Scaling and thresholds in earthworm abundance and diversity in grassland agricultural systems

Dr Paul Eggleton, Dr Daniel Carpenter, Professor Mark Hodson, Dr Ron Corstanje, Dr Dan Carpenter. Natural History Museum, University of York, Cranfield University.

Given the beneficial role of earthworms in the environment it makes sense to manage soils in a way that helps earthworms flourish. We can only do this if we understand what impact soil properties and land management practises have on the distribution of earthworms. In the UK semi-natural grasslands account for about  16% of land use and managed, nutrient enriched grasslands account for an additional 20%. These grasslands are used for food production; animals used for dairy and meat production graze on them. Traditionally agricultural management has focussed on improving the nutrient quality of the grass so as to maximise production. But as society increasingly appreciates the various services that the environment can provide such as biodiversity and water storage as well as food production it is worth asking what impact management strategies have on the earthworms that contribute so strongly to so many vital services.

Our research aims to look at how earthworms are distributed along a gradient of grassland intensification, from low input, low grazing intensity grasslands to high input, high grazing intensity grasslands. We are particularly concerned with understanding the spatial distribution of earthworms in these grasslands and how this relates to soil properties and grassland management. By sampling earthworms and soil properties at a range of spatial scales, from fields to farms to the whole of the UK, we will be able to determine whether there are critical thresholds of agricultural intensification beyond which earthworms, and hence the ecosystem services that they provide, are lost from grassland systems.