Article: Interspace/Undercanopy Foraging Patterns of Beef Cattle in Sagebrush Habitats
Authors: France, K.A. Ganskopp, D.C. Boyd, C.
Journal: Rangeland Ecology Management
Dated: July 2008
Grazing management can affect ecosystem geometry, which is often a critical factor determining a habitat’s suitability for a species, particularly wildlife. Ecosystem geometry is a function of many complex variables, including: canopy cover, understory angles, ground surface variations, and vegetation density, to name just a few.
Research objectives were driven by concern for the impact of grazing on the nesting habitat of ground-nesting sagebrush-steppe avians like sage-grouse, lark sparrow, and sage thrasher.
As a treatment, four ~6 ha paddocks were subject to grazing by four yearling heifers (~325 kg) for 18 days in 2003 and three heifers for 18 days in 2004.
Herbage utilization was measured for interspace grass tussocks and for undercanopy grass tussocks. Sagebrush-grass geometries were measured in relation to accessibility and visual obstruction.
Not surprisingly, herbage utilization increased with time. After 8 days of grazing and 70% utilization of interspace tussocks, the cattle seem to have turned their attention to the under-utilized undercanopy tussocks, beginning to graze and defoliate them much more heavily. After 18 days, 100% of interspace grass tussocks were grazed and 62.5% of undercanopy tussocks were grazed.
Herbaceous coverage is important for ground-nesting birds to safely conceal themselves from predators. This paper suggests that “herbage utilization to <40% could be used to help sustain screening cover for nesting birds beneath sagebrush.” Management recommendations will vary depending on site specific conditions, namely ecosystem geometry.
Holistic Planned Grazing offers the practical tools to control herbage utilization with the type of precision described (See Interview with Judi Earl). Research-based ecosystem response analysis (like this paper) combined with Holistic Grazing Planning permits very granular control over habitat and landscape management within the context of an economically viable land-based enterprise. Now and in the future, we will need more collaboration with researchers to shed light on ecoystem responses to management decisions.