Change takes place continually in plant communities and the type and extent of change that occurs is greatly influenced by the grazing management, as explained by Fred Provenza, professor emeritus, Utah State University, in Rangelands, a publication of the Society for Range Management.
Provenza suggests that we must move away from prescription grazing.
The grassland ecosystem is composed of dynamic, ever-changing life forms. These are not always predictable and it is often necessary to make adjustments as changes happen.
Inflexible, one-size-fits-all, or prescription grazing can cause management to get off track. Successful grazing is a product of adaptive management.
A key element in adaptive management is the continual monitoring and assessment of the life forms in the ecosystem, especially the plant community. All pasture and grassland ecosystems are complicated biological entities which are difficult to totally understand and hard to predict. Thus, it is prudent that managers assess the biological processes, health of the various life forms and the trends taking place in their ecosystem, on a continuing basis and adjust their practices based on their assessment.
Decisions on how to manage must be based on what is taking place in the ecosystem. We must determine whether we are giving the preferred plants enough time for full recovery after defoliation. Full recovery means allowing them to increase their proportion of the plant community through vegetative means and seedling recruitment.
“Many managers think of rest as any time a paddock is not grazed, without considering the growing conditions during the interval between grazing periods,” Provenza says.
A non-grazing period may or may not allow plants to meet their physiological needs.
Adaptive management graziers will only move animals back to a paddock when environmental conditions have supported the plants in meeting their physiological needs.
They practice deferment. “A delay of grazing to achieve a specific management objective.”
This allows time for plant reproduction, establishment of new plants and restoration of plant vigor, which readies the plant community for grazing or an accumulation of forage for later use.
With moderate stocking rates, preferred plant species are often grazed severely by the time optimum overall utilization is achieved.
So, higher stocking densities will help achieve more uniform utilization of the total forage with less pressure on the more palatable, preferred plant species.
Adequate recovery depends on the species, size, general health and condition of the plants, the intensity of defoliation and the extent of seed production and recruitment of new plants.
The time required for these things to take place will vary with the season and the year. It depends mostly on the moisture available.
Adequate recovery is ultimately a management judgment based on the timing of critical parts of the growth cycle of the most desired plant species.
Regular deferment to allow adequate recovery should be timed so that desired species can maintain or increase their proportion of the plant community. In semi-arid climates this can require most of the growing season.
In periods of drought or other stress, it can require a year or more for recovery.
Allowing enough time for existing plants to express their potential and new plants to come into the system enhances diversity and builds resilience.