Benda, LE; Miller, DJ; Dunne, T; Reeves, GH; Agee, JK
Dynamic landscape processes influence the supply, storage and transport of water, sediment, and wood, thereby shaping many aspects of riparian and aquatic habitats. These processes comprise the disturbance regime of a watershed.
The study of natural disturbance (and cumulative effects) in riverine and riparian areas requires a fundamental shift in focus from individual landscape elements (such as a forest, a hillslope, and a stream reach) over short timescales (years) to populations of landscape elements over long time scales (decades to centuries). The study of landscapes as a system expands the focus from predictions about exact
future states to predictions about the relationships between large-scale properties of landscapes (i.e., climate, topography, and channel networks) and the long-term behavior of aquatic systems.
The study of natural disturbance (and cumulative effects) in riverine and riparian areas requires a fundamental shift in focus from individual landscape elements (such as a forest, a hillslope, and a stream reach) over short timescales (years) to populations of landscape elements over long time scales (decades to centuries). The study of landscapes as a system expands the focus from predictions about exact future states to predictions about the relationships between large-scale properties of landscapes (i.e., climate, topography, and channel networks) and the long-term behavior of aquatic systems.
Characteristics of landscapes that vary naturally over time can be described by four
components: (1) climate, which drives environmental variability; (2) topography, which comprises comprises a population of diverse hillslopes that creates spatial variability in the sediment and wood supplied to channels; (3) channel networks, which govern how sediment and wood are routed through a population of linked stream reaches and unevenly redistributed in time and space; and (4) basin history, which effects the volume of sediment and wood stored on hillslopes and in stream channels, and which
influences how sediment and woody debris are redistributed during storms, fires, wind, and floods.
The study of landscapes as systems, focusing on the collective behavior of populations of landscape elements over time, provides the necessary framework for investigating natural disturbance and cumulative effects. The field application of this framework provides insights into how channel and riparian morphologies are related to the recent environmental history of a watershed.