One of the principles regarding our knowledge about life on earth is that no organism can be fully understood without taking into account its surrounding environment. This study examines the extent to which ecosystem-focused field studies may be associated with students' academic performance and potential to contribute to the advancement of science and conservation. Pilot studies conducted in Panama and California established methods used in this project from 1993-2003. Two hundred and sixty-seven students conducted field studies in either Kenya or Costa Rica. Students worked in cognitive apprenticeships, in which research staff trained each student to conduct field research. At the conclusion of their fieldwork, the research staff assessed the students written field reports. The students' reports were then sorted according to the extent to which their studies were ecosystem-focused. Data analysis through nonparametric, Kruskal-Wallis statistical tests revealed no significant difference in academic performance on field study reports, in regards to whether the studies were narrow in scope (species-specific) or broad (ecosystem-focused). Marginal significance was revealed between ecosystem-focused studies and the potential for students' fieldwork to contribute to the advancement of science and conservation. Also addressed in the data were injuries, disease, and potential hazards, which were influenced by prudent and decisive leadership. Successful field studies require consideration of the content, context, and design of the intended field projects. Many of the solutions to environmental problems on the planet will come from the working hands of teachers and students that conduct explorations in the field. / Life Sciences in Education / D. Phil. (Mathematics, Science and Technology Education)

One of the principles regarding our knowledge about life on earth is that no organism can be fully understood without taking into account its surrounding environment. This study examines the extent to which ecosystem-focused field studies may be associated with students' academic performance and potential to contribute to the advancement of science and conservation. Pilot studies conducted in Panama and California established methods used in this project from 1993-2003. Two hundred and sixty-seven students conducted field studies in either Kenya or Costa Rica. Students worked in cognitive apprenticeships, in which research staff trained each student to conduct field research. At the conclusion of their fieldwork, the research staff assessed the students written field reports. The students' reports were then sorted according to the extent to which their studies were ecosystem-focused. Data analysis through nonparametric, Kruskal-Wallis statistical tests revealed no significant difference in academic performance on field study reports, in regards to whether the studies were narrow in scope (species-specific) or broad (ecosystem-focused). Marginal significance was revealed between ecosystem-focused studies and the potential for students' fieldwork to contribute to the advancement of science and conservation. Also addressed in the data were injuries, disease, and potential hazards, which were influenced by prudent and decisive leadership. Successful field studies require consideration of the content, context, and design of the intended field projects. Many of the solutions to environmental problems on the planet will come from the working hands of teachers and students that conduct explorations in the field. / Life Sciences in Education / D. Phil. (Mathematics, Science and Technology Education)

This study presents the results of a study on introduced giraffe diet and feeding effects within the Eastern Cape Province of South Africa. Five sites were selected over a moisture gradient from the mesic east to the arid west of the Eastern Cape to describe giraffe diet and provide baseline data for feeding effect experiments. At each site faecal samples were collected seasonally and diet composition determined by microhistological analysis. Plant species availability was measured using the point intersect method in order to compare plant availability to plant consumption to determine diet preferences. Giraffe diet across the sites showed a unimodal response to rainfall by utilising fewer species in drier areas where plant availability is low and increasing the number of species consumed as the rainfall increases. In higher rainfall areas, giraffe reduced the number of plant species fed upon because of the high availability of important species that reduces the need for a varied diet. Across all sites, plant availability was dominated by woody plant species (more than 90 percent at each site). A total of 57 plants species were recorded as being eaten across the five sites. Several PDI (Principle Diet Items) plant species (Acacia karroo, Schotia afra, Pappea capensis and Euclea undulata) were eaten across sites. Over all the sites, significantly preferred species were Asparagus striatus, Schotia latifolia, Asparagus suaveolens, Commelina benghalensis, Viscum rotundifolium, and Acacia cyclops. Acacia karroo, Schotia afra, Pappea capensis, Rhus crenata, A. tetracantha, and Grewia robusta were utilised in proportion to their availability. Euclea undulata, Rhus longispina and Putterlickia pyracantha were avoided. Feeding effects were tested by erecting exclosures around trees, covering one half of each tree. Ten trees were selected for these manipulative experiments which ran from September 2003 to February 2005. The number of branches, number of leaves, branch orders, branch diameter, branch length, leaf length and leaf width were measured for ten samples per side (enclosed vs. exposed) and analysed using a Wilcoxon matched pairs test and tested for effect size using Cohen’s d. Although no significant differences were detected between the sides measured, the effect size indicated differences in all measurements between sides ranging from low to moderate. Leaf length was greater on the outside of exclosures and showed a moderate difference between the sides in terms of the d-value with the p-value (0.059) tending towards significance. Although leaf width was higher on the inside of exclosures, it only showed a moderate difference for d with no statistical significance. Leaf area was higher on the inside of exclosures and tended to significance (p = 0.059) and similarly the d value indicated moderate differences between the sides in terms of effect size. Similarly branch length was higher on the inside of exclosures although not significantly, the p-value (0.07) approached significance. The effect size for branch length also showed a moderate difference between the sides. The number of branches and the number of leaves showed no statistical differences between the sides although the p-value (0.059) for the number of branches, as well as number of leaves (p = 0.07) approached significance. For both these variables, effect size showed a moderate difference. Giraffe showed diversity in their diet selection across sites but mainly fed upon available species. Some preferred species were however less available and this preference could possibly result in increased pressure on the selected plant species Exclosure experiments showed no significant differences in leaf and shoot characteristics although all measurements showed differences in terms of effect size meriting further investigation. It is concluded that giraffe impact on sites may be reduced if populations are properly managed however, high densities of giraffe could lead to similar vegetation impacts as observed in other areas where giraffe have been introduced and potentially change vegetation structure and plant community composition.

The giraffe at Nyaru were found to be browsers who made little use of graze during the study period. They utilized a diversity of 20 browse species. Two species, Acacia karroo and Acacia cyclops, formed the bulk of the giraffe diet throughout the year. A definite seasonal dietary shift was evident. A. karroo was favoured in summer and autumn and formed the main food species in spring, summer and autumn. A. cyclops was favoured throughout the study, but its contribution to the diet increased during winter when less A. karroo was consumed. This seasonal shift is related to the deciduous nature of Acacia karroo. Although a seasonal shift in species contribution to giraffe diet has been observed in many other giraffe feeding studies, no studies on giraffe feeding have been done in the Mosaic Thicket of the southern Cape. The ecological browsing capacity for giraffe in thicket was estimated to be between 0.020 BU/ha and 0.095 BU/ha. The browsing capacity for giraffe at Nyaru, based on the available phytomass 2–5 m above the ground, was estimated using those species that formed the bulk of the giraffe diet, and amounted to 0.063 BU/ha. A maximum of three giraffe could thus be stocked on the 157 ha of suitable giraffe habitat on Nyaru. This stocking rate recommendation lies within the range commonly recommended by local consultants for giraffe introductions into the southern Cape. Their recommendations are, however, not based on quantitative assessments such as performed in this study. The recommendation of this study should not be applied as a fixed ecological capacity for giraffe in thicket, but should be seen as a starting point in the adaptive management cycle. Ongoing monitoring of parameters, such as herbaceous composition and phytomass; as well as the condition of key browse species, is strongly advocated. A. karroo was browsed significantly more and carried significantly fewer pods per tree at a heavily used site compared to a lightly used site. Heavy browsing thus appears to affect the reproductive success of A. karroo significantly. Fewer pods are likely to lead to lower regeneration and thus reduced density of A. karroo. Whether A. karroo will maintain its dominance within the thicket vii community in the long run will be related to how individual plants survive and reproduce and if some can escape from herbivory. Fewer G. occidentalis were clumped with other species at the heavily used site compared to the lightly used site. This could possibly be attributed to the fact that intense browsing pressure at the heavily used site caused protective clumps to be eaten away, thus exposing G. occidentalis to higher ungulate browsing. Previous studies have found that nurse shrubs protect G. occidentalis against ungulate browsing. G. occidentalis was browsed significantly more at the heavily used site compared to the lightly used site. There was a general trend of fewer fruits at the heavily used site compared to the lightly used site, while fruits were absent on G. occidentalis growing alone at the heavily used site. This suggests a negative effect of heavy browsing on plant reproductive success and emphasizes the importance of nurse plants for the successful recruitment and hence long term prevalence of G. occidentalis in Mosaic Thicket.