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Effects of Grazing Management on Prairie Grouse Habitat
Llewellyn L. Manske PhD
Associate Range Scientist
North Dakota State University
Dickinson Research Extension Center
The effects of grazing on grassland plants depend on season of use, phenological stage of growth, intensity of grazing, and duration of grazed and ungrazed periods. Differential responses of the vegetation to grazing management treatments affects the prairie grouse populations that depend on grassland plants for habitat. The different affects on the plant communities and prairie grouse habitat by the various types of grazing management treatments is important to know so that management treatments that benefit the grassland plants and enhance prairie grouse habitat can be selected. The purpose of this project was to determine the effects of grazing management treatments on the grassland plant communities and prairie grouse habitat and evaluate prairie grouse use of the different grazing treatments.
The effects of grazing management on grassland plants and prairie grouse habitat were studied for six field seasons 1975 - 1980. The methods and treatments have been described by Manske and Barker 1977, Manske and Barker 1978, Manske and Barker 1979, Manske and Barker 1981, Manske, Barker, and Biondini 1988, and Manske 1990. Effects of grazing were analyzed by comparing the changes from year to year on the treatments and the ungrazed control plots on a per pasture basis. Replications had the same grazing periods and stocking rates. Pasture treatments were categorized by the number of pastures in the allotment system and the season of grazing use. Plant species composition was determined by the ten pin point frame method (Cook and Stubbendieck 1986) during August and reported as percent basal cover. Vegetation visual obstruction was used to sample the structure differences of the habitats and treatments by the height-density method developed by Robel et al. (1970) and modified by Kirsch (1974) (Table 1 and 2). Mean 100% visual obstruction measurements (VOM) of 1.5 decimeters (5.9 inches) was considered to be the minimum level for good concealment cover, and nesting and roosting habitat for prairie grouse (Manske and Barker 1981, Higgins and Barker 1982). The Panicum virgatum (switchgrass) portion of the midland grassland community located on the foot slopes was the primary prairie grouse concealment cover habitat on the Sheyenne National Grasslands (Manske and Barker 1981, Manske and Barker 1988) and was used as the key vegetation to evaluate the effects of different grazing treatments. Habitat use index (% of display location / % of study area) as described by Robel et al. (1970) was used to evaluate display ground locations and grazing management relationships. The habitat use index was also used to evaluate nest site selection.
Seasonlong grazing treatments were used on all the allotments on the Sheyenne National Grasslands from 1940 through 1967. The prairie grouse population was very low (less than 25 males) during this period and did not show any increase. In 1968, 22 allotments had multiple pasture once over rotation grazing treatments started. By 1973, 75% of the public land was managed by some type of multiple pasture rotation system with one grazing period per pasture. Eighteen pastures in 15 allotments had two grazing periods in 1971. There was a large increase in prairie grouse population between 1971 and 1972. During the period of 1968 to 1974 the population of prairie chicken and sharptailed grouse increased appreciably. Management with two grazing periods on multiple pastures within an allotment started in 1974. There was a very large increase in the prairie grouse population in the spring census of 1975. Management with twice over grazing periods increased from 10% of the public land in 1974 to 54% in 1978. The prairie grouse population increased substantially during this 5 year period. The increasing trend for management with multiple grazing periods on pastures was changed to single grazing periods and deferred type grazing management in 1979. Seventy and seventy-one percent of the public land was managed by treatments with single grazing periods in mid season or deferred until late season in 1979 and 1980, respectively. The prairie grouse population responded negatively to these changes in management and greatly declined in the spring census of 1981 and have continued to declined in numbers. The prairie grouse populations increased during the periods that the grazing management was with systems that used multiple grazing periods in several of the pastures in an allotment. The prairie grouse populations declined or remained low during periods where the major portion of the grasslands were managed with seasonlong grazing or when the rotation pastures were grazed for only one grazing period or were managed with deferred type grazing systems.
The vegetation data collected during this study (Manske and Barker 1981, Manske and Barker 1988) shows that the seasonlong, once over, and deferred type grazing management does not provide the type of structural habitat that has been shown to be beneficial for the prairie grouse.
Seasonlong grazing treatments showed no benefit to grass basal cover even at low stocking rates. Spring 100% visual obstruction measurements (VOM) were below rotation grazing treatments. These readings were below the minimum 1.5 decimeter level and did not provide adequate prairie grouse concealment cover for nesting or roosting. Prairie grouse selected against seasonlong grazing treatments for spring courtship display ground and nest locations.
Two pasture systems with three grazing periods showed significant (P<0.05) reduction in basal cover of warm season grasses and switchgrass on the lowland plant community. These decreases were significantly (P<0.05) greater on the two pasture, thrice over treatments than on the seasonlong treatments. Basal cover of vegetation on the two pasture, four times over was not significantly changed. Pastures in two pasture treatments should be managed with no less than four grazing periods each. Spring 100% VOM readings were greater on two pasture treatments than one pasture, seasonlong treatments and were not different than readings from three pasture rotation treatments for permanent and nonpermanent transects. Prairie grouse selected pastures managed with two pasture grazing treatments for courtship display locations but not for nest site locations.
Pastures grazed for one period during mid season, June to September, showed no positive response in grass basal cover but did show significantly greater 100% VOM readings compared to seasonlong grazing treatments. Prairie grouse did not select for pastures managed with one mid season grazing period for display ground and nest locations.
Three pasture, once over deferred grazing treatments had 11 to 13 months of ungrazing prior to the deferred grazing treatments. No significant changes in basal cover of the vegetation occurred during this one year ungrazed period, but a consistent decreasing trend in basal cover for warm season grasses and switchgrass in the midland and lowland was shown. The vegetation height did visually appear to be impressive as prairie grouse habitat after one year of ungrazing. The 0% VOM was significantly taller than grazed treatments but the 100% VOM was not different than rotation grazed treatments. After 60 days of grazing during the late season, the 0% VOM was reduced but still taller than the other treatments and the 100% VOM was greatly reduced but not different than rotation treatments in the spring. The deferred grazing treatment was intended to delay grazing pressure on one pasture in a system until after grass seed development which occurred by late August or early September for the purpose of improving grass plant density but deferred grazing significantly (P<0.05) decreased basal cover of warm season grasses and reduced basal cover of switchgrass significantly (P<0.05, P<0.1) on the midland and lowland plant communities, respectively. The 100% VOM was significantly decreased during the first growing season after deferred grazing treatments and the level fell below the minimum of 1.5 decimeters. Prairie grouse selected against pastures managed with deferred grazing the previous year for spring display ground locations. Deferred grazing was not considered to be a desirable grazing treatment for grassland vegetation and prairie grouse habitat.
Three pasture, twice over treatments were grazed early-late, early-mid, mid-mid, and mid-late season of use. Warm season grasses and switchgrass on the midland and lowland communities and sedges on the lowland communities increased significantly (P<0.05) in basal cover on pastures managed with two grazing periods compared to pastures managed with one pasture, seasonlong treatments. The 100% VOM on pastures with two grazing periods was significantly greater than on pastures grazed seasonlong. Prairie grouse selected pastures with two or three grazing periods for display ground and nest locations. Management treatments with the pastures grazed for two periods showed benefit to grassland vegetation, prairie grouse habitat and prairie grouse populations. Treatments with twice over grazing on each pasture should be used to manage the allotments on the Sheyenne National Grasslands.
Cow and calf weight performance of average daily gain, gain per acre, and accumulated weight gain was significantly (P<0.05) lower on deferred grazing treatments compared to twice over rotation grazing treatments (Manske et al. 1988, Manske 1994).
Table 1. Visual obstruction measurements in decimeters from permanent transects read spring and fall of 1979 and 1980.
(click on image for lager view)
Table 2. Visual obstruction measurements in decimeters from nonpermanent transects read spring of 1979 or 1980.
(click on image for lager view)
Cook, C.W. and J. Stubbendieck. 1986. Range research: basic problems and techniques. Society for Range Management. Denver, Colorado. 317 p.
Higgins, K.F. and W.T. Barker. 1982. Changes in vegetation structure in seeded nesting cover in the prairie pothole region. USDI, Fish and Wildlife Service. Special Scientific Report - Wildlife No. 242, Washington D.C. 26 p.
Kirsch, L.M. 1974. Instructions for use [of] a height-density pole for obtaining vegetative measurements on upland habitats. Unpublished. 3 p.
Manske, L.L. 1990. Compatibility of ecological management for native prairie, prairie chicken habitat, and livestock production. 52nd Midwest Fish & Wildlife Conference. Minneapolis, Minnesota. Abstract No. 41. p. 131-132.
Manske, L.L. 1994. Grazing management for western North Dakota rangelands. 42nd Annual Research Roundup. NDSU - Dickinson Research Extension Center. Dickinson, N.D. p. 11-25.
Manske, L.L. and W.T. Barker. 1977. The 1976 species composition and biweekly productivity data from a study of the affects of different grazing systems on the vegetation on the Sheyenne National Grasslands. Research Annual Report to Sheyenne Valley Grazing Association and U.S. Forest Service. McLeod, North Dakota. 356 p.Manske, L.L. and W.T. Barker. 1978. The 1977 species composition and biweekly productivity data from a study of the effects of different grazing systems on the vegetation on the Sheyenne National Grasslands. Research Annual Report to Sheyenne Valley Grazing Association and U.S. Forest Service. McLeod, North Dakota. 472 p.
Manske, L.L. and W.T. Barker. 1979. The 1978 species composition and biweekly productivity data from a study of the effects of different grazing systems on the vegetation on the Sheyenne National Grasslands. Research Annual Report to Sheyenne Valley Grazing Association and U.S. Forest Service. McLeod, North Dakota. 495 p.
Manske, L.L. and W.T. Barker. 1981. The prairie grouse on the Sheyenne National Grasslands, North Dakota. NDSU Research Report, Fargo, N.D. 238 p.
Manske, L.L. and W.T. Barker. 1988. Habitat usage by prairie grouse on the Sheyenne National Grasslands. USDA Forest Service. General Technical Report RM-159. p. 8-20.
Manske, L.L. W.T. Barker, and M.E. Biondini. 1988. Effects of grazing management treatment on grassland plant communities and prairie grouse habitat. USDA Forest Service. General Technical Report RM-159. p 58-72.Manske, L.L., M.E. Biondini, D.R. Kirby, J.L. Nelson, D.G. Landblom, and P.J. Sjursen. 1988. Cow and calf performance on seasonlong and twice over rotation grazing treatments in western North Dakota. Proceedings of North Dakota Cow/Calf Conference. Bismarck, N.D. p. 5-17.
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