Soils and Biodiversity Hotspots

Soil forms through the slow interaction of five principal factors, commonly summarized by soil scientists as parent material, climate, organisms, topography, and time, a framework often attributed to twentieth-century soil scientist Hans Jenny. Parent material, the underlying rock or sediment, supplies the initial mineral composition, which is then broken down through physical weathering, such as freeze-thaw cracking, and chemical weathering, such as the dissolution of minerals by slightly acidic rainwater. Climate strongly influences both the rate and character of these processes, since warm, wet conditions accelerate chemical weathering and organic decomposition, while cold or dry conditions slow it considerably. Living organisms, from burrowing earthworms and termites to the roots of plants and the vast populations of soil bacteria and fungi, actively mix and enrich the developing soil, and given sufficient time, these interacting processes produce the layered soil profile, with distinct horizons, that characterizes mature soils.