The soil is alive

Researchers unravel soil diversity

Earthworm at work: Cherry leaf is being pulled into the ground. Otto Ehrmann
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No breakfast without ground. Without him we would not have bread, no muesli, no orange juice in the morning. Because all these ingredients do not exist without the fertility of the earth. Soil is our livelihood - in the truest sense of the word. But who of us knows a lot about it? What influence does the non-renewable resource soil have on plant and animal life? What does soil fertility depend on and above all, who lives down there in this subterranean living community of earthworms, jumping swans, mites and Co.?

It may come as a surprise, but even soil ecologists can not answer all these questions completely. Compared to what researchers have found so far about the supernatural parts of ecosystems, the knowledge about soil animals, the composition of their communities and the interaction with their environment is sparse. "And that, although presumably a large part of all species of our earth live in the soil, " comments Bodenkundlerin Professor Gabriele Broll of the Federal Association of Soil.

This may be because mites, nematodes and bacteria do not nearly have the cuteness bonus of an ibex Knut, an elephant like in the movie "Our Earth" or a cute panda bass. Ground animals want to be conquered. Only at second glance through a microscope do they show their bizarre variety of forms, their very own beauty. And just as gradually, scientists are succeeding in understanding the meaning and potential of soil organisms. These are probably much larger than previously assumed.

The jobs of underground activists

The soil organisms are real all-rounders and affect the environment more than we realize by their work. In this way, they control and regulate entire ecosystems by processing the resulting organic substance and thereby re-preparing plant nutrients such as nitrogen and carbon for the material cycle. However, soil animals also improve the soil structure and ensure that humus-rich soil is formed. The activity of soil organisms is also an important motor for the dynamics and development of the plant world and thus the landscapes. In addition, soil animals create the basis for agriculture and, as soil designers, influence the foundation for all human life.

The ground-WG under the magnifying glass

Invisible to the naked eye: amoeba in the fungus. Otto Ehrmann

Although numerically most strongly represented, the naked eye sees nothing of them: The speech is about microorganisms in the soil such as bacteria and fungi. In a layer of five centimeters of grassland soil up to 250 kilograms of fungus can be per hectare stuck. Even bacteria rarely come alone. In a handful of earth, up to 10, 000 different species can be detected. display

The second most frequent "tenants" of the soil WG are the representatives of the microfauna, such as protozoa and threadworms (nematodes). With a size of less than 0.1 millimeters, they move within the thin water film that surrounds the soil particles. If the water dries up, the animals survive in inactive permanent stages.

Jumping Swans: Life in air-filled soil pores. Otto Ehrmann

The next largest fraction in the soil is the so-called Mesofauna. These include, among other things, jumping swans and mites. Of these small arthropods, up to 300, 000 individuals can be found in one square meter of green land. The macrofauna can be recognized with the naked eye. These include earthworms, woodlice, centenarians, cows, snails, spiders, ants and termites. The many different soil animals are connected by a widely branched food web. Some feed on dead plant parts and foliage, others on the sap of plant roots and some of other smaller and larger animals.

Bodendiversit t is not a stable size

The composition and number of soil animals are not the same everywhere. They vary between ecosystems and may even be completely different within the same ecosystem at different times. Because of the complexity of the soil, it is usually impossible to specify the reasons and triggers for shifts and changes, says soil researcher Broll,

According to the scientists, however, there are some indications that soil communities sometimes have different dynamics and influences than aboveground systems. For example, the distribution along the geographical latitudes, as observed in animal and plant species, is unlikely to be transmitted to soil animals. Penguins live exclusively in the polar regions, never at the equator. The different types of nematodes, however, occur both in arctic soils and in the tropics.

Another difference is that there is less competition in the ground. Instead of displacement processes, redistributions, shifts in the spectrum of species and enhanced niche formation therefore tend to take place.

Site diversity obtained

Some factors today are known to exert a significant influence on soil organisms. These include climate, soil type, human intervention and plants. These factors affect the diversity of soil organisms and cause different, typical communities in the soil. This site diversity must be maintained, emphasizes soil researcher Broll.

Thus, an acidic heathland with relatively low soil biological activity, but special soil community, is positive and worth preserving. By destroying this landscape, the local community is first wiped out.

Intensive farming scares off ground animals

Dramatic changes in soil activity and the number of soil animals are observed by researchers, where natural areas are converted into agricultural fields. The management ensures that, among other things, the content of organic material is reduced and the soil microclimate is changed. Both can significantly reduce the activity and biodiversity of the soil fauna.

According to the European Commission, this is true for almost all European countries today. Thus, on 45 percent of the surface strongly reduced contents of organic material were measured. Only mediocre contents also own another 45 percent of the earth. Particularly affected by this development are southern European countries, but Germany, Sweden and the UK also have to cope with the same problem. But this trend is reversible. With the conversion to so-called conservative, gentle tillage, soil animals can recover and increase their activity.

Why diversity matters

Soil diversity is determined not only by the number of species, but also by the turnover of soil animals. It is the metabolic performance that the animals produce in the soil and determines the quality and function of the earth. The organisms make nutrients available and are able to break down some organic pollutants such as some pesticides and medicines.

"Everyone has a role to play in this close-knit network of soil communities, " emphasizes Broll. Therefore, it is urgently necessary to maintain soil diversity. "It is important to have a Europe-wide regulation", Reinhard Gierse appeals from the European Land Alliance. A European Soil Framework Directive, for example, would help to sustainably protect the earth from increasing destruction. The Framework Directive is a project of the European Union under its Sixth Environmental Action Program (EAP), which was scheduled for 2012.

No European directive in sight

So far, however, the responsible body could not agree on a common strategy. The decision-making is currently suspended. It is important that the work and negotiations be resumed as soon as possible, Broll emphasizes, with a view to urgently needed soil protection throughout Europe.

Until then, it is important to consistently implement existing guidelines. This includes, for example, the German Federal Soil Protection Act a binding working basis that aims to provide comprehensive and sustainable soil protection. Applying it consistently is very important for soil organisms and their conservation. Because only with diverse communities and food webs beaches remain stable. And only then can they react to changes and fulfill their tasks for future generations.

Left:

Bundesverband Boden: www.bodenwelten.de and www.bvboden.de

Museum Underworlds

Environmental campaign floor wants to live of the Nature and Environmental Protection Academy NRW

European Commission

German Soil Science Society

(Kerstin Schmidtfrerick, 23.05.2008 - DLO)