1.2 Soil, the essential terrestrial habitat

1.2 Soil, the essential terrestrial habitat

The conventional estimate is that 75% of the Earth is covered with water; oceans, lakes, rivers, streams. However, less than 1% of the known species of fungi have been found in marine habitats (see pp. 346-351 in Carlile et al., 2001). Fresh water is inhabited by many water moulds (an informal grouping that includes the most ancient fungi and fungus-like organisms, which we will discuss in more detail in Chapter 3), but the overwhelming majority of fungi occur in association with soil; where ‘in association with’ means in or on the soil, or in or on some live or dead plant or animal that is in or on the soil.

The soil environment is the most complex habitat on earth and provides a range of habitats that support an enormous population of soil organisms. The soil habitat being characterised by a heterogeneity, which is measured across physical scales varying from nanometres to kilometres, and differs in chemical, physical, and biological characteristics in both space and time. The nature of the habitat is determined by the interaction of geology, climate, and vegetation and is a biochemical product of the organisms participating in its formation (Voroney & Heck, 2015).

As Wikipedia points out (https://en.wikipedia.org/wiki/Soil) ‘Soil is commonly referred to as earth…’ so it is the substance from which our planet takes its name. Soil is, therefore, the essential terrestrial habitat. In saying this we do not underestimate the importance of other categories of habitat. But they are categories: grassland, forest, coastal, desert, tundra and even cities and suburbs, and ultimately all these habitats depend on their soil. Without soil, no grass; so, no grassland habitat. Without soil, no trees; so, no forest habitat, and so on. Few, if any, organisms can be found on bare rock, wind-blown sand or ice. Fundamentally, terrestrial life on Earth depends upon ‘earth’, and to show how fungi contribute to the formation of soil, this is where we choose to start our story.

Updated July, 2018