Plant-pollinator interactions of the ground flora of a deciduous woodland

Abstract

The relationship between plants and pollinators were investigated in Shincliffe Woods, Durham, using 35 fixed quadrats. For three months, May, June and July, flowering phenology of the ground flora, general insect abundance and pollinator abundance were examined. Most of the plant species present at the site flowered during May. This was also the month during which overall insect and pollinator abundance were greatest. General insect abundance fell during the next two months, while the number of plant species in flower and pollinator numbers fell in June but recovered in July. After May the majority of plants in flower were found at the site margins. Most pollinators were generalists in nature and found on a number of plant species. This agrees with the findings of previous studies conducted in deciduous woodland. Few groups appeared to show a preference for any particular floral morphology, except Apidae which were found almost entirely on tubular flowers. These findings tend to support recent studies which suggest that plant-pollination relations are very general. Coleoptera and Diptera were the most numerous pollinator classes. The array of pollinators seen changed with season, both in composition and abundance. The majority of flowers had an open morphology and were white in colour. This may have been an adaptation to conditions where pollinators are scarce or erratic. Fruit-set in most species was generally quite high. This was probably because of the widespread occurrence of autogamy and self-compatibility in the species studied. Because of the abundance of small, immobile pollinators such as Coleoptera and Diptera it is unlikely that the amount of outcrossing experienced by most plant species was high. Plants which relied on outcrossing for their reproductive success generally showed low fruit-set.