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History of the <I>Pinus sylvestris </I>L. treeline at Creag Fhiaclach was investigated using a palynological approach. A modern pollen rain study demonstrated that the current treeline was detectable from a significant (p < 0.0001) reduction in the <I>Pinus/(Pinus </I>+ <I>Calluna vulgaris </I>(L.) Hull) pollen quotient. Heath vegetation typically has a P/(P + C) pollen quotient of less than 30%. Quotients higher than 30% represent <I>Pinus </I>woodland. A three year study on variation in <I>Calluna </I>flowering with altitude showed that the relative reduction in the <I>Pinus </I>pollen component at the treeline is caused primarily by changes in the density of <I>Calluna </I>flowering rather than <I>Pinus </I>pollen influx. The results have implications for the design of palynological studies, indicating the importance of replication, as well as aiding interpretation of fossil pollen data. Five replicate cores from six altitudes spanning the treeline were subjected to pollen analysis for the historical investigation. Twenty six palynomorphs including four Rhizopod taxa were described. Discriminant analysis was used in addition to quotients to classify the fossil pollen assemblages as either heath or forest types. The palynogical data were reduced using PCA and RDA and showed that a higher treeline may have been previously present at the more sheltered southern end of the treeline. However, an alternative hypothesis, of pollen assemblages similar to those of <I>Pinus </I>forest being produced by relatively infertile <I>Juniperus communis </I>L. canopies, was also tested by looking at the pollen spectra from transects across <I>Juniperus communis </I>patches. Dense patches of <I>Juniperus communis </I>result in pollen assemblages which cannot be distinguished from those of <I>Pinus sylvestris </I>woodland. <SUP>210</SUP>Pb and <SUP>14</SUP>C dates, while indicating stratigraphic validity, gave conflicting evidence for the ages of the peat deposit at Creag Fhiaclach. Evidence from dendrochronology on the site suggests that the <SUP>14</SUP>C dates are more correct and that the peat deposit dates from 1227-940 BP. A model of pollen distribution at the treeline on the basis of modern pollen deposition is proposed. The relative stability of this treeline poses interesting questions about how the treeline established and the inertia of this type of vegetation boundary to changes in climate.

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The cell cycle is the life of a cell from one mitotic division to the next. In yeast and animals the transition from G2 to mitosis is regulated by the Weel kinases and Cdc25 phosphatases. Phosphoregulation of G2/M is also maintained by 14-3-3 proteins, which function in a wide range of additional processes including signal transduction and stress responses. The scope of this thesis was to investigate how the plant G2/M checkpoint functions and how features of the yeast and animal G2/M model apply to the plant model. A better knowledge of the mechanisms that regulate AtCDC25 and AtWEEl activities was achieved by identifying interaction partners for the two proteins. Both proteins interact with proteins involved in protein biosynthesis, cell division and plant stress responses leading to many hypotheses about the localization, regulation and function of both AtCDC25 and AtWEEl. Moreover, AtWEEl interacts with proteins involved in ubiquitin-mediated degradation, which might be the mechanism regulating WEE1 protein levels (Chapter 4). Additionally, AtWEEl interacts with 14-3-3 proteins and its interaction with 14-3-3 was confirmed in vivo in plant cells (Chapter 5). Furthermore, greater insights into the role of WEE 1 in cell cycle regulation and plant development were obtained by investigation of the biochemistry of <italic>N. tabacum</italic> WEE1 during the cell cycle of synchronized <italic>N. tabacum</italic> BY-2 cells showing that both WEE1 protein level and kinase activity are sensitive indicators for the timing of mitosis (Chapter 6). Moreover, <italic>A. thaliana </italic> weel T-DNA insertion lines were characterized Under standard growth conditions the T-DNA insertions in the WEE1 gene only mildly affect the plant root development. However, exposure to hydroxyurea results in a hypersensitivity response leading to a reduced primary root length and decreased rate of lateral root production linking AtWEEl with both stress responses and plant development (Chapter 7).

The importance of fluvial dissection in upland blanket peat erosion is well-established but knowledge of the significance of peatland gully system development is limited. This thesis investigates the stability of upland blanket peat in relation to recent re-vegetation and historical erosion of peatland gully systems. It combines regional morphological surveys in a GIS framework with detailed field and laboratory analyses. Detailed research was carried out at three study areas across Northern England: The Cheviot (Northumberland), Moor House (North Pennines) and Wessenden Head Moss (Southern Pennines). A regional-scale investigation into gully development at the three sites demonstrated that the end members (Type 1 and Type 2 dissection) in Bower's 1960 classification of dissection types could be identified but a revised dissection classification including a third category of anastomosing dissection was needed. Regional variations in erosion and gully form were observed. The most extensive aerial erosion was on The Cheviot (80 %) and least at Moor House (48 %). Re-vegetation was most well-established at Moor House (80 % of the eroded peat) and least on Wessenden Head Moss (45 % of the eroded peat). The local topography of each site was the key in explaining erosion patterns. Linear dissection dominated on steeply sloping ground and anastomosing dissection on gentle sloping summit areas. Dendritic dissection occurred on intermediate slopes. Approximate slope angles for the dentritic transitional zone vary in relation to the local topography; however, the means for the three study sites are 3.7 (Moor House), 4.9 (The Cheviot) and 1.4 (Wessenden Head Moss).Local-scale variations in erosion were observed on the interfluves and within existing gully systems. On the interfluves peat accumulation rates were estimated from Spheroidal Carbonaceous Particle deposition. Average rates were 0.5 mm yr( -1) under moorland grass and 1.2 mm yr( -1) under heather. Erosion potential of these sites was estimated from rainfall simulation experiments. The potential for erosion was high (243 t km( -2), 0.243 mm yr( -1)), though not atypical of local directly measured erosion rates. However, experimental results showed that sediment production rarely occurred below a rainfall intensity of 12 mm hr( -1) (high intensity for the Pennines) and with a presence of an intact vegetation cover sediment is only locally entrained and re-deposited and actual erosion under current climatic conditions is likely to be low. The onset of peat erosion was estimated by comparing eroded and uneroded cores. It is thought the most recent phase of erosion resulted from climatic change and land management and occurred some 570 years ago on Wessenden Head Moss and between 300 - 330 years ago at Moor House and on The Cheviot. Over the last approximate 50- years, infilling and re-vegetation of the bases of gully systems has been observed. The peat within the gully stratigraphy appears to be eroded, re-deposited or grown in situ. The future of upland blanket peat will likely involve further stabilisation of the gully systems; however, in severely eroded areas where the peat is totally stripped and surface hydrological regime destroyed, the peat will not recover.

The peat deposits of a limited area of the North Yorkshire Moors were studied through pollen analysis and associated techniques. The aim of the project was to provide details about the inception of peat growth and man's effect on the vegetation of the area throughout time. Altogether thirteen sites were examined and pollen diagrams constructed from the results. The pollen diagrams gave an outline of the conditions which prevailed on the North Yorkshire Moors from about 6000 years B.P. up to the present day, and showed that the influence of man on the vegetation of the area was very marked. The active removal of woodland by man is seen in three major phases which have been tentatively assigned to the cultural periods of the Neolithic, Bronze Age and Mediaeval. In addition to these three phases, burning of the vegetation appears to have taken place continuously on the upland areas of the moors from the start of peat accumulation. From this it is suggested that man played a part in the formation of the upland peat deposits, although probably only in the role of assisting in the degradation of an already 'poor’ environment. The effects of man, which are so clearly reflected in the pollen diagrams of the present study, appear to rule out the possibility of widespread climatically induced vegetation changes for most of the period under examination. It is concluded that while a great deal of new information on the historical ecology of the area has been revealed a great many gaps in knowledge still remain. However, the study provides for a better understanding of an environment created by man through many thousands of years of mis/use, and this information may assist in the formulation of an appropriate conservation policy for the future.

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mechanisms such as Payments for Ecosystem Services (PES). Whilst the rising importance of these has attracted much comment by observers of conservation, there is little empirical research on how ecosystem services concepts are being adopted. Meanwhile, the recent emergence of empirical literature on PES implementation opens up space to inform the development of this policy mechanism. This thesis adopts a critical social science perspective to pursue two empirical aims: firstly, to investigate the discourses surrounding ecosystem services concepts and the policy implications of the adoption of these by tropical forest conservation interest groups; and secondly, to investigate the practical implementation of key innovations of PES. To investigate policy and practice in this way, the thesis adopts a multi-scale research design, encompassing a policy level study and a case study of a PES project. At the policy level the sample includes a comprehensive range of non-governmental organizations, representing conservation or tropical forest people's interests. Q Methodology, a statistically supported tool for discourse analysis was used to identify the discourses, and more conventional qualitative research used to explore them in detail. A case study research design allowed the depth required to respond to calls for qualitative research on the practice of PES. The case study focuses on an afforestation PES scheme in western Uganda, in which people are paid through voluntary carbon markets to plant trees on private lands nearby forest reserves. This case is particularly interesting because it closely matches theoretical tenets of PES, with relatively strong conditionality and the use of monetary incentives. The discursive analysis is used to identify three particular interpretations of ecosystem services concepts and associated policy mechanisms. These distinct discourses are manifest in vibrant debates around utilitarian and intrinsic natural value, and the use of economic valuation and market instruments. As well as these discursive changes in the arguments they make for nature, organisations also undertake more practical changes in their partnerships and funding, and some display shifts in objectives towards ecosystem services. Furthermore, the practice of many organisations is changing through the adoption of PES. This is driven by an instrumental motivation, the expectation that PES will deliver sustainable finance. However, this expectation is often accompanied by concerns about PES; conditionality is often regarded to be unfeasible in practice and many practitioners are reluctant to use direct payments. The case study is used to interrogate the practice of these innovative aspects of PES. The use of conditional mechanisms has a number of implications. In particular, a focus on monitoring tends to inhibit the development of a shared understanding of the project rationale. Conditionality also tends to prioritise those able to secure ecosystem services, for instance through land ownership, and hence may not support distributional equity objectives. Livelihood adaptability is also a concern under long conditional agreements associated with carbon. Furthermore, there are indications that the use of individual contracts does not foster cooperative action. The thesis also investigates the use of direct payments, in particular to understand where payments feature in relation to participants' other motivations for involvement, and how payments interact with environmental values. Empirical results are used to engage with a question in the literature about the temporal sustainability of a payments approach, and whether payments foster a 'no pay, no care' environmental ethic. The thesis concludes by discussing the uptake of ecosystem services and PES mechanisms in conservation. It questions whether a transition 'from metaphor to science' can be observed in the use of ecosystem services, and furthermore, how these trends might be understood in relation to broader developments including neoliberalism. Overall, the thesis questions the tendency to present ecosystem services as simply a rhetorical tool, as these concepts and associated policy mechanisms have fundamental implications for the priorities and practice of conservation, in particular the way in which local people are engaged