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Integrated Management of the Greater Prairie Chicken and Livestock on the Sheyenne National Grassland

Grazing Systems

The land comprising the Sheyenne National Grassland has been grazed by domestic livestock since the late 1800's. In 1940, the USDA Soil Conservation Service, which had been providing its expertise to the Farm Security Administration for the reclamation of the arid lands assumed administrative authority over the Land Utilization Lands. The land comprising the SNG was divided into 10 common grazing blocks which were grazed season-long for eight months, May through December. In 1954, the administration of the L.U. land was transferred to the U.S. Forest Service and the grazing season was changed to a six month season (May to early November) in 1955. The common grazing blocks were divided into grazing allotments. Today the North and South Units of the SNG are divided into 11 blocks which are subdivided into 52 grazing allotments. The North Unit is comprised of 10 blocks and 51 allotments. (Appendix 2). Cross fencing of allotments to create more pastures and more management options began in 1967 (Manske et al. 1988). The standard of season-long grazing gave way to rotational grazing systems. By 1974, 84% of the federal land was managed by rotational grazing systems.

Today, the majority of the SNG is managed under twice-over deferred rotation systems (Table 2). Most of these are 3-pasture systems, although 4-pasture is also common, with a smaller number of 2-pasture and 5-pasture systems. One allotment is managed as a 6-pasture deferred rotation system. Several allotments, or a pasture within an allotment, are managed as season-long systems. Grazing usually begins about 15 May and lasts for 5.5 to 6 months, ending about mid-November.

Stocking on the SNG is measured in terms of animal units (AU) and animal months (AM). An animal unit is considered to be a cow/calf pair. Thirty days of grazing by 1 cow/calf pair constitutes one animal month. Appendix 2 gives some history of the stocking of the 51 allotments of the North Unit. The 1995 stocking was: 9,391 cow/calf pairs utilizing 50,076 AM's, 424 yearlings utilizing 2,255 AM's and 342 bulls utilizing 1,819 AM's (USFS, personal commun.). An animal unit month (AUM) is the basic unit of grazing capacity and is defined as potential forage intake (animal demand) of one animal unit for one month or 30 days (Valentine 1990). As a quantitative measure of carrying capacity, the AUM is further described as 750 pounds of air dry forage (2.5% of body weight X 1000 pounds X 30 days). The AUM's available on the SNG can be estimated from the stocking values given for 1995, although there is not complete agreement on how this should be translated. The USFS gives the following estimates: 1 cow/calf pair AM = 1.32 AUM's; 1 yearling AM = 1 AUM; 1 bull AM = 1.5 AUM. The total AUM's available for 1995 using these values was 71,084. Given the total acreage of the SNG of 70,180, this translates into about 1 acre per AUM. The value of accurate stocking rate data cannot be overstated. The stocking rate will greatly affect the quantity and/or quality of the available and residual forage, which will directly affect livestock production as well as many wildlife species.

Table 2. Grazing systems used on the 51 allotments of the North Unit of the Sheyenne National Grasslands.

Twice-over, Deferred Rotation
------------------Number of Patures--------------------
Season Long Three Four Two Five Six
A Annex
South S West
East A4
West A
North Durler
SA Jordheim
East S
North Frisk6
South Frisk7
West I
South Durler
Olerud Sagvold
Milton Sr.10
Pfingsten Olson12
North S
South S East
East I14
Froemke- Hoy
South Brown15
Milton Jr.18

1Yearling pasture in Ekre allotment is grazed season long. East-West pastures are managed as twice-over, deferred rotation system.
2The West pasture is grazed season-long by yearlings. The other four are grazed as a thrice-over, deferred rotation system. One pasture is grazed twice over.
3East pasture grazed season long with yearlings. The remaining three pastures are grazed as a twice-over, deferred rotation system.
4One of the pastures is grazed thrice-over.
5One of the pastures is grazed only once.
6Two pastures of the three are grazed thrice-over.
7Two pastures are grazed four times and one three times.
8One of the pastures is grazed only once.
9Two of the pastures are grazed only once.
10All four pastures are grazed thrice-over.
11The West S 1/3 pasture is grazed only once at a reduced rate.
12The West pasture is grazed only once, and one of the four pastures is private land.
13All four pastures are grazed thrice-over.
14One of the pastures is grazed only once.
15Both pastures grazed thrice-over.
16This allotment is managed as a two-pasture deferred rotation with private land.
17The five pastures are managed as two three-pasture deferred rotation systems with one pasture being used both ways.
18Operated as a six-pasture deferred rotation system by using private land.

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