In contrast, uncontrolled or wildfires disrupt such processes and can have a catastrophic impacts. The vast majority of wildfires are intentionally set and often occur in conifer forests. In recent years extended droughts, together with the rapidly expanding exploitation of tropical forests and the demand for the conversion of forests to other land uses, have resulted in a dramatic increase in wildfires. While some conifers have evolved to be fire dependent by having serotinous cones that open and release their seed in response to fire, their populations are so small or fragmented that even natural fires may be catastrophic. This is particularly evident in areas with a Mediterranean climate. It is the introduction of inappropriate fire regimes (frequency, severity, or seasonal timing) that can have the most severe impact.