This hall exploring the ecology of North American forests features a piece of a giant sequoia tree. The sequoia, which was cut down in 1891, had survived for more than 1,300 years and its full height exceeded 300 feet. Around the central point of the tree slice are concentric rings, some of which are invisible to the naked eye; each of these represents one year's growth. Conveying the immense age of the tree are markers on some of the growth rings corresponding to significant historical events, such as Charlemagne being crowned Holy Roman Emperor (800 A.D.).
Traveling through scale rather than time, a diorama of the forest floor represents a cross section of the soil, enlarged to 24 times its actual size. This scene demonstrates the process of decomposition, by which natural debris is broken down into new substances, which exist in the soil as nutrients. While bacteria and fungi help break the debris down, so do some of the creatures re-created in the diorama.