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The 'earthworm factor' - how biodiversity affects soil erosion

Effects of soil organisms on soil erosion by water and wind Effects of soil organisms on soil erosion by water and wind
Sep 07 2018

The JRC has published an innovative article proposing, for the first time, the introduction of a biological factor to help better estimate soil loss.

Soil is a hugely important, non-renewable natural resource. It is the basis of all agriculture, and plays a major role in regulating global climate, limiting flooding, ensuring clean water, filtering pollutants and sustaining biodiversity. It is therefore important to protect it, and avoid soil loss at all costs.

To address soil loss (through run-off by water and wind) and its potential negative effects on agriculture and climate change, reliable soil erosion estimates are needed.

The myriad of organisms that live in the soil can both reduce soil loss (e.g. microorganisms such as bacteria and fungi improve soil structure), and add to it (e.g. megafauna such as soil-living mammals reduce soil stability as a result of their mixing activities). Soil erosion also has negative ecological impacts on belowground communities. For instance, an estimated 20 000 earthworms can be displaced by runoff of 1 tonne of soil.

Despite these clear interactions, soil erosion models to date do not consider biodiversity when estimating soil loss.

To fill in this gap, the JRC has come up with a new biological factor based on the soil's richness (number of species) and abundance (number of individuals) of earthworms – the "earthworm factor" (Et-factor). The feasibility of the new approach was demonstrated by mapping the revised susceptibility of a soil to erode (soil erodibility) due to the Et-factor in 11 EU countries.

Abundance and richness data are derived from Rutgers et al. (2016) and cover 11 European countries: Belgium, Denmark, France, Germany, Hungary, Ireland, Luxembourg, Slovenia, Spain (partly), the Netherlands and the United Kingdom.
Abundance and richness data are derived from Rutgers et al. (2016) and cover 11 European countries: Belgium, Denmark, France, Germany, Hungary, Ireland, Luxembourg, Slovenia, Spain (partly), the Netherlands and the United Kingdom.

New, likely more reliable, estimates of soil loss can be obtained by including this biological factor in soil erosion models.

The earthworm factor represents a first step in filling current knowledge gaps about the interaction between soil biodiversity and soil erosion, and one that the authors hope will attract the acknowledgement by soil ecologists and soil erosion modellers of the strong connection between their respective research subjects.

Quite the feat for such a humble little worm.

Further information

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