No description available.

The effect of temperature, pH, humidity and spore density on the germination of aeciospores of Peridermium pini were studies in vitro and the optimum conditions for germination determined. Inoculation of scalpel wounds 2 mm deep on current year's shoots gave higher infections than wounds 1 mm deep. Some lesions resulting from these infections developed pyenidial droplets, and a few also produced social blisters within the first year after infection. Counts of aeciospores at various times after placement showed that they do not adhere firmly to needle surfaces and that many are rapidly lost. The reminder tond to drift down and to accumulate in the needle fascicles. Infection of P. sylvestris by aeciospores of P. pini can take place by direct stomatal penetration. This was observed only inside the needle sheaths and not above them. The hyphae developing from these penetrations pass intercellularly through the mesophyll to the vascular tissue of the needles where they proliferate and grow to the shoots and stems thus establishing infection. Internal needle extracts and needle and shoot juices taken from a healthy tree standing beside diseased trees showed a marked retarding effect on the germination of aeciospores and subsequent germ tube development compared with those from an already infected tree. Chromatography work showed that quantitative differences between the phenolic content of needles from both the healthy and the infected trees did not exist. Resistance of P. sylvestris to P. pini infection may be due either to qualitative phenolic differences or to other substances.

This work is concerned with resolving contradictions found in previous research on Lophodermium pinastri (an ascomycete fungus inhabiting pine needles). The literature review shows how a number of species of Lophodermium on pine needles have been recognised and named, and how researchers have ignored largely these names and have used repeatedly the name L, pinastri regardless of the species involved, Not surprisingly therefore reports are contradictory and confused, some for example calling L,_ pinas tri a saprophyte, others a strong pathogen, A careful examination of the morphology of L" pinastri on secondary needles of Pinus sylvsstris in Scotland revealed that four distinct forms (A, B, C & P) can be recognised using characteristics of size, shape and colour. In particular, the depth to which asco'carps of each form are inserted in the host needle, and the character of the stromatic lines produced by each form are useful guides for identification. Form A produces many, and form D few black stromatic lines, while forms B & 0 produce few brown stromatic lines. Similarly, ascocarps of forms A. B & D are situated at least partly under the cuticle alone of the host, whereas ¦ascocarps of form C are totally subepidermal. Three of the forms we re recognised also on cones, and two on primary needles, though work on these was limited. Using samples from abroad and on many species of pine the morphology of the four forms was shown to be largely unaffected by variation of host anThis work is concerned with resolving contradictions found in previous research on Lophodermium pinastri (an ascomycete fungus inhabiting pine needles). The literature review shows how a number of species of Lophodermium on pine needles have been recognised and named, and how researchers have ignored largely these names and have used repeatedly the name L, pinastri regardless of the species involved, Not surprisingly therefore reports are contradictory and confused, some for example calling L,_ pinas tri a saprophyte, others a strong pathogen, A careful examination of the morphology of L" pinastri on secondary needles of Pinus sylvsstris in Scotland revealed that four distinct forms (A, B, C & P) can be recognised using characteristics of size, shape and colour. In particular, the depth to which asco'carps of each form are inserted in the host needle, and the character of the stromatic lines produced by each form are useful guides for identification. Form A produces many, and form D few black stromatic lines, while forms B & 0 produce few brown stromatic lines. Similarly, ascocarps of forms A. B & D are situated at least partly under the cuticle alone of the host, whereas ¦ascocarps of form C are totally subepidermal. Three of the forms we re recognised also on cones, and two on primary needles, though work on these was limited. Using samples from abroad and on many species of pine the morphology of the four forms was shown to be largely unaffected by variation of host an locality of collection. Each form was related to a distinct cultural type and three forms were shown to occupy a distinct habitat in the field. Form A fruits on senesced needles which have fallen into the litter, and form B on healthy needles killed prematurely by, for example, damage to their branch; while form C fruits on young needles whioh it has infected and killed. Form D is probably mainly an inhabitant of haploxylon pines, and. may replace form A on the senesced needles of these pines.

The practical problem of studying the nutritional status of trees under field conditions has given rise to the present research, which examines some aspects of the use of chemical composition of plants as an index of their nutritional status The need for a comprehensive investigation on this subject with tree crops, was felt by the author during his studies on rubber plant, Hovea brasilionsis, a tree crop of considerable economic importance in Malaya where expensive fertilizer practices are followed to maintain and improve the plantations Availability of spectrochemical methods for the analysis of plant materials has made such an investigation possible at the Macaulay Institute for Soil Research, where, for practical reasons, the work was carried out using three species of deciduous trees that are commonly found in Scotland. The conclusions drawn from this investigation are often general in nature and are considered likely to prove useful in understanding similar problems of tree crops under widely varying conditions. The work embodied in this thesis is presented in eight chapters. Chapter 1 indicates the relation of the present investigation to the published work on this subject. Chapter 2 describes the experimental methods and the materials used. Chapter 3 consists of a short discussion on the reported accuracy and reproducibility of the several spectrochemical methods of analyses that were used throughout this investigation. Chapters 4, 5, 6 and 7 present all results of the investigation. Finally, in Chapter 8, all observations are considered together, and their implications on both theoretical and practical aspects of tissue analysis, and the indicated lines of further work, are briefly discussed.

The literature concerning conifer inhabiting fungi is reviewed, in particular that concerning Henderaonia caseload Tub., Hypedormella suleigeaa (Rostr.) V. Tub., Lophoderrnium ainastri (Sehrad. ox Hook.) Chev. and Naemacyelus niveus (Pers. ox Fr.) Sace. The four fungi are found to play an important role in the discolouration and premature defoliation of Pinus sylveatrio L. at Glenlivet. L.niinastri is found to have the different fruiting habitats and two correspondingly different grouth forms in artifioial cultur. Detailed observations on the development of disease symptoms and tread in neelde east indicate an ecological ouceesaien of these fungi on the needles, This is further substantiated by inoculation experiments. The data are diseussd and it is concluded that H. suleigena is the primary coloniser of young flushing needles. H. acicola is dependent on H. suleigena to prepare a suitable substrate for its growth. L. pinastri is indirectly dependent on H. suleigena. depending on the type of zeaction of the tree to the initial infection by H. suleigena. N. niveus causes the ultimate shedding of one year old needle faseioles celonised by H. suleigena.

This thesis aims to use molecular methods to investigate the genetic diversity and population structure of two commercially important neotropical tree species in a human-influenced Central American landscape. Red Yemeri, <i>Vochysia ferruginea </i>Mart., is recommended as a potentially highly useful species for forestry reclamation of degraded land. Populations from throughout its range in Costa Rica were analysed for both organellar (chloroplast specific PCR-RFLP) and total genomic (AFLP) variation. All populations were fixed for one of two chloroplast DNA (cpDNA) haplotypes identified. One haplotype was distributed exclusively throughout the Atlantic watershed, whilst the second was found only on the Pacific slope. AFLP diversity was partitioned primarily within populations (80.5%) and small but significant between-population differentiation was detected (Φ_ST = 0.195). The relationships between populations fitted an isolation by distance model when an ecological distance metric linking populations through suitable habitat was used, and indicated gene flow around a central mountain range. In combination with the cpDNA data, these data suggest that pollen flow around the mountain range is maintained whilst seed flow appears to be more restricted and cpDNA structure is more probably a consequence of historical population processes. Spanish Cedar, <i>Cedrela odorata </i>L., is a globally important timber species which has been severely exploited in Central America for over 200 years. Populations from throughout its range in Costa Rica were analysed using PCR-RFLP and AFLP. Two cpDNA haplotypes were identified and, in all but a single case, populations were fixed for one haplotype. Generally, haplotypes were distributed exclusively between different habitat zones (wet and dry), indicating the likely presence of two ecotypes, as previous studies had concluded. AFLP analysis (AMOVA) confirmed the genetic divergence of ecotypes (83.5% between ecotypes) and showed that dry ecotype populations maintained almost twice as much diversity as wet ecotype populations <i>(h - </i>0.093 and 0.056 respectively).

No description available.

In Australia, as in many countries, there is an increasing requirement for spatial and temporal information on forest structure and particularly biomass (carbon). The use of remote sensing data is well suited for the provision of such data, in particular Synthetic Aperture Radar (SAR) data. However, the majority of studies have concentrated on empirical relationships between above ground biomass (AGB) and radar backscatter. Limitations of such approaches include saturation of the signal (e.g., above certain biomass levels), structural variations, and the influence of environmental conditions (e.g., surface moisture). Recognising these limitations, this study focused on the retrieval of parameters through inversion of a physically based backscatter model (that of Durden et al., 1989) using a non-linear estimation algorithm (Moghaddam and Saatchi, 1999). The study focused on the Brigalow Belt Bioregion of Queensland, Australia, and particularly regrowth forests dominated by Acacia harpophylla. A generalised method of parameterisation has been described and validated using relationships established through fieldwork for three Australian species, used to develop parametric scattering equations for use in a non-linear estimation algorithm for the retrieval of structural and dielectric parameters from AIRSAR and ALOS PALSAR data with Landsat derived Foliage Projective Cover (FPC). Four case studies were presented in which the sensitivity of the estimation algorithm to noise was tested for a variety of scenarios. Following sensitivity analysis the algorithm was applied to real data for the product of structural maps. Although currently only modest levels of accuracy have been obtained with the approach there is much scope for improvement (i.e., better backscatter modelling, more data channels) and enhancement (i.e., inclusion of LiDAR data) of the algorithm.

One of the main causes of tropical deforestation is conversion to agriculture, which is continuously increasing as a dominant land cover in the tropics. The loss of forests greatly affects biodiversity and ecosystem services. Tree-based farming, in a range of agroforestry systems, has been proposed as a mechanism for sustaining both biodiversity and its associated ecosystem services in agricultural areas, by increasing tree cover, while maintaining agricultural production. The main aim of this thesis is to assess the rate of return resulting from incorporating trees into food-crop-based smallholder agricultural systems, in order to assess the economic potential of agroforestry systems that may also help protect local forest, the barriers to their widespread adoption, and how the landscape approaches (land sharing and land sparing) work best in the study sites in eastern Bangladesh and West Java, Indonesia. The four papers included in the thesis specifically address the following issues. 1. The types of agroforestry practiced, in order to characterize their differences in basic structure, management and associated crop plant diversity, and the problem of classifying them into a specific land-use category (i.e. agriculture or forestry). 2. The economic and social potential of agroforestry systems and the barriers to their widespread adoption, as a land use alternative to swidden cultivation, which may potentially help protect local forest. 3. The trade-offs between income and tree cover when incorporating trees into food-crop-based smallholder agricultural systems, and the associated factors that influence farmers’ choice of tree-based farming in place of seasonal cultivation. 4. The major challenges facing farmers using current local land-use systems, the conditions and policy context that could facilitate smallholder tree farming, and how landscape-scale approaches work best in a local perspective to reconcile agricultural and environmental goals. Data were collected through rapid rural appraisals, focus group discussions, field observations, semi-structured interviews of farm households and key informant interviews of state agricultural officers. Data have been analysed through narrative qualitative methods, and through quantitative methods such as descriptive statistics, analysis of variance, and cost-benefit analysis. x Five main agroforestry systems (homegarden, fruit tree, timber tree, mixed fruit-timber, and cropping in the forest understory) exist in the Java study area, and can be categorized into two main types, i) integral, rotational and ii) integral, permanent, both of which exhibit a noticeable diversity in terms of both species composition and utilization. In both Java and Bangladesh the inclusion of tree crops in seasonal agriculture improved the systems’ overall economic performance (NPV), even when it reduced understorey crop production. In the Java study area, tree ownership was associated with more permanent rights to farmland and was prestigious in the community, which also helped strengthen social cohesion when the products (fruit, vegetables, etc.) were shared with neighbours. In the Java study area, agroforestry farmers were less involved in forest clearing and forest product collection indicating that agroforestry may contribute positively to reduce pressure on local forests. However, seasonal agriculture (food-crop-based monoculture agriculture in Java, and swidden in Bangladesh) has a higher income per unit of land area used for crop cultivation compared with the tree establishment and development phase of agroforestry systems. There is thus a trade-off between short-term loss of agricultural income and longer-term economic gain from planting trees in farmland. However, constraints of local food crop cultivation traditions, insecure land tenure, insufficient investment capital, lack of knowledge, lack of technical assistance, and perceived risk of investing in land due to local conflict (in Bangladesh) limit farmers’ willingness to adopt this land use alternative. Various conditions can facilitate tree farming, including a carefully designed landscape approach, with the elements of both segregation and integration of land uses, supported by competent government policies and local communities having sufficiently high social capital. In land-use classifications agroforestry systems are not recognized as forestry, but like forests they provide tree products and services. Classification will always be problematic if a binary system is applied, thus a more sophisticated approach should be adopted that incorporates the economic and environmental characteristics of a wider range of systems.

The objective of this study was to investigate altitudinal and geographical variation in the productivity of Sitka spruce in upland Scotland, to relate this to environmental variables and to use the information to develop a basis for predicting Sitka spruce yield form site factors. A total of 188 0.04 ha temporary sample plots were established in 15 to 50 year old Sitka spruce stands at 37 sites in Scotland and northern England, mostly spanning the upper 200m elevation range of plantations. At each plot estimates of General Yield Class (GYC) were made and the following site factors were assessed; elevation, geomorphic shelter (topex), aspect, slope, soil type and rooting depth. In addition, estimates of wind-climate, mean summer temperature (June-September), mean annual accumulated temperature > 5.6°C and annual rainfall were made by extrapolation of forestry Commission "tatter flag" records and Meteorological Office data. GYC declined by about 3.2 - 4.0 m3 ha -1 yr -1 per 100 m increase in elevation due to the effects of increasingly adverse climatic and edaphic conditions, GYC was fairly closely correlated with elevation at the individual sites, but there was considerable site to site variation. GYC values at specific elevations were higher in inland and southern areas than in coastal and northern ones. The geographical pattern of the relationship between GYC and elevation was strikingly similar to the distributions of growing season temperatures and wind-climate. Correlation and multiple regression analysis demonstrated that GYC was well correlated with extrapolated values of accumulated temperature and tatter rate, these two variables accounting for up to 78 per cent of the variation in GYC in the best multiple regression models. GYC also proved to be correlated with aspect, topex, soil type and crop age. Productivity was highest on north and east-facing aspects and increased with greater levels of geomorphic shelter. Differences in soil type only accounted for a small amount of variation in GYC (2-3 per cent). GYC was significantly negatively correlated with crop age, probably as a result of improved standards of silvicultural treatment. The best multiple regression models accounted for 78-86 per cent of the variation in GYC and were associated with confidence limits of ±2.2 - 2.6 m3 ha -1 yr -1. The mean figure for predicting GYC for a single site (acquisition) was calculated to be ± m3 ha -1 yr -1, and this figure was confirmed by results of a validation survey. The information presented could easily be adapted for predicting productivity and assessing suitable upper planting limits in practical forestry.