No description available.

Since shortly after the formation of the Forestry Commission, experimental plantations have been made on the worst types of deep peat, and the best of these now form stands up to 35 feet high. With the development of mechanical methods of ground preparation and the use of phosphatic fertilizers, the afforestation of poor quality deep peat has been shown to be a practical possibility. The object of the present investigation has been to study the changes that have taken place in the peat as a result of 30 years tree growth, and hence to determine whether further mineral fertilization, or modification of ground preparation techniques and silvicultural treatment will be necessary in the future, and whether there is any evidence which would render inadvisable the large scale afforestation of deep peat in the west and north-west of Scotland.

Agriculture, forestry, and heather management --- insofar as it relates to sporting and grazing purposes --- are the major means of obtaining economic returns from plant production in upland areas of North-East Scotland, The conflicting interests of these forms of land-use have often led to bitter altercations over the choice of crop to be planted on particular areas of land. Some well-publicised cases have occurred in North-East Scotland where reportedly sound agricultural land has been afforested. It seems likely that the lack of sound, objective research into site classification is a contributory factor to these arguments over land-use. During the last decade, research on land capability has been carried out to provide objective information on multiple uses of upland, based On experimental knowledge of site potential. In 1965, the Soil Science Department at Aberdeen initiated a pilot scheme at Strathdon, West Aberdeenshire, for the study of land-use in the North-East, The final aim of this scheme is to provide a land capability map for the area founded on an objective basis, Adu (196S) and Cook (1971) have investigated the growth of Scots pine within the area, and complementary to this Beavington (1967) and Jones (1971) studied grass production. Thus, work has progressed on grasslands and forests, but the third major upland vegetation type of the area, namely heather moorland, has received scant attention. Research on heather in Scotland has been concerned principally with its nutritional value for hill sheep and grouse (e,g, Moss, 1969; Thomas, 1956), The boundary between forest plantations and heather moorland is determined as much by the whims of land owners, and the position of estate boundaries as by ecological factors such as exposure to wind. Thus many areas of moorland are capable of afforestation. The area of land at lower altitudes likely to become available for forestry is. becoming increasingly limited, so that forester are being forced to plant at higher altitudes, where the soils and climate are unfavourable fox' agricultural purposes, except for extensive rough grazing. Trial plantations at high elevations are long term projects because of the age trees take to come to maturity. However, it was thought that possibly the performances of the heather at present growing on these upland areas could give some insight into the potential for the growth of Scots pine. The aim of this study, therefore, is to see whether the growth of heather could be used to assess site potential for Scots pine. Towards this aim, there were four main stages to the research a) to assess the effects of various soil, site and climatic factors on the growth of Scots pine b) to carry out a similar investigation for heather within the same areas of study c) from a comparison of the results from (a) and (b) to assess the extent to which the growth of the two species is limited by the same factors d) from (c) to evaluate the use of heather growth to predict site potential for Scots pines.

In view of the taxonomic state of the genus Betula in Europe in general and in Britain in particular, it was felt that a detailed cytological study of a population of Betula might contribute to a better understanding of the taxonomic and evolutionary status of Betula. The study areas were located in the north-east of Scotland. The Glen Gairn area contained a mixed stand Betula pendula and Betula pubescens types together with intermediate forms. The second area near Braemar was formed of an apparently pure stand of B.pubescens. This study had three main objects, firstly to study the pattern of meiosis in B. pendula and B. pubescens. Secondly to survey the chromosome complements of randomly selected individxiivis in the population and to determine whether or not there were intermediate trees with 2n = 42 chromosomes, and thirdly, to determine whether trees with 2n = 42 chromosomes were of allotriploid or autotriploid origin. In order to achieve the above objectives four lines of investigation were followed. The first was to examine the appearance of chromosomes during meiosis in pollen mother cells, the second line of approach was to study chromosome behaviour of all stages of meiosis in both B. pendula and B. pubescens catkins and the third entailed counting somatic chromosome numbers in cells of leaf base squashes,the fourth method of approach was to Investigate the meiotic division, male and female fertility and morphological characteristics of the trees with intermediate chromosome numbers.

No description available.

The project was designed to study genetic variation in species of tropical rainforest trees. Shorea leprosula (an emergent species) and Xerospermum intermedium (an understorey species) were chosen, to see if they differed in breeding patterns. Genetic variation was studied by measurement of isozyme differences and also morphological variation. The isozyme patterns of 10 species of Shorea were compared with the indices of morphological similarity. The provisional estimate for proportion of polymorphic loci works out at 0.5--0.6 for Shorea leprosula, a high figure, and 0.3 for Xerospernrum intermedium. Both species are outbreeders. For Shorea leprosula, there is strong indication of spatial heterogeneity in isozyme frequency together with evidence that genetic similarity between populations is inversely related to the distance which separates them. In Xerospermum intermedium, variation in leaf size and morphology between individuals is highly significant and there is a distinct tendency for trees growing together to be more alike. Since both species are out breeders, this degree of spatial heterogeneity was unanticipated. It implies interruption of free gene exchange and this may help us to account for the origin of the great species diversity in the rainforest. Comparative isolation of populations, the means of fruit dispersal, the means of pollen distribution and possibly also the pattern of flowering time may jointly contribute to relative isolation. It appears that one of the major enigmas of evolution is at last accessible to systematic study.

The annual organic matter production and cycling of mineral nutrients are compared in two birchwood ecosystems in north-east Scotland. One is a pure stand of Betula pendula. at an altitude of 300 feet; the other an almost pure stand of B. pubescens subsp. odorata. at an altitude of 950 feet. Both stands are about fifty years old. The total above-ground tree biomass of the B. pendula stand (123 x 10³ kg ha⁻¹) is much greater than that of the B. odorata stand (78 x 10³ kg ha⁻¹), hut the biomass of twigs is similar in the two stands, B. odorata carries a greater biomass of leaves, having a much denser canopy than B. pendula. In 1971 about 20% of the B. pendula leaves were apparently removed from the site by high winds: this is a significant drain of nutrients from the site. That this does not occur in the B. odorata stand is probably due to the more bushy growth form of the trees, which is not prone to losses of leaves by wind, and acts as an efficient trap for wind-blown leaves. Annual death of perennial parts is greater in B. pendula than in B. odorata, but annual non-perennial part litter production is greater in B. odorata. Total annual above-ground production of the trees is similar in the two stands (just under 11 x 10³ kg ha⁻¹), but the production per gram of leaves is 6.0 g in the B. pendula and only 4.4 g in the B. odorata. The annual above-ground production of the ground vegetation accounts for 16% of the total above-ground production in the B. pendula stand, but only 10% in the B. odorata stand. Both stands utilise about 3% of the photosynthetically active radiation energy received during the growing season in their organic matter production. A new mathematical model of twig growth and death was used in the calculation of the seasonal biomass of twigs, buds, leaves and catkins. It gave results which were consistent with other observations, including measurement of litter fail. Annual uptake, and return in litter and rainwater, of N, P, K, Ga and Mg are greater in the B. odorata than in the B. pendula stand, not only as a result of the greater biomass of nutrient-rich non-perennial parts, but also because of higher nutrient concentrations in the B. odorata. Rainfall percolating through the canopy contains a significant proportion of the annual return of nutrients (particularly K) to the forest floor. Minor components of the litter are also of considerable importance in this respect, especially in the return of P. A very large proportion of the annual uptake of nutrients is recycled: over 95% of the K uptake (hut only 84% of the Ca uptake) returning annually to the floor of the B. odorata stand. One year after litter fall, virtually all the P, K and Mg in the leaves has been incorporated into the soil by decomposition. Almost all the differences between the stands outlined above result from the contrasting growth forms of the two species. Water and light penetration, temperature and relative humidity, and production and floristics of the ground vegetation are among the other features of birchwood ecology influenced by growth form of the trees. Branching pattern (which generates growth form) was analysed using a simple mathematical model, and the more open canopy of B. pendula was shown to result from greater twig and branch death rather than less profuse branch production. The results of the project are discussed with reference to the distinct geographical and ecological ranges of the two species. The theory is advanced that B. odorata is adapted to the cooler climate and shorter growing season of higher altitude by a greater leaf production (permitted by greater longevity of its branches) and to nutrient-poor soils by a capacity to take up a greater proportion of the available nutrients than B. pendula.

Sitka spruce, Picea sitchensis (Bong.), Carr, has attained a a position in British forestry unrivalled by any other exotic species and as a consequence has been planted on an increasingly wider range of sites. However, where Calluna vulgaris is a major component of the vegetation young spruce trees often show the condition known as 'check' in which growth is slow and the foliage short and yellow. Various techniques for alleviating this condition have been tried with some success but the mechanism of 'check' remains unknown at present. In Durris Forest, Aberdeenshire, Calluna heathland inter-spersed with grassy flushes is planted with young Sitka spruce which show considerable variation in growth from healthy to the 'checked' condition. Experimental plots were established on 8 sites differ-ing in elevation and vegetation and studies were made of the sites and the trees growing upon them. The results suggest that exposure to wind depresses the growth of young trees more strongly than had been previously realised. The species composition of the vegetation was found to be a useful indicator of the future growth of young Sitka spruce. Growth was poorer on sites dominated by Calluna where the peat was found to be lower in nitrogen, phosphorus and potassium, had a higher moisture content, lower air content and greater depth than that obtained from comparable sites dominated by grasses where tree growth was consistently better. At a given elevation and aspect the differ-ences and similarities in dry matter production of the trees could be satisfactorily explained by careful assessment of the compo-sition of the vegetation.

First, the thesis investigates the interrelationships between the forestry sector and other components of the rural economy, through the application of the Generation of Regional Input-Output Tables (GRIT) technique to the estimation of an input-output table for the rural areas of Scotland. This is followed by a forestry-centred multiplier analysis. Second, the thesis considers the implications of alternative forestry development scenarios in Scotland over the next several decades for land use, timber production and processing, agriculture, and rural employment. Six alternative afforestation scenarios ranging from 'no further planting' to 'accelerated expansion' are defined, including 'lowland' and 'green forestry', and a 'most-likely' scenario. This analysis is carried out through a simulation model which is built on a spreadsheet, and consists of base-period data and parameters, followed by successive projected decade blocks. Taking account of labour productivity trends in both forestry and agriculture, scenario-specific calculations produce future values of forest area, wood output, transfer of farmland, displaced agricultural employment, and forest employment created. A distinction is drawn between current (decade-specific) and accumulated (rotation-specific) forest jobs created on transferred agricultural land and existing forest areas. In this way, the future implications of different assumptions as to future forestry policy are produced. Finally, scenario-specific projections for the year 2050 concerning new planting area and total wood production are converted into gross input value estimates for the Forestry Planting and Harvesting sectors. Alternative assumptions which represent extremes of correspondence between the domestic Forestry and Wood Processing sectors yield new levels of gross national (Scottish) output. The adjustment of the national input-output tables is then followed by their regionalisation through the application of GRIT and the estimation of scenario-specific regional direct, indirect and induced output, income and employment effects.

The rapid growth of Lusaka, to a population of around 1 million by the early 1990s, has generated considerable pressure on hinterland resources. Amongst others, there is a high demand for wood as the majority of Lusaka's population rely on charcoal for their domestic energy. It is estimated in this study that at least 150 km2 of indigenous woodlands are currently cleared annually to meet this need. The bulk of this woodfuel production is unlicensed and uncontrolled but accurate data on its location and the resulting deforestation do not exist. Airborne remote sensing and ground data were used to assess woodland status and land cover change in twelve Sample Areas at varying distances from the city. The results show that, although woodlands seem to be generally degraded in the Lusaka area, they also have a considerable capacity for regeneration under suitable conditions. In addition, deforestation around Lusaka has not followed the radial pattern common to many Third World cities; the land tenure system in place adjacent to the city has been effective in maintaining a fairly large proportion of woodland cover in this area. As a result, the bulk of the woodfuel production is taking place on more remote, largely unalienated land. Satellite data may be an appropriate source of information for monitoring these, and other, extensive deforestation activities. Promising results were obtained in a preliminary assessment of the woodland information available form the visual interpretation of Landsat MSS imagery.