“It took 400 million years to produce this tree; it takes four minutes with a chainsaw to destroy it,” intones a voice-over in the Smithsonian’s latest IMAX feature, Tropical Rainforest. Meanwhile, one more acre of the forest primeval is reduced to toothpicks and tinderwood, tree frogs and lemurs are evicted from their ancestral homes, and another species is obliterated…perhaps the exotic herb that would have yielded a cancer cure. Filmed in Australia, Costa Rica, French Guiana, and Malaysia, this cautionary documentary is heavy on visual grandeur: billowing treetops that harbor hundreds of species who never touch ground; neon-colored parrots and toucans; a metamorphosing Ulysses butterfly. Wall-to-wall jungle noises, digitally recorded, give the film an immediacy that National Geographic can only covet. Ultimately, however, the movie is short on solutions: Given our species’ insatiable need for Lebensraum, Rainforest Crunch ice cream isn’t enough. Shown daily at 6 p.m. at the National Air and Space Museum’s Langley Auditorium, 6th & Independence Ave. SW. $2.75-3.75. (202) 357-2700. (Greg Kitsock)