Pollinators, and the pollination services they provide, are essential for the reproduction of the majority of angiosperms, but also for a wide variety of crops. However pollinators are increasingly threatened by many human activities including land use change and agricultural intensification. A major shift in agricultural land use is beginning with the widespread promotion and cultivation of bioenergy crops as an alternative fuel source to combat climate change, with potentially major implications for biodiversity.

The aim of this thesis was to examine the impacts of changes in agricultural regions, specifically the growth of bioenergy crops, on pollinators and pollination services in Ireland. Using a large network of commercial fields, I investigated the impacts of growing two model bioenergy crops (oilseed rape Brassica napus L. and Miscanthus X giganteus) on pollinator diversity, abundance and community composition in comparison to the crops they replace in the landscape.

I found varying effects of bioenergy production on different pollinator taxa, with the solitary bees the group most affected. Higher abundances and species richness of solitary bees were found in bioenergy crops than in conventional ones, and community composition of this group differed between bioenergy crops also. This may be due to increased floral resources in the bioenergy crops, although perennial Miscanthus did not provide more nesting resources for bumblebees than annual crops. Overall, field margins and hedgerows were the most important habitats for pollinators. This indicates that bioenergy production at the field scale in agricultural areas does not have negative implications for pollinators and may even have positive benefits for some taxa, and that a variety of crop types within the landscape can be beneficial for solitary bees.

In the same fields, I used plant-pollinator networks to examine effects of mass flowering oilseed rape during and after flowering, different bioenergy crops, and the composition of the landscape surrounding the fields on the interactions between flower visiting insects and plants. Networks were robust to changes in a mass flowering resource, but replacing arable land with bioenergy crops caused changes in network structure. However, landscape context also affected network properties, suggesting that both local and landscape effects should be considered when studying species interactions and resulting pollination services. The most common visitors to mass flowering oilseed rape in Ireland are a cryptic bumblebee complex, but little is known about the proportions or requirements of the different cryptic species. I investigated, using molecular methods, what the proportions and colony densities of the different species were in spring oilseed rape fields, in comparison to the second most common bumblebee visitor. I found different proportions and colony densities of the different cryptic species, and that the different species responded differently to the composition of landscape surrounding the fields suggesting different ecological requirements. Interestingly, large numbers of bumblebee colonies (up to 880) were found to use individual spring oilseed rape fields as a resource.

Although oilseed rape provides forage resources for pollinators when the crop is in flower, pollinators are often associated with semi-natural habitats and field margins. I investigated whether pollinators use wild plants as a forage resource in addition to oilseed rape when the crop is in flower, and whether this has implications for pollination services to these wild species. I found that oilseed rape shares pollinator taxa and individuals with a variety of wild plants in the margins and hedgerows, and that the majority of insects foraging on oilseed rape also carried wild plant pollen. However, little crop pollen becomes deposited on wild plant stigmas suggesting this is not a mechanism for interference with pollination services to wild plants.

Lastly, in a final study I examined the pollinators and pollination of oilseed rape in Ireland. Oilseed rape is visited by a wide range of insect species, with bumblebees the most abundant pollinators followed by honeybees. Winter oilseed rape produces more seed with insect pollination, showing that insects can improve crop yields, and therefore market value, of the crop in Ireland. Finally, I conclude with a synthesis of results and some methodological considerations. I propose some suggestions for both pollinator conservation in farmland, and bioenergy policy to mitigate impacts on biodiversity. I also highlight some potential areas for further research.


The data uploaded from this project has contributed to the following papers published in peer reviewed international journals - see below for details:

Stanley DA, Stout JC (2013) Quantifying the impacts of bioenergy crops on pollinating insect abundance and diversity: a field-scale evaluation reveals taxon-specific responses. Journal of Applied Ecology, 50, 335-344.

Stanley DA, Knight ME, Stout JC (2013) Ecological Variation in Response to Mass-Flowering Oilseed Rape and Surrounding Landscape Composition by Members of a Cryptic Bumblebee Complex. PLoS ONE 8(6): e65516. doi:10.1371/journal.pone.0065516

Stanley D, Gunning D, Stout J (2013) Pollinators and pollination of oilseed rape crops (Brassica napus L.) in Ireland: ecological and economic incentives for pollinator conservation. Journal of Insect Conservation, 1-9. 10.1007/s10841-013-9599-z

Bourke, D., Stanley, D., O'Rourke, E., Thompson, R., Carnus, T., Dauber, J., Emmerson, M., Whelan, P., Hecq, F., Flynn, E., Dolan, L. and Stout, J. (2013), Response of farmland biodiversity to the introduction of bioenergy crops: effects of local factors and surrounding landscape context. GCB Bioenergy. doi: 10.1111/gcbb.12089

Stanley DA, Bourke D, Stout JC (in review) Local and landscape factors influence plant-pollinator network structure in agricultural systems. Functional Ecology.

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This resource has SEMI-PUBLIC availability. This means that the metadata for the resource is available to the public but the data files and information objects connected to the resource are not. There are currently 1 data files and/or information objects connected to this resource. You will need to contact the owners of this resourceto seek their consent to access the files. Contact information for the owners of this resource can be found in the Responsible Parties information section of the metadata.

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SAFER-Data Display URL	https://eparesearch.epa.ie/safer/iso19115/display?isoID=3028
Resource Keywords	pollinators, ecosystem services, Miscanthus, oilseed rape
EPA/ERTDI/STRIVE Project Code	2007-B-CD-1-S1
EPA/ERTDI/STRIVE Project Theme	Biodiversity
Resource Availability:	Semi-Private
Limitations on the use of this Resource	Time restrictions based on publishing peer reviewed articles from this research are requested. Please contact Dr Dara Stanley for more details stanleyd@tcd.ie
Number of Attached Files (Publicly and Openly Available for Download):	0
Project Start Date	Tuesday 1st April 2008 (01-04-2008)
Earliest Recorded Date within any attached datasets or digital objects	Monday 1st September 2008 (01-09-2008)
Most Recent Recorded Date within any attached datasets or digital objects	Sunday 30th June 2013 (30-06-2013)
Published on SAFER	Monday 21st October 2013 (21-10-2013)
Date of Last Edit	Wednesday 4th December 2013 at 17:30:05 (04-12-2013)
Datasets or Files Updated On	Monday 21st October 2013 at 15:13:18 (21-10-2013)

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Description of Geographical Characteristics of This Project or Dataset
Data were collected in 2009 and 2010 in South-East Ireland, where arable, beef and dairy farming are interspersed and government grants have resulted in relatively small-scale commercial planting of Miscanthus on both former arable land and grassland since 2006. We compared each bioenergy crop to a conventional crop that it commonly replaces on farmland: Miscanthus planted on former arable land and winter oilseed rape were compared with a common arable crop (winter wheat), and Miscanthus planted on former grassland to a common grass crop (grass silage). Ten fields of each crop type were selected in the study region. All fields were selected to be as similar as possible in terms of management, size (median field size 4 5 hectares), number of hedgerows and altitude and were at least 1 km apart from each other and from any other mass flowering crops. Only one field was selected per farm to allow for independence of management, and fields of different crop types were interspersed geographically.

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