Droughts increasingly threaten the world's major tropical rainforests. El Nino episodes cause severe drought and widespread forest damage by fire. In this project, the investigators are looking into the future of the Amazon rainforest by experimentally excluding rainfall from a one-hectare (2.5 acre) patch of forest in Brazil. This experiment will determine how much drought the rainforest can tolerate before its trees begin to lose leaves, stop growing and reproducing, and die. The researchers will also be investigating how drought affects the role of the rainforest in the changing chemistry of the atmosphere. It is no small task to exclude rain from a rainforest. The project upon which this research follows hired 26 laborers for a year to build a wooden frame containing 6100 plastic panels held 2-4 meters above the forest floor. Gutters carry the rainwater away from the site. The project also built 8 towers into the forest canopy, 10-stories above the ground, to monitor the physiology and dynamics of leaves. In addition, shafts 3-stories deep were dug to study soil water and roots.
