Thesis (M.S.)--Kent State University, 2010. / Title from PDF t.p. (viewed May 17, 2010). Advisor: Barbara Andreas. Keywords: Floristic Survey; Geauga County, Ohio. Includes bibliographical references (p. 437-441).

I investigated the return of plant canopy diversity to degraded spekboom thicket landscapes under restoration treatment. I attempted the reintroduction of five nursery propagated and naturally-occurring plant species in severely degraded Portulacaria afra Jacq. (spekboom) dominated thickets that have been subjected to a restoration method involving the planting of dense rows of P. afra truncheons for various time periods and also in degraded and intact thickets. I also planted nursery propagated P. afra cuttings. An average of 30 propagules of each species, were planted in each of the chosen areas in two distinct seasons that exhibited distinct rainfall peaks. Sixteen propagules of P. afra were also planted in each treatment only once. Propagules of the two thicket woody canopy species (S. longispina and P. capensis) showed a total survival of 1% and 9%, respectively. Survival of L. ferocissimum and R. obovatum was 19% and 70% and all propagules of P. afra survived. Analyses showed that survival is primarily tied to a species effect, with R. obovatum and P. afra showing significantly better survival than the other species. Within the other surviving few species a significant preference for overhanging canopy cover was observed. The results show little significance of restoration treatment for propagule survival, suggesting that a range of conditions is needed for the successful establishment of canopy species that likely involves a microclimate and suitable substrate created by canopy cover and litter fall, combined with an exceptional series of rainfall events. I found that the high costs involved with a biodiversity planting endeavour, and the low survival of propagules of thicket canopy plant species (P. afra excepted), renders the proposed biodiversity planting restoration protocol both ecologically and economically inefficient. Restoration success involves the autogenic regeneration of key species or functional groups within the degraded ecosystem. Heavily degraded spekboom-dominated thicket does not spontaneously regenerate its former canopy species composition and this state of affairs was interpreted in terms of a state-and-transition conceptual model. Floristic analyses of degraded, intact and a range of stands under restoration treatment for varying time periods at two locations in Sundays Spekboomveld revealed that the stands under restoration are progressively regenerating canopy species biodiversity with increasing restoration age, and that intact sites are still the most diverse. The high total carbon content (TCC) measured within the older restored stands Rhinosterhoek (241 t C ha-1 after 50 years at a depth of 50 cm) rivals that recorded for intact spekboom thickets, and the number of recruits found within older restored sites rivals intact sites sampled. 2 The changes recorded in the above- and belowground environments potentially identify P. afra as an ecosystem engineer within spekboom dominated thickets that facillitates the build-up of carbon above- and belowground and the accompanying changes in soil quality and the unique microclimate aboveground, which enables the hypothetical threshold of the degraded state to be transcended. This restoration methodology is accordingly considered efficient and autogenic canopy species return was found to be prominent after a period of 35-50 years of restoration treatment.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Thesis documentation sheet inserted. Appendix reproduces five manuscripts and journal articles co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix of papers.

No description available.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2007. / Thesis documentation sheet inserted. Includes appendix of four papers and manuscripts co-authored with others. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available in print.

Thesis (M. Ed.)--Kutztown University of Pennsylvania, 1997. / Source: Masters Abstracts International, Volume: 45-06, page: 3071. Typescript. Abstract precedes thesis as preliminary leaves [1-2]. Includes bibliographical references (leaves 76-79).

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Mechanisms that favour rare species are key to the maintenance of diverse communities1–3. One of the most critical tasks for conservation of flowering plant biodiversity is to understand how plant–pollinator interactions contribute to the maintenance of rare species4–7. Here we show that niche partitioning in pollinator use and asymmetric facilitation confer fitness advantage of rarer species in a biodiversity hotspot using phylogenetic structural equation modelling that integrates plant–pollinator and interspecific pollen transfer networks with floral functional traits. Co-flowering species filtered pollinators via floral traits, and rarer species showed greater pollinator specialization leading to higher pollination-mediated male and female fitness than more abundant species. When plants shared pollinator resources, asymmetric facilitation via pollen transport dynamics benefitted the rarer species at the cost of more abundant species, serving as an alternative diversity-promoting mechanism. Our results emphasize the importance of community-wide plant–pollinator interactions that affect reproduction for biodiversity maintenance.

In urban areas, residential and community gardens are potential floral resources for pollinators. Pollinator "friendly" gardens are a popular way to support this ecosystem service, but the pollinator plant list recommendations lack empirical evidence to show which plants are most attractive to potential pollinators. This project used a community science survey based on a morpho-species protocol to monitor five community orchards in Portland, Oregon during six months of the growing season in 2017. Overall, orchards with higher floral species richness supported higher richness and abundance of pollinators, but the pollinator communities were not significantly different among the orchard sites. Orchard fruit-set had a variable correlation with pollinator richness and abundance. At the landscape level, the number of miles of street within 500m showed a strong negative correlation with the overall pollinator community richness. Bumble bee abundance showed a strong negative correlation with the percentage of single family residential zoning, and NDVI at 2000 meters. Our community science approach promoted volunteer awareness of pollinator diversity in Portland, but did not increase volunteer intention to conserve pollinators. This research helped build evidence of the dynamics of urban pollinators and the role that community science can play in pollinator biodiversity monitoring.