PhD research project

PhD student: Lauren Fuller
Supervisors: Prof. John O'Halloran & Dr. Tom Kelly 
Funders: Department of Agriculture, Food and the Marine

Project Description:
Invertebrates comprise a large proportion of the biodiversity found within forested habitats. In particular, spiders play an important role in food-webs as both predators and prey and respond to small-scale changes in habitat structure, meaning they are particularly sensitive to forest management. Hoverflies play an important role in biological control and pollination and have been successfully used as indicators of habitat disturbance and quality.

This research addressed a number of topics pertinent to the forest types present in the contemporary Irish landscape and aimed to investigate the invertebrate diversity of these forests. Spiders were sampled using pitfall trapping and hoverflies were sampled using Malaise net trapping. Research to inform management for biodiversity conservation in forests is important from the initial planning stages and throughout the forest cycle. Therefore, topics included the impacts of afforestation and forest management practices, the importance of open space, the choice of tree species, and the use of indicators for biodiversity assessment, as well as rare native woodlands and the effect of grazing on invertebrate diversity.

Project Findings:
A total of 196 spider species (n=32,422) and 76 hoverfly species (n=1,828) were identified during this research in a range of forest types. Afforestation in agricultural grasslands positively affects the species richness of ground-dwelling spiders and the species composition of ground-dwelling spiders and hoverflies, but no effect was found on the species richness of hoverflies. The open habitat in young plantation forests is important for spider species of conservation concern and road-verges should be protected as the forest matures to maintain open areas for invertebrate diversity. The choice of tree species in plantation forests is an alternative method of enhancing forest biodiversity. Semi-native Scots pine (Pinus sylvestris) was found to support higher ground-dwelling spider diversity and specialist species compared to two commonly planted North American conifer species, Sitka spruce (Picea sitchensis) and lodgepole pine (Pinus contorta). Rare native woodlands in Killarney National Park were found to provide important habitat, which is otherwise scarce in Ireland, for five spider species. Additionally, deer grazing impacts on the structural diversity of vegetation in these woodlands which has a negative effect on spider diversity.

These results will inform forest policy and management to protect and enhance invertebrate biodiversity in order to promote sustainable forest management in Ireland and Britain.

Publications:

• Fuller, L., Oxbrough, A., Irwin, S., Kelly, T.C. & O'Halloran, J. 2013. The importance of young plantation forest habitat and forest road-verges for ground-dwelling spider diversity. Biology & Environment, X: X-X
• Coote, L., Dietzsch, A.C., Wilson, M.W., Graham, C.T., Fuller, L., Walsh, A.T., Irwin, S., Kelly, D.L., Mitchell, F.J.G., Kelly, T.C. and O'Halloran, J. 2013. Testing indicators of biodiversity for plantation forests. Ecological Indicators, 32: 107-115.

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