Ferns are an integral part of the world’s flora, appreciated for their beauty as ornamentals, problematic as invaders and endangered by human interference. They often dominate forest understories, but also colonize open areas, invade waterways, and survive nutrient-poor wastelands and eroded pastures. This is the first comprehensive summary of fern ecology, with worldwide examples from Siberia to Hawaii. Topics include a brief history of the ecological study of ferns, their biogeography and population dynamics, their role in ecosystem nutrient cycles and adaptations to xeric environments, and their responses to disturbance and interactions with other organisms. Fully illustrated concepts provide a framework for students and professionals in ecology, conservation, and land management, and a wealth of information for anyone interested in ferns.