BACKGROUND:Traditional morphological and biological species concepts are difficult to apply to closely related, asexual taxa because of the lack of an active sexual phase and paucity of morphological characters. Phylogenetic species concepts such as genealogical concordance phylogenetic species recognition (GCPSR) have been extensively used / however, methods that incorporate gene tree uncertainty into species recognition may more accurately and objectively delineate species. Using a worldwide sample of Alternaria alternata sensu lato, causal agent of citrus brown spot, the evolutionary histories of four nuclear loci including an endo-polygalacturonase gene, two anonymous loci, and one microsatellite flanking region were estimated using the coalescent. Species boundaries were estimated using several approaches including those that incorporate uncertainty in gene genealogies when lineage sorting and non-reciprocal monophyly of gene trees is common.RESULTS:Coalescent analyses revealed three phylogenetic lineages strongly influenced by incomplete lineage sorting and recombination. Divergence of the citrus 2 lineage from the citrus 1 and citrus 3 lineages was supported at most loci. A consensus of species tree estimation methods supported two species of Alternaria causing citrus brown spot worldwide. Based on substitution rates at the endo-polygalacturonase locus, divergence of the citrus 2 and the 1 and 3 lineages was estimated to have occurred at least 5, 400 years before present, predating the human-mediated movement of citrus and associated pathogens out of SE Asia.CONCLUSIONS:The number of Alternaria species identified as causing brown spot of citrus worldwide using morphological criteria has been overestimated. Little support was found for most of these morphospecies using quantitative species recognition approaches. Correct species delimitation of plant-pathogenic fungi is critical for understanding the evolution of pathogenicity, introductions of pathogens to new areas, and for regulating the movement of pathogens to enforce quarantines. This research shows that multilocus phylogenetic methods that allow for recombination and incomplete lineage sorting can be useful for the quantitative delimitation of asexual species that are morphologically indistinguishable. Two phylogenetic species of Alternaria were identified as causing citrus brown spot worldwide. Further research is needed to determine how these species were introduced worldwide, how they differ phenotypically and how these species are maintained.

Unlike Sweden, Denmark is a major industry when it comes to christmas tree cultivation. More than ten million christmas trees are processed in Denmark annually. The primary purpose of this report is to investigate the technology, treatment and maintenance of christmas trees in Sweden and Denmark, and to find differences in the management between Swedish and Danish christmas tree cultivators. Since an opinion poll has been made, the investigation method mainly used for this report is quantitative. But a qualitative investigation method has also been used to some extent as a few unstructured interviews has occurred while visiting a couple of the cultivators.   63 % of the christmas tree cultivators consider themselves knowledgeable about christmas tree cultivation and 68 % wants to learn more. There is both similarities and differences along those cultivators that has been visited. Obvious similarities has mostly been found when visiting farms engaged in developing christmas trees to a bigger extent. Denmark conducts their maintenance methods with the aim to produce a large amount of high quality Christmas trees. This tendency does also occur in Sweden at, for example, Gunnars Granar located in Degeberga. Gunnar manages his cultivation almost identically to Denmark's management methods. However, the big christmas tree cultivators are still mainly located in Denmark.

The dimensions, manufacture and application of a mini-borer to take 3-mm cores are described. This new instrument seems particularly well-suited to determining ages of saplings in situations where collection of cross-sections and coring with standard increment borers are too destructive, and where node-counting may not be sufficiently accurate. The design has resulted in trouble-free use in the field, and the mini-cores can be stored in the straws, and mounted and sanded in the core mounts used for collections of the standard 4-5-mm increment cores.

No description available.

The world's forests sequester roughly a quarter of anthropogenic emissions of carbon dioxide and store it in wood. Assessing this carbon sink includes quantifying annual wood production, establishing baselines, and characterizing both long-term trends and inter-annual variability. Direct measures of forest wood production are often based on measures of individual tree growth along the stem, often taken at a single height: basal height (1.3 meters). This assumes that a measurement of wood production at a single height is representative of wood production along the whole stem. In violation of this assumption, it is known that trees do accumulate wood differentially along the stem, and that this longitudinal variability can change from year to year. Few efforts have been made to describe annual longitudinal variability, and quantify the error in estimated annual whole-stem wood production related to assuming that constant wood production along the stem. In the present study, I present a stem analysis of 30 Populus grandidentata to address this. Dendrochronological techniques are used to develop three chronologies: a traditional tree-ring width chronology from basal height, a novel chronology developed from tree rings grown in the crown of the trees, and a specific volume increment chronology calculated from measured annual volume increment data. A novel taper chronology is also presented. In Chapter 2, comparisons are made between the chronologies to explore differences in inter-annual variability, and the suitability for using tree-ring data from basal height as a proxy for annual wood production. Both basal and crown tree-ring width chronologies were strongly correlated with the volume chronology (r = 0.96 and 0.88, respectively), suggesting that the basal chronology is a superior proxy for stem volume. However, a chronology of taper along the stem indicates that the reliability of either chronology to represent specific volume increment (SVI) changes over time, resulting in different common signals, especially in the last decade of this dataset. If accurately capturing the relative year-to-year changes in stem wood volume is desired, stem dissection and development of an SVI chronology is required. In Chapter 3, two models that use tree-ring data to estimate annual wood production are compared to volume measurements from the stem analysis. The two models are a site-specific allometric model of biomass, and a simplified conic model of volume. Additionally the conic model is decomposed into the three dimensions of growth along which variability exists (around the circumference, along the length of the stem, and height) to identify which dimension introduces the most error when no variability in that dimension is assumed. Relative error (RE) analysis and regression analysis show that stem analysis is superior in cases where few trees are used and accurate measures of wood increment are needed. At the population level, the allometric and conic models show different strengths. Allometric models are more accurate than the conic model (RE = -16% and -18%, respectively) and are better for carbon budgets, whereas the conic model was more precise than the allometric model (R² = 0.94 and 0.86, respectively; interquartile range = 24% and 41%, respectively) and maintains inter-annual variability, which is necessary in cross-validation efforts. Decomposition of the conic model supports previous findings that height is the second most important parameter, following diameter at breast height, in models of woody tissue growth. In Chapter 4, basal, crown and specific volume chronologies are compared to eddy covariance estimates of carbon dioxide flux between the forest and the atmosphere, including net ecosystem exchange, gross primary production and ecosystem respiration. At the University of Michigan Biological Station (UMBS), crown-grown tree-ring widths from P. grandidentata individuals are good recorders of the inter-annual variability of net ecosystem production. Coupled with other environmental information from UMBS, these records implicate defoliating insects as a previously under-appreciated modifier of stand level respiration and gross primary production. These histories of ring widths, volume and taper have unique potential to improve our understanding of how carbon is stored in and flows through forests within the terrestrial biosphere. In the face of global change, forests will experience new stressors, and changes in frequency of known stressors, that reduce the ability of trees to store carbon in woody tissues. A diversity of tree-ring-based chronologies can describe the sensitivity of carbon stores to these stressors, improving predictions of how forests respond to environmental changes.

Thesis (M.D.S.)--University of Adelaide, Dental School, 2002. / "June 2002" Bibliography: leaves 118-128.

Thesis (Ph. D.)--Ohio State University, 2002. / Heading on electronic reproduction: Anderson, Nancy Lee. Vita. Includes bibliographical references (leaves 168-176).

In 1992 Du and Hwang published a paper confirming the correctness of a well known 1968 conjecture of Gilbert and Pollak suggesting that the Euclidean Steiner ratio for the plane is 2/3. The original objective of this thesis was to adapt the technique used in this proof to obtain results for other Minkowski spaces. In an attempt to create a rigorous and complete version of the proof, some known results were given new proofs (results for hexagonal trees and for the rectilinear Steiner ratio) and some new results were obtained (on approximation of Steiner ratios and on transforming Steiner trees). The most surprising result, however, was the discovery of a fundamental gap in the proof of Du and Hwang. We give counter examples demonstrating that a statement made about inner spanning trees, which plays an important role in the proof, is not correct. There seems to be no simple way out of this dilemma, and whether the Gilbert-Pollak conjecture is true or not for any number of points seems once again to be an open question. Finally we consider the question of whether Du and Hwang's strategy can be used for cases where the number of points is restricted. After introducing some extra lemmas, we are able to show that the Gilbert-Pollak conjecture is true for 7 or fewer points. This is an improvement on the 1991 proof for 6 points of Rubinstein and Thomas. / Mathematical Sciences / Ph. D. (Mathematics)

Importance of research on the provenance problem, which is basically one of seed transfer from collection site to outplanting area, is discussed with special emphasis on coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii). The "Co-operative Douglas-fir provenance test," begun in 1957 and involving sixteen coastal seed sources from British Columbia, Washington and Oregon, is described in detail. Height measurements collected at the University of British Columbia Research Forest, when the trees were eleven years old, are analysed and the results are discussed. Due to site heterogeneity and young age of the Co-operative test, no significant height growth differences between provenances can be shown, although the local seed source, from the University of British Columbia Research Forest, seems to be the fastest growing and the southernmost origin, Butte Falls, the slowest of all provenances investigated. The Co-operative test is critically evaluated and specifications for further studies are recommended. / Forestry, Faculty of / Graduate

This application software system of Tree Alignment and Reconstruction (TAAR) is an X Window based interactive system developed mainly for sequence analysis. It provides a user-friendly graphical interface and convenient operations for performing Pairwise Alignment, 3-Star Alignment, Phylogeny Reconstruction and Generalized Tree Alignment algorithms. The algorithms for Phylogeny Reconstruction and Generalized Tree Alignment are designed based on heuristic stepwise addition and internal node sequence alignment induction methods. All above algorithms are space-efficiently implemented. For each algorithm, both fast and optimal versions are provided for user's convenience. TAAR can be used for DNA, RNA and PROTEIN sequences analysis. In general, as long as the sequence characters are in the range of a-z and A-Z, and the score matrix alphabet contains the sequence alphabet, the sequence would be accepted by this application and all calculations could be carried out. This software system is programmed in C, Motif and X Window Library functions. It is intended to be running in a UNIX and X Window environment. / Thesis / Master of Science (MS)