Sam Tarrant

Project Title:
The Potential of Restored Landfill Sites to Support Assemblages of Pollinating Insects

Introduction

Insects play a crucial role in most terrestrial ecosystems, and one of the key functions they perform is providing pollination services. Pollinating insects include a wide variety of orders that are vital for effective pollination of wild plants and crops [1, 2], and their loss can have a cascading impact on other species [3]. Populations of pollinators are being lost due to habitat degradation and fragmentation across the world [3, 4]. For example, bumblebees have been decreasing in both diversity and abundance, mainly due to loss of habitat from agricultural intensification [5], and the research community seems to be in consensus that the decline in pollinators is an important issue in conservation biology [6, 7].

There has been considerable interest in restoration of habitats, but only recently has this specifically centered on restoring pollinator communities. One possible large reserve of land for habitat restoration and creation is landfill sites that have reached the end of their working life. There are approximately 2,200 working landfill sites in England and Wales, and they are closing at a rate of about 100 per year [8]. If the closing sites can be restored in a way that supports pollinating insect communities, then this may have positive effects for biodiversity conservation efforts. Research has been conducted on the potential for restored landfill sites for community forests [9], but no such work has been related to pollinating insect assemblages.

Aims

This project is aimed at understanding the potential of restored landfill sites for supporting ecological habitats suitable for pollinators. The major research questions are:

1. How is the plant assemblage being affected by the landfill site in terms of plant growth, phenology, and pollen production?
2. What factors are affecting the pollinator assemblage?
3. How is the assemblage of pollinators structured, comparing restored landfill with control areas?
4. an these results be used to understand the broader factors relating to the potential of restored landfill sites to support pollinating insects?

Field Research Methods

The approach being used in this research will be similar to that used by Forup and Memmott 2005 [10]; three 100 x 2 m transects will be randomly chosen in the study area. The transect will then be surveyed for entomophilous plant species, and following a 20-minute break, will be surveyed for flower-visiting insects. Surveys will be conducted on the sites on three days through spring, summer, and early autumn. Sampling will be carried out on sunny days with no more than moderate wind speeds. The data collected will be used to examine the pollinator and plant assemblages including species diversity and structure. Interaction webs will be examined, and measures of plant fitness will be analyzed.

References

1. Dicks, L.V., S.A. Corbet, and R.F. Pywell. (2002) J. Anim. Ecol. 71:32-43.
2. Kevan, P.G. (1999) Agr. Ecosyst. Environ. 74:373-393.
3. Allen-Wardell, G., et al. (1998) Conserv. Biol. 12:8-17.
4. Corbet, S.A. (2000) Conserv. Biol. 14:1229-1231.
5. Forup, M.L., and J. Memmott. (2005) Ecol. Entomol. 30:47-57.
6. Carvell, C., et al. (2006) Biol. Conserv. 132:481-489.
7. Morandin, L.A., et al. (2007) Basic Appl. Ecol. 8:117-124.
8. Environment-Agency. (2006) What are landfill sites? [cited 1/10/2006].
9. Rawlinson, H., et al. (2004) Forest Ecol. Manag. 202:265-280.
10. Forup, M.L., and J. Memmott. (2005) Restor. Ecol. 13:265-274.
11. This Ph.D. research project has been funded by the Sita Environmental Trust, through money gained from the landfill tax credit scheme. I welcome any comments or suggestions regarding this research.