From the text ... 'Fire is not often considered as an important force in nature despite it being the most ubiquitous natural disturbance on the planet. Several of the modern world's major biomes are controlled by fire regime (grasslands, Mediterranean shrubland and boreal forests), and fire-prone ecosystems cover 40% of the modern globe (Bond et al., 2005). Depending on fire frequency and/or severity, fire can result in the replacement of trees with shrublands or grasslands. Indeed, 'switching off' fire would double the Earth's forest cover (Bone et al., 2005). Fire therefore promotes the expansion of flammable ecosystems in parts of the world that would otherwise be vegetated according to the physiognomic limits set by climate (Bond et al., 2005).' © 2010 The Author. New Phytologist © 2010 New Phytologist Trust.