In arid and semi-arid climates, the physical and chemical nature of the soil seedbed greatly effects success or failure of plant recruitment. We hypothesized that the presence or absence of microphytic soil crusts may influence the character of soil seedbeds. To test this hypothesis, we compared chemical and physical attributes of the soil seedbed (0-6 cm) between adjacent areas of well-expressed microphytic soil crusts and non-microphytic soil surfaces for 2 sites on granitic alluvial fans in north-western Nevada. As compared with non-microphytic areas, microphytic soil seedbeds were finer-textured and contained more DTPA-extractable Mn, Cu, and Zn. Further research should examine in greater detail the role of microphytic soil surfaces in eolian dust entrapment, its relationship to nutrient deposition, and the interaction with seed recruitment.

To quantify effects of forage canopy properties, soil surface relief, and hill slope on the hydrologic properties of the soil in a New Zealand hill land pasture, duplicate plots (15 x 3 m) with 3 canopy heights (6, 20, and 47 mm) were trodden with 0, 4, or 8 mature cows for 40 min on a moderate (15-18 degrees) slope (Trial 1), and similar plots with the low and high canopy heights were trodden by 8 mature cows for 40 min on gentle (8-14 degrees), moderate (15-18 degrees), or moderately steep (20-25 degrees) slopes (Trial 2). Pre- and post-treading measurements included canopy heights; bare soil proportions; soil moisture contents; hoof prints and skids; roughness coefficients, surface water detention storage volumes, and soil clump volumes with a 38-pin contometer; and water infiltration and sediment loss by rainfall simulation. In Trial 1, increasing canopy height resulted in lower (P < 0.01) proportions of bare ground, roughness coefficients, soil clump volumes, and sediment losses. Increasing treading damage resulted in higher (P < 0.05) post-treading roughness coefficients, proportions of bare ground, hoof print and skid densities, surface water detention volumes, and soil clump volumes. In Trial 2, soil hydrologic properties did not differ between canopy height or hill slope treatments. In the two trials, water infiltration rate was significantly related to the roughness coefficient (r2 = 0.31) and the number of hoof prints (r2 = 0.26). Results imply that a 20-mm canopy height of the forage species common on a New Zealand hill land pasture is adequate to minimize the effects of a short-term treading event on soil water infiltration rate and sediment loss.

It is necessary to quantify rates of woody plant encroachment on southwestern USA rangelands to determine the economic feasibility of treatments designed to manage these plants. This study observed changes in honey mesquite (Prosopis glandulosa Torr.) canopy cover over a 20-year period (1976-1995) in 2 treatments: an untreated area that initially had a moderately dense mesquite stand (14.6% cover), and an area cleared of mesquite with root-plowing in 1974. Canopy cover of mesquite was estimated from scanned color-infrared aerial photograph images by manually delineating mesquite canopies with a computer using ArcView software. During the 20 years, mesquite cover in the untreated area increased (P less than or equal to 0.05) from 14.6 to 58.7%, averaging 2.2 percentage units per year. Cover in the root-plow treatment also significantly increased during the same period from 0 to 21.9% (1.1 percentage units per year), but the rate of increase was significantly lower than in the untreated area because mesquite growth was from new seedlings instead of established plants and/or new seedlings as occurred in the untreated area. Rate of increase was significantly lower from 1976 to 1990 (1.6 and 0.2 percentage units per year) than from 1990 to 1995 (4.1 and 3.7 percentage units per year) in the untreated and root-plow treatment, respectively. These differences were attributed to precipitation which was near normal from 1976 to 1990 but 25% above normal from 1991 to 1995.

Supplemental polyethylene glycol (PEG) increases intake of foods high in tannins, but it is not known if PEG affects preference when herbivores forage on a variety of foods that differ in concentrations of macronutrients and tannins. We investigated how macronutrients, tannins, and PEG affected preferences of goats (Caprus hircus) for current season's and older growth twigs from the shrub blackbrush (Coleogyne ramosissima Torr.). In blackbrush, current season's twigs are higher than older twigs in macronutrients, but goats prefer older twigs because high levels of tannins in current season's twigs decrease preference. We conducted a pen trial and a paddock trial. During the 7-day pen trial, goats were offered current season's twigs and older twigs throughout the day. Eight goats were supplemented with 20 g PEG mixed with 100 g ground alfalfa (Medicago sativa L.) pellets, and 8 goats were supplemented with 100 g ground alfalfa pellets. Goats supplemented with PEG ate more current season's twigs than goats that did not receive PEG (P = 0.04). During the 17-day paddock trial, 10 goats were supplemented with 50 g PEG mixed with ground alfalfa/barley (Hordeum vulgare L.), and 10 goats were supplemented with ground alfalfa/barley. Goats supplemented with PEG preferred current season's to older twigs, whereas PEG-unsupplemented goats preferred older to current season's twigs (P = 0.0001). Goats had equal preference for juniper (Juniperus osteosperma Torr.) trees (P = 0.243). Collectively, our findings show that supplemental PEG can change food preferences.

Introducing and establishing competitive plants is essential for the successful management of spotted knapweed (Centaurea maculosa Lam.) infested rangeland where a desirable understory is absent. Our objective was to determine a herbicide-mix that would maximize grass establishment in spotted knapweed-cheatgrass (Bromus tectorum L.) bluegrass (Poa pratensis L.) infested rangeland in a single fall application. On 2 sites in Montana, 8 herbicide treatments [none, glyphosate (N-[phosphonomethyl] glycine) at 0.5 kg a.i. ha(-1), picloram (4-amino-3,5,6-trichloropicolinic acid, potassium salt) at 0.14 kg a.i. ha(-1), picloram at 0.28 kg a.i.ha(-1), clopyralid (3,6-dichloro-2-pyrdinecarboxylic acid, monoethanolamine salt) at 0.21 kg a.i. ha(-1) plus 2,4-D (2,4-dichlorophenoxyacetic acid) at 1.12 kg a.i. ha(-1), picloram at 0.14 kg a.i. ha(-1) plus glyphosate at 0.5 kg a.i. ha(-1), picloram 0.28 kg a.i. ha(-1) plus glyphosate at 0.5 kg a.i. ha(-1), and clopyralid 0.2 kg a.i. ha(-1) plus 2,4-D at 1.12 kg a.i. ha(-1) plus glyphosate 0.5 kg a.i. ha(-1)] and 3 seeded grass species ['Luna' pubescent wheatgrass [Thinopyrum intermedium (Host) Barkworth D.R. Dewey], bluebunch wheatgrass [Pseudorogneria spicata (Pursh.) Love], and 'Bozoyski' Russian wildrye [Psathyrostachys junceae (Fisch.) Nevski] were applied in a split-plot design with 4 replications in the late-fall of 1994 and 1995. Spotted knapweed and grass density were measured in 1995, 1996, and 1997, and biomass was measured in 1997 at peak standing crop. Density data were analyzed as a split-split-plot in time, and biomass data were analyzed as a split-plot using analysis of variance. By the end of the study, picloram applied at either 0.14 or 0.28 kg a.i. ha(-1) in the late-fall consistently yielded lowest spotted knapweed density and biomass. Initially, glyphosate alone lowered spotted knapweed density and increased grass biomass compared to that of the control. However, glyphosate treated plots had more spotted knapweed and less seeded grass established by the end of the study. 'Luna' pubescent wheatgrass consistently yielded the high test density and biomass of the seeded grasses. We believe a single-entry revegetation program applying picloram in late-fall combined with a fall-dormant seeding will maximize seedling establishment in spotted knapweed infested rangeland.

Stubble height, a measure of the amount of vegetation remaining after grazing, is thought to be a useful variable in the management of riparian areas. A number of riparian and grazing processes appear to be directly or indirectly affected by the residual stubble height. Thus, average stubble height is often used to evaluate the livestock impact a pasture has received, particularly in riparian zones. Stubble height sampling methodology has received little previous attention. A sequential sampling procedure for stubble height was investigated. The procedure provides statistically defensible answers in the shortest possible amount of time. The procedure does not require a rigid sample size and involves simple yes/no answers at each observation. A small initial sample of readings is selected and evaluated. If there is sufficient information to make a clear decision, then grazing is either continued or stopped. If the initial evidence does not clearly support either decision, then sampling proceeds. This may continue for several iterations before a decision is reached. Statistically supportable decisions can typically be made within a short time frame using this method. This method may also be applied to evaluate trampling and other yes/no responses.

Two grazing trials were conducted during early winter (December 1996-January 1997) and spring (April-May 1997) to evaluate the effect of shape of pasture on forage use and behavior of grazing sheep (Ovis aries). Two treatments were tested, square and rectangular paddock, with 2 replicates for each treatment of 9 ewes each. Groups were homogeneous for age and weight. Paddock size furnished 10 m2 per sheep per day. Each paddock was divided into 8 equal plots to determine herbage intake and grazing efficiency along the boundary and in the middle of paddocks. The shape of paddock affected sheep grazing efficiency and herbage intake both in the winter and in the spring. Because of a greater amount of herbage destroyed within boundary plots, the ewes in rectangular paddocks grazed less time, had lower herbage intake and used forage less efficiently than ewes in square paddocks. These results suggest that the shape of pasture can affect the behavior and herbage intake of sheep grazing in small paddocks and indicate that square paddocks should be used for research studies on sheep grazing behavior.

In Utah during the early 1990s it was theorized that substantive change was under way in the management of private grazing land. Change was thought to be spearheaded by grazing permittees who feared losing access to public forage and thus wanted to increase carrying capacity of private grazing land as a hedging tactic. We synthesized results from socioeconomic surveys conducted among a target population of 5,067 grazing livestock producers during 1993, 1996, and 1997. This population was evenly divided between permittees and operators wholly dependent on private grazing (e.g., private operators). Our primary objectives were to: (1) test the hypothesis that a sustained upswing in management change was occurring; (2) identify factors associated with operations that "actively" invested in their properties versus those that were "passive"; and (3) identify producer priorities for applied research. Mail and phone surveys were used. Data analysis included descriptive statistics and logistic regression. Compared to private operators, permittees controlled far more private land and livestock and were more profit-oriented and dependent on live-stock-derived income. Managers of both groups were aged—37% of the population was >65 years old. Eighty percent of 393 managers surveyed in 1996-7 classified their operations as passive and ranked factors related to aging and economics as main reasons for passivity. Logistic regression and ranking exercises revealed that the active minority was most associated with higher gross annual incomes, more stewardship values, greater willingness to incur debt, and being a permittee. Permittees were more inclined to be active managers because of a greater entrepreneurial orientation compared to private operators, who tended to be hobby ranchers. Our work supported an alternative hypothesis that passivity in land management has been maintained in Utah during the 1990s, largely because incentives were lacking for most of the population to do otherwise. A wealthier minority, however, could still make large investments in their operations because of a superior risk tolerance. We concluded that demographic and economic factors exert the most control over producer behavior today, not access to information or new technology. One consequence is that demand for information and technology can be episodic due to coincident economic, demographic, and policy factors, which also implies that applied research, extension, and policy formulation need to be more opportunistic in response to change. Producers felt that forage improvements, policy, and economics were top research priorities. A looming crest of retirements among traditional landowners bodes for substantive and rapid change in the use of Utah private grazing land. Nearly one-third of those planning retirement hope to sell property to land developers.