Despite the availability of potentially profitable range improvement alternatives, private land ranch managers in the central U.S. are not readily adopting recommended range improvement practices. One explanation for this behavior is that managers may not be willing to accept the increased risk associated with implementing range improvement programs. The objectives of this study were to estimate the expected value and variability of net returns derived from several range improvement practices and use this information to assess the influence that manager risk attitudes have on the selection of range improvement practices. A stochastic range simulation model was used to provide estimates of the expected value and variability of income following the application of several range improvement practices in the Cross Timbers Region. Generalized stochastic dominance procedures were then used to rank these practices for managers characterized by alternative risk attitudes. Results of the analysis illustrate that optimal range improvement practices may be sensitive to manager risk attitudes. Managers willing to accept the possibility of low or negative incomes may prefer more intensive range improvement practices such as application of tebuthiuron for brush management followed by annual prescribed burning. In contrast, risk averse decision makers are inclined to implement lower cost range improvement practices or fail to utilize any range improvement practice.

Hypotheses are frequently posed that require comparisons among diet samples. Hierarchical cluster analysis is suited to this task, but has received little attention in food habits research. By grouping samples so that similar diets are close together and dissimilar diets are spaced farther apart, hierarchical cluster analysis reveals patterns in data difficult to recognize in the matrix of similarity coefficients typical of most food habits studies. We provide an example of this type of analysis, and indicate its application to management of large herbivores.

Globemallows (Sphaeralcea spp.) have potential in rangeland seedings. Thirty-seven accessions of globemallow were grown at 2 sites in northern Utah and southern Idaho to quantify their agronomic attributes. Data for transplant survival, standing crop, and seed yield were collected in 1987 and 1988. Total globemallow survival (mean = 92%) and seed weights (mean = 0.8 g/plant) differed significantly (P is lesser than or equal to 0.05) among locations. Plant weight (mean = 102 g/plint) differed significantly (P is lesser than or equal to 0.05) among locations, species (S. grossulariifolia, S. coccinea, S. parvifolia, S. munroana, and interspecific hybrids), and years. In a second study, 5 globemallow accessions of 2 species and ‘Spredor 2’ alfalfa (Medicago sativa) were grown with ‘Hycrest’ crested wheatgrass (Agropyron desertorum X A. cristatum) to determine forage yields from 1985-1988. Globemallows produced significantly (P is lesser than or equal to 0.05) less forage (62 g/ml) than alfalfa (389 g/m2). Forage yield of S. munroana (76 g/m2) did not differ significantly (P>0.05) from that of S. grossulariifolia (48 g/m2). Forage yield of crested wheatgrass (mean = 101 g/m2) did not differ significantly (P>0.05) when grown with globemallow versus alfalfa. Plant breeding and selection could probably improve these agronomic attributes for globemallows seeded on rangelands.

Sixteen ruminally cannulated beef steers grazing native summer range in the Northern Great PIains were assigned to 4 treatments in a 2 X 2 factorial arrangement. Main effects were barley grain and monensin. Rolled barley (RB) containing 7.5% molasses was fed at 0 and 1.36 kg head-1 day-1. Steers received no monensin (M) or M released at 101 mg/d via a ruminal delivery device. Forage intake and digestibiIity, ruminal fermentation, and ruminal passage rate were measured during trials in: (1) June, (2) July, and (3) August. Diet samples were collected from esophogeally fistuIated steers during each trial. Dietary crude protein was greater (P<0.05) during trials 1 (15.2%)and 3 (14.3%) than in trial 2 (10.2%). In vivo organic matter (OM) digestibiiity, ruminal fluid passage rate, and fermentation variables varied by trial (P<0.01). Forage OM intake was reduced (P<0.10) by RB, but was not influenced (P>0.10) by M or the M and RB combination. In vivo OM digestibility was increased (P<0.05) by M, while RB had no effect. Particulate passage was not affected by M or RB but gastrointestinal tract fill was reduced by monensin (P<0.05). Ruminal fluid passage rate was affected by the RB X M X Trial interaction (P<0.05). Within June and July, fluid passage rate was similar among treatments and ranged from 14.0 to 11.3 %/h, respectively. During trial 3, a RB X M interaction (P<0.05) increased fluid passage rate. Ruminal ammonia-N concentration was similar among treatments. Barleey lowered (P<0.05) ruminal pH and increased (P<0.10) total volatile fatty acids. A RB X M X Trial interaction (P<0.05) was noted for molar proportions of acetate, propionate, and butyrate. Within trials, RB, M, and their combination affected (P<0.01 to P<0.10) acetate, propionate, and butyrate. We conclude that barley, monensin, and forage quality infiuence ruminal fermentation, passage rate, and intake traits of steers grazing summer range.

The possibility of attenuating the negative effects of high stocking rate (SR) on animal production by using inexpensive low energy supplements (mainly poultry litter) was examined in a herd of small, crossbred cows graxing year;ong on Mediterranean grassland. Herds of 15 to 25 cows were stocked at 0.50, 0.67, and 0.83 cows/ha in replicated blocks. Weaning weights and ADG of calves were higher (P<.001) at the low SR, but there were no differences between the moderate and heavy stocking treatments. Weaned weight per hectare as well as supplementary feed consumption were highest at the high SR, but differences between the low and moderate stocking treatments were not significant. Conception rates fluctuated between years and declined at the heavy SR, only to recover dramatically in the inst year of the experiment. Weaning rates were variable both within and between SR’s from year to year, but overall 5-year SR means were not significantly different. It is concluded that on the seasonal Mediterranean grassland typical of eastern Galilee where quality of dry summer pasture is low, supplementation based mainly on poultry litter and straw can buffer some of the effects of high stocking rates on animal production but cannot ensure consistently high productive performance even at low SR.

Plots dominated by Japanese brome (Bromus japonicus) and western wheatgrass (Agropyron smithii) were burned in Badlands National Park, South Dakota, in April 1983 and/or 1984. Standing crop of all species and tiller densities of the 2 dominate species were determined for 4 years. Burning favored western wheatgrass and reduced Japanese brome tiller density and standing crop for at least 1 growing season. In years where no burning occurred, Japanese brome standing crop and tiller density were dependent on the presence of litter on the soil surface. Burning in April killed Japanese brome seedlings for 1 growing season and reduced subsequent generations by reducing surface litter accumulations, with the effect being greatest when autumn precipitation was below average. April burning reduced the standing crop of green needlegrass (Stipa viridula) for at least 3 growing seasons after burning but increased standing crop of buffalograss (Buchloe dactyloides) and sand dropseed (Sporobolus cryptandrus) for 3 to 4 years after burning. Threadleaf sedge (Carex filifolia) standing crop was not significantly affected by burning.

Harvester ants are a major component of western rangeland. Little is known about ants' role in soil water dynamics. Annual patterns of soil moisture under mounds of the harvester ant (Pogonomyrmex owyheei, Cole) were studied in southeastern Idaho. Soil moisture at 20-cm intervals to a depth of 100 cm was estimated monthly with a neutron probe. Between 60 and 100 cm, higher levels of moisture were found below mounds than in control areas. The amount of water added to the soil during spring recharge was greater in control areas at 20 cm but greater under ant mounds at depths below 60 cm. Under ant mounds, approximately 1.3 cm more water was added to the soil between 60 and 100 cm.

Three rates of dried sewage sludge (22.5, 45.0, and 90.0 Mg (megagrams) ha-1), were applied to a degraded semiarid grassland site on the Upper Rio Puerto Watershed in west-central New Mexico. Various soil and plant parameters were determined over 4 growing seasons. Most soil macronutrients, such as nitrogen (N), phosphorus (P), and potassium (K), and micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), increased linearly with increasing sludge amendment rates. Heavy metals (cadium (Cd) and lead (Pb)) did not change as a result of sludge amendment in the first 3 growing seasons. However, concentrations of soil Cu, Mn, and Cd were just above maximum acceptable standards in the heaviest sludge treatment after 4 growing seasons. Plant density, specks richness, and diversity all decreased with increasing sludge rates. However, total plant foliar cover and herbaceous yields increased significantly with the application of sludge. Blue grama (Bouteloua gracilis (H.B.K.) Lag.) cover and yields, in particular, increased 2 to 3 fold over the control as a result of sludge amendment, whereas broom snakeweed (Gutierrezia sarothrae (Pursh) Britt. + Rusby) density decreased over 4 growing seasons. The most favorable soil and vegetation results were from the 22.5 and the 45 Mg ha-1 sludge application rate.

A controlled environment experiment was performed on plants from 2 Agropyron smithii Rydb. (western wheatgass) populations to determine how defoliation at 1-week intervals and graxing history affected total silicon accumulation in shoots, and how Si was distributed within the plant. Plants were collected from a heavily grazed, 10-year-old prairie dog colony and an ungrazed, 40-year-old exciosure at Wind Cave National Park, South Dakota. After 18 weeks, the total amount of Si accumulated in shoots was similar in plants from both populations, regardless of whether or not the plants were clipped. However, the Si concentration in shoots was greater in nondefoliated than defoliated plants of both populations because of Si dilution resulting from greater shoot production in defoliated pIants. In both populations, roots and leaf blades had the highest Si concentrations, rhizomes had the lowest concentrations, and sheaths, crowns, and belowground stems had intermediate concentration.

Differences in growth rate among 3 subspecies of big sagebrush (basin big sagebrush, mountain big sagebrush, and Wyoming big sagebrush) for mature plants have been reported by a number of workers. Little has been reported on comparisons of seedling growth rate among these 3 subspecies. Results of this study indicated that (1) over an extended period and in a non-water-limiting environment, the rate of seedling growth In Wyoming big sagebrush approached zero and was less than that of seedlings of basin and mountain big sagebrush; (2) basin and mountain big sagebrush continued to have nonnegligible growth rates even at the end of the study; and (3) Wyoming big sagebrush reached its point of maximum growth rate approximately 2 weeks earlier than did the other 2 subspecies. It appears that Wyoming big sagebrush has evolved, placing 2 important growth characteristics under genetic control: (1) the maximum growth rate is attained earlier (when more water is available to sustain such growth) than in the other 2 subspecies, possibly enhancing its ability to survive on xeric sites during the early stages of growth; and (2) top growth produces smaller aboveground parts, enhancing survival after the early stages.