The Rise of Plants and Their Effect on Weathering and Atmospheric CO ₂

The appearance of rooted plants during the Devonian period (400 to 360 million years ago) probably had a dramatic effect on atmospheric carbon dioxide levels and weathering of rock. As discussed in the Perspective by Berner, results presented in the same issue by Retallack (p. 583) show that well differentiated forest soils had developed by the Devonian, coinciding with a drop in carbon dioxide levels as deep-rooted vascular plants spread to upland areas.