Human societies rely on the vast diversity of benefits provided by nature, such as food, fibres, construction materials, clean water, clean air and climate regulation. All the elements required for these ecosystem services depend on soil, and soil biodiversity is the driving force behind their regulation. With 2010 being the International Year of Biodiversity and with growing attention on the importance of soils to remain healthy and capable of supporting human activities sustainably, the European Commission has contracted out a report on 'Soil biodiversity: functions, threats and tools for policy makers', completed in February 2010.
The report reviews the state of knowledge of soil biodiversity, its functions, its contribution to ecosystem services and its relevance for the sustainability of human society. It should be seen in the context of the European Union's Thematic Strategy on soil protection and the proposed Soil Framework Directive which have the objective to protect European soils from degradation. Moreover, soil biodiversity is an integral component of biodiversity in general and is part of the commitment of the EU to halting biodiversity loss in Europe and significantly reducing the rate of loss worldwide.
Soils are home to over one fourth of all living species on earth, and one teaspoon of garden soil may contain thousands of species, millions of individuals, and a hundred metres of fungal networks. Bacterial biomass is particularly impressive and in a temperate grassland soil can amount to 1-2 tonnes per hectare – which is roughly equivalent to the weight of one or two cows.
Soil organisms provide numerous and essential services. Some are supporting services, or services that are not directly used by humans but underlie the provisioning of all other services. These include nutrient cycling, soil formation and primary production. In addition, soil biodiversity influences all the main regulatory services, namely the regulation of atmospheric composition and climate, water quantity and quality, pest and disease incidence in agricultural and natural ecosystems, and human diseases. Soil organisms may also control, or reduce environmental pollution. Finally, soil organisms also contribute to provisioning services that directly benefit people, for example the genetic resources of soil microorganisms can be used for developing novel pharmaceuticals.
The soil organic carbon pool is the second largest carbon pool on the planet and is formed directly by soil biota that produce humus out of litter and aboveground residues that accumulates on the top soil. Every year, soil organisms process 25,000 kg of organic matter (the weight of 25 cars) in a surface area equivalent to a soccer field. Soil organisms affect the infiltration and distribution of water in the soil, by creating soil aggregates and pore spaces. It has been observed that the elimination of earthworm populations due to soil contamination can reduce the water infiltration rate significantly, in some cases even by up to 93%. Soil organisms, with their astonishing diversity, are an important source of chemical and genetic resources for the development of new pharmaceuticals. For instance, many antibiotics used today originate from soil organisms, for example penicillin, isolated from the soil fungus Penicillium notatum by Alexander Fleming in 1928, and streptomycin, derived in 1944 from a bacteria living in tropical soil. Given that antibiotic resistance develops fast, the demand for new pharmaceutical products is unending.
To date, no legislation or regulation exists that is specifically targeted at soil biodiversity, whether at international, EU, national or regional level. This reflects the lack of awareness for soil biodiversity and its value, as well as the complexity of the subject. The management of soil communities could form the basis for the conservation of many endangered plants and animals, as soil biota steer plant diversity and many of the regulating ecosystem services. This aspect could be taken into account or highlighted in future biodiversity policies and initiatives.
A press release is also available here.
One of the authors of the report (professor Van der Putten) has intervened at Green Week in the session 'The soil life we walk on - does it matter?'. His presentation as well as those of the other speakers is available here.
The report was officially presented at a high-level conference on 'Soil, Climate Change and Biodiversity – Where do we stand?' that took place on 23-24 September 2010 in Brussels. More information on the conference is available here.
The content of the report has been summarised in a leaflet and a brochure for the general public which are available here in English, French, German, Italian, Polish and Spanish.