Introduction
The landscape is a dynamic place. Rain falls; snow melts; water moves across the land and seeps into the ground. Vegetation grows, producing foliage. Leaf litter and downed wood decompose, providing food and building soils. The landscape is constantly changing, sometimes catastrophically with landslides and floods, but most often at speeds too slow, or at scales too small, to observe directly.
The ways that energy and materials are produced, stored, and move across the land are processes that occur naturally, and have been the primary drivers that have shaped the development of habitat. In turn, human development of the land can significantly alter the magnitude and timing of the processes themselves. It is also true that these alterations can cause changes in habitat formation and stability downstream and downslope from the original disturbance. Most commonly, this effect is mediated by hydraulically driven processes: the delivery and routing of water, sediment, large and small wood, nutrients and toxicants.