Based on recent circumstances in connection with compensation of livestock killed by large, protected carnivores in Norway, this paper discusses what type of logic should be used to establish which animal is the perpetrator. We suggest that the use of a "modus tollens" logic based upon tracks and signs which are not found at the site is invalid for management purposes. Instead, we suggest "modus ponens" logic based upon what is actually found by a carcass.

The canopy of Quercus douglasii H. & A. (blue oak) has been variously reported to enhance or suppress understory production. The effects of canopy removal have been reported only for the northern portion of blue oak's range. We removed all blue oaks from 6 plots in the central coast of California and found no significant change in understory biomass over 3 years. Understory herb cover averaged 32.6% on cleared plots, compared to 24.3% on uncut plots, but composition changed little with the exception of an increase in Erodium cicutarium (L.) L'Her. Clearing did not produce the distinctive species composition and forage enhancement under Q. douglasii canopy reported in other studies, an based on comparisons between unmanipulated canopy and adjacent grassland. Our results suggest that the canopy effect could instead be caused by differences in sites occupied by trees. Clearing of Q. douglasii in regions with 50 cm or less of mean annual precipitation is not recommended for increasing forage production.

Many ranchers claim that if a cow starts eating locoweed, she will teach others to eat it. Three grazing trials were conducted to evaluate the role of social facilitation in starting cattle to graze locoweed. The first trial was conducted near Gladstone, N.M., using mature cows grazing woolly locoweed (Astragalus mollissimus var. mollissimus Torr). The second trial was conducted on the Raft River Mountains in northwestern Utah, using yearling cattle grazing white locoweed (Oxytropis sericea Nutt). The third trial was conducted to determine if aversion-conditioned yearling cattle would consume white locoweed when placed with cattle that were eating locoweed (loco-eaters). Cattle conditioned to eat locoweed and naive animals in trials 1 and 2 first grazed in separate pastures to evaluate their initial acceptance of locoweed. The groups in the respective trials then were placed together to evaluate the influence of social facilitation on locoweed consumption. Locoweed consumption was quantified by bite count. Naive cattle in trials 1 and 2 sampled small quantities of locoweed while grazing separately. However, they greatly increased locoweed consumption when placed with the loco-eaters. Aversion-conditioned cattle in trial 3 did not consume locoweed while grazing separately. When placed with loco-eaters, they gradually increased consumption of white locoweed, in contrast to the immediate acceptance of locoweed by naive cattle in trials 1 and 2. The aversion extinguished and averted animals eventually accepted white locoweed at levels comparable to loco-eaters. Results of this study demonstrate that social facilitation can cause cattle to start eating locoweed.

Diet, dietary selection, and nutritional composition of the food of sage grouse (Centrocercus urophasianus) hens were determined during the pre-laying period in southeastern Oregon in 1990 an 1991. We collected 42 female sage grouse during a 5-week period preceding incubation (4 March-8 April). Sagebrush (Artemisia spp.) was the most common among 21 foods consumed but forbs composed 18 to 50% of the diet by weight. Desert-parsley (Lomatium spp.), hawksbeard (Crepis spp.), long-leaf phlox (Phlox longifolia Nutt.), everlasting (Antennaria spp.), mountain-dandelion (Agoseris spp.), clover (Trifolium spp.), Pursh's milk-vetch (Astragalus purshii Dougl.), buckwheat (Eriogonum spp.), and obscure milk-vetch (A. obscurus) were the primary (greater than or equal to 1% of the diet by weight) forbs consumed. Forbs were used selectively over sagebrush in both low and big sagebrush cover types. All forbs were higher in crude protein and phosphorus and many were higher in calcium than sagebrush. Consumption of forbs increased nutrient content of the composite diet. Substantially fewer forbs were present in the diet in 1991 than in 1990, which coincided with reduced sage grouse productivity on the study area. These results suggest that consumption of forbs during the pre-laying period may effect reproductive success by improving nutritional status of hens.

Japanese brome (Bromus japonicus Thunb.), an alien annual grass, is an important component of some northern mixed-prairie communities. Understanding the relationship between environment and population dynamics for this species is critical for efficient management of infested ranges. Our objective was to determine the germination pattern of seed harvested in the Great Plains with varying collection dates, storage conditions, incubation temperatures, and light regimes. Seeds were collected from inflorescences (nondisseminated seed) during July in Oklahoma a Montana and during November and December in Montana. July collections were stored in paper sacks in a laboratory, and November and December collections were divided into thirds and stored in an unheated warehouse, oven-dried at 46 degrees C, or frozen at -18 degrees C. Seeds were germinated in 2 regimes, where temperatures alternated every 12 hours and light was provided during the hours of high temperature. One regime provided 10 days of prechilling (0 and 10 degrees C) followed by 18 days of a warm temperature (8 and 23 degrees C) (chilling). Another regime consisted of 28 days of the warm temperature (warm). Samples of seeds were also imbibed in the warm regime with 12-hour or intermittent periods of light. July collections germinated rapidly to > 90% regardless of temperature. November and December collections stored in the warehouse germinated > 70% in the warm regime, but germination was reduced to < 20% with chilling, suggesting secondary dormancy was induced by imbibition at 0 degrees C. Oven drying was the only treatment that consistently reduced maximum germination. Darkness enhanced 7-day germination, but light improved 28-day germination, and more recently collected seeds were more sensitive to light than older ones. These and earlier findings from Kentucky suggest Japanese brome seeds grown in different locations respond similarly to changing environmental conditions.

Reestablishment of spiny hopsage (Grayia spinosa [Hook.] Moq.) in the shrub steppe requires development of appropriate seeding technology. We examined the effect of planting date and seedbed environment on germination and seedling establishment of 2 seed sources at 2 southwestern Idaho sites. Seedbeds were prepared by rototilling. In 1987-88, seeds collected in 1986 were drilled at 66 viable seeds m-1 of row at Birds of Prey in late fall, winter, and early spring and at Reynolds Creek in late fall, early spring, and late spring. Seeds collected in 1986 and 1988 were broadcast at 400 viable seeds m-2 at both sites in late fall, early spring, and late spring 1988-89. Seeds in nylon bags were also planted at each site in late fall, winter, and early spring in 1987-88 and in late fall, winter, early spring, and late spring in 1988-89. On each succeeding planting date and in early summer, 5 bags of each seed source from each of the earlier planting dates were recovered. Water content, viability, and germination were compared among seeds from previous plantings and control seeds stored in the laboratory. Each year, first-year seedling establishment at both sites was favored by late fall compared to other planting dates. In 1988, seedlings established only from late fall plantings at a density of 1 m(-2) st each site. In 1989, late fall planting at the 2 sites increased seedling establishment 6 (51 vs 8 m-2) and 20 (41 vs 2 m-2) times compared to early spring planting. Germination was generally greater for seeds incubated at field sites compared to controls. Germination total and rate increased 6-11 times and 13 days from late fall 1987 to early spring 1988, 1-6 times and 4 and 9 days from winter 1988 to early spring 1988, 17 times and 10-11 days from late fall 1988 to winter 1989, and 4-7 times and 11 days from winter 1989 to early spring 1989. Late fall or early winter planting is essential to permit early spring germination when surface soils are moist.

We compared the preference of cattle for 12 entries, 2 of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes], 5 of thickspike wheatgrass [Elymus lanceolatus (Scribner & J.G. Smith) Gould ssp. lanceolatus], 3 of Snake River wheatgrass (proposed name E. lanceolatus spp. wawawaiensis), and 2 of bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) A. Love] in May 1989 and 1990 at Logan, Utah. Spaced plants were randomly arranged in 4 paddocks which were grazed once by 2 animals in late spring each year. Number of bites and number of visits were recorded for each entry in each paddock for the 2 animals individually. Cattle preferred Hycrest and Nordan crested wheatgrasses both years. Number of bites per plant for crested, thickspike, Snake River, and bluebunch wheatgrasses averaged 9.1, 4.3, 3.1, and 4.1, respectively, in 1989 and 6.7, 3.3, 3.5, and 3.6, respectively, in 1990. Number of visits was highly correlated with number of bites across entries. Grazing preference among entries was more highly correlated with biomass score and canopy height than basal area or maturity. Cattle preferred crested wheatgrass over the native wheatgrasses tested here during the spring grazing season.

Multi-variable analysis of grazing research has seen little conceptual development and even less application. To advance research on the multiple relationships of livestock grazing, computer-based analyses using multiple variables are needed. Dynamic variables describing livestock-herbage relationships must be developed to describe dynamic processes such as herbage growth and disappearance. Such variables could be used either alone or in combination with other variables as indicators to analyze and manage grazing. This paper presents 4 arrays of derived variables and discusses their individual and combinational value in analyzing and managing grazing. Greater power in analyzing grazing will come from use of combinations of variables rather than relying on single variables, e.g., stocking level. The variables described are useful in comprehensive analyses of research or in ad hoc roles aiding decisions in management. The paper also discusses possible future uses of variables as indicators in computerized analyses of other ecological systems.