A variety of grazing systems are available to manage animal impact. These include continuous grazing, rest-rotation grazing, deferment grazing, and management-intensive grazing (or variations on rotational grazing), among finer gradations of each.
Figure 1. Summary of four prevalent grazing systems. Terminology does not always align, but this illustrates several options (Reece et al. 2008). Note the variation seasonally and spatially in how grazing and rest are distributed. This variation represents potential niches for flora and fauna.
The strengths and weaknesses of different grazing systems vary, among other ways, in terms of:
Suitability to enhance habitat
Suitability to improve pasture or range condition (from a livestock production perspective)
Affordability (infrastructure required)
Management knowledge and time
A few examples of the impact of grazing systems are noted below
A deferment (A) versus a continuous grazing system with high grazing pressure (B) on the same pasture in the same month (April) in two sequential years. In 2021 (A) a deferment system was used to withhold grazing in April and May for spring-blooming forbs. In 2022 (B) the ranch ran out of hay due to economic and supply chain issues. The pictures illustrate the interaction of grazing system, stocking rate, and grazing resistance on the use by livestock of Common camas (Camassia quamash), a native forb. Continuous access to the plant, high stocking rate and lack of avoidance mechanisms resulted in high percent use of this forb, but also created low-stature and patchy bare ground. Continuous grazing paired with high grazing pressure resulted in non-selective use of all available forage, including forbs, in spring of 2022.
Heterogeneous vegetation structure can be achieved by integrating different grazing systems on different pastures and rotating these systems among pastures over the years. This project in northeastern Colorado on shortgrass steppe shows how adaptive multi-paddock grazing (top panel) is most effective at creating habitat for bird species that prefer tall and medium-height vegetation stature (Grasshopper sparrow; Song sparrow preferences approximately equivalent in Puget prairies), but less effective at creating habitat for species preferring short-stature (Thick-billed longspur. Season-long continuous grazing on productive soils (bottom left panel) is moderately effective at creating habitat for bird species that prefer tall and medium-height vegetation stature, while the same season-long grazing on low-productivity soils was highly effective at creating habitat for bird species preferring short-cropped vegetation. In the diagram, more birds indicates better habitat outcomes. Combined, these two grazing systems are more effective than when used alone, in creating habitat for bird species with divergent preferences. Figure from Raynor et al. (2022).
