Thesis (Ph.D.)--Michigan State University. Plant Biology, 2008. / Title from PDF t.p. (viewed on Mar. 30, 2009) Includes bibliographical references (p.197-216). Also issued in print.

Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on May 1, 2009) Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2004. / Title from PDF t.p. (viewed on Dec. 19, 2005). Includes bibliographical references (leaves 144-163). Also issued in print manuscript.

No description available.

Woody vegetation patches play an important role in the savanna ecosystem. They provide habitat for animal species and are important for some ecological processes such as. However, the coexistence of trees and grass depend on several factors such as fire, elephant, rainfall and soil type. In Kruger National Park, factors that affect the survival of woody vegetation patches are elephants and fire. The loss of woody vegetation patches leads to fragmentation of the landscape. The main aim of this study was to determine the relative difference in the composition, complexity and configuration of woody vegetation patches in and out of the enclosures, and to evaluate the changes in number and size, shape and connectivity of woody vegetation patches between basalt and granite soils over a period of time. There was no linear relationship between composition and complexity and mean nearest neighbour with year, whilst edge density appeared to have a linear relationship with year. Based on edge density results, the results suggested that there was increase in landscape fragmentation in Kruger National Park. The increase in woody patch fragmentation can be attributed to the increase in elephant population, as well as fire frequency and intensity. There was no difference in the composition, complexity and configuration between the inside of the enclosure and the outside. The results show that there is difference between the basalt (Makhohlola) and granite (Nwashitshumbe) region. The results indicated that Makhohlola seems to be highly fragmented than the Nwashitshumbe. The basalt region is situated on rich soils and receives more rainfall than the granite region; hence thus plant growth is greater than that on granite region. High plant growth is associated with high fire frequency and intensity, which result high influence on woody vegetation. The basalt region is dominated with palatable vegetation, as result; the basalt region is associated with large number of herbivores. Due, to high number of herbivores, and high frequency and intensity, the basalt region may be highly fragmented. The change in woody vegetation patches over time, on both basalt and granite region was associated with the interaction between the increase in elephant density, and fire frequency and (or) intensity.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 31 October 2014, Johannesburg. / Over one-third of South Africa’s surface area is covered by savanna woodlands. The structure and dynamics of savannas within communal rangelands have not only been formed by environmental determinants (rainfall and soil) but have also been influenced and manipulated by anthropogenic disturbances (fire, herbivory by livestock, harvesting of resources and cultivation). The aim of this study was to determine the individual and interactive influences of rainfall and catenal position on woody vegetation composition and structure in human-impacted woodlands of Bushbuckridge, Mpumalanga Province, from 2011 to 2013. Three zones were selected that differed in mean annual rainfall: (a) wet west (>700mm), (b) mesic (600-700mm), and semi-dry east (<600m), with three villages per zone. For the rangeland of each village, plots were sampled in 2011, 2012 and 2013 to cover the upland and bottomland variations in catenal position. All trees >6m in height, and their individual stems, were counted and measured within a total of 56 circular plots (only 28 in 2011) each with a radius of 50m. Trees <6m, and their stems, were counted and measured in a circular plot with a radius of 6m, nested centrally within each 50m plot. All analyses were undertaken on (a) total trees and stems and (b) recently harvested (within the last 12 month) trees and stems. The density of small trees (<6m in height) was significantly higher than that of large trees (>6m in height) from 2011 to 2013. Trees and stems were more abundant in the smaller height and diameter classes, respectively, indicating stable populations. The densities of stems for large trees did not show any change over time, whereas the densities of small trees decreased from 2011 to 2013. When comparing across time between rainfall zones, the densities were higher in the high rainfall zone than in the low and medium rainfall zones for each survey year. On the other hand, densities were similar between uplands and bottomlands for each survey year. The intensity of harvesting increased for large trees over time (between 0% in 2011, 2.3% in 2012 and 10.6% in 2013), whereas small trees did not show any change over time. The most harvested trees were between 0.6-4m in height and 1.1-10cm in stem diameter. There were however some signs that harvesting in the larger size classes (>6m in height and >20cm diameter) were increasing over time. The highest proportion of trees was harvested in the medium rainfall zone compared to the other two rainfall zones, but there was similar harvesting intensity between uplands and bottomlands. Overall species richness, Shannon and Simpson’s (Diversity), and Evenness at the plot level did not change for either large or small trees from 2011 to 2013. The species richness and Shannon’s diversity was higher in the high rainfall zone than in the other two rainfall zones, whereas there was no difference in species richness, diversity or evenness between catenal positions for either large or small trees over time. Because there are similar patterns between the species accumulation and rarefaction curves for both the large and small trees, species are distributed at random across the plots, and this is consistent for the three survey years. The most abundance large tree species were Sclerocarya birrea > Philenoptera violacea > Pterocarpus angolensis, which were very different from the most abundant small tree species that were dominated by Dichrostachys cinerea, Terminalia sericea, Acacia exuvialis, Strychnos madagascariensis and Combretum hereroense. A greater species richness, diversity and evenness of harvested trees were observed in 2013 compared to 2011 and 2012. Species that were most harvested for large trees comprised Combretum collinum, Acacia gerrardii, T. sericea, Acacia robusta, Combretum zeyheri and S. birrea, whereas harvested small trees comprised D. cinerea, T. sericea, A. exuvialis and C. hereroense. Even though there were no differences in density, structure, species richness, diversity or harvesting intensity, the species composition did however differ between the uplands and bottomlands. The bottomlands had more abundant fine-leaved species (e.g. Acacia spp. and Dichrostachys cinerea) and the uplands had more abundant broad-leaved species (particularly Combretum spp.). There was a greater difference in species composition in the high rainfall zone relative to the low and medium rainfall zones. This difference in species composition was consistent with the findings that the high rainfall zone had higher density, and a taller, single stemmed tree structure, as well as species richness and diversity when compared to the low and medium rainfall zones. Harvesting intensity was higher in the bottomlands than in the uplands and also higher in the low and medium rainfall zones than in the high rainfall zone. Recent harvesting appeared to have had less influence on species composition than catenal position or rainfall zone. The harvesting of these resources has an impact on both human livelihoods and the ecosystem and must therefore occur in a sustainable way. When the rate of wood production is less than or equal to the rate of wood harvesting, harvesting can be defined as sustainable. The rate of fuelwood harvesting is driven by the demand for the resource, which in most cases is driven by local human population size. With the increase in human population size over time, and the scarcity of fuelwood from the surrounding rangelands, the existence of fuelwood markets is fast becoming a part of daily life as it ensures fuelwood for daily usage such as cooking. For this reason, long-term monitoring is needed. Long-term monitoring will not only allow for better future management of natural resources, but it also allows for the communities to get involved in protecting the resources which are so vital to a vast number of people for daily living. Future studies analysing the data from these plots over longer time periods will provide a better understanding of the role that environmental and anthropogenic determinants play in the changes observed over time in the woody vegeta

An initial study of samples from 30 recently felled Irish oak trees established the validity of the dendrochronological method in Ireland and provided a standard chronology from A.D. 1649 to the present. Using timbers from previously undated post-medieval buildings in the north of Ireland this chronology has been extended back to A.D. 1380. The chronology has been used for the dating of numerous post-medieval timbers, of which two groups are discussed.

Tree-ring investigations on samples from modern oaks in the Swedish southwest region of Scania show that the area is a dendrochronological unit and that a chronology for the province is similar to a chronology for southern Denmark.

Extensive rescue excavations in Exeter during 1972 produced large quantities of waterlogged oak timbers. These were used to construct a tree-ring chronology for the period A.D. 799-1216. The chronology crossmatches well with tree-ring sequences from other areas of the British Isles. It will thus form an important building block in the construction of a long English tree-ring curve which can be used to date archaeological timbers from most regions of Britain.