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ARS Home » Research » Publications at this Location » Publication #153928


item Northup, Brian

Submitted to: Society for Range Management
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2003
Publication Date: 1/25/2004
Citation: Northup, B.K. 2004. Assessing the potential utilization of a tallgrass paddock with indicator kriging [abstract]. Society for Range Management. p. 152.

Interpretive Summary: Abstract Only.

Technical Abstract: Available forage, energy and nutrients of native prairies are heterogeneously distributed within landscapes, and may impact how cattle make use of available grazing stations. Such heterogeneity is a problem in achieving uniform application of grazing pressure. This paper describes a technique, based on simple constraints, which can predict potential spatial use of paddocks. A study was conducted on a 30 x 150 m (0.45 ha) plot within a 13 ha paddock, described as a tallgrass prairie site (>65% of annual forage produced by four dominant tallgrasses), in central Oklahoma. Seven transects running the length of the plot (150 m, perpendicular to the slope) were located at 5-m intervals across the slope. Along each transect, biomass was collected at 34 random sample points from 0.25 m^2 quadrats during mid-June 2001. Collected materials were analyzed to define available forage (g, dry matter basis), nitrogen and phosphorus concentrations of patches available for grazing, and distribution maps were developed. Indicator kriging was used to describe probability maps of potential use by stocker cattle, based on forage characteristics and simple control factors (daily intake requirements, bite size, daily grazing times, patch residence time). Distributions of forage, N, and P were heterogeneous, with entire ranges of observable values occurring across <28 m. These distributions affected potential forage use on the plot. Some areas had high probabilities of heavy grazing, while other areas showed only limited potential use. Indicator kriging, particularly multiple-variable approaches, could define potential spatial impacts of grazing, and identify areas prone to over-grazing.