gramado alteram a qualidade das águas superficiais dos canais fluviais tanto na área urbanizada quanto na área rural. Desta forma, este trabalho analisou possíveis relações entre variáveis físicas e químicas da água, bioindicadores da qualidade de água e uso e cobertura da terra na bacia hidrográfica do Córrego do Gramado, município de Presidente Prudente. As amostras de água foram processadas em campo e em laboratório. Os macroinvertebrados aquáticos foram amostrados com um coletor de bentos surber, com malha de 250 µm e então levados ao laboratório, onde foram triados e identificados. Os organismos foram coletados, entre os meses nov./16, fev./17 e jun./17. Foram identificados 33 taxons de organismos bentônicos. Chironomidae, Oligochaeta e Simuliidae estiveram presentes nos três pontos e nas três amostras. Os Ephemeroptera e Trichoptera foram encontrados nos P1 e P3, porem ausentes no P2. Resultados para analises físico-químicas houve alteração em nov./16 quando não houve precipitação de chuva. A composição da fauna mostrou-se distinta entre todos os municípios estudados. Os resultados indicaram famílias presentes nos canais fluviais são mais tolerantes a alterações ambientais com media e/ou baixa pontuação no BMWP. Porém o P3 do Córrego do Gramado esta com melhor pontuação comparado aos P1 e P2. O estudo revela que as condições ambientais da bacia hidrográfica do Córrego do Gramado, no que diz respeito à presença de vegetação natural e/ou reflorestada possuem influência na determinação da estrutura e composição da comunidade de macroinvertebrados bentônicos. Além disso, fatores espaciais (distribuição geográfica) podem estar exercendo influência sobre a diversidade regional. / Land use and land cover without adequate planning changes the natural conditions of a river basin. This situation can be observed in several municipalities, as in the case of Presidente Prudente - SP, and in particular, in the catchment area of Córrego do Gramado, which is located in the eastern part of the municipality. The anthropic activities developed in the catchment area of the Gramado stream change the quality of the surface waters of the river channels in the urbanized area as well as in the rural area. In this way, this work analyzed possible relationships between physical and chemical variables of water, bioindicators of water quality and use and land cover in the catchment area of the Gramado stream, in the municipality of Presidente Prudente. The water samples were processed in the field and in the laboratory. The aquatic macroinvertebrates were sampled with a surber bent collector, with a mesh of 250 μm and then taken to the laboratory, where they were screened and identified. The organisms were collected between the months of Nov./16, Feb./17 and Jun./17. 33 taxa of benthic organisms were identified. Chironomidae, Oligochaeta and Simuliidae were present in the three points and in the three samples. Ephemeroptera and Trichoptera were found in P1 and P3, but absent in P2. Results for physicalchemical analyzes were changed in November / 16 when there was no rainfall. The fauna composition was distinct among all the studied municipalities. The results indicated families present in the fluvial channels are more tolerant to environmental changes with mean and / or low scores in the BMWP. However, the Gramado Creek P3 has better scores compared to P1 and P2. The study reveals that the environmental conditions of the Gramado Creek watershed, with respect to the presence of natural and / or reforested vegetation, influence the structure and composition of the community of benthic macroinvertebrates. In addition, spatial factors (geographic distribution) may be influencing regional diversity.

The aim of the diploma thesis was a statistical evaluation of the impact of farming methods and the land cover on hydrochemical parameters of surface waters. The area for the evaluation is located in Novohradsko and consist of lower and upper parts of the basin of Vackovy potok and a lower part of Pasecky potok. The area was chosen to include different landscape managements (arable soil, forest and meadows). Due to this fact, it is possible to compare the impact of the management on values of the chosen hydrochemical parameters, which were conductivity, N NO3-, TOC, NL105 and the outflow. Based on the results, it is possible to say that the surface waters from the intesively farmed part of the basin of Vackovy potok have the higher values of all chosen parameters compared to the forest basin or the meadow basin. There was a trend of the increase of the outflow and the values N NO3- in the surface waters always one day after a heavy rainfall. Overall, it is possible to claim that the arable soil has reduced abilities of the retention. This is supported by the large water drainage from the agricultural area.

Pour améliorer la prévision des crues dans les bassins versants torrentiels, les hydrologues doivent connaître les conditions initiales de l'état hydrique des sols précédant les événements pluvieux. La cartographie de l'humidité des sols, dont les variations sont principalement influencées par la topographie, la couverture végétale et l'hétérogénéité des propriétés des sols, constitue alors un outil précieux pour étudier les processus de formation des écoulements. Ce travail aborde la problématique de la spatialisation des variations spatio-temporelles de l'état hydrique des sols en utilisant la modélisation géostatistique et hydrologique appliquées au bassin versant expérimental marneux du Laval (0.86 km², ORE Draix-Bléone, France). Le suivi in situ des épisodes pluvieux de mai 2015 à novembre 2016 a permis de mettre en évidence une relation significative entre la teneur en eau des sols, la topographie et l'occupation de surface dans les badlands. Il a également permis de mieux appréhender la dynamique spatio-temporelle des variations de teneur en eau des versants à l'échelle saisonnière et événementielle, et de confirmer la majeure contribution aux écoulements de crue des horizons superficiels dénudés. Enfin, la modélisation hydrologique associée au traçage chimique et isotopique des eaux du bassin a apporté une amélioration de la compréhension de l'organisation spatiale de la réponse hydrologique du bassin à l'échelle événementielle. / Hydrologists need to know soil moisture antecedent conditions before rainfall events to improve floodforecasting in torrential catchments. Soil moisture mapping, whose variations are mainly influenced bytopography, vegetation cover, and heterogeneity of soil properties, is therefore a valuable tool to studyhydrological processes. This work adresses the issue of the spatio-temporal variations of soil water statusspatialization using geostatistical and hydrological modeling applied to the Laval marly experimental catchment(0.86 km², ORE Draix-Bléone, France). In situ monitoring of rainfall events from May 2015 to November 2016revealed a significant relationship between soil water content, topography and land cover in the badlands. Italso led to better assess soil water content spatio-temporal dynamics at the hillslope scale and the seasonaland event time scales. It confirmed the major contribution of bare areas to stream flows. Eventually, thehydrological modeling associated to the chemical and isotopic water tracing made it possible to better understand the spatial organization of the catchment hydrological response at the event scale.