By Warren P. Clary and Wayne C. Leininger
Excerpt from J. Range Manage. 53:562-573.
The use of stubble height, a measure of the herbaceous vegetation remaining after grazing, as a management tool is not new. Its use in riparian management has been questioned in some situations, however, as we understand more about the complexities and interactions within riparian areas we realize why this tool has meaningful applications. One of the most obvious benefits for the use of stubble height as a management guide is the ease in which this criterion is communicated among livestock permitees and public land managers; stubble height is much easier for people to estimate and visualize, as compared to forage utilization (which is an estimate of what has been removed).
Based on numerous observations by experienced professionals and limited research, we conclude that a streamside stubble height of approximately 10 cm (4 inches) may be near optimal in many situations when considering a number of riparian issues simultaneously, such as preserving plant vigor, entrapping and stabilizing sediment under inundated flow, trampling of streambanks, sustaining forage intake and cattle weight gains, and retaining adequate forage to minimize cattle browsing of willows. We recognize that any given stubble height can be satisfactory for some ecosystem processes and less so for others. Therefore, no single height will likely be optimal for all riparian processes. It appears, however, that the 10 cm height may be the best compromise in many situations. We anticipate that this criterion will be most meaningful when applied to sites near the stream edge. We also expect that stubble height criteria will be most effective in protecting “small stream” systems (a few centimeters to approximately 5 meters (~ 15 feet) in stream width) occurring in meadow settings. Such settings are often associated with Rosgen’s C, D, and E stream types.
This suggestion of a specific streamside stubble height is for the purpose of a starting point when initiating improved riparian management, one that can be changed if monitoring indicates adjustment is needed. In some situations (e.g. where streambanks are dry and stable or where vegetation is naturally of low stature), 7 cm or even less stubble height may provide for adequate riparian ecosystem function, while under other conditions (e.g. willow/tall sedge communities) 15-20 cm of stubble height may be required to reduce willow browsing or to limit animal impact on vulnerable streambanks. The 10 cm criterion is not suggested for specific application on dry meadows or other similar sites.
Short-term management guides, such as stubble height, do not fill the role of a long-term management objective (e.g. Properly Functioning Condition, Desired Future Condition, etc.). A resource manager should have a clear picture of the desired ecological structure and function of the riparian area in question before setting a specific height standard. As ecological succession progresses, the stubble heights that yield the desired results could also change. The grazing management system applied by the manager should meet both short- and long-term objectives. Remember, a management system or guide is applied to help achieve a goal or objective; the management system or guide is not the objective.