In two sentences, identify the main idea and at least one supporting detail of this paragraph.
Most forest fires and wildfires are natural. They clear away debris, old brush, and dying trees, leaving heartier trees better able to grow. In fact, some trees only produce seeds when heated by fire. If a wildfire removes thick shrubs and undergrowth, the water supply increases, which helps other plants and local animals. Fire may also kill predatory insects or pests that live on and damage otherwise healthy trees.