• Richard Sands

    Student thesis: Master of Philosophy


    A reduction in floral resources and the use of pesticides has led to sever pollinator declines. In response to these declines, Environmental Stewardship Schemes use conservation initiatives such as the planting of wild flowers rich in nectar and pollen around field margins with the aim of increasing pollinator numbers. Within nectar and pollen mixes, red clover (Trifolium pratense) is an important plant that helps to attract bumblebees. However, to reduce the cost of these mixtures, wild T. pratense seed is often exchanged for seed from agricultural cultivars, but it is not clear whether these cultivars are suitable for inclusion to nectar and pollen mixes and the genetic homogeneity of these cultivars may reduce their effectiveness. We therefore tested the hypothesis that plots of wild-type T. pratense produce more flowers with better provisions than agricultural cultivars, leading to a greater abundance of bumblebees and the hypothesis that plots of multiple agricultural cultivars will out-perform single plots of agricultural cultivars. Furthermore, we also tested the hypothesis that plots of T. pratense from different sources host different invertebrate communities due to the heterogeneity of plant phenotypes. We compared the growth and floral characteristics of two wild-type T. pratense populations, five agricultural cultivars grown in isolation, and plots of multiple agricultural cultivars over a 14 week period. A total of 160 pots of T. pratense were planted (20 pots of each plant type) at the botanical grounds at the University of Manchester. A second experiment compared the invertebrate communities and number of Bombus spp. visiting wild-type, agricultural and mixed agricultural T. pratense plots over an eight week period. Wild populations of T. pratense produced more inflorescences than agricultural cultivars, although agricultural cultivars produced larger inflorescences containing more pollen grains than wild populations. More bumblebees were found on wild type plants, although greater numbers were found per inflorescence on single and mixed agricultural cultivars, and the invertebrate communities were different between wild-type and agricultural plants. Wild-type populations were very different from each other and the selection of a poorly performing population could reduce the effectiveness of nectar and pollen mixes. There is also the risk of selecting a poorly performing agricultural cultivar. Therefore, this thesis concludes that the selection of multiple agricultural cultivars is the best management choice as it reduces the risk of selecting a poorly performing T. pratense type without extensive trials of plant types.
    Date of Award31 Dec 2013
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorAnthony Ennos (Supervisor), Richard Preziosi (Supervisor) & Jennifer Rowntree (Supervisor)


    • Community
    • Environmental Stewardship
    • Red Clover
    • Pollen
    • Bumblebees
    • Interaction

    Cite this