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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Assessment of foliar nitrogen as an indicator of vegetation stress using remote sensing : the case study of Waterberg region, Limpopo Province

Manyashi, Enoch Khomotso 06 1900 (has links)
Vegetation status is a key indicator of the ecosystem condition in a particular area. The study objective was about the estimation of leaf nitrogen (N) as an indicator of vegetation water stress using vegetation indices especially the red edge based ones, and how leaf N concentration is influenced by various environmental factors. Leaf nitrogen was estimated using univariate and multivariate regression techniques of stepwise multiple linear regression (SMLR) and random forest. The effects of environmental parameters on leaf nitrogen distribution were tested through univariate regression and analysis of variance (ANOVA). Vegetation indices were evaluated derived from the analytical spectral device (ASD) data, resampled to RapidEye. The multivariate models were also developed to predict leaf N. The best model was chosen based on the lowest root mean square error (RMSE) and higher coefficient of determination (R2) values. Univariate results showed that red edge based vegetation index called MERRIS Terrestrial Chlorophyll Index (MTCI) yielded higher leaf N estimation accuracy as compared to other vegetation indices. Simple ratio (SR) based on the bands red and near-infrared was found to be the best vegetation index for leaf N estimation with exclusion of red edge band for stepwise multiple linear regression (SMLR) method. Simple ratio (SR3) was the best vegetation index when red edge was included for stepwise linear regression (SMLR) method. Random forest prediction model achieved the highest leaf N estimation accuracy, the best vegetation index was Red Green Index (RGI1) based on all bands with red green index when including the red edge band. When red edge band was excluded the best vegetation index for random forest was Difference Vegetation Index (DVI1). The results for univariate and multivariate results indicated that the inclusion of the red edge band provides opportunity to accurately estimate leaf N. Analysis of variance results showed that vegetation and soil types have a significant effect on leaf N distribution with p-values<0.05. Red edge based indices provides opportunity to assess vegetation health using remote sensing techniques. / Environmental Sciences / M. Sc. (Environmental Management)
2

Enviromentální aplikace obrazové spektroskopie / Hyperspectral Remote Sensing for Environmental Mapping and Monitoring

Kopačková, Veronika January 2013 (has links)
The main purpose of this thesis is to use Image Spectroscopy as a tool to monitor the environmental conditions in a region affected by anthropogenic activities via estimating both geochemical and biochemical parameters on a regional scale. The research has been carried on the Sokolov lignite mine, NW Bohemia, a region affected by long-term extensive mining. The thesis is divided into two thematic parts. First part is devoted to applications of Image Spectroscopy into Acid Mine Drainage mapping and its related issues (chapters 2 and 3). In chapter 2 the equivalent mineral end-members were successfully derived from the ASTER image data (Advanced Space-borne Thermal Emission and Reflection Radiometer satellite data). In the chapter 3 the pH was estimated on the basis of mineral and image spectroscopy. The Multi Range Spectral Feature Fitting (MRSFF) technique was utilized for mineral mapping and the multiple regression model using the fit images, the results of MRSFF, as inputs was constructed to estimate the surface pH and statistical significant accuracy was attained. In the second thematic part (chapters 4-6) Image Spectroscopy is applied into monitoring of vegetation stress. A new statistical method was developed to assess the physiological status of macroscopically undamaged foliage of Norway...
3

Assessment of foliar nitrogen as an indicator of vegetation stress using remote sensing : the case study of Waterberg region, Limpopo Province

Manyashi, Enoch Khomotšo 06 1900 (has links)
Vegetation status is a key indicator of the ecosystem condition in a particular area. The study objective was about the estimation of leaf nitrogen (N) as an indicator of vegetation water stress using vegetation indices especially the red edge based ones, and how leaf N concentration is influenced by various environmental factors. Leaf nitrogen was estimated using univariate and multivariate regression techniques of stepwise multiple linear regression (SMLR) and random forest. The effects of environmental parameters on leaf nitrogen distribution were tested through univariate regression and analysis of variance (ANOVA). Vegetation indices were evaluated derived from the analytical spectral device (ASD) data, resampled to RapidEye. The multivariate models were also developed to predict leaf N. The best model was chosen based on the lowest root mean square error (RMSE) and higher coefficient of determination (R2) values. Univariate results showed that red edge based vegetation index called MERRIS Terrestrial Chlorophyll Index (MTCI) yielded higher leaf N estimation accuracy as compared to other vegetation indices. Simple ratio (SR) based on the bands red and near-infrared was found to be the best vegetation index for leaf N estimation with exclusion of red edge band for stepwise multiple linear regression (SMLR) method. Simple ratio (SR3) was the best vegetation index when red edge was included for stepwise linear regression (SMLR) method. Random forest prediction model achieved the highest leaf N estimation accuracy, the best vegetation index was Red Green Index (RGI1) based on all bands with red green index when including the red edge band. When red edge band was excluded the best vegetation index for random forest was Difference Vegetation Index (DVI1). The results for univariate and multivariate results indicated that the inclusion of the red edge band provides opportunity to accurately estimate leaf N. Analysis of variance results showed that vegetation and soil types have a significant effect on leaf N distribution with p-values<0.05. Red edge based indices provides opportunity to assess vegetation health using remote sensing techniques. / Environmental Sciences / M. Sc. (Environmental Management)

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