Looks like Leonardo DiCaprio's mother is going to be a little bit lonely on Sunday. DiCaprio, perhaps Mother Earth's favorite son, intends to spend the day planting trees with the Los Angeles based group TreePeople. "We're helping reforest the decimated Southern California mountains. It's time to do what we can for the planet," says DiCaprio. Additionally, his global warming film, The 11th Hour, is slated to come out this fall. He's also rumored to be attached to a biopic about American conservationist President Theodore Roosevelt. Hopefully Mama DiCaprio has somebody else to go to brunch with…