Miscanthus is found in many different environments in the wild and thus may have a broad genetic base which could be exploited by a genetic improvement programme. Miscanthus sinensis is found in higher and colder latitudes than Miscanthus sacchariflorus, which is usually found closer to sea level. However, M sacchariflorus achieves taller canopy height and is later in maturing. Therefore, for United Kingdom (U.K.) conditions the combination of the lower temperature adapted traits of M sinensis with the higher productive potential of M sacchariflorus is required. No previous work has been performed on the effect of the altitude at which plants are collected on their adaptation to U.K. conditions. Therefore, the aim of the current study was to differentiate by physiological and molecular methods between and within the genotypes of Miscanthus sampled from different altitudes in Japan. Physiological analysis was undertaken, in the field, over 3 seasons in order to determine which parameters could be used as predictors of productivity. In the second growth season a modified method was used to measure leaf extension rate (CliftonBrown, 1997) and this was found to correlate positively to annual production when measured during the vegetative phase of growth. Results also confirmed that genotypes with a flowering date in September and October were more productive since the length of the vegetative growth stage was increased. Considerable variation was found to be present both between, as well as within, the genotypes and ecotypes of Miscanthus studied, which could be exploited in an improvement programme. Further analysis was also carried out at the genetic level using the AFLP fingerprinting technique; this confirmed the results obtained using the physiological parameters. However, no clear link could be found between the altitude at which the plant was collected and the traits exhibited. It was found that late flowering M. sinensis outperfonned M. sacchariflorus genotypes primarily because of differences between stem densities. The results obtained show that a Miscanthus breeding programme for U.K. conditions is feasible as considerable variation in productivity related traits is present at the genetic as well as the physiological level.

In the UK reedbeds dominated by Phragmites australis have been identified as a priority habitat for most regional Biodiversity Partnerships. Information on the current distribution and quality of reedbed sites across the UK is lacking, yet such information is vital in developing suitable management plans for the conservation and expansion of this threatened habitat. The focus of this thesis is to develop a suitable methodology for accurately mapping the distribution and assessing the biophysical properties of reedbed habitats using remotely sensed data. Three study sites situated in the North West region of the UK were used: Leighton Moss nature reserve in Lancashire, and the River Leven and Esthwaite Water situated in Cumbria. The remotely sensed data used in this study included high-resolution satellite and airborne imagery and ground-based spectral data. Results of the first analytical chapter (i.e. chapter 3) demonstrated the potential of using high resolution QuickBird multi spectral satellite imagery to derive accurate maps of reedbeds through appropriate analysis of image texture, careful selection of input bands, spatial degradation of input bands, selection of a suitable classification algorithm and post-classification refinement using terrain data. Results of the second analytical chapter (chapter 4) demonstrated the benefits of using multi-seasonal images over single-date images and the effectiveness of incorporating spectral bands with textural measures. Through careful selection of appropriate classification technique, the input image datasets could be used to generate optimal reedbed maps. The results of the multi-seasonal reedbed mapping experiment conducted using QuickBird imagery was the basis for the field spectrometry experiment. The study aimed at monitoring and understanding variations in the spectral reflectance and biophysical properties of reedbeds canopies throughout the seasonal phenological cycle and to identify the optimal spectral indices for quantifying biophysical properties (chapter five ). The results of the experiment indicated that the narrow- band derived Difference Vegetation Index (DV I) and Renormalised Difference Vegetation Index (RDVI) provided the most accurate e'~~iIi1~tes of the leaf area index (LAl) for reedbed canopies (r = 0.77 and 0.72 respectively). Having observed the limitations of accurately deriving canopy heights from experiments conducted in chapter 5, the potential for quantifying canopy biophysical properties from light detection and radar (LiDAR) data (elevation and intensity) was investigated in chapter 6. The study demonstrated some of the potential and limitations of using LiDAR data for characterising reedbed canopies. A canopy height model (CHM) was generated by subtracting the Ordnance Survey (OS) derived digital terrain model (DTM) from the LiDAR- derived digital surface model (DSM). The density of first return points was high for reedbeds and these were able to generate an accurate CHM, when validated against field measurements. LiDAR intensity data displayed specular reflection along the centre of the flight line over reedbeds and water bodies, but not for other land cover/vegetation types. The LiDAR intensity data showed potential for containing considerable information on reedbed canopy structure and pattern that is valuable from an ecological perspective. Results of the final analytical chapter (chapter 7) demonstrated the value in combining appropriately compressed hyperspectral imagery with LiDAR data for the effective mapping of reedbed habitats. The most effective image compression technique was the spectrally segmented principal component analysis (SSPCA), which had the optimal combination of reedbed accuracy and processing efficiency. A substantial improvement in the accuracy of reedbed delineation was achieved when a mask generated by applying a 3m threshold to the LiDAR- derived CHM was used to filter the reedbed map derived from the optimal SSPCA image dataset. Based on the fmdings of chapter 5 and 6, the hyperspectral and LiDAR data was used to derive LAI and canopy height (CH) maps of reedbeds respectively, two vital biophysical measures needed in estimating the quality of reedbed canopies. Hence, this study is a step forward in utilizing spectral, spatial and structural data contained in remotely sensed data for the mapping of reedbed quantity and quality. This research has demonstrated the potential of using remotely sensed data, complemented with adequate ground based information for mapping the spatial extent and quality of reedbed canopies in three specific sites across the North " West region in the UK. Based on the success with a specific habitat type, suggestions are made to further expand these techniques to explore fine scale mapping of more habitats using remotely sensed data of high spatial resolution. Hence, two major studies are recommended for future work, namely (1) updating the Phase 1 habitat survey map using remote sensing techniques, and (2) the integration of high spatial resolution satellite imagery (hyperspectral or QuickBird) and LiDAR data for vegetation mapping and deriving biophysical measures.

The aim of this study was to evaluate herbage quality of perennial ryegrass Lolium perenne using thermogravimetry. Both Dynamic and isothermal thermal analyses were investigated over a range of heating rates to first establish any association between thermal profiles and dry matter digestibility values. The results suggested thermal methods could be used to predict dry matter digestibility (in vitro DMD) and identified the best experimental protocols for further study. Further investigations were carried out to predict DMD values using discrete and continuous TG weight loss data streams by multivariate analysis. This approach enabled the successful modelling and prediction of DMD. Further studies were undertaken to investigate the application of the technique to predict digestible organic matter in the dry matter (in vivo DOMD) and Metabolisable energy values (ME). The results were again positive and indicated potential for the application of thermal methods and for further investigation. Thermal combustion and pyrolysis techniques were employed to study the key fibre fractions associated with neutral detergent fibre, acid detergent fibre and lignin to establish their relationship with thermal profiles. The results indicated that there was potential to further develop the method to predict the fibre fractions.

No description available.

An explanation for the ubiquity of sexual reproduction remains elusive although it is commonly suggested that sex and recombination facilitate a more rapid response to environmental change than clonal reproduction. If this suggestion is true then one would expect the frequency of sexual reproduction within populations to increase with rate of environmental change. The study described here investigates the potential correlation between mode of reproduction and rate of environmental change in red fescue, Festuca rubra, a clonal/sexual species of perennial grass. Populations are identified that have experienced contrasting histories of change over the past 138 years, and within which the ratios of clonally to sexually derived individuals have been determined. From these ratios the selection pressures on mode of reproduction in each of the Festuca rubra populations investigated are inferred. The unexpected discovery that Festuca rubra is represented by two sub-species at the main study site has also prompted investigations into the factors governing their relative frequencies and distributions. Since the sub-species represent different cytotypes within the red fescue aggregate, this has allowed for inferences to be made relating to their observed coexistence and the apparent overcoming of minority cytotype exclusion by the subspecies found at lower frequencies.

Das Scheidenblütgras ist ein nur wenige Zentimeter großes und kurzlebiges Gras mit außergewöhnlichen ökologischen Anforderungen. In Sachsen ist es vor allem im Gebiet der Bergwerksteiche im Raum Freiberg und im Oberlausitzer Heide- und Teichgebiet zu finden. Diese Art steht europaweit unter Schutz, Sachsen trägt in hohem Maße Verantwortung für den Erhalt. Die reich bebilderte Broschüre informiert über die Biologie und Ökologie, die weltweiten Vorkommen und die besondere Bedeutung des Scheidenblütgrases.

Das Scheidenblütgras ist ein nur wenige Zentimeter großes und kurzlebiges Gras mit außergewöhnlichen ökologischen Anforderungen. In Sachsen ist es vor allem im Gebiet der Bergwerksteiche im Raum Freiberg und im Oberlausitzer Heide- und Teichgebiet zu finden. Diese Art steht europaweit unter Schutz, Sachsen trägt in hohem Maße Verantwortung für den Erhalt. Die reich bebilderte Broschüre informiert über die Biologie und Ökologie, die weltweiten Vorkommen und die besondere Bedeutung des Scheidenblütgrases.

Un modèle de morphogenèse aérienne de graminées fourragères, nommé L grass, a été développé lors de travaux précédents. Le but de la thèse est de proposer une méthode d'insertion de la morphogenèse racinaire dans ce modèle afin de tenir compte de l'impact des ressources telluriques sur la structure et le fonctionnement de la plante.</br>Un simulateur de plante entière de ray-grass anglais (Lolium perenne L.) incorporant (i) des règles d'autorégulation de l'architecture aérienne, (ii) le développement architecturé du système racinaire, (iii) des processus de coordination entre les parties aérienne et racinaire et (iv) un système d'allocation du carbone a été développé. La nature autorégulée du modèle lui permet de reproduire les réponses à l'intensité d'une défoliation et à la compétition pour la lumière sans nécessiter de contrôle central. Le couplage du modèle avec un modèle de sol permet de simuler le développement de la plante subissant différents scénarios d'apport en eau sans nécessiter de consignes morphogénétiques données a priori.</br>La représentation architecturée du système racinaire présente quelques limites, principalement en termes de ressources informatiques, pour les simulations de peuplements. Afin de pallier ces limites, un modèle continu de dynamique de densités racinaires a aussi été incorporé pour simuler l'enracinement. Les comparaisons entre les deux modèles de système racinaire ont montré l'intérêt indéniable des modèles de densités racinaires notamment pour les études à l'échelle d'un couvert végétal. / A model of the shoot morphogenesis of forage grasses, called L-grass, was developed in previous studies. The aim of this thesis is to propose a method for introducing root morphogenesis in the current model so the effect of telluric resources availability can be taken into account for shaping plant form and functioning.</br>A simulator of perennial ryegrass (Lolium perenne L.) whole plant, which includes (i) the rules of shoot architecture self-regulation,(ii) the architectural development of the root system, (iii) the coordination processes between shoot and root parts and (iv) a system of allocation of carbon, was developed. The self-adaptable character of the model allows the reproduction of the responses to the intensity of defoliation and the competition for sunlight without the need of any central control. The coupling of the model with a soil model enables to recreate the development of the plant undergoing different scenarios of water supply with no requirement of previously established morphogenetic guidelines.</br>The architectural representation of the root system presents some shortcomings, mainly regarding the need in computing power when simulating plant populations. In order to overcome these limitations, a continuous model of the dynamics of root densities has been also incorporated to simulate plant rooting. The comparison between both models of root systems has shown the undeniable interest of modeling root density, especially for the studies at the vegetation cover level.