Los Angeles Mayor Antonio Villaraigosa launched a $70 million initiative last month to plant 1 million trees in the city over the next few years to improve the city's air quality — among the worst in the nation — and create more shade in the hot climate. Earlier this year, the Sacramento region launched its own initiative to plant 4 million trees in the city and six surrounding counties over the next 40 years. Many of the trees in Los Angeles, paid for mostly with grants and donations, will be planted on public property, and residents have been asked to report their newly planted trees to the city's 311 information line or at the program's Web site, www.milliontreesla.org. Sacramento residents can call the Sacramento Municipal Utility District to request up to 10 free trees.