Flowers and bees in the city: The impact of urbanisation on native plants and their insect pollinators

Eakin-Busher, Emily L. (2021) Flowers and bees in the city: The impact of urbanisation on native plants and their insect pollinators. PhD thesis, Murdoch University.

Abstract

Urbanisation is one of the most intensive and irreversible ecosystem changes facing the plants, animals, and people that live in the world’s cities. Where native vegetation is cleared, habitat loss and fragmentation have major impacts on the viability of animal and plant populations. Removal of vegetation reduces plant population size, which impacts the resources available to flower visitors. In turn, this can reduce plant pollination and subsequent reproductive success. Understanding how landscape alteration affects ecosystem services such as pollination is fundamental to the conservation of native plants and their pollinating insects.

The aim of my research was to contribute knowledge of the interaction between native plants and pollinating insects in an urban environment. The study region included remnant native vegetation and native gardens in Perth, Western Australia that likely provide novel resources for some insects, while degrading resources for others. I aimed to establish the importance of insects to the reproductive success of native plants, to identify the site and landscape characteristics that influenced particular insect groups, and to determine pollen movement within a remnant bushland.

After hours (50) of careful observations of insects visiting flowers of five common native plant species, and pollinator exclusion studies, I found that four plants were reliant on insects for pollination to varying extents, but predominantly outcrossing species such as Dianella revoluta and Jacksonia sericea may be more vulnerable to urbanisation. I passively sampled insects and found that remnants and gardens were complementary in providing resources and introduced and native bees were observed, but their richness was generally low. Using detailed genetic data, I found that Patersonia occidentalis showed moderate outcrossing, which was maintained by insects moving pollen up to 116 m between plants within a small remnant. My studies point towards the importance of connectivity between small remnants, gardens and larger remnants for maintaining plant–insect interactions in the world’s urban landscapes.

Item Type:	Thesis (PhD)
Murdoch Affiliation(s):	Environmental and Conservation Sciences
United Nations SDGs:	Goal 11: Sustainable Cities and Communities Goal 15: Life on Land
Supervisor(s):	Standish, Rachel, Fontaine, Joe and Ladd, Phil
URI:	http://researchrepository.murdoch.edu.au/id/eprint/59262

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