The activity of earthworms in the soil is essential for agriculture, but they are being affected by climate change.
Precipitation and temperatures are the factors that most affect earthworms as reported by a team of more than 140 scientists coordinated by the German Center for Integrative Biodiversity Research (iDiv).
Earthworms play a fundamental role. Unlike organisms that live on the earth's surface, the diversity of earthworms (Eisenia foetida)It is higher in temperate regions than in the tropics, according to an international study collected inScience in which, among other Spanish institutions, the Complutense University of Madrid (UCM) participate.
“We have found that rainfall and temperature are the environmental factors that most influence the global distribution of earthworms, so it is to be expected that climate change will cause drastic changes in the communities of these animals”, Explains Mónica Gutiérrez, researcher at the Soil Zoology group at the UCM.
Experts have compiled the largest earthworm database in the world, which includes 6,928 locations from 57 countries. The greatest local diversity and the greatest abundance and biomass of these animals are found in temperate regions such as Europe, the northern US and New Zealand, according to the study.
Cascade effect in other species
Earthworms are considered ecosystem engineers and provide important services that have not been adequately valued by society: they mix mineral and organic components of the soil, accelerate nutrient cycles making them more accessible to plants, improve water retention, they contribute to the dispersion of seeds and increase the fertility of the soils.
“Earthworms are the most important group of animals for biomass in temperate zone soils (there may be more biomass of earthworms than mammals). All this biomass is the food base for other animals such as many birds and small mammals”, Points out Juan B. Jesús, also a researcher in the Soil Zoology group of the UCM.
According to the study, its average abundance per square meter on a global scale is 78 individuals and the biomass can be up to 2 kg at some specific points.
That is why UCM experts qualify as “matter of concern”The strong relationship between climatic variables and earthworm communities, as the climate will continue to change due to human activities over the next decades.
“This will affect the functions and services that these animals perform in the ecosystem, producing a cascade effect on other organisms such as microorganisms, insects or plants.”, They affirm.
The earthworm, an unprotected annelid
In addition, scientists warn that protected areas may not be fulfilling their role in the case of worms. Biodiversity is a key element when defining protected areas such as natural parks, among others. The soil continues to be the great black box in the study of this biodiversity and has not been taken into account for conservation policies.
Phillips H.R.P. et al. "Global Distribution of Earthworm Diversity".Science, October 25. 2019.