For ecologists who study the budgets of nutrients such as nitrogen, phosphorus, or calcium, one of the first steps is to inventory their distribution within an ecosystem. Inventories by Nalini Nadkarni changed our ideas of how tropical and temperate rain forests are structured and how they function. With the aid of mountain-climbing equipment, Nadkarni slowly made her first ascent into the the canopy of the Costa Rican rain forest, a world explored by few others and where she was to become a pioneer. She stood on the rain forest floor and wondered about the diversity of organisms and ecological relationships that might be hidden in the canopy high above. Her wonder soon gave way to determination, and she not only visited the canopy but was among the first to explore the ecology of this unseen world