Abstract
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][1]) 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. [1]: http://www.sciencemag.org/cgi/content/full/276/5312/583