Functionally intact systems
There are three ecological groups of earthworms. Their feeding and burrowing behaviours shape the soil ecosystem.
Surface worms (epigeic)
Muck and mulch feeding behaviours (so associated with dung and leaf litter). Not good burrowers, seem to use burrows made by topsoil and deep burrowing worms. Sensitive to tillage (disrupts habitat and food supply).
Topsoil worms (endogeic)
Geophagous - meaning they eat soil, which probably explains why they are found almost everywhere. They are good burrowers, making temporary burrows in the topsoil which are backfilled with their casts.
Deep burrowers (anecic)
Nocturnal, they emerge from their burrows at night to feed and gather plant debris on the soil surface. They are known as "drainage worms" because they form a permanent, deep vertical burrow which can extend down to over 1m deep in the soil profile. Sensitive to tillage (disrupts habitat and food supply)
Surface worms (epigeic)
Muck and mulch feeding behaviours (so associated with dung and leaf litter). Not good burrowers, seem to use burrows made by topsoil and deep burrowing worms. Sensitive to tillage (disrupts habitat and food supply).
Topsoil worms (endogeic)
Geophagous - meaning they eat soil, which probably explains why they are found almost everywhere. They are good burrowers, making temporary burrows in the topsoil which are backfilled with their casts.
Deep burrowers (anecic)
Nocturnal, they emerge from their burrows at night to feed and gather plant debris on the soil surface. They are known as "drainage worms" because they form a permanent, deep vertical burrow which can extend down to over 1m deep in the soil profile. Sensitive to tillage (disrupts habitat and food supply)
Three types of worms present in your soils?
Surveys to date indicated that 50 % field surveys find three types of earthworms in five soil pit assessments. Topsoil earthworms are routinely found, but epigeic and anecic earthworms are not detected in 1 of 5 fields. These earthworms are most sensitive to weather and soil management practices e.g. tillage.
Earthworm surveys
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Agile survey design processEach annual survey cycle includes research and development, prototyping, usability and evaluation feedback from farmers. Once paper based it now has a digital community results forum to share and compare results.
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Ecosystem engineers
Earthworms influence water infiltration rates and crop rooting depth, plant susceptibility to pests and pathogens like aphids and Fusarium sp., aggregate stability and porosity, nutrient cycling, and are an important food source for native wildlife... This is why it is useful to check which ecological groups of earthworms are present - each type uniquely influences soil functions.
Other earthworm surveysClick this link to find out about all the earthworm surveys around the world.
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References
Ecosystem engineers:Edwards C. A., Bohlen P. J. (1996) Biology and ecology of earthworms: Chapman and Hall Ltd., 2-6 Boundary Row, London SE1 8HN, England; Chapman and Hall, Inc., 29 West 35th Street, New York, New York, USA.
Ecological group based surveying:
Stroud J. L. (2019) Soil health pilot study in England: Outcomes from an on-farm earthworm survey. PLOS ONE, 14, e0203909.
Ecosystem engineers:Edwards C. A., Bohlen P. J. (1996) Biology and ecology of earthworms: Chapman and Hall Ltd., 2-6 Boundary Row, London SE1 8HN, England; Chapman and Hall, Inc., 29 West 35th Street, New York, New York, USA.
Ecological group based surveying:
Stroud J. L. (2019) Soil health pilot study in England: Outcomes from an on-farm earthworm survey. PLOS ONE, 14, e0203909.