Utilization Measurements on Rangelands
By Barton Stam
Frequently, I’m asked by permittees across Wyoming for help with issues concerning their federal grazing allotments. One of the common issues is utilization monitoring on herbaceous forages – sometimes referred to as intensity – and how it is being used to manage the allotment.
Federal agencies estimate utilization in many ways, including visual estimates, stubble height, Robel pole or clipping and weighing residual forage. Often, these measurements are done on an annual basis at the end of the grazing season.
The Society for Range Management (SRM) defines utilization as the proportion of a current year’s forage production consumed or destroyed by grazing animals. This may refer either to a single species or to the vegetation as a whole. SRM defines stubble as the basal portion of herbaceous plants remaining after the top portion has been harvested either artificially or by grazing animals. The association defines residue as the forage remaining on the land as a consequence of harvest.
So, what can these measures be used for? And, why should they be considered by permittees and federal agency range conservationists?
Intensity, along with timing and frequency of grazing and rest periods, should be considered together when managing grazing allotments. SRM’s Rangeland Assessment and Monitoring Committee (RAM) in the technical note “Utilization and Residual Measurements: Tools for Adaptive Rangeland Management” published in the SRM peer-reviewed journal Rangelands states utilization should be used, in conjunction with other monitoring methods, to determine distribution of animal use, cause and effect interpretations of range trend data and to aid in the adjustment of stocking rates and season of use of grazing.
These annual monitoring methods should be used to make decisions to improve grazing management such as to determine places which may need more or less grazing or grazing at a different time.
Once those areas are identified and steps taken to improve or alter distribution, utilization or other short-term methods can be used to evaluate how well the new management has worked. Distribution can be managed through a variety of methods including fencing, herding, supplementation, water development and animal selection etc. Poor livestock distribution is often the cause of problems with grazing, especially in arid areas or places with rough topography.
So, having a tool such as utilization monitoring can be valuable if and when it is used appropriately. Proper livestock distribution can help with avoiding localized overgrazing, animal performance and extending the grazing season by efficiently using forage and water supplies – adjustments which can be good for both animals and the environment.
Improving livestock distribution can be a difficult proposition that is not so easily put into reality. Some improvements can usually be made, though, which are more palatable than other potential options such as cuts in AUMs or even livestock exclusion.
As stated by the RAM committee, utilization can also be employed to adjust stocking rates or timing of grazing. It is critical utilization be used with other monitoring information such as long-term trend monitoring and a research-based reason for their use.
Utilization and long-term trends are not always closely related, so it is important to have and use both in management decisions.
Utilization measurement is affected by many factors including the technique used and the amount of training the observer has received. The timing of the measurement in relation to the growing season and when livestock are grazing is critical and very dependent on the specific management objective.
Measuring utilization in a riparian area in the fall is probably not very useful when worried about soil stability in high flow events during spring runoff or precipitation events.
Even using utilization on key species can be problematic. As the grazing season continues, species and grazing area preferences change, which can alter the relevance of a certain few key species.
To use utilization or other such methods as a management objective, or automatic trigger for some action, such as removal of livestock from a pasture or an arbitrary guideline, is a misuse of the method.
Utilization standards not being met should be used as a trigger for the range conservationist, permittee and others involved to look at other measures such as soil cover, species composition, frequency of invasive species, etc.
Additionally, land managers should consider the overall health of the entire grazing system including grazing allotments on lands managed by other agencies, private grazing lands, the health of grazing animals and other diverse factors included in the system. It is also critical decisions incorporate management in the context of long-term trends, season of use and frequency of grazing data.
This is sometimes called adaptive management, and it should be the goal of all grazing lands. The reality is grazing management on private lands is adaptive and is constantly being informed by observations.
For federal grazing, it takes more effort and frequently calls for another meeting where those involved may need to have difficult or awkward conversations. As range managers, we have a lot of tools in the toolbox. Each tool should be used for the right job.
Barton Stam is a University of Wyoming Extension Educator. He can be reached at BrStam@uwyo.edu.