The soil ecosystem supports plant growth through interactions of millions of organisms that work together to break down chemicals and aerate the soil.


“Across all biomes, from the tundra to the savanna, complex communities thrive in the top five to ten centimeters of the soil, where much of the annual flow and exchange of carbon and nutrients takes place. This hubbub is not scattered uniformly throughout the soil but is concentrated in tiny hot spots of activity around the roots of plants, where microbes fuel themselves on sugars and organic acids exuded from the growing root tips…Arguably most important, and certainly least censused of the soil organisms, are the microflora, the hordes of bacteria and fungi that are the most abundant and metabolically versatile organisms in the soil–indeed, on the earth…Each functional group among the microflora specializes in one of the multitude of chemical reactions needed to break down proteins, carbohydrates, and other complex organic molecules into simpler organic acids, then mineralize these into inorganic forms, such as the nitrate that plants can use. Some organisms excel at minute aspects of a larger task, such as the multi-stage processing of slow-rotting natural polymers like lignin, cellulose, and pectins. In any given patch of soil, there may be hundreds of species of fungi and bacteria working at a task in sequence like teams on a factory assembly line…If all the microflora were to disappear, life on earth would quickly come to a halt, wilting and perishing into a never-to-rot compost pile across the land. Yet even these vital creatures do not work in isolation. The soil community includes ranks of invertebrate animals, some of which graze on bacteria and fungi, assuring the release and recycling of energy and materials tied up in even the smallest life forms. Many of these soil animals also speed the work of decomposition by shredding, consuming, digesting, and excreting organic debris, turning it into more accessible crumbs. The tiniest of the soil animals are the microfauna, such as nematodes (roundworms) and protozoa that live mostly in water films around soil pores. Although some are plant parasites that cause serious crop damage, others graze on bacteria or fungi. They are joined by intermediate-sized soil animals, the mesofauna, which include highly specialized invertebrates, such as mites and springtails, that occupy air-filled soil pores and prey mostly on fungi…Largest and most noticeable of the soil invertebrates are the macrofauna: earthworms, ants, termites, millipedes, woodlice, beetles, insect larvae, and others. All are large enough to alter the physical structure of the soil and fragment the litter as they tunnel and feed, aerating the soil and forming channels for infiltration of water.” (Baskin 1997:108-110)

Work of Nature: How the Diversity of Life Sustains UsJanuary 1, 1997
Yvonne Baskin

Black PennantSelysiothemisSpecies