Fire plays a major role in the ecology of the forest with many plant species needing fire to regenerate. Sometimes the fires can be extremely hot, spread very quickly and threaten nearby properties as well as laying waste to entire ecosystems. If these fires occur less than 15 years apart there can be a loss of plant and animal biodiversity. The size of the Pilliga bushfires is linked to the El Nino Southern Oscillation phenomena, with El Nino (dry) years having the most severe fires.