. >> so, so this is from los padres national forest. this is what it looks like when you fly over. grey green, looks like your typical southern cal forest. this is what it looks like in chemical detail. >> those trees are doing okay but everything else is showing severe drought stress and that's showing here in red. >> now that we have the view from above, we decided to head out for a boots on the ground perspective. >> i'm standing here in the middle of los padres national forest, and as you can tell from all the dead trees behind me, there's plenty of evidence of the impact of a multi-year drought. >> one of the biggest problems here? a bug that attacks water-stressed pine trees. >> now we're talking, ah, there's a bunch. >> tom coleman is an entomolgist with the u.s. forest service. >> there's a lot of dead trees right here. >> yeah, this is a nice little active spot for bark beetles. >> bark beetles kill more trees than any other kind of insect or disease in north america. when you look across the landscape and see this patch work of dead trees. the mortality is quite dramatic.