Evaluating the Sensitivity of Process Domains for Logjams to Spatial and Temporal Sample Size in River Networks of the Southern Rockies, USA

Modification of river corridors, particularly deforestation and the removal of large wood, has greatly altered the abundance and influence of large wood in most rivers in the temperate latitudes. The conceptual framework of large wood process domains can assist in both directing research and facilitating large wood‐related management and restoration in rivers. Large wood process domains are spatially or temporally distinct portions of a river network or region with distinct processes of wood recruitment, transport, and storage. Previous research has shown wood to be unevenly distributed across space and time. We use a data set of logjam distribution density (# of channel‐spanning logjams/100 m length of channel) in 304 spatially distinct reaches of mountain streams in the Colorado Front Range, and up to 11 years of repeat measurements at some reaches, to (a) statistically evaluate whether a priori designated process domains for logjam distribution density are distinctly different and (b) evaluate the sensitivity of process domain delineations to spatial and temporal sample size. Our results indicate that the major spatial controls on logjam process domains for logjam distribution density in the Southern Rockies are drainage area, reach morphology, and wildfire disturbance history. Greater logjam distribution densities were present in wide reaches and undisturbed catchments. Using subsets of the data set composed of under 100 reaches created similar results. The relationship between geomorphic and hydrologic characteristics and their ability to describe logjam distribution density was minimally affected when using fewer than 10 years of data.