Expansion of western juniper (Juniperus occidentalis spp. occidentalis Hook.) woodlands in the sagebrush steppe has the potential to change composition, structure, and productivity of understory vegetation. Cutting of western juniper woodland can potentially restore understory productivity and diversity. Understory responses were assessed after cutting a juniper woodland in southeastern Oregon in 1991. The experimental design was a randomized complete block with eight, 0.8 ha sized blocks and 2 treatments, cut and uncut woodland. Understory cover, density, diversity, biomass, and nitrogen (N) status were compared between treatments after cutting Plants were separated into S functional groups: bluegrass (Poa spp.), perennial bunchgrass, perennial forte, annual forte, and annual grass. Cutting of juniper reduced below ground interference for soil water and N. Leaf water potentials were less negative (p < 0.01) and understory N concentration and biomass N were greater (p < 0.05) in the cut versus woodland treatment. Cutting of juniper trees was effective in increasing total understory biomass, cover, and diversity. In the second year post-cutting total understory biomass and N uptake were nearly 9 times greater in cut versus woodland treatments. Perennial plant basal cover was 3 times greater and plant diversity was 1.6 times greater in the cut versus woodland treatments. In the cut, perennial bunchgrass density increased by 1 plant m-2 in both duff and interspace zones and bluegrass increased by 3 plants m-2 in interspaces. Plant succession was dominated by pants present on the site prior to juniper cutting suggesting that pre-treatment floristics may be useful in predicting early successional understory response. Early plant dynamics on this site supports the multiple entrance point model of succession as perennial grasses and bluegrass made up the majority of total herbaceous biomass and cover.

We investigated how experience early in life and macronutrient content of the diet influenced intake of mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) by sheep. In the first part of our study, 2-month-old lambs were exposed as a group for 2 mo to a 70% barley-30% soybean meal ration (300 g/hd/day) that contained increasing amounts sagebrush (1 to 20%). Control lambs received grain without sagebrush. All lambs had access to alfalfa hay and pellets ad libitum. When lambs were tested at 6 months of age, prior exposure had no effect on sagebrush consumption after the first 4 days of the trial. When sagebrush comprised 20% of an alfalfa/barley ration, lambs ate the sagebrush ration readily even when a nutritious alternative was offered indicating the flavor of sagebrush did not prevent lambs from feeding. Increasing the amount of sagebrush in the ration from 50% to 75% resulted in lambs eating less of the barley/sagebrush ration, but daily intake of sagebrush remained constant throughout the 4 day trial, presumably because toxins (terpenes) limited intake of sagebrush. In the second part of our study, lambs experienced with sagebrush were fed 250 g/hd/day of barley, and nutritional status was varied by offering alfalfa pellets at 33% or 80% of ad libitum (1.2 and 2.7 times maintenance, respectively) to determine if dietary energy levels affected intake of sagebrush. Each day lambs received a 50/50 sagebrush/barley supplement ad libitum for 1 hour. Lambs fed at 33% of ad libitum consumed more of the sagebrush/barley supplement than lambs fed at 80% of ad libitum. Thus, additional energy did not enable lambs to consume more sagebrush. In the last trial, lambs in both treatments were fed a basal ration of alfalfa pellets at 50% of ad libitum. Each morning for 1 hour, lambs were offered macronutrient supplements containing either 50% barley/50% sagebrush (high energy) or 25% barley/25% soybean meal/50% sagebrush (high energy and protein). Lambs consumed the same amount of sagebrush regardless of supplement. Thus, supplemental protein did not improve sagebrush consumption. We conclude lambs readily ingested a high-energy ration containing sagebrush, regardless of exposure early in life, suggesting toxins, not flavor, control intake of sagebrush. Further, supplementing lambs with energy or protein failed to improve intake of sagebrush, which suggests these macronutrients did not enhance detoxification of sagebrush.

This work investigates 2 US Army Construction Engineering Research Laboratory revegetation experiment sites (Phase I and II) on Kaho'olawe Island, Hawai'i (USA) to determine the long-term success of several revegetation strategies and to identify species that are best suited for future restoration activities in the highly eroded central plateau region of the island. Only the Phase I treatments receiving the highest rates of phosphorus and nitrogen fertilizer and the Phase II strategy (moderately high fertilization and landscaping) produced enough cover to begin providing protection from erosion processes. Buffelgrass (Cenchrus ciliaris L.), glycine (Neonotonia wightii (Wight Arnott) Verdc.), Natal redtop (Rhynchelytrum repens (Willd.) Hubb.), and siratro (Macroptilium atropurpureum (DC) Urb.) appear to be resilient to the harsh island conditions, which include strong winds, low annual rainfall, acute erosion, and a nutrient-depleted soil profile. Although all 4 species offer some protection against erosional processes, none are particularly desirable for long-term restoration of the island. Glycine and siratro, both of which volunteer readily in planting sites, are considered invasive in that they may smother other more desirable species, particularly less competitive natives. Finally, native woody species are shown to have difficulty in surviving on the island without special attention to planting and maintenance.

Grazing distribution and forage use patterns are important influences on rangeland ecosystems. Spatial patterns of grazing by domestic cattle (Bos taurus) were observed over 2 consecutive years under 2 grazing systems, intensive-early stocking and season-long stocking. The purposes were to determine factors influencing observed patterns and develop predictive models for grazing distribution and forage removal. Field-collected data on grazing distribution were linked with associated geophysical properties of pastures utilizing a GIS. Separate models were developed to predict grazing distribution and forage utilization using a backward stepwise regression procedure. The forage utilization model was linked with grazing distribution by utilizing Tobit analysis. Nineteen independent variables were used to interpret the observed variation in grazing distribution. Comparison of predicted probability of grazing values from the model with the observed grazing distribution in a hold-out data set yielded a close fit (R=.99). Eighteen independent variables were included in the forage removal model. Comparison of predicted forage removal with observed values in a hold-out data set yielded a poor fit (R=.28). Lack of forage quality variables probably accounts for the poor performance of the forage removal model. Differences in the success of the 2 models support the hypothesis that grazing distribution and forage utilization operate at different spatial scales and parameters. The use of GIS holds promise as a technique for developing useful predictive models for range management.

The seasonal variations in nitrogen and phosphorus fractions and cations in 2 species of Atriplex common to Western Australia (Atriplex amnicola P.G. Wilson and Atriplex nummularia Lindl.) were investigated. Both species contain high concentrations of nitrogen (N) in winter as compared with summer when both species contain high concentrations of sodium. The sum of soluble protein-N, amino acid-N, nucleic acid-N and nitrate-N is about half of the total nitrogen. The remainder includes non-soluble protein-N and other N associated with cell membranes and walls. Phosphorus was more uniformly distributed among pools of inorganic-P, phytate-P, nucleic acid-P and other (residual) fractions. We suggest that interpretation of animal nutrition studies based on similar trichloroacetic acid (TCA) fractionations might be improved by independent estimation of soluble proteins. Fractionation using TCA provides valuable information about the subcellular distribution of both N and P in foliage tissues for study of plant physiology and animal nutrition. Concentrations of major nutrients in foliage of both species were significantly and negatively correlated with monthly maximum temperature and significantly and positively correlated with monthly rainfall. In summer and early autumn the apparent nutritive value of both species is well below the basic requirement of sheep or other grazing ruminants such as goats.

Leafy spurge control with glyphosate [N-(phosphonomethyl)glycine] plus 2,4-D [2,4-dichlorophenoxy)acetic acid] applied annually for 3 years alone or rotated with auxin herbicides was evaluated at 3 locations in North Dakota. Glyphosate applied with 2,4-D averaged 67% leafy spurge control 3 months after treatment which was a 10-fold increase compared to glyphosate alone. Glyphosate plus 2,4-D applied annually for 3 years or rotated with dicamba (3,6-dichloro-2-methexybenzoic acid) or picloram (4-amino-3,5,6-trichloro-2-pyridine carboxylic acid) plus 2,4-D provided 80 to 90% leafy spurge control, which was similar to the standard annual picloram plus 2,4-D treatment but at 30 to 65% less cost. Herbage production was similar regardless of treatment. The absorption and translocation of 14C-2,4-D increased 2- to 3-fold when applied wit glyphosate compared to 14C-2,4-D applied alone. However, both absorption and translocation of 14C-glyphosate was severely reduced when applied with 2,4-D compared to 14C-glyphosate applied alone. The increase in control when glyphosate is applied with 2,4-D may be because sublethal concentrations of glyphosate break root bud dormancy in leafy spurge, thereby increasing the amount of 2,4-D in the root. Glyphosate plus 2,4-D provided good leafy spurge control at less cost than current widely used treatments and should provide a new tool for leafy spurge management.

Emaciation is one of the clinical signs of locoweed poisoning but few studies have documented impacts of locoweed poisoning on weight gains. Stocker steers (British X Continental cross, 200-210 kg) were grazed on locoweed-infested, short-grass prairie in 1996 and 1997 in northeast New Mexico. Each year, half the steers were averted to locoweed to allow them to graze locoweed-infested pastures without eating locoweed. They did not graze locoweed and steadily gained weight (0.50 kg/day in 1996 and 0.71 kg/day in 1997). The other group of steers were allowed to graze locoweed under natural grazing conditions and became intoxicated. Weight gains were not affected for the first 3 weeks, but thereafter the steers lost weight in both years. In 1996, non-averted steers consumed locoweed for a season average of 20% of bites. They were severely intoxicated and did not begin gaining weight for 50 days after they stopped eating locoweed. Steers in the 1997 trial consumed less locoweed (11% of bites) than those in 1996 and they recovered more rapidly. Seasonal weight gains were 21 to 30 kg less for locoed steers than control steers in 1996 and 1997, respectively. Locoweed poisoning will cause weight loss, and severely intoxicated cattle require a lengthy recover period after they cease grazing locoweed before weight gains resume. Stocker cattle should not be placed on locoweed-infested rangelands until green grass is abundant and locoweed begins to mature.

Productivity of Barzona, Brangus, and Beefmaster cattle was evaluated on conservatively (n=2) (40 ha AU-1) and moderately (28.5 ha AU-1) stocked pastures (n=2) in the Chihuahuan Desert of south-central New Mexico. Equivalent numbers of suckled, first-calf heifers of each breed (n=31) weighing 333+/-11 kg were randomly assigned to the study pastures in the spring of 1992. Pastures were grazed continuously and herd productivity data were collected from 1992-1994. In late August 1994, all pastures were destocked due to onset of severe drought. No effect of breed (P > 0.10) was detected in the analyses, so data were pooled across breeds and compared between the stocking rates. Calf crop percentages (1993, 1994) were higher in conservative than moderate stocked pastures (82 vs 62%, respectively, P < 0.01). Financial analyses standardized to a hypothetical medium size (8,094 ha) New Mexico Chihuahuan Desert cattle range showed net returns per ha did not differ (P > 0.10) between stocking rates. However, the main effect of year and stocking rate X year interaction were significant (P < 0.05). These analyses suggest that the drought in 1994 lowered returns per ha compared to 1993 when precipitation was near average and that conservative stocking may present less financial risk than moderate stocking when drought occurs. These data are consistent with other studies from arid and semi-arid rangelands demonstrating that conservative stocking can give financial returns from cattle production equal to or greater than those from moderate stocking.

We assessed the potential of activated charcoal to attenuate bitterweed (Hymenoxys odorata DC.) toxicosis in 3 trials. In Trial 1, lambs were offered a subacute level (.264% BW) of bitterweed and received either 0, .5, 1, or 1.5 g/kg BW of activated charcoal. In Trial 2, lambs were dosed (by gavage) with .264% BW of bitterweed and varying levels of activated charcoal followed by feeding milo (Sorghum sp.) immediate after dosing. A decrease in milo intake, which indicates aversive postingestive feedback, was interpreted to indicate that toxicosis occurred. In Trial 3, lambs were fed a 20% CP supplement with or without activated charcoal and then exposed to bitterweed and other forage species growing in pots; we counted the number of bites of each. In Trial 1, lambs refused to eat bitterweed after 10 days of exposure, thus the study was stopped. In Trial 2, lambs that received 1 or 1.5 g/kg BW of activated charcoal consumed more (p < 0.05) milo than those receiving 0 g/kg BW. In Trial 3, lambs supplemented with activated charcoal took more (p < 0.05) bites of bitterweed than lambs receiving a protein supplement alone. Lambs readily ate activated charcoal when added to a 20% crude protein supplement in a 10% mixture. Collectively, these results suggest activated charcoal will result in continued consumption of bitterweed which suggests avoidance of toxicosis. Activated charcoal also may be effective in preventing bitterweed toxicosis when combined with a supplement.

Historically, there have been several seminal achievements in management and utilization of privately-owned rangelands. The most important of the early achievements were domestication of livestock, fencing, haying, and the transfer of federal lands to private ownership. Later, federal programs to stimulate range research and extension were the springboard for the modern range research complex. The Morrill Acts established the land-grant institutions with agricultural research as one of the founding principles. The Hatch Act later provided funding for agricultural research, and the Smith-Lever Act funding for the extension of that research to the agricultural industry. Recent trends have been away from funding applied research and towards funding for basic research defined by the political scientific bureaucracy. Those achievements that I consider of major influence in management and utilization of rangelands include: defining stocking rate-animal performance relationships, refining prescribed burning techniques, formulation of selective-translocated herbicides, developing plant varieties and seeding methods for reseeding, matching forage quality with nutritional requirements of livestock, basic research on morphologic and physiologic characteristics of range plants, and information dispersal through extension and federal agencies for better management of rangelands. The future is uncertain, and unless we can reverse the trend away from applied to wholly basic research funding, we will have fewer achievements in managements of privately-owned rangeland.