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This thesis describes a series of laboratory and field experiments that quantify the population dynamics of the heather beetle (Lochmaea suturalis Thomson), in relation to temperature and its host plant heather (Calluna vulgaris (L. ) Hull). The sex ratio, fecundity, egg laying threshold temperature, emergence threshold temperature, life stage development periods, and life stage mortalities were investigated. It was shown that the life stages were significantly dependent on temperature, whilst it was shown that there was no significant relationship between larval growth and Calluna vulgaris plants sourced from the study sites. The results of the population dynamics experiments were incorporated into a temperature driven, cohort based, and daily looped, stochastic population dynamics computer model. The temperature component of the model was derived from temperature data collected from nine moorland sites, at different altitudes, where there was shown to be a significant relationship between temperature and altitude. The population dynamics model was run for a fifty year period with a population of I million beetles at seven temperature regimes and five different altitudes. The model predicted that as daily mean temperatures rose, so there was a greater chance of increasing populations and that as altitude increases, so the chance of increasing populations decreases. At a predicted daily mean temperature rise of 2-3'C there was evidence of considerable population increases at lower altitudes, and with a daily mean temperature rise of 4-6'C the beetle population exhibited persistent, large, fluctuating populations in the region of three to sixty fold increases at all modelled altitudes over a number of years. An uncertainty and sensitivity analysis of the model was undertaken utilising a Latin Hypercube Swnpling regime, where it was shown that fecundity, egg mortality and pupal mortality were the most important life history variables in i contributing to the model output imprecision. The thesis discussesth eser esults in the light of predicted climate change and their use as an aid to moorland and heathland managers.

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In Scotland, bilberry is well known as a member of the dwarf shrub community on moorlands, which provide valuable habitats for wildlife. Recently it has been envisaged that bilberry populations could play an important role in improving the dwarf shrub vegetation in degraded moorland areas. This study was therefore undertaken to investigate the above-ground growth dynamics of bilberry with emphasis on responses to grazing by sheep and seedling establishment. The leaf production of bilberry was increased by higher nitrogen availability. High nitrogen supply also led to greater activation of dormant buds. Abortion of buds was less when nitrogen was continuously supplied. The reproductive capacity of bilberry was shown to be decreased by herbage removal. In contrast flowering was increased following supply of high nitrogen in glasshouse conditions. Almost all the flowers developed into fruits in the field, but a very low production of fruits was reported from bilberry plants that were grown in the glasshouse. Results of a series of laboratory experiments on seed production, germination, seed storage and evaluation of a moorland seed bank confirmed that the scanty seedling recruitment of bilberry was due to the limited production of 'germinable' seeds in berries and risks imposed by the environment after dispersal particularly when seeds are in the litter layer and/or soil. This could suggest that limited picking of bilberry fruits would not have a detrimental effect on establishment of bilberry populations in moorlands. Therefore, areas could be identified which were suitable for public access and berry exploitation in Scotland. The berry production was estimated approximately to be about 3220-9660 tones per year in this zone.

Concerns have been raised on the deterioration of heather moorland due to management in the UK. A study was therefore conducted on the impacts of moorland management on the soils and hydrology of a catchment on Dartmoor. Soil moisture was measured gridwise using TDR on 19 occasions. At 23 sites within this grid, physical properties of the topsoil were obtained. At three locations, tensiometer nests were installed, recording soil suction at 10 cm depth intervals. At the catchment scale, stream discharge and rainfall were recorded. Grazing densities within the watershed were estimated and the observed patterns were related to vegetation types. Results from the TDR grid showed that in dry conditions, soil moisture patterns are heterogeneous in contrast to a more uniform pattern in wet periods. A threshold soil moisture content of about 0.60 cm3 cm-3 divides the two conditions. The exponential relationship between average hillslope soil moisture content and stream discharge also revealed the division between wet and dry states. A regression analysis showed that during dry conditions, the vegetation plays a significant role in determining the soil water status. During wet conditions, topography becomes more important. In these conditions, the soil water movement is mainly lateral, whereas in the dry state, this is vertical in the soil profile. Tensiometer data showed that most soil water movement is in the topsoil. Analyses suggested that soil moisture under vegetation classes associated with higher grazing pressures is higher in similar topographic conditions. Soil bulk density is higher and the total porosity is lower near the soil surface. This suggests that less rainfall is required to reach the soil moisture threshold and water will be transported laterally down the slope. A heather burning experiment revealed that the direct effect of temperature is shallow. Soil moisture levels do not change over the course of the burn. However, in dry situations during summer, soil moisture contents under burned plots are higher than under unburned vegetation probably due to reduced transpiration. If this effect is similar at the hillslope scale, when the soil is wetting up, the soil moisture threshold value could be reached at an earlier stage and accelerated lateral water movement could be the result. It can be concluded therefore, that moorland management could accelerate water movement on the hillslopes causing higher discharge peaks in wet periods and consequently low flows in summer. However, the effects are subtle and encouraging vegetation heterogeneity could play a role in buffering water to prevent loss to the stream.

Natural organic matter (NOM) is described as an intricate mixture of organic compounds that occurs universally in ground and surface waters. After treatment for potable use, there is NOM remaining in the water that reacts with the chlorine used for disinfection to form disinfection by-products (DBPs). Some of the DBPs, trihalomethanes (THMs) are regulated. Several water treatment works (WTWs) in the Yorkshire Water and United Utilities (previously North West Water) region in England have recently experienced difficulty in meeting THM limits (100 µg L-1) in their finished drinking water at certain times of the year. An investigation into how NOM changes seasonally, pragmatic methods of NOM analysis and its reactivity with chlorine was undertaken. By separating the NOM using adsorbent resins into fractions, it was possible to gain an insight into the seasonality of NOM. It was observed that a particular, difficult to remove fraction was always more reactive with respect to THM formation in autumn. Some of the methods proposed in the literature were used here with varying successes. It was found that High Performance Size Exclusion Chromatographic methods were most useful to the WTW operators for optimising treatment processes. It is known that the formation of DBPs is very complex. An attempt was made to predict the reactivity of a raw water in terms of THM-FP by looking at the NOM makeup. However, it was found that the fluorescence spectra combined with the fluorescence index of raw water and chlorinated samples gave more insight into the reactivity of the raw water at a particular time than knowing the fraction distribution. The use of fluorescence as a tool for understanding chlorine-NOM reactions is promising.

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Peatlands are unique habitats that have absorbed large amounts of carbon dioxide and locked it away as carbon buried in peat for millennia. In the UK, blanket peatlands form one of the largest terrestrial stores of carbon (Milne and Brown, 1997). Recent research suggests that the carbon sequestering potential and carbon stores of UK blanket peatlands are at risk from changes in land use practices and climate. Although, to date, little research has considered blanket peatland at a landscape scale and a comprehensive understanding of land use and degradation impact upon carbon sequestration has not been gained. This thesis presents a study of Dartmoor, a blanket peatland in south west England vulnerable to climate change (Clark et al, 2010). A landscape scale carbon inventory, using a methodology designed for blanket peatlands is presented. Nearly 1000 peat depths and 30 cores were taken using stratified sampling across Dartmoor’s landscape. Functional relationships between peat depth, bulk density and carbon content and topographic parameters were found. In arc GIS 9.3 these were used to model landscape scale carbon, this estimates that Dartmoor contained 9.7 (-2.91 + 2.97) Mt of carbon, a value similar to that of the national inventory (Bradley et al, 2005). The thesis then considers the impact of drainage and degradation on carbon accumulation. Fifteen cores were dated from a drained, degraded site with a history of burning and control site using Spheroidal Carbonaceous Particles (SCPs) and radionuclide techniques. Previous studies have raised concern surrounding accuracy dating recent peats. Results indicate that although dating was largely successful, some discrepancies existed related to poor calibration of SCPs and mobility of radionuclides. To avoid error in dating, it was concluded that multiple dates should be used per core. With consideration of this, carbon accumulation was found to be active but significantly lower in the degraded site and unchanged in the drained site. Further analysis suggested that this outcome may vary with changing management and topographic situations. Future carbon accumulation at a landscape scale was calculated under different scenarios. This found degradation could potentially reduce carbon sequestration on Dartmoor by up to 32%. Economic valuation of accumulation values was used to demonstrate how this data could be used to inform management. This thesis provides an insight into the carbon storage and threats to Dartmoor, an under investigated, yet threatened blanket peatland environment. This helps broaden the spatial

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