This book offers a readable and accessible account of the way in which the world's plant life partly controls its own environment. Starting from the broad patterns in vegetation which have classically been seen as a passive response to climate, the authors build up from the local scale - with microclimates produced by plants - to the regional and global scale. The influence of plants (both on land and in the ocean) in making clouds, haze and rain are considered, along with plant effects on the composition of greenhouse gases in the earth's atmosphere. Broad global feedbacks that either stabilize or destabilize the earth's environment will be explored, in the context of environmental change in the recent geological past, and in the near future. Common contentions and misconceptions about the role of vegetation or forest removal in the spread of deserts will also be considered.