The spatial variation of tree growth and site factors was studied in a silvopastoral system at Glensaugh in Northeast Scotland. Sycamore (<I>Acer pseudoplatanus</I> L). Hybrid larch (<I>Larix </I>x <I>eruolepsis</I> Henry) and Scots pine (<I>Pinus sylvestris</I> L) were planted at 5 m x 5 m, 7.1 m x 7.1 m and 10 m x 10 m spacings on plots replicated over three blocks in a Randomised Complete Block design on a rye grass (<I>Lolium perenne</I> L) pasture which was grazed by sheep yearly from April to October. Included in the design were an agricultural control, forestry control and mowed plots. The agricultural control had no trees but grazed pasture and the mowed plots had trees but the pasture was not grazed, instead it was cut at intervals and left to decompose on site. The forestry control plots had no pasture and as such were not given fertiliser treatments and soil samples were not collected from them, in these the trees were planted at the standard 2 m x 2 m spacings and fenced off from the animals. Pastures received 160 kg N/ha^-1 annum^-1 in four equal applications. The objective of this work is to study at tree-scale the spatial variation of tree growth and site factors in grazed and ungrazed silvopastoral system plots. Total soil N, available Mg and Ca, as well as organic matter (OM), %C, pH in water and Calcium chloride increased significantly with distance from the tree while P decreased significantly with distance from the tree in grazed plots. The presence of trees or animals alone in a treatment did not significantly influence soil nutrient redistribution in a silvopastoral system. Therefore it takes the combined presence of trees and animals in a silvopastoral treatment for a significant redistribution of soil nutrients around the tree to occur.

Four species of Conifers were used in an investigation on the effect of self-, cross- and open pollination on cone and seed setting. Both Cedrus atlantica and Tsuga canadensis are shown to he completely self-incompatible, and in the latter species, incompatibility is associated with parthenocony. In Chamaecyparis lawsoniana. the individual trees behave differently and show either complete or partial self-incompatibility. Pinus silvestris is found to be partially self-incompatible. Possibly because of the small number of pollen parents used, no crossincompatibility has been demonstrated in any of the four species. The behaviour of pollen in the self-incompatible pollinations is shown to be different in the four species. In C. atlantica. all self-pollinated cones fail to develop and fall off the tree within a few months of pollination. Pollen in the cross-pollinated cones remains dormant for about eight months before it germinates. In T. canadensis, self-pollen does not germinate whatever its position on the cone-scales; hut cross-pollen within a certain radius of the ovules germinates after six to eight weeks. In P. silvestris and C. lawsoniana, all pollen germinates, hut in most self-pollinations pollen-tube growth is inhibited either in the nucellus or the embryo-sac. Experiments on pollen germination in vitro show that pollen of all four species germinates readily at 18&deg; C and higher temperatures. The long period of pollen dormancy in the female cones of C. atlantica is partly explained by the direct effect of temperature. The nature of the incompatibility reaction is discussed, and it is suggested that in all four species the reaction is more likely to be oppositional rather than complementary.

Chapters I-III. A review of the Regional Geography of the Black Forest, comprising (a) an analysis of the relief, morphology, and drainage, considered in the light of recent research; (b) an outline of the climate and leading features of the soils represented; (c) a survey of plant life and land utilisation, based on maps constructed from 'Gemeinde' data, and on field studies. Chapters IV-V deal with the evolution of settlement, considered in the various phases: Pre-historic, Roman, Allemannish, early Mediaeval, and late Mediaeval; and the initial growth of industries, based on the exploitation of the forest resources, is noted. Chapter VI outlines the present distribution and forms of rural settlement, by reference to specific examples. Chapter VII treats the urban settlements in a similar way, paying special attention to the manufacturing centres of the Forest proper, and to the marginal towns of historic and modem significance. Chapter VIII surveys the distribution and evolution of factory industries in the Black Forest region, and discusses the various localising factors, where possible. Chapter IX summarizes population trends, during the last I20 years, noting areas of rural depopulation, static population, and areas of increasing density. Finally, a short study of the history of migration and emigration is made, and some of the causes are suggested.

The recent trend in climate has shown that UK temperatures are increasing, summers are getting drier and winters are getting wetter. It is thought that this trend is set to continue for the foreseeable future and that this will have an impact on the growth and quality of timber in the UK. Sitka spruce (Picea sitchensis (Bong.) Carr) is one of the most widely planted and important commercial tree species in the UK but our knowledge of tree growth and wood properties is based on tree growth in the climate of the past 40 – 80 years. The rotation time for Sitka spruce is approximately 40 years so trees planted now will mature in the 2050s, when the climate could be different from today leading to impacts on the quality and quantity of the wood being produced. This project aims to predict the effect that changes in climate will have on Sitka spruce, by looking not only at growth but also at different properties of the wood and their susceptibility to any change in climate. This information could then be used to help make decisions as to whether Sitka spruce is the best tree to be planting now, at any specific site in the UK, to obtain the best quality wood in the future. The effect of seasonally changing weather on growth was measured at two sites by the use of LVDT point dendrometers to record changes in the radius of the tree stems. The data were compared to meteorological data collected from the site and from local weather stations, to determine how weather affected the growth of the trees. Data collection from the site at Griffin Forest near Aberfeldy was initiated in 2008 as part of a long term project at that site. Measurements taken during 2008 and 2009 were used as part of a previous PhD study and continued as part of the present study from 2010. The second site was newly established at Harwood Forest in Northumberland, northern England. At both sites the onset of growth at the beginning of the season was found to correspond to temperature >5°C. Deficit of soil moisture was found to decrease the growth rate during the peak growth period. Radial density, radial growth and the radial profile of longitudinal stiffness were investigated by analysing increment core samples taken from sites covering the full latitudinal range that Sitka spruce grows in Great Britain, with the aim of quantifying the effect of site factors such as latitude, longitude, initial spacing and elevation. The cores were measured from density and ring width using an ITRAX x-ray densitometer and analysed using Windendro software. Stiffness was investigated using acoustic velocity measurements taken directly on the increment cores using an ultrasonic scanner, modified to measure cores. A wide range of published radial growth models and a smaller number of radial density models were explored to see which were able to describe the data and compared to simpler linear segmented models. The sample population was found to be highly variable and the ability of the models to predict ring width or density from ring number alone was limited. Improved prediction of density was possible when ring width was included along with ring number as a predictor. The linear segmented models were found to be able to predict growth and density from ring number alone and this provides a useful and powerful tool. In practice ring width may not always be available and so there is a need for models which can predict density from ring number alone. Ring width was found to be negatively correlated with density, although the nature of the relationship was different between juvenile and mature wood. Most of the variation in both density and growth was between trees at the same site. Initial spacing was found to be the only significant effect on growth and then only by having a positive effect on the growth rate of the juvenile wood, which had a knock on effect on the size of the trees at the end of the juvenile phase. Both spacing and latitude were found to have significant effects on the mean density of the juvenile wood with spacing having a negative effect and latitude a positive effect. In the mature wood, cambial age was found to be the only significant effect on radial density.

No description available.

No description available.

No description available.

In plantation grown Sitka spruce, timber density is an important quality concern. Currently Sitka spruce timber meets the requirements for C16 strength grading which is the minimum requirement for construction uses. However, the margin is not exceeded by much and a small reduction in density could lower the log grading. Therefore it is essential to understand how timber density is impacted by site factors and climate in order to predict the potential effects of climate change on timber quality in Sitka spruce in the future. This has important economic implications for UK forestry. To assess the influence of site factors and climate on growth and resulting timber properties in Sitka spruce, three experiments were established; a large scale wood quality survey (“The Benchmarking experiment”), a detailed inter-site density study (“The Level II experiment”) and a continuous growth monitoring experiment (Dendrometer experiment). In the ‘Benchmarking’ experiment, increment cores were collected from 68 sites over a geographically wide area in Scotland and Northern England in order to quantify the effect of selected site factors on density. These samples were not suited for climate analysis at annual ring level and therefore disks that allowed reliable dating of the tree rings were collected from three Level II sites. The Level II samples were also used in an acoustic velocity study and an assessment of the within-tree patterns in density. Material from both Benchmarking and Level II sites was used for modelling radial density. In addition to this the Level II data functioned as a test dataset for the different density models that were developed on the Benchmarking data. Density and other tree ring variables were measured with an ITRAX X-ray densitometer and WinDENDRO software. Some acoustic measurements were also carried out with a purpose built ultrasonic scanner to allow calculation of radial variation in stiffness. A dendrometer experiment was established to monitor short term growth variation in Sitka spruce in real time. The aim was also to use the growth data to date density profiles and hence identify causes for the density differences. Data analysis was carried out in R mainly using linear and non-linear mixed effects models, the dendrochronology software package dplR and methods of time series analysis. It was found that the largest part of the variation in density was between trees within each site. Both density and stiffness were mostly influenced by the growth rate or by another variable describing the tree vigour. Fast growth decreased density both by increasing earlywood proportion as well as decreasing the density of both earlywood and latewood. Models for the radial behaviour of density and stiffness could be fitted to the data, but random tree effects remained large. This limits the applicability of these models to new sites as reparameterisation would be required, which requires data from time consuming density and acoustic velocity measurements. The possibility of modelling the model coefficients from easily measurable stand and tree variables was investigated but the results were not promising. The Dendrometer experiment indicated that annual growth in Sitka spruce was initiated in late May and terminated by mid September. Ring widths detected by the dendrometers, micro core measurements and X-ray density based tree ring analysis differed, which caused difficulties in dating the density profile. To decrease these problems in the future the microcore sample storage protocol was revised. The dendrometer data indicated that the growing season was divided into several sections between which the growth rate differed. Latewood density and maximum density had the strongest correlations with the climatic variables. At one site the correlations included temperature and rainfall in April whereas at the other precipitation throughout the growing season or during the May-August period were important. Temperature was correlated positively with density variables and rainfall negatively.

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No description available.