Soil biodiversity can be found across the globe in natural as well as in man-made habitats, yet not all species are present everywhere. The factors that determine the distribution of soil biota remain under investigation as novel techniques to identify soil biota reveal different results than more traditional techniques based on culturing of soil microbes. In general, the presence and activity of soil biota differs in space and in time and is dependent on the size and life history traits of the soil biota as these determine the mode of dispersal, range of operation and sensitivity to disturbances. Larger soil biota like earthworms are usually more constrained in their dispersal and are more sensitive to disturbances than soil microorganisms that disperse via wind and water or remain dormant to survive adverse conditions. Overall soil abiotic factors such as soil pH and soil texture play an important role in determining which species of soil biota can thrive where, whereas at larger spatial scale also climatic factors such as temperature and moisture contribute to explaining the distribution of soil biodiversity. A very important local scale biotic factor is the plant species composition; not only do plant roots represent belowground diversity themselves, they also provide the basis for the soil food web. In turn many plants live in symbiosis with beneficial soil biota in their root system, associations which range from low to highly species specific. Lastly soil biodiversity at a given location can change over time due to pulses of nutrients from plant inputs or fertilizer applications and seasonal changes in precipitation and temperature to which populations of soil biota respond.
Summary written by Prof. Gerlinde De Deyn, Wageningen University & Netherlands Institute of Ecology