Thesis (MSc.(Pasture Science)--University of Pretoria, 2007. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Hedgerow fruits provide a food resource for several UK farmland bird species from late summer, through winter and into spring. This project aims to develop the understanding of the interactions between fruit-bearing hedgerow flowers, their pollinators, hedgerow fruits and frugivorous birds. Experiments revealed that flowers of blackthorn, hawthorn and ivy all benefited from insect visits in order to develop fruit. The flowers of bramble and dog rose showed little requirement for insect pollination, and produced fruit when insects were excluded. There was evidence that for the hedges under study, the pollination service provided by insects to blackthorn and hawthorn flowers was inadequate since the flowers of these plants were pollen limited. The relative abundance of different insect groups foraging on blackthorn flowers was highly variable between hedges, suggesting that the contribution of a particular insect group to blackthorn pollination may vary according to their local density. Bumblebees, bristly flies and solitary bees were considered to have the greatest value for pollinating blackthorn flowers, based on foraging attributes (bumblebees and solitary bees), and abundance (bristly flies), but their activity did not correlate with the proportion of flowers that set fruit. Solitary bee activity correlated with hawthorn pollination, and there was strong evidence that social wasps were the best pollinators of ivy flowers on the hedges studied. Environmental factors such as hedge aspect did not significantly affect the activity of most pollinators (with the exception of solitary bees) or the proportion of blackthorn flowers that set fruit. Equally, the presence of the mass-flowering, attractive forage source, oilseed rape in fields adjacent to hedgerows, did not significantly influence the activity of most pollinators or the proportion of hawthorn flowers that set fruit. The abundance of some frugivorous birds, in particular the migratory thrushes (redwings and fieldfares) was positively related to the yield of fruits, including sloes and haws in hedges. So the evidence suggests that on these farms, pollinator communities are important for ensuring some hedgerow shrubs provide copious fruit, which may be vital for birds during winter months when invertebrate food is scarce. These links between flowers, pollinators, fruits and birds are discussed, alongside suggestions for safeguarding the fruit supply for farmland birds in the future.

Thesis (Ph.D.). / Written for the Dept. of Plant Science. Title from title page of PDF (viewed 2009/06/11). Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

No description available.

The effect of field margin management on crop yield and weed biomass in the crop edge (headland) was investigated. Treatment did not have any significant effect on cereal yields, and taking a one metre strip out of crop production to establish a sterile, natural regeneration or sown strip, did not significantly reduce yields compared to cropping to the field edge. Conservation headlands generally contained greater amounts of weed biomass than fully sprayed headlands, but grain yields were not significantly reduced. Soil compaction affected yield in one of the field experiments, but not the other, where soil density values were fairly uniform. No relationship was found between fertiliser application and yield. In a survey of cereal headlands, distance from the field boundary was the most important factor affecting yield. Where yield increased with distance from the field boundary, there was a strong linear relationship with log distance (P < 0.001). Weed dry matter was related to distance, and there was a significant relationship between weed dry matter and grain yield in the first year of the survey (p < 0.001), but not in the second. Communities of herbaceous field margin species were established, and the effects of nitrogen fertiliser and sublethal glyphosate application were examined over two years. Cover abundance of grasses was greater than that of dicotyledonous species throughout. Bromus sterilis was the most abundant species in 1995, but by 1996 it had been replaced by Arrhenatherum elatius. Increasing fertiliser rate had a negative effect on total vegetation cover in 1995, due to individual plants lodging. During 1996, fertiliser application increased the cover abundance of the dominant perennial species A. e/atius (p < 0.001), and also the annuals B. sterilis and Galium aparine (p < 0.05). Sublethal doses of glyphosate significantly reduced total cover abundance (P < 0.001), and had a greater effect on grasses compared to dicotyledonous species. Measurement of spray drift into a hedgerow showed that positioning the end of the tractormounted spray boom 2m or 6m away from the crop edge reduced drift into the hedgebottom compared with spraying up to the crop edge (P < 0.001).

Thesis (M.S.)--University of Missouri-Columbia, 2007. / 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 April 3, 2008) Includes bibliographical references.

No description available.

If upland rice production is to be sustained on sloping land, soil erosion and fertility decline must be addressed. Where soil profiles are deep, hedgerows of Gliricidia sepium and Cassia spectabilis, planted on the contour, reduce soil erosion by promoting terrace formation and overcome fertility depletion by providing nutrient rich biomass. G. sepium and C. spectabilis established by seed survived better than by cuttings. Although increased hedgerow biomass was initially obtained when both species were intercropped, intense competition was observed in established hedgerows. Consequently, mixing both species at high planting density is not recommended as C. spectabilis, a non-fixing legume, may deplete soil-N reserves. In acid soils, biomass production of G. sepium was significantly increased when lime (6 t/ha) was applied. On 18 to 30% slopes, upland rice and maize production improved along fertility and moisture gradients. Rice yields were increased when biomass of G. sepium was incorporated into the soil, up to an optimum level equivalent to 40 kg N/ha. Mulching C. spectabilis increased maize productivity during the drought prone second season. Competition was observed at the hedgerow-crop interface particularly at the upper one as a result of terracing. Although green manuring increased crop yield, broadleaf weeds, seedling maggot, stemborer and blast also increased. Strategies to manage hedgerow biomass that minimize these problems need to be developed.