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Eileen Power (PhD student)

photo of eileen power

Research Profile

PhD: The impacts of management and landscape context on plants and pollinators in intensive agricultural grasslands (2008-2011, Department of Agriculture, Fisheries and Food Research Stimulus Fund (RSF) funding)

Agricultural intensification may have caused significant declines in plant and pollinator diversity and pollination services. Efforts to reduce management intensity through the development of novel technologies and funding of agri-environmental schemes, particularly organic farming, have often proved effective in arable systems. However, little is known about the impacts of new technologies and organic farming in grassland systems, despite the widespread distribution of intensive grasslands in Europe.

Using experimental plots, at three silage sites in Ireland, I investigated impacts of different herbicide types applied using traditional (blanket and spot spraying) and novel (automated spot-spraying) techniques on non-target plant diversity and production. I found that all herbicides and traditional techniques reduced non-target plant diversity. The novel technique did not reduce non-target plant diversity. Production levels were unaffected by weed infestation. Findings indicate that the effects of herbicides on non-target plants can be much more significant than their perceived benefits to production and that efforts to reduce their application be encouraged in grassland systems.

I investigated the effects of organic versus conventional farming on insect-flower interaction networks; bee and hoverfly diversity, and pollination in ten pairs of organic and conventional dairy farms in Ireland. All the networks (organic and conventional) were vulnerable to collapse. Nevertheless, organic farming provided more flowers, particularly Trifolium spp., that attracted more flower visitors (a higher abundance of bees in particular) and improved pollination of a wild plant. Organic farming, though not a solution in its present form, can benefit insect biodiversity and insect-mediated pollination.

At the same farms, I investigated whether insect- and non-insect pollinated forb richness was related to local and landscape factors. Organic fields contained more insect-pollinated forbs than conventional fields. Insect-pollinated forb richness increased with increasing landscape complexity, whereas non-insect pollinated forb richness was unrelated to landscape complexity. Insect-pollinated forbs show relationships to landscape complexity similar to those documented for many pollinators, particularly bees, with interesting implications for their management.

I investigated how hoverfly diversity was related to local and landscape factors at the same farms. Hoverfly abundance was higher on organic farms, while species richness was positively correlated with floral abundance. Homogenous landscapes supported higher hoverfly diversities locally but there was no interaction between farming system/floral abundance and landscape complexity for hoverfly diversity. Findings illustrate complex relationships between hoverflies, local factors and the landscape matrix that seem to differ from previous findings for bees.

On the same farms I conducted a sociological survey of 10 organic and 10 conventional farmers and related it to the plant richness data. I found that organic farmers, who had more positive attitudes to the environment and were better informed about it, had higher biodiversity on their farms compared to less positively inclined, less informed organic farmers. Thus, farmer environmental attitudes and knowledge can influence the effectiveness of an agri-environmental scheme.

Intensive grasslands are important in maintaining wild plant and pollinator populations, their interactions and pollination in the agricultural landscape. However, intensive grassland biodiversity is vulnerable to disturbance from farm management activities and changes in the landscape matrix.

Contact details

Botany Building, School of Natural Sciences, Trinity College Dublin, Dublin 2. Tel: +353-1-8962208 Email



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Last updated 11 September 2013