Acid soil infertility has been associated with excess of Al, either Mn toxicity or deficiency, deficiencies or toxicities of one or more other trace elements, or deficiencies of certain major nutrients such as Ca, Mg, P and K. Studies on the influences of these factors on the tree growth are useful in identifying the mechanisms and the genetic sources of tolerance to acid soil. A series of five culture experiments, under controlled conditions, were carried out using Greek and British Scots (Pinus sylvestris L.) seedlings as well as black pine seedlings of Greek (Pinus nigra Arnold var. nigricans Host) and 'British' (Pinus nigra var. maritima (Ait.) Melville) origin. Nine major and trace elements (N, P, K, Ca, Mg, Fe, Mn, Zn and Cu) were determined in the growth components of pine seedlings. The Mn and Ca requirements of the pine seedlings of all growth components were assessed. Foliar values found for the Mn (ppm) and Ca (%) concentrations associated with 90% of maximum yield were: a) Greek-derived Scots pine: Mn 84-855 and Ca 0.34-1.00, b) British-derived Scots pine: Mn 77-1,450 and Ca 0.43-0.87, c) Austrian pine: Mn *-2,100 and Ca 0.27-*, and d) Corsican pine: Mn *-1,400 and Ca 0.30-0.73 (* denotes not estimated). The results suggested that under conditions of low Ca availability, excessive Mn uptake could result in toxicity in Greek pines and the feed solution Ca/Mn concentration ratio is an important factor in determining the ability of British pines to tolerate adverse Mn conditions. The relative tolerance of Corsican pine to Mn toxicity is related both to immobilisation of Mn in roots by increased Ca uptake, particularly at low solution Ca availability, and to inhibition of Mn translocation from roots to the foliage, while that of British P.sylvestris is associated to its ability to withstand high Mn concentration in shoots. The characteristic nutritional behaviour of Corsican pine (exclusion of some essential elements from the foliage) appeared to be partly responsible for the induced Mg and Fe deficiencies by excess Mn availability. Furthermore, the adverse influence of increasing solution Mn availability on Ca concentration of pine seedlings is dependent on the availability of Ca in the nutrient solution, on the component part analysed, on the genotype and on the experimental conditions. The presence of two absorption mechanisms for Mn and a close functional relationship between Ca and Mn in foliage of seedlings is suggested.

Investigations have been carried out into the effects of nitrate and ammonium on: the growth dynamics of mycor-rhizal fungi, the relative infection success of these fungi when associated with Douglas-fir and Sitka spruce seedlings, and the growth and nitrogen uptake by mycorrhizal and non-mycorrhizal seedlings. Fungal isolates were obtained from sporocarps collected in Douglas-fir or Sitka spruce stands. On the basis of growth rate and nitrogen utilisation patterns, Paxillus involutus and Lactarius rufus were chosen for further study. Both fungi were capable of rapid growth; but while P. involutus grew equally well when either ammonium or nitrate was supplied, L. rufus could only utilise ammonium. In aseptic culture with seedlings of Douglas-fir or Sitka spruce, both fungi readily formed ectotrophic mycorrhizas. These experiments were carried out in Erlenmeyer flasks. Although pure cultures of P. involutus grew well when either nitrate or ammonium was the nitrogen source, those supplied ammonium were always the heaviest. However, when the calculated energy cost of nitrate reduction was deducted from the ammonium cultures, the weights of nitrate and ammonium cultures became nearly identical. Furthermore, nitrogen form had no effect on the growth rate of P. involutus cultures. When the quantity of glucose supplied was increased from 0.5 g/1-1 to 2.0 g/1-1 , the culture weight increased proportionally, but increasing the glucose to 4.0 g/1-1 brought about a less than proportional weight gain. Regardless of original nitrogen form, or amount of glucose supplied, whenever P. involutus cultures entered the senescent phase of growth ammonium was released into the nutrient solution. In pure culture L. rufus grew well when ammonium was supplied, but was completely unable to utilise nitrate. Increasing the amount of glucose supplied brought about less than proportional increases in the weight of the colony, with the least glucose producing the greatest relative weight. Lactarius rufus never released nitrogen during the senescent phase of growth. The three previously mentioned mycorrhizal conditions (inoculated with P. involutus or L. rufus, or uninoculated) were factorially combined with nitrate and ammonium in a series of experiments that used Douglas-fir and Sitka spruce seedlings. Unlike the initial synthesis testing, these experiments used an improved culture unit that allowed the frequent replenishment of water and nutrient supplies. Sitka spruce was used in the first experiment. As expected the P. involutus/ammonium and the L. rufus/ammonium treatments formed abundant mycorrhizas (72.3% and 70.5% respectively). In contrast when nitrate was the nitrogen source, L. rufus formed no mycorrhizas and P. involutus infected only 6.4% of the short roots. Plants supplied ammonium produced more dry matter than those given nitrate, with the uninoculated plants being larger than either of the mycor-rhizal treatments. In the second experiment, the amount of nutrient was reduced by 80% and Douglas-fir seedlings were used. The same general patterns of growth and mycor-rhiza infection seen in the first experiment were repeated. Leaks in the culture units used in the first two experiments made the nitrogen uptake data unusable. In the third experiment, Sitka spruce seedlings were grown with the same reduced amount of nutrient as the plants in the second experiment. The same pattern of mycorrhizal infection was repeated, but unlike the other experiments the various treatments within the ammonium treatment were not statistically different. Although nitrogen uptake was similar among the different treatments within the nitrate group, mycorrhizal infection increased ammonium uptake. This increase resulted in a higher nitrogen content in the roots. The exact role of nitrate in the disruption of mycorrhizas was examined by alternating from ammonium to nitrate (and vice versa) and by adding root exudates and macerates to pure cultures of P. involutus and L. rufus. When the nitrogen supply was changed from nitrate to ammonium, the rate of formation of P. involutus mycorrhizas was apparently increased. However, when the nitrogen supply was changed from ammonium to nitrate the mycorrhizas already formed became unstable. In the case of the L. rufus and ammonium then nitrate treatment, the metabolism of the entire plant was apparently effected by the nitrogen form change. In contrast to work by others, the exudates and macerates did not stimulate or retard the growth of L. rufus or P. involutus.

Aspects of natural regeneration were studied in the native Scots pinewood of Glentanar near Aboyne in Aberdeenshire during 1978 and 1979. Quantities of seed produced, the time and distance of seed dispersal, and germination capacity and energy of the seed, were assessed in the laboratory and the forest. In characteristics of different seed beds litter, mineral soil, humus and mixtures of these were examined and mixtures of humus and mineral soil were most favourable to seed germination and early survival of seedlings. The group shelterwood system of germination was compared with uniform shelterwood. The former appeared more favourable to Scots pine regeneration at Glentanar.

This study of the adoption of farm level forestry in one eastern Indian state, Orissa, focused on the above issue. 428 farm owners, both tree planters and non planters from 24 villages in two districts were interviewed with a questionnaire and household level data on socio-economic resources, tree products demand and their attitude towards forestry were collected. Descriptive statistical analysis was employed to identify factors influencing the decision of farmers to adopt/reject tree growing on farm. The social status, progressiveness of the households, and participation in village organisations were the important variables on social aspects, whereas land, credit, agricultural production and livestock ownership on the economic front were seen to be affecting householders decisions. Household supply of labour, land tenancy and family structure did not have a relationship with farm decision to adopt. Result of Chi-square and Spearman test indicated the land ownership to be positively correlated with most social and economic variables, but having little effect on demand for biofuels. The result of the cross tabulation between participation and householders interaction with extension agents, mass media and awareness about social forestry established that dissemination across socio-economic groups was influenced by communication factors rather than household demands of firewood or timber. There was no distinct difference in the attitude of tree planters and non-planters towards the forestry problems. The stepwise discriminant analysis resulted in prediction models of agroforestry adoption. The social and economic models based on selected variables were able to classify about 66% and 64% of the cases, whereas the communication factors successfully distinguished 74% of planters and non planters. The integrated model resulted in a prediction rate of 90%. The parameters estimated from the discrimination function showed the relative impact of the determinants in identifying adopter and non adopter. The variance in the production of the major crop, paddy, was higher for the tree planter which might have motivated them to grow trees to reduce uncertainty in the farm production.

The location of cones in crowns of grafts and mature planted tress was studied in detail and relationships between cone type and shoot characteristics were investigated. The results enabled a regression model to be developed to relate cone counts in certain crown zones to overall cone bearing. It was demonstrated that there are patterns of cone production in the crowns of <I>Picea sitchensis. </I>Preferred zones for female bearing are high in the tree. Male cones tend to occur lower in the tree and more proximal to the stem than female cones. As total female cone production increases, cones are borne progressively further down the tree and towards the main stem. In all cases there were shoots that remained vegetative, regardless of total cone bearing. There were also interactions between the type of cone and the nature of the bearing shoot. On lower order shoots both male and female cones tended to be borne in the proximal lateral position. On progressively weaker shoots there is a tendency for cones to be borne in progressively more distal positions. The same progress of cone bearing - from proximal to distal positions - occurred on shoots of decreasing size. On forest trees the vast majority of cones are borne on trees of above average dimensions. Of the three measured variables (height, dbh and crown depth) height appeared to be the most important in influencing cone production. Prognostic tree and stand models were developed which were quite successful in predicting cone production in forest stands, particularly at low or zero levels of bearing. The presence of female cones on the bearing shoots affected both the development of more proximal buds on that shoot and the characteristics of offspring shoots. Offspring shoots on bearing parents were smaller and tended to bear fewer needles. The effect on the number of buds formed was not conclusive.

The spatial pattern of state afforestation in the Republic of Ireland is fragmented and dispersed. The aim of this work is to discover how significant are the economic effects of this pattern, with a particular view to seeing whether there are implications for future land acquisition policy. The forests of County Wicklow (the county with the longest history and the highest percentage area of state forestry) are examined as a test case using methods drawn from quantitative geography and from forestry. Most land for state afforestation is acquired by buying holdings no longer required in agriculture. The fragmented forest pattern has thus resulted from the fragmented pattern of private land ownership. Holdings are particularly small on poor agricultural land and in addition most unimproved lands are owned as commonage. These factors, and the determination of most owners to retain their lands even if they are not using them, make the assembly of state forest land a slow and difficult process. The evolution and the structure of the forest pattern in Wicklow are described quantitatively, the pattern being examined both as a whole and in terms of its component parts. It is found that site productivity is highest in the most fragmented forests. It is also found that there is a continuing trend towards consolidation. An economic model is then constructed and applied to the different forest patterns in order to compare their relative levels of economic efficiency. Results of these analyses confirm the greater cost of running a fragmented as opposed to a consolidated forest but also show that when, as is usually the case, site productivity, is higher in fragmented forests then the resulting higher revenues will more than offset the increased running costs. In other words, site productivity has a stronger influence on forest economics than has the spatial pattern. The concluding recommendation is that an accompanying high degree of fragmentation should not usually deter the state from giving preference to better sites when acquiring land. This course will be more profitable even in the short term and in the long term the trend towards consolidation, provided every effort is made to ensure that it is maintained, will help to alleviate the disadvantages of fragmentation.

Bamboo growing is strongly associated with farm size (landholding), wealth, household size, food sufficiency, irrigation facility, livestock owned, land tenure, household off-farm and on-farm incomes, physiography of the land, and access to forests. The landholding is the most important socioeconomic factor that influences households decision to grow bamboos. Bamboo growing also varies with ethnicity as socially and economically disadvantaged ethnic groups are less likely to grow bamboos on farmland than other ethnic groups. The literacy and age of the household heads are not strongly associated with bamboo growing on the farmland. Bamboo is the most commonly planted species in villages in the Midhills. They are the preferred species for planting, both on private land and in community forests. As timber is getting scarce, bamboo is increasingly used as a replacement for timber. They are also the best fodder species (particularly Bambusa nutans) in the Terai and the fifth best in the Midhills. The interest in bamboo planting is particularly high where there is better access to the markets and bamboos have already been identified as one of the important species for use in income generation programmes. There are many taboos, superstitions and beliefs, particularly in eastern Terai, against bamboo planting which prohibit households from further bamboo planting. Had there not been such beliefs, there could have been more bamboos on the farmlands of eastern Terai and Midhills than at present. Bamboo is also one of the most remarkable woody perennials in eastern Nepal. There are many households, both in the Terai and the Midhills, who are dependent on the income from bamboo craftmaking. Most of the traders are newcomers with lack of resources to expand the trade. Many bamboo growers who sold bamboos, craft makers and traders were not happy with their income and suggested various steps for improvement. There is also a need to review many of the HMGN policies as many of them contradict each other and are therefore unfavourable towards stimulating the growing of bamboos in Nepal. It is clear that a detailed development plan to improve the use of bamboo resources is needed. Socioeconomic research on bamboos should be extended to other regions of Nepal in order to inform the new development plan.

Ancient semi-natural oakwoods have never been as intensively studied in Scotland as they have in England and Wales. The aim of this study was to assess the structure and regeneration status of a range of oakwoods throughout Scotland concentrating specifically on the effects of disturbance factors such as grazing regime and canopy gap size on the natural regeneration of oak (Quercus petraea (Matt.) Liebl. and Quercus robur L.). Specific factors affecting the natural regeneration of oak, such as seed predation, seed-bed treatment, insect herbivory, and competition from established ground vegetation were investigated by field experiments. It was found that all these factors contributed in some way to the failure of oak regeneration within the oakwood environment. Oak regeneration was only successful in open conditions such as Calluna vulgaris L. heath. The implications of these findings for oakwood management are discussed.

The consequences of using low stocking density as a management tool to increase individual tree growth rate of silver birch, and thereby shorten rotation length, were investigated. Low stocking density was found to result in greater diameter and basal area increment but may also result in trees with larger branches, a shorter length of clear bole, and possibly a reduced total height. The rapid growth had little effect on wood properties. Grain angle was unaffected, longitudinal shrinkage increased slightly, but conversely transverse and volumetric shrinkage declined. Density was not affected directly, but the increased proportion of juvenile wood in rapidly grown trees was estimated to result in a 5% reduction in density compared with conventionally managed trees. While fast growth resulted in only a slight decline in the strength and stiffness of <I>small clear</I> wood specimens, a reduction of about 30% in these properties was found for <I>large</I> beams. This reduction in strength was correlated with high knot and grain angle values for the timber. Modulus of rupture was found to be correlated with modulus of elasticity for both small clear specimens and for beams, suggesting the possibility of machine stress grading of birch. Hardness was generally unaffected by growth rate. All the timber tested was suitable for typical domestic flooring. The use of low stocking density to reduce rotation lengths therefore appears to be technically feasible, allowing the production of 30 cm trees in as little as 40 years, although an economic appraisal of the practice was not performed. If, however, knot free timber is required then pruning will be necessary to remove the large branches that otherwise would persist on widely spaced trees. Following the removal of branches, rapid occlusion of branch scars can be expected and the production of a large volume of clear timber.

LANDSAT-Data show that, despite the ban on all forest activities in the Dominican Republic, an accelerating rate of deforestation is taking place. To date no study investigating the political and socio-economic aspects of 'conventional forest management' (timber production) has been carried out resulting in a total lack of knowledge concerning forest management and its constraints. The present study attempts to measure the impact of an existing natural pine forest management project on forest dwellers' living standards and on employment in the small-scale timber-processing industry of rural areas. A tentatitive assessment of the impact of forestry and forest industry on employment at a nation-wide scale was also attempted. Non-parametrical statistics were used to measure the impact of the project by comparing the results of a survey of project-beneficiaries with results from non-beneficiaries of a Project and a Control area. The results indicate that the project had certain positive effects on the living standards of the beneficiaries in terms of employment and income. The impact, however, was not strong enough to cause a significant difference compared with the living standards of non-beneficiaries. Results also indicate that other important factors such as ownership of land and agricultural and forest activities were not influenced at all or even negatively. It is recommended that socio-economic studies should be carried out before projects are planned and implemented in order to take account of the needs of 'target groups' and to achieve positive impacts which significantly improve living standards.