Plants in wildfire-prone ecosystems often have adaptations to their local conditions. Such adaptations include physical protection against heat, increased growth after a fire event, and flammable materials that encourage fire and eliminate competition. For example, plants of the genus "Eucalyptus" contain flammable oils that encourage fire and hard sclerophyll leaves that resist heat and drought. This makes them dominant over less fire-tolerant species. Dense bark, shedding lower branches, and high water content in external structures may also protect trees from rising temperatures. Fire-resistant seeds and reserve shoots that sprout after a fire encourage species preservation, as in 'pioneer' species that specialize in restarting ecological succession after a fire.