Plants make profound contributions to ecosystem services—processes by which the environment maintains resources that benefit human society. Once life moved onto land, it was largely plants that shaped the terrestrial environment.

Plants produce oxygen and remove carbon dioxide from the atmosphere, and they play important roles in forming soils and renewing soil fertility. Plant roots help hold soil in place, providing protection against erosion by wind and water (Figure 28.22). Plants also moderate the local climate in various ways, such as by increasing humidity, providing shade, and blocking wind. All of these ecosystem services permit a great diversity of fungi and animals to exist on land.