This study was designed to discover whether there are patterns in tree communities and to examine their possible links with environment in undisturbed gallery forests. The study focused on the Pitoco, Monjolo and Taquara streams, within the Ecological Reserve of the 'Instituto Brasileiro de Geografia e Estatístca' in the Federal District, in Central Brazil. The three gallery forests are representative of an endangered and extremely important vegetation formation, which is closely related to the maintenance of environmental health and to the volume and quality of the water supply in the region. The conspicuous flora, including species which reflect characteristic environmental features, guided the choice of sites. An intensive study focused on the vegetation and soils of each gallery. Tree species were recorded using the Point Centred-Quarter (PCQ) method from the stream margins to the forest-cerrado border. Soil samples were taken to reflect environmental changes within each catchment. Analysis of the galleries' phytosociology and diameter distribution highlighted their considerable heterogeneity. Only <I>Copaifera langsdorffii</I> and <I>Tapirira guianensis</I> occurred as important species in all three sites. This probably reflects environmental differences between the three areas. Classification by TWINSPAN distinguished forest communities at each locality, referred to as 'wet' and 'dry' according to their position in relation to the stream margins and site topography. The floristic links between the galleries and communities were investigated by cluster analysis (UPGMA), which reinforced the model of a strong association between communities and soil moisture. In fact there was a stronger relationship between communities from areas of similar soil moisture at different stream locations, than between 'wet' and 'dry' communities within the same stream. The soil properties were also found to follow a consistent spatial patterning at all three sites.

The origin and extent of water deficits in Sitka spruce are discussed in relation to external conditions and the nature of the internal water transport pathway. Resistances to liquid water movement are calculated and compared with other resistances in the soil-plant-atmosphere continuum (SPAC). Under non steady-state conditions, plant resistances may be an important factor in controlling water deficit in the needles. The extent of stem shrinkage points to the presence of large stores of water which can buffer the effect of transpirational loss upon the level of water deficit in the needles by providing a source more readily available than that in the soil. Studies of the site of shrinkage suggest that water is stored by young unlignified cambial derivatives. The tissue water relations of Sitka spruce are investigated using the pressure chamber, and the pressure-volume curve is developed to generate equations which describe the variation of total water potential, solute potential, turgor potential, matric potential, bulk modulus of elasticity, and bound water content in relation to tissue water content. The water potential - relative water content curve (the water potential isotherm) shows that Sitka spruce has a high water retention capacity which enables low potentials to develop with only small losses of water content. The variation of solute potential with water content shows large deviations from the behaviour predicted by the Boyle-Van't Hoff relation. This results from large volumes of .matric or bound water, much of which appears to be held in the smaller interstices of the cell walls. The bound water content of twigs shows a large increase in autumn which coincides with the time when cold hardiness of photosynthesis develops in Sitka spruce.

No description available.

No description available.

The objective of the project is to determine which survey technique provides the most practicable and efficient basis for forest site classification. Prior knowledge of the potential growth rates of Sitka spruce and of the management inputs required for various soil and physiographic units is of paramount importance if an accurate survey of previously unplanted hill land is to be made. Such information would provide the basis for a scientifically based and meaningful land capability for forestry. The soils of two Forestry Commission forests (Kirkhill and Bennachie) with a total area of 560 ha were" surveyed following the Forestry Commission Site Survey methods and classification system. For the same two areas physiographic units (facets) were drawn on air photographs. The two areas have also been surveyed by the National Soil Survey. In this way three systems of land survey were available for the two forested areas. To test the homogeneity of the three sets of survey units 158 plots (0.01 ha circles) were located over both forests and within the three sets of classification units, each plot being a random point-sample of each of the three survey systems. Plot data collected were: various depth measures, texture, percent and size of stones in the profile; altitude, slope and aspect; age, topheight, diameter and five year intercept of trees; soil samples for chemical analyses. Initially, coefficients of variation and pair-wise t-tests of survey unit means were used to examine the plot data within each forest, and two-way analysis of variance to compare differences between forests. These analyses showed no significant differences in timber yield between soil or physiographic units in Bennachie forest; in Kirkhill forest gley soils provided significantly greater yields than podzolic soils, with peaty gleys having significantly greater yields than other soil groups. In both forests, for virtually all chemical variables measured there is a significant increase from podzolic to gley soils, and from hill summits to low lying facets. Nutrient levels in the organic layer from profiles in Bennachie forest are about twice those recorded in Kirkhill. Correlation analysis was performed for all plots taken together and then on plot data subdivided into soil and physiographic units for each of Kirkhill and Bennachie forests. In Bennachie the site factors most consistently correlated with tree growth indices were acetic acid extract- able K and Mg in the organic sample and acetic extractable K in the mineral sample; all were negatively correlated. In Kirkhill, eastern aspects, depth of organic matter and total phosphate in both the organic and mineral sample were positively correlated with tree growth. Depth of rooting was negatively correlated. In general the subdivision of each forest into soil and physiographic units greatly reduces the number of significant correlations, particularly in gleys and peaty gleys and in low lying physiographic units. This reduction in correlations arises from the reduced variation within these units and also from the fewer degrees of freedom. From the factor analysis of Bennachie forest twelve factors were extracted, accounting for 80% of total variance. The first factor accounted for all the tree growth indices as well as acetic extractable K in the organic sample. In Kirkhill ten factors were extracted and accounted for 78% of the total variation. Again, the first factor contained all the tree growth indices along with eastern aspect, depth to mottling and rooting depth. The factor analysis thus summarizes the trends shown by the correlation analyses of close relationships between tree growth and soil chemical variables at Bennachie, whereas topographic and soil physical variables are more closely related to growth in Kirkhill. Abstract not available.

No description available.

The literature on P.pini is reviewed. The mycelium and spore stages of P.pini are described. Extension of the lesion takes place by growth of the hyphae along the edge of the functional phloem. Both longitudinal and centripetal growth ocours in the xylem along the resin canals. Tissues formed by a diseased cambium are severely altered. In xylem tracheids decrease in length and diameter, rays increase in height and number, ray cells increase in width but not in height, fusiform rays increase in number and diameter. In phloem formed by discased cambiun, longitudinal parenchyma cells are larger and more numerous, while changes in phloem rays are similar to those of the xylem rays. The bi- or tri-nucleate aeciospores produce an aseptate bi- or tri-nucleate germ tube. On vesicle formation, the nuclei in the germ tube split into 8 individual chromosomes which fuse to form 4 tetrads. These move out of the vesicle into the tube beyond, divide twice, and give rise to 4 nuclei. The process is parallel to meiosis except that no diploid interphase nucleus is formed. 10-15 percent of natural lesions result from wound infection. The remaining are associated with unwounded needle bearing shoots. The differences in symptoms between these two types of infection, the formation of vesicles in stomatal cavities of needles, and the presence of a single needle with mycelium in its vascular tissue on each lesion, indicates that the latter type of lesion results from needle infection. The development of lesions on trees, particularly the factors which determine the probability that a given branch lesion will reach the main stem, are discussed, using the data from 270 natural lesions in two pine stands.

There is increasing pressure to integrate the economics of timber sale and logging planning with environmental considerations and strategic sustainability. Some forestry organisations are hoping to replace pre-harvesting inventory with a database designed for periodical inventory and long-term timber production planning to facilitate continuous (rolling) planning. The aim of this study is to analyse the possibilities of integrating different forest planning levels with each other and a Geographical Information System (GIS), and replacing the pre-harvesting inventory with a GIS. An integrated GIS and planning system is implemented. Firstly, the production system is analysed to define the system requirements in detail. Then the data model and processes together with system architecture are designed. A new concept of treatment stand is adopted for modelling site-specific restrictions into the calculation units of a Finnish forest simulator, MELA. Thereafter corresponding databases are defined and implemented. System interfaces are developed to provide data flow between subsystems. Additional modules for economic analyses are developed to sit on top of the linear programming (LP) package. A case study is undertaken to test the functionality of the integrated planning system. In the case study, forest inventory data and GIS-analyses are used for modelling both site-specific restrictions and harvesting conditions. New LP-formulations are defined and implemented using a Finnish LP-package, JLP. The 'production possibility frontiers' (extremes of possible production) are used to estimate the value of GIS in taking into account the effects of site-specific constraints. The results from a combinatorial model are compared with the results of a standard model to measure the benefits of GIS in timber sale and logging planning.

This thesis explores the factors affecting the supply of and demand for two major outputs of forests in Britain: timber and opportunities for recreation. It also examines the recreation and landscape benefits of a recent policy initiative to expand the area of forests around towns (the Community Forest Initiative). Much of the thesis discusses the construction of models of supply and demand for these outputs, and a range of future supply and demand scenarios that were produced from them. It also shows how the models were used to appraise forestry policy in the areas of timber production, forest recreation and community forestry. This was done first by assessing the relative importance of various aspects of policy in light of the results of these models; then future directions for policy were appraised using the forecasting capabilities available in some of the models. The results of the modelling exercise were also used to critically examine some of the previous assumptions underlying forestry policy, as part of this process.

As society's demands for goods and services from forests increase, there is a corresponding increase in demand for high quality science which can help shape forestry policies for the sustainable management of natural resources. Forestry research is now undertaken in a very diverse Range of institutions. The increased outputs from researchers in domains other than traditional forestry schools have not been matched by systematic methods of utilising new or existing information for policy or to identify future research needs that reflect the priorities of people in forestry's extended networks. An analysis of academic papers and informal articles indicated that the term 'evidence- based' is widely used in environmental literature, matching the rates of popularity of the term 'evidence-based medicine', but without the rigorous methodological processes that medicine has adopted to justify the phrase. Two strands of participatory research were undertaken to examine the potential for adopting rigorous evidence-based frameworks for forestry. The first focussed on a process for identifying important questions for policy-focussed forestry research. Using a combination of internet-based surveys and a workshop, some 480 people representing broad interests in the UKforestry sector set out a priority list of research questions. In the second, a group of international researchers and policy makers explored the possibility of using systematic reviews for validating the evidence base for carbon stock assessment under the REDD (Reducing Emissions from Deforestation and forest Degradation) process. The results indicate that there is capacity to collaborate to frame questions and critically appraise evidence for important policy issues. The longer-term benefits of adopting gold-standard systematic reviews are clear, however, there are also short-term advantages to be gained from moving incrementally towards this goal. In the aftermath of society's concerns about possible manipulation of science by experts (in the climate science arena), it would be folly for the forestry sector to ignore the benefits that would accrue from adopting genuinely evidence-based procedures for matters of global significance.