Using the Rosgen Stream Classification System to aid in Riparian Complex Ecological Site Descriptions Development

Authors: MEEHAN, MIRANDA - North Dakota State University; O'Brien, Peter

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2019
Publication Date: 8/5/2019
Citation: Meehan, M.A., O'Brien, P.L. 2019. Using the Rosgen Stream Classification System to aid in Riparian Complex Ecological Site Descriptions Development. Rangeland Ecology and Management. 72(5):729-735. https://doi.org/10.1016/j.rama.2019.05.001.
DOI: https://doi.org/10.1016/j.rama.2019.05.001

Interpretive Summary: Classification frameworks are useful tools to discuss the ecological status of land and identify risks of land degradation. Ecological Site Descriptions (ESD) are a commonly used framework to categorize rangelands by soils, vegetation, and topography, but they are not suitable in riparian areas because hydrology is the primary determinant of ecological function. This study is part of an ongoing effort to develop ESDs that are suitable for riparian complexes by categorizing them using stream geomorphology and the Rosgen Stream Classification System (RSCS). The RSCS classifies channel types by a series of parameters, including entrenchment ratio (ER), width-to-depth ratio, sinuosity, slope, channel bed material, bank height ratio (BHR), and meander width ratio (MWR). Data from seventy-five locations along nineteen streams in North Dakota, USA indicate that these parameters were statistically different based on both channel type and stability class. Stable channels were characterized by high ER and MWR, while high BHR typically indicated unstable channels. Overall, these findings confirm that categorizing reaches by RSCS channel type can be used to consistently determine stream stability, which validates the continued use of RSCS in ESD development for riparian complexes.

Technical Abstract: Land managers need consistent terminology and classification frameworks to discuss the ecological status of the land. A common framework used in upland terrestrial systems is an Ecological Site Description (ESD), where systems are categorized by soils, vegetation, and topography. Creating ESDs in riparian areas must follow a different framework than upland systems because function of riparian systems is driven by hydrology. This study categorized riparian areas by hydrology using stream geomorphology and the Rosgen Stream Classification System. Stream cross section and longitudinal profile data was collected from seventy-five reaches from nineteen streams in North Dakota, USA from 2012-2018. Each reach (i.e., one full meander) was classified by channel type (E, C, B, F, and G), and stability class (stable and unstable). A stream parameter matrix was constructed using entrenchment ratio (ER), width-to-depth ratio, sinuosity, slope, channel bed material, bank height ratio (BHR), and meander width ratio (MWR). A multiple response permutation procedure showed that the parameters differed based on both channel type and stability class. An indicator analysis showed that entrenchment ratio, bank height ratio, and meander width ratio were the parameters most influential in separating the reaches by stability class. The strongest indicator stable reaches was ER, but MWR and BHR were also significant indicators of stable and unstable reaches, respectively. The parameters used in this study to delineate channel type can be used to consistently discriminate between stable and unstable channels. This information may be a useful tool in describing the states and transitions of prairie stream development in riparian complex ESDs, validating the continued use of Rosgen Stream Classification System in ESD development.