A combined field, laboratory and modelling approach to the study of vegetated filter strips (VFSs) was carried out in order to provide guidance on optimum design and placement for trapping sediment from overland flow. Monitoring of fifteen established filter strips in the Parrett Catchment, England, informed on the complexity of intercepting flow pathways to optimise filter strip performance. Results suggest that a 6 m VFS will trap an average of 1.74 t year -1 of material from a field of 1 ha, but this is highly variable depending on design, placement and management factors. In most cases the majority of coarse sediment is trapped at the upslope edge of the VFS and is typically >85% sand. A revised Morgan-Morgan-Finney model was tested against a range of field and laboratory datasets and an efficiency coefficient of 0.7 was achieved. When testing the model against the field results from the Parrett Catchment, an active filter strip area was used. This took into account only the area of the filter strip effective in trapping sediment due to the convergence and bypassing of flow pathways. In the field, filter strip performance will be improved by reducing concentrated flow reaching the strip and ensuring that flow does not bypass the strip through burrows and gateways, using in field erosion control, maintaining level ground between the field and filter strip edge and managing the strip to maximise the density of vegetative material, particularly the number of vegetative stems. Potential applications for the research include a field based Decision Support System, design of filter strip biophysical architecture and catchment planning.

No description available.

Biological resources are particularly important in resource-limited countries where utilisation demands challenge conservation efforts. The study focussed on Berberis holstii, a plant resource on high demand in northern Malawi restricted to Nyika National Park. The uses, distribution, habitat characteristics, demography and seed germination requirements of this important species were investigated. Uses were investigated by means of ethnobotanical interviews. The species distribution in the park was mapped employing GIS. Habitats were characterised employing multivariate methods implemented in the programmes PC-ORD and PRIMER. Demographic studies employed matrix projections to characterise representative populations. Finally, laboratory germination trials allowed determination of light, cold stratification and temperature requirements for seed germination. Forty-seven uses were documented. Of these, thirty were medicinal and the rest for income generation. The most common uses included infusion for coughs, malaria, stomachache, sexually transmitted infections and pneumonia. Because roots are employed, whole plants are dug out. This lead to the extinction of five of the recorded 94 sites. Fire periodically kills the aerial part of plants, which then tend to recover through resprouting. The species is restricted to high altitude, open areas on sandy/loamy soils. Despite harvesting and fire, demographic projections showed positive population growth. Population growth rate is more sensitive to mortality of late juvenile stages and early adult stages than it is to demographic transitions and contributions by other stage classes. Germination was higher when seeds were stored for one year, had a prechilling treatment (cold stratification) and were germinated under light at -20°C. Seeds did not lose viability during two years of storage raising prospects for their artificial storage. The study provides important information for the conservation and management of this important African endemic. It highlights some of the difficulties confronted in projecting the population dynamics of species with sporadic simultaneous recruitment and tests the ability of a recently proposed model to determine germination requirements. In a wider context, the study shows that a combination of methodological approaches (ethnobotany, biogeography, demography and germination) allows a more complete understanding of the evolutionary, ecological and social factors that must be taken into account in the conservation of individual species.

No description available.

No description available.

Increased interest in native woodlands has exposed gaps in our knowledge of our native species. Aspen (Populus tremula L.), one such species, is of considerable conservation value though has been subject to very little previous research. It is widely distributed in Scotland at low density occupying a marginalised niche. Aspen is dioecious but reproduces mainly by asexual means and recruitment is reputed to occur only very rarely. Low population density , a marginal niche and an inability to colonise new sites renders the Scottish aspen resource potentially vulnerable to genetic erosion from natural and anthropogenic disturbance potentially compromising its long term future. Intervention is clearly required. Successful conservation management requires a thorough understanding of genetic structure at the national, regional and stand scale. The genetic structure of the Scottish native aspen resource was therefore investigated at the national, regional and stand scales using selectively neutral molecular markers. Isozyme analysis was used to estimate genetic variation and investigate population structure and genetic differentiation in six Scottish aspen populations. Eight systems, yielding eleven putative loci, were employed in screening 275 aspen samples. Genetic variation was shown to be greater than mean values obtained for species sharing similar characteristics and comparable with the homologous species P. tremuloides (Pp=54.5, Hep=0.174, Ap=2.00. Aes=0.121) suggesting that no significant loss of genetic variation has occurred. Some inbreeding was detected (f=0.153) and attributed to assortive mating between a small subset of clones retaining sexual function. A small but significant amount of structuring was detected (q 0.014) although UPMGA clustering of genetic identity (I) indicated little differentiation amongst populations providing little support of r a multiple origin hypothesis. It is concluded that the genetic structure in the present Scottish native aspen resource (SNAR) is little changed from the genetic structure in the SNAR when aspen ceased widespread flowering. The genetic structure of Tomnagowhan Wood, Strathspey, Scotland's largest aspen dominated woodland, was investigated using the same suite of markers. 186 aspen were samples, mapped and genotyped in an area of 4.6 ha. Twenty one clones were identified using a combination of isozyme analysis and probability theory. Clonal diversity in large aspen stands would appear much greater than is often asserted. A wide variety of clone sizes and strategies were also uncovered and leaf flushing date was shown to be an efficient phenotypic clonal marker. Analysis of the distribution of DBH suggests that aspen ramets flow a 'window of opportunity' mode of regeneration with the last burst of regeneration occurring around World War II in Tomnagowhan. Genotypic diversity in the small relict island apsen population of Orkney was estimated using the same suite of markers. Fifteen aspen locations were sampled. Multi-locus genotyping, probability theory and local knowledge were used to identify 12 independent clones. A review of the literature and legislation on the "safe" minimum number of clones to use in plantations suggests that the twelve Orkney aspen clones are sufficient to be safely used in the expansion of native woodland in Orkney thus enabling only locally derived stock to be used. The findings of the three surveys are discussed within an ecological and historical context providing a basis for recommendations for the future management and genetic conservation of the Scottish native aspen resource including guidelines on the conservation of the existing resources, expansion of the resource, the production and deployment of aspen planting stock and strategic initiatives.

The vegetation of Widdybank Fell, Upper Teesdale, was classified, mapped at 1:10,000 and (in parts) 1:2,500 and related to comparable British communities. The phytosociological role of the “Teesdale Assemblage” was also investigated. The methods of Zurich-Montpellier phytsociology were used. Field analysis was followed by a polythetic sub-division and linear ordination of the data. Thirty-six vegetation units or noda encompassing eleven alliances, and orders of eight classes were found. The complement of noda within each alliance was termed an ɤnodal group. The classes and alliances found are as follows: Class Asplenitea rupestris Festucco-Brometea Violetea calaminariae Molinio-Arrhenatheretea Montio-Cardaminetea Parvocaricetea Oxycocco-Sphagnetea Nardo-Callunetea Alliance Androsacion vandellii – siliceous rock crevice vegetation (Sub-all. Seslerio-Mesobromion – semi-dry calcareous grasslands Thlaspeion calamnaries – heavy metal mineheap vegetation Molinio-Arrhenatheretea Ranunculo-Anthoxanthion – sub-alpine pastures Montio-Cardaminetea Caricion davallianae – eu-trophic sedge-marsh Oxycocco-Sphagnetea Ericion tetralicis – damp heath Erico-Sphagion – ombregenous and raised bogs Nardo-Callunetea Violion caninae – rough grasslands Empetrion nigri - heaths.

Both nationally and globally, UK upland peat is an important store of carbon as well as a source of other important ecosystem services. However, concerns have been raised regarding the stability of these stores. Significant increases in water colour and dissolved organic carbon (DOC) from catchments draining upland peat have been observed across the UK. Unlike many boreal peats, the peat soils of UK uplands are heavily managed for sheep grazing and recreational shooting. Productivity of these landscapes has been increased through managed burning of the vegetation. Burning has been linked with increases in water colour and inappropriate burning can lead to ‘unfavourable’ conditions in these landscapes. This thesis presents the results from a monitoring programme at Moor House National Nature Reserve. Results show that burning does not lead to dramatic increases in DOC and that longer rotations may have benefits for carbon by reducing water colour. Increases in the occurrence and changes in the quality of runoff water following burning could help explain changes in water quality parameters such as DOC. Experimental studies into biomass loss during burning, combined with a survey of a wildfire, have shown that the production of char is an important carbon store that should be accounted for in fire prone upland settings. Modelling studies suggest that rotation lengths of 15 years are suitable for char production and that on these longer rotations char becomes a more important carbon store than any remaining unburnt biomass or litter. Therefore this work would suggest that longer rotations may have benefits for carbon storage and water quality. Longer rotations may be sustainable in some areas but that this is unlikely to be appropriate across the entire of the UK. The caveats to this work should always be presented and local knowledge be consulted when drawing up management plans.

The effect of pH, calcium and potassium on the performance of Carex flacca and C. panicea is investigated using tillers growing in solution culture. Performance is determined "by changes in fresh weight, dry weight, leaf length and the uptake of mineral nutrients into the plants. Possible age response is taken into consideration by using tillers of two different initial sizes and seeds, as starting material, No differential response due to initial age of the plant parts is detected, pH affects the final fresh and dry weights but not the relative concentrations of the elements present in the plant leaves, Above a certain external calcium concentration (about 50 p.p.m.) uptake of calcium by the plants greatly increases. Performance of both species increases with increase in external calcium concentration until the influx concentration is reached, and then it decreases, The germination and potassium variation experiments show that both species are very efficient in removing potassium from the culture solutions and maintaining a high internal concentration of this element, These observations could have important implications in natural plant communities. There is evidence to suggest that Carex flacca and C. panicea exhibit different responses to calcium and pH which could lead to different ecological tolerances. In a parallel study, the role of calcium and potassium in the nutrient dynamics of the two species is investigated over the two-year growing period. With progressive ageing, percentage potassium content decreases; total potassium increases over the first year, but falls sharply after flowering; both percentage and total calcium content increase steadily over the life span, but tend to decrease after fruiting, Analysis of different plant organs reveals considerable variation in the concentrations of calcium and potassium between adjacent parts of the same plant. There is evidence to suggest that calcium and potassium re-cycle in different ways. Potassium is probably being supplied to the next generation of tillers from the parent plant, either by absorption from the substrate, or by translocation from dying leaves, Calcium, on the other hand, has to be absorbed by the tillers themselves when they have established their own root system

The flora of Upper Teesdale contains a large number of "relict" species of disjunct geographical distribution. 'Why is this rich assemblage of species present in Teesdale. It was assumed that arctic alpine and other rare species, supposedly intolerant of competition, were able to survive in the face of lowered competition from typically lowland species. This study was designed to test this hypothesis by answering three questions: (i) What are the communities? (ii) What is their productivity (as a general measure of competition)? (iii) What are the reasons for this level of production? Initial analyses on Widdybank Fell indicated the importance of Limes convergens situations, sharp zones of biotic and abiotic transition, as key habitats for many of the rarities. Detailed phytosociological analyses of a grid matrix on Widdybank Fell, produced an optimum classification of vegetation units. These communities contained many rare species and the affinities of these units with continental phytosociologica groups was considered. The distribution of the quadrats of these communities on the grid was compared with abiotic variables. The productivity, in this context used as a general measure of competition, of those communities delimited in the phytosociological analyses and other sites was determined. A single species increment cropping technique was developed to determine the net annual aerial standing crop of the communities considered. A composite picture of community dynamics in terms of vertical biomass distribution, net annual aerial production and mineral flux was obtained. The rare species were found to be most common in the communities studied that were of low net annual aerial production, particularly those of less than 150 gm/m(^2)/per annum. The importance of grazing and climate in maintaining these low levels of production was emphasised by exclosure and cold frame experiments. Chemical analysis indicated the importance of the highly calcareous sugar limestone soils and indicated that high zinc levels appeared to coincide with low production.