Manipulating stocking rate and duration of grazing is fundamental to range management. It has been claimed that rotation grazing systems wiil increase stocking capadty of range whiie maintaining or improving anhnal gains, range condition, and forage production. To test these claims, we compared continuous, Qpasture rotationally de&r&, and &paddock short-duration rotation grazing on mixed-grass range near Cheyenne, Wyo. from 1982 through 1987. Grazing pmsures ranged from 19 to 81 steerdays per tonne of forage dry matter produced. Steers were weighed biweekly; forage production, utilization, and botanical composition were estimated by clipping; and basai cover was estimated by inclined point frame. Basal cover of litter and bare ground responded to stocking rate or grazing systems, but basal cover of vegetation was affected only by years. Steer average daily gain decreased as grazing pressure increased (r' = 0.66); systems had no significant effect. The most profitable stocking rate at 1986-87 costs and prices was approximately 60 to 80% above SCS recommendations, but the increase in return was small and range conditions and forage production probably could not be maintained a1 this rate.

Rangeland grazing management strategies have been developed in an effort to sustain efficient use of forage resources by livestock. However, the effects of grazing on the redistribution and cycling of carbon (C) and nitrogen (N) within the plant–soil system are not well understood. We examined the plant–soil C and N balances of a mixed‐grass rangeland under three livestock stocking rates using an area that had not been grazed by domestic livestock for more than 40 years. We established nongrazed exclosures and pastures subjected to continuous season‐long grazing at either a light stocking rate (20 steer‐days/ha) or a heavy stocking rate (59 steer‐days/ha, ∼50% utilization of annual production). Twelve years of grazing under these stocking rates did not change the total masses of C and N in the plant–soil (0–60 cm) system but did change the distribution of C and N among the system components, primarily via a significant increase in the masses of C and N in the root zone (0–30 cm) of the soil profile. The mass of soil C (0–60 cm) under heavy grazing was comparable to that of the light grazing treatment. Grazing at the heavy stocking rate resulted in a decrease in peak standing crop (PSC) of aboveground live phytomass, an increase in blue grama (Bouteloua gracilis [H.B.K.] Lag. Ex Steud.), and a decrease in western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) compared to the light grazing treatment. The dominant species under light grazing was western wheatgrass, whereas in the nongrazed exclosures, forbs were dominant and appeared to have increased at the expense of western wheatgrass. The observed increase of soil C and N in the surface soil where roots dominate indicates a greater opportunity for nutrient availability and cycling, and hence enhanced grazing quality.

Rotation grazing strategies have been proposed to increase stocking capacity, improve animal gains, and improve forage production and range condition. We compared continuous or season-long, 4-pasture rotationally deferred, and g-paddock time-controlled rotation grazing on mixed-grass rangeland near Cheyenne, Wyo. from 1982 through 1994. Stocking rates under light, moderate and heavy grazing averaged 21.6,47.0, and 62.7 steer-day ha-'; grazing pressures were 11.0 to 90.1 steer-day Mg-' of forage dry matter produced. We estimated above-and belowground biomass, botanical composition and basal cover. Bare ground and cover of warm-season grasses, forbs, and lichens were greater under heavy stocking; cover of litter, western wheatgrass, and total cool-season graminoids were greater under tight stocking. Stocking rate and grazing strategy had no effect on above-ground biomass and little effect on below-ground biomass. Under heavy stocking, percent of above-ground biomass contributed by forbs increased, especially under time-controlled rotation grazing, and that of western wheatgrass decreased. Otherwise+ effects of grazing strategy, level vs. slope, and north vs. south slope on vegetation were insignificant. Steer average daily gain decreased linearly as grazing pressure increased (3 = 0.44); grazing strategies had no significant effect. When cattle prices are favorable, the stocking rates that are most profitable in the short run may be high enough to reduce range condition.

Selective grazing can modify the productive capacity of rangelands by reducing competitiveness of productive, palatable species and increasing the composition of more grazing-resistant species. A grazing system (season-long and short-duration rotational grazing) 3 stocking rate (light: 16 steers ? 80 ha 21 , moderate: 4 steers ? 12 ha 21 , and heavy: 4 steers ? 9 ha 21) study was initiated in 1982 on northern mixed-grass prairie. Here, we report on the final 16 years of this study (1991-2006). Spring (April + May + June) precipitation explained at least 54% of the variation in peak standing crop. The percentage of variation explained by spring precipitation was similar between stocking rates with short-duration grazing but decreased with increasing stocking rate for season-long grazing. April precipitation explained the greatest percentage of the variation in peak standing crop for the light stocking rate (45%), May precipitation for the moderate stocking rate (49%), and June precipitation for the heavy stocking rate (34%). Peak standing crop was 23%-29% greater with light (1 495 6 66 kg ? ha 21 , mean 6 1 SE) compared to moderate (1 218 6 64 kg ? ha 21) and heavy (1 156 6 56 kg ? ha 21) stocking rates, which did not differ. Differences in peak standing crop among stocking rates occurred during average and wet but not dry springs. Neither the interaction of grazing system and stocking rate nor grazing system alone affected standing crop across all years or dry, average, or wet springs. Grazing-induced modification of productive capacity in this northern mixed-grass prairie is attributed to changes in species composition with increasing stocking rate as the less productive, warm-season shortgrass blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Griffiths) increases at the expense of more productive, cool-season midheight grasses. Land managers may need to substantially modify management to offset these losses in productive capacity. Resumen El apacentamiento selectivo puede modificar la capacidad productiva de los pastizales al reducir la competitividad de las especies productivas y apetecibles e incrementar la composición de especies más resistentes al apacentamiento. En 1982 se inició un estudio en las praderas de zacates mixtos del norte, en el que se evaluó un sistema de apacentamiento (continuo y rotacional de corta duración) en combinación con cargas animal (ligera 16 novillos ? 80 ha 21 , moderado 4 novillos ? 12 ha 21 , y alta 4 novillos ? 9 ha 21). Aquí, reportamos el final de este estudio de 16 añ os (1991-2006). La precipitación de primavera (abril + mayo + junio) explicó al menos 54% de la variación de la producción pico de la biomasa en pie El porcentaje de variación explicado por la precipitación de primavera, fue similar entre cargas animal en el apacentamiento de corta duración, pero disminuyó al incrementar la carga animal en el sistema de apacentamiento continuo. La precipitación de abril explicó el mayor porcentaje de la variación del pico de producción de la biomasa en pie en la carga animal lig...

Reduced pasture size and distance to water may be responsible for the alleged benefits of intensive time-controlled rotation grazing systems. We compared cattle gains, activity, distance traveled, and forage utilization on a time-controlled rotation system with eight 2&a pastures, on two 24-ha pastures grazed continuously (season-long), and on a 207-ha pasture grazed continuously, all stocked at the same rate. Utilization on the 207-ha pasture, but not on the 24ha pastures, declined with distance from water. At distances greater than 3 km from water in the 207-ha pasture, utgization was significantly less than on adjacent 24ha pastures, at distances of 1.0 to 1.6 km from water. Cows on the 2071a pasture travelled farther (6.1 km/day) than cows on the 24ha rotation pastures (4.2 km/day), which travelled farther than cows on the 24ha continuously grazed pastures (3.2 km/day). Grazing system, range site, slope, and weather had minimal effects on cow activity patterns. Gains of cows and calves were less on the 207-ha pasture (0.24 and 0.77 kg/day, respectively) than on the 24ha rotation pastures or 24-ha continuously grazed pastures (0.42 and 0.89 kg/da, respectively), with no differences between the latter. Calculated "hoof action" on the rotation pastures was less than that demonstrated to increase seed burial and seedling emergence. Intensive rotation grazing systems are unlikely to benefit animal performance unRss they reduce pasture size and distance to water

Beef cattle distribution patterns on foothill rangeA 3-year experiment designed to quantify the spatial and temporal utilization patterns of range sites by beef cattle on summer foothill range was conducted on the Wick Brothers Management Unit of the Wyoming Game and Fish Commission, 8 km w. of Arlington, Wyo. The grazing seasons, in replicate pastures, were from 15 July-9 August, 15 June-26 July, and 15 June-2 August in 1980,1981, and 1982, respectively. Daily observations were made of radio-telemetry collared cattle (3 per pasture). Cattle dispersion was constrained by the spatial distribution of water and slope. Across 3 seasons, 77% of observed use was within 366 m of water. Approximately 65% of the land area WPS beyond 723 m from water and sustained only 12% of observed use. Cattle concentrated use (79%) on slopes less than 7%. Consequently 35% of the area, on or surrounded by slopes >lO%, received only 7% of observed use. Loamy, grszable woodland and wetlandfsubirrigated range sites were most preferred and accounted for over 65% of observed use while occupying less than 35% of the land area. Overall, course upland, very shallow and shallow loamy sites were not preferred; however, site preference varied as areas further from water were utilized. Observed usewassigniticantly (P

Shortgrass rangeland, dominated by blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Steud), was grazed at 3 intensities, equivalent to mean stocking rates of 16.7, 23.0, and 36.5 beiferdays ha-', from 1939 through 1994. Few changes in plant communities had been documented by the early 1970's. In 1992-1994, frequency of occurrence, basal and foliar cover, and biomass at peak standing crop (PSC) were determined on the remaining pasture at each grazing intensity, and on 3 ungrazed exclosures. Blue grama and buffalograss (Buchloif dactyloides [Nutt.] Engelm.) increased, and western wheatgrass (Puwopyrum smithii [Rydb.] A. Love) and needle-and-thread (Spa coma&z Trin. & Rupr.) decreased, as grazing intensity increased. Redthree-awn (Aristiah longisetu Steud.) was most plentiful under light grazing. Basal cover and biomass of forbs were lower under grazing than in exclosures, but differences in biomass were not significant. Shrubs and half-shrubs decreased as grazing intensity increased. Frequency and cover of plains pricklypear (Opuntia polyacantha Haw.) were higher in the exclosures and under fight grazing than under moderate or heavy grazing; biomass was 4 to 6 times as high in the exclosures as under any grazing intensity, Heifer gains declined linearly with increasing grazing pressure index. Optimum (most profitable) stocking rate was about 20% higher than that under the moderate grazing intensity, under which biomass production was maintained and shrub and pricklypear remained at low levels. Returns to land, labor, and management were only slightly higher under the optimum stocking rate than under the moderate grazing intensity. The moderate grazing intensity appears to be both profitable and sustainable.

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