Article type : Primary Research Articles INCREASED TREE DENSITIES IN SOUTH AFRICAN SAVANNAS:> 50 YEARS OF DATA SUGGESTS CO2 AS A DRIVER Running title: CO2 and woody encroachment in savannas

This is an Accepted Article that has been peer-reviewed and approved for publication in the Global Change Biology, but has yet to undergo copy-editing and proof correction. Please cite this article as an “Accepted Article”; doi: 10.1111/j.1365-2486.2011.02561.