Identify global hotspots for soil conservation

The areas most important for conserving the soil’s ecological resources are only partially covered by current protected areas, according to the findings of a new study published in the journal Nature.

The soils of this pine forest in Seville were included in the study. Photo credit: Manuel Delgado Baquerizo.

A multinational team of scientists analyzed different dimensions of soil biodiversity (local species richness and uniqueness) and ecosystem services to identify global hotspots for conservation of soil ecological values ​​(such as water regulation or carbon storage).

They discovered that these dimensions peaked in different regions of the world. For example, temperate ecosystems have greater local soil biodiversity (species richness), but colder ecosystems have been designated as hotspots for soil ecosystem services. In addition, the results show that tropical and arid ecosystems have the most diverse groups of soil organisms.

The new analysis shows where efforts to preserve the soil’s ecological values ​​are most needed. Soil ecological values ​​are often ignored in nature conservation management and in political decisions.

Soils are a realm of their own, hidden beneath people’s feet and teeming with life. Countless earthworms, nematodes, insects, fungi, bacteria and other organisms call it home. However, scientists know very little about these organisms or their significant impacts on ecosystems. There would be little life on land and probably no people without soil.

In fact, soil fertility directly or indirectly affects most of the food consumed. Soils, on the other hand, are subject to climate and land use changes. To effectively protect soil’s ecological resources, one must first understand where they are most vulnerable.

Biodiversity hotspots for plants and animals living above ground were recognized decades ago. So far, however, no equivalent assessment has been or could be carried out for soil-ecological values.

First global assessment considering several soil ecological values

A group of international researchers led by the German Center for Integrative Biodiversity Research (iDiv), the University of Leipzig, the Martin Luther University Halle-Wittenberg (MLU) and the Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS) published the first global estimate of hotspots for the preservation of soil ecological values ​​in the journal Nature.

Researchers conducted an amazing global field study, collecting over 10,000 observations of biodiversity (bacteria, fungi, archaea, protists and invertebrates) and indicators of ecosystem services from 615 soil samples from all continents. These observations were combined to determine three soil ecological dimensions: (1) local species richness, (2) biodiversity uniqueness, and (3) ecosystem services (such as water regulation or carbon storage).

Soil ecological values ​​peak in contrasting regions of the planet

The results show that each of the three dimensions peaked in different parts of the world. For example, temperate ecosystems had the highest local soil species richness, while arid ecosystems and the tropics had the highest biodiversity and uniqueness.

If you dig in a European soil, for example a forest, you will find many different species in a single place. If you go into a forest a few kilometers further, you will find different but similar species. Not so in the tropics, where a few kilometers can mean completely different communities.

dr Carlos Guerra, first author of the study, German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig

Guerra is now associated with iDiv and the University of Leipzig and began working on the project at iDiv and MLU. Ecosystem services, the third dimension assessed, often peaked in the colder high-latitude ecosystems, alongside the two dimensions of biodiversity.

Hotspots identified for soil conservation

The different spatial patterns for the three different dimensions show how difficult it is to protect all three at the same time.

It is much more demanding than in plants and mammals, where there is usually a better spatial correspondence of the different dimensions. When protecting soils, we should probably not focus on maximizing all soil ecological dimensions locally at the same time, but on integrated approaches that show the local potentials.

dr Carlos Guerra, first author of the study, German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig

Despite these challenges, the researchers were able to identify ecosystem hotspots where conservation of soil nature should be given top priority. These hotspots were mainly found in North America, Asia, Northern Europe and the tropics.

Prioritization of soil conservation in international politics

The authors assessed these priority hotspots in already protected regions. They found that only half of the hotspots are still protected by nature conservation.

Protected areas were mainly chosen to protect plants, birds or mammals. We must include soils, their biodiversity and services in our perspective. Therefore, governments and decision-makers must prioritize soil conservation in international negotiations for the 2030 biodiversity goals.

dr Manuel Delgado-Baquerizo, senior study author, Instituto de Recursos Naturales y Agrobiología de Sevilla

The new study may be useful as it shows where conservation efforts are most needed for soil nature.

The study was funded by the German Research Foundation (DFG; FZT-118), among others.

Magazine reference:

Guerra, C. et al. (2022) Global soil conservation hotspots. Nature.


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