“It may be doubted if there are many other animals which have played such an important part in the history of the world as these lowly organised creatures” – Charles Darwin, The Formation of Vegetable Mould through the Action of Worms (1881).
This is the quote that Matt Shepherd opened World Earthworm Day at Yarner Wood with. But why are earthworms so important? Matt is a specialist on soil biodiversity for Natural England, he explained that worms are integral members of any ecosystem which they inhabit, and have been since they evolved around 400 million years ago. Often the most abundant animal biomass in an ecosystem, worms are a food source for a wide array of other organisms. Furthermore, worms are “ecosystem engineers”, helping to recycle nutrients and restructure the soil.
Earthworms also provide a range of “ecosystem services”. They help prevent flooding by improving drainage. Soil that has passed through the gut of an earthworm is enriched in nutrients and has elevated levels of “good bacteria” that help plants to fight disease, thus improving crop yields. There is even evidence that they may help clean up land contaminated with toxic waste materials.
However, despite their significance, earthworms are understudied. The UK has 29 known species of earthworm, but little is known about their abundance and distribution. Matt pointed out that earthworms are so understudied that there is a reasonable chance of finding a species never before recorded in an area, simply because nobody has been looking.
Matt then explained that UK earthworms are divided into four groups based on their ecology:
- Anecic – these are earthworms that live in vertical burrows and forage by dragging leaves from the soil surface into their burrows.
- Endogeic – these earthworms live entirely within the soil.
- Epigeic– this group lives entirely about the surface of the soil.
- Compost – a subset of the epigeics that live in rich rotting vegetation.
With new found knowledge on earthworm ecology, we then went into the field to collect some earthworms using the Earthworm Society of Britain’s (ESB) “Standard Sampling Protocol”. This involved digging 5 small pits across a sample area, the soil from which was thoroughly searched for the shallow living endogeic and anecic worms. We also poured a mustard solution onto the pit, to draw deeper living worms to the surface. We then looked for epigeic worms in a selection of microhabitats, for example in leaf litter, or under rocks.
Matt then showed us how to identify worms to species level by looking at the shape of the head, positioning and structure of reproductive organs, the positioning of hair-like structures used in movement, size of the worm, and colouration. Our data on what species we found and where, will now be given to the ESB and join their national records, hopefully helping to improve our understanding of this vital group.
The ESB’s Sampling Protocol is part of their Recording Scheme, which aims to get members of the public involved in earthworm data collection. More information is available on their website, which would encourage you to look and get involved in collecting data on these hugely important but understudied animals.
Thurs 20th July: Soils walk
For a chance to learn more about the secret world of soils – join us on a guided walk lead by soil scientist, Dr Rob Parkinson on 20th July, starting at the Haytor Visitor Centre. To book please contact Albert Knott at East Dartmoor National Nature Reserve on 01626 832 330