Gangs taking over U.S. land: ; Mexican traffickers are using national parks as growing fields

SEQUOIA NATIONAL FOREST, Calif. - Not far from Yosemite'swaterfalls and in the middle of California's redwood forests,Mexican drug gangs are quietly commandeering U.S. public land togrow millions of marijuana plants and using smuggled immigrants tocultivate them.

Pot has been grown on public lands for decades, but Mexicantraffickers have taken it to a whole new level: using armed guardsand trip wires to safeguard sprawling plots that in some casescontain tens of thousands of plants offering a potential yield ofmore than 30 tons of pot a year.

"Just like the Mexicans took over the methamphetamine trade,they've gone to mega, monster gardens," said Brent Wood, …