The massive drought that has dried out Texas over the past year has killed as many as half a billion trees, according to new estimates from the Texas Forest Service. "In 2011, Texas experienced an exceptional drought, prolonged high winds, and record-setting temperatures," Forest Service Sustainable Forestry chief Burl Carraway told Reuters on Tuesday. "Together, those conditions took a severe toll on trees across the state." He said that between 100 million and 500 million trees were lost. That figure does not include trees killed in wildfires that have scorched an estimated 4 million acres in Texas since the beginning of 2011. A massive wildfire in Bastrop, east of Austin in September that destroyed 1,600 homes, is blamed for killing 1.5 million trees. The tree loss is in both urban and rural areas and represents as much as 10 percent of all the trees in the state, Carraway said. "This is a generational event," Barry Ward, executive director of the nonprofit Trees for Houston, which supports forestry efforts, told Reuters on Tuesday. "Mature trees take 20 or 30 years to re-grow. This will make an aesthetic difference for decades to come."