Thesis (M.S.)--University of Wisconsin-Madison, 1991. / Typescript. Includes bibliographical references (leaves 39-42).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 119-125). Also available via the Internet.

Thesis (M.S.)--University of Wisconsin-Madison, 1991. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 39-42).

Thesis (Ph. D.(Botany))--Rhodes University, 2001.

Most elephants in South Africa live in enclosed areas such as the Tembe Elephant Park in Maputaland. The Park also protects sand forest. This can create a conflict of interest as elephants may influence species typical of these forests. To assess the effects that elephants may have for vegetation, I compare variables of similar plant communities inside and outside the Park. I then compared the space and landscape utilization of elephants living in the Park with those of free-ranging elephants living in southern Mozambique. In the final analyses, I used meta-analytical methods to interpret my findings. Woody seedlings showed no measurable response to tree canopies that elephants have altered, but the response of grasses and woody saplings depended on the landscape type. In closed woodlands, elephants generated gaps in the canopy layer that increased structural heterogeneity. These gaps favoured the establishment of grasses, and along with herbivory, may have been responsible for reduced occurrence of woody saplings. In the open woodlands, elephants and frequent hot fires in the Park apparently homogenised this landscape. In this case, altered tree canopies reduced grass and woody sapling presence. The species compositions of sand forests, closed woodlands and open woodlands between inside and outside the Park differed. However, tree and shrub densities, their abundance-incidence and rank-abundance relationships were similar for a given landscape inside and outside the Park. Ecological events operating at larger scales, such as seed dispersal and droughts, mask the influence elephant have for these community variables. Elephants in the Park had smaller home ranges than free-ranging elephants living in southern Mozambique. The size of these home ranges were however, similar to that predicted by rainfall, as suggested by my analysis of data collected across southern Africa. The elephants that roamed freely in southern Mozambique prefer closed woodlands throughout the year. However, elephants confined to the Park avoided reed beds (with natural surface water) in the dry season and showed no landscape preference in the wet season. My meta-analysis on the effects of elephants on other taxa included 230 peer-reviewed studies. These were published over a 40-year period and included information from 74 sites. From only those studies used in the effect size calculations, when conducted over a period of less than 5 years show a negative impact while those conducted over longer periods show a neutral effect. Site-specific differences, such as rainfall, may also influence the effect elephants have for plants. Twenty of the 230 studies shared more than 50% of all citings. The majority (16 of the 20) claimed that elephants had a negative influence for plants. This is in contrast with the findings of all studies included in the analysis – half of these concluded a positive effect and the other half a negative effect. In short, elephants do not decrease the diversity of other species present in the system, despite their adverse effects for individual trees. Elephants affect ecosystems at small scales. Providing an opportunity for elephants presently living in Tembe Elephant Park to disperse across their former ranges may negate negative influences on sensitive vegetation in the Park. / Thesis (PhD (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

"Last biannual progress report and final report describing work under NASA contract no. NAS5-21812."

Arctic air temperatures have increased at two to three times the global rate over the past century. As a result, abiotic and biotic responses to climate change are more rapid and pronounced in the Arctic compared to other biomes. One important change detected over the past several decades by satellite studies is a lengthening of the arctic growing season, which is due to earlier onsets and/or delayed ends to growing seasons. A handful of studies also suggest the peak green season (i.e. when the tundra is at maximum leaf-out and maximum carbon uptake potential) is starting earlier in the arctic tundra. The vast majority of studies detecting shifts in the growing season suggest this is due to increasing spring and fall air temperatures, which lead to earlier spring snowmelt and later fall snowfall. Less well understood is how indirect consequences of arctic warming, such as ongoing changes in plant community composition, may also be contributing to these satellite signals. For instance, there is mounting evidence that deciduous shrubs are expanding into previously non-shrub dominated tundra in several parts of the Arctic. Deciduous shrubs may alter tundra canopy phenology and contribute to the regional shifts in timing of phenological events being detected by satellites. Concurrently, in many areas where deciduous shrubs are expanding they are also becoming taller. As taller shrubs become increasingly dominant, arctic landscapes may retain more snow, which could lengthen spring snow cover duration, and offset advances in the start of the growing season that are expected as a result of earlier spring snowmelt. As a consequence, deeper snow and later snowmelt in taller shrub tundra could delay plant emergence, and shorten the period of annual carbon uptake. Thus greater dominance of taller stature deciduous shrubs in the Arctic may actually delay the onset of the growing season, which would suggest that increasing deciduous shrub dominance may not be contributing to satellite signals of an earlier start to the growing season. To contribute to satellite-detected shifts in the onset of the growing and peak seasons, tall deciduous shrubs would need to have accelerated leaf development to compensate for deeper snow packs and later spring snowmelt relative to surrounding tundra. Understanding the drivers of shifts in tundra phenology is important since longer (or shorter) growing and peak green seasons would increase (or decrease) productivity and the period of carbon uptake, which will have implications for landscape-level carbon exchange, and ultimately global carbon balances. Given the rate and magnitude of changes occurring in the face of acute arctic warming, there is a need to monitor, understand, and predict ecological responses over large spatial and temporal scales. However, compared to more southern environments, the arctic tundra is characterized by considerable heterogeneity in vegetation distribution, as well as a short and rapid growing season. In addition, the arctic tundra is relatively vast and inaccessible. These characteristics can make it difficult to monitor and study changes in the Arctic, and make it difficult to develop landscape-level models able to predict changes in ecosystem dynamics and tundra vegetation. The use of airborne and satellite sensors has at least partially fulfilled these needs to monitor, understand, and predict change in the Arctic. The normalized difference vegetation index (NDVI) acquired from these sensors, for instance, has become a widely adopted tool for detecting and quantifying spatial-temporal dynamics in tundra vegetation cover, productivity, and phenology. This suggests that remote sensing technology and vegetation indices may be similarly applied to characterizing patterns of primary and secondary consumers (e.g. arthropods), which would be enormously useful in a region as vast and remote as the Arctic. The research presented in this dissertation provides useful insight into the influence vegetation community composition, particularly increasing deciduous shrub dominance, has on phenology, carbon flux, and canopy arthropod biomass in the arctic foothills region of the Brooks Range, Alaska. Findings in Chapter one suggest that delayed snowmelt in areas dominated by taller shrubs may have a short-lived impact on the timing of leaf development, likely resulting in no difference in duration of peak photosynthetic period between tall and short- stature shrubs. Findings in Chapter two suggest that greater deciduous shrub dominance not only increases carbon uptake due to higher leaf area relative to surrounding tundra, but may also be causing an earlier onset of, and ultimately a net extension of, the period of maximum tundra greenness and further increasing peak season carbon sequestration. Findings in Chapter three suggest that measurements of the NDVI made from air and spaceborne sensors may be able to quantify spatial and temporal variation in canopy arthropod biomass at landscape to regional scales in the arctic tundra.

An inventory of the vascular flora at Munsee Woods in Delaware County, Indiana revealed 399 species and varieties representing 255 genera and 86 families. The 10 families containing ~52% of the documented species (in order by number of species) were Asteraceae, Poaceae, Cyperaceae, Rosaceae, Brassicaceae, Lamiaceae, Fabaceae, Scrophulariaceae, Polygonaceae, and Liliaceae. Of the documented flora, 300 were native and 99 were exotics. The Floristic Quality Index (FQI) was 47.7, and the mean Coefficient of Conservation (Cav) was 2.4. A plot-based analysis of the woody vegetation was conducted for the southern mesic, upland woodland. Based on the relative importance values (RIV), the important species in order were Acer saccharum, Quercus alba, Celtis occidentalis, Prunus serotina, and Ulmus americana. Relative importance values were used to compare Munsee Woods to Christy Woods in Delaware County, Ginn Woods in Delaware County, and Yuhas Woods in Randolph County. The results of these comparisons were interpreted with regards to the disturbance history of the site, age of the stand, and the stage of succession. / Department of Biology

Thesis (Ph.D.)--University of Adelaide, Dept. of Geographical and Environmental Studies, 2001. / Includes bibliographical references (p. 301-319).

Thesis (MSc)-- University of Stellenbosch, 2007. / Masters of Science (Geographic Information Systems - Environmental Geography) Bibliography. Also available via the Internet.