Range improvement practices have been criticized by scientists and the public because of negative impacts on biodiversity. I present a conceptual model based on ecological theory for designing and planning woody plant control to maintain plant and wildlife species richness and diversity. Broad areas of rangeland have been impacted by overgrazing by livestock and attempted brush control in a manner that has resulted in dense woody plant communities that are resistant to natural disturbances such as fire. State-and-transition models of vegetation dynamics predict these biotic assemblages to be temporally stable and not responsive to successional trends. Cultural energy input in the form of woody plant control is required to change the vegetation configuration of these ecosystems. Anthropogenic input conceptualized and designed based on the intermediate disturbance hypothesis can maximize landscape diversity and may result in a landscape mosaic that supports greater species richness, provides increased forage for livestock, and enhances habitat for many wildlife species. A problem with this approach is that continuing inputs are required to maintain the selected landscape architecture. Development of models to predict the effects of woody plant control patterns on biodiversity will enable range managers to implement management strategies that maintain or increase plant and vertebrate species richness and diversity.

Three annual applications of a factorial combination of N (0, 40, 80, 120 kg ha-1), P (0, 25 kg ha-1) and K (0, 100 kg ha-1) were applied to Florida flatwoods range where 45 plant species were initially present. Addition of P and K had no effect (P > 0.05) on indices of plant diversity, density, or above-ground biomass. Both Shannon's (Y = 1.6 - 0.005N, where N is kg ha-1) and Simpson's index (Y = 0.28 + 0.002N) indicated diversity decreased with increasing N because the community was being dominated by goldenrods (Solidago fistulosa and Euthamia minor) and dogfennel (Eupatorium spp.). Density of all fortes increased with increasing N (1990 plants m-2 = 17.4 + 0.4N and 1991 plants m-2 = 35.1 + 1.4N). Density of beaked panicum (Panicum rhizomatum) increased quadratically with increasing N, while density of decumbent carpetgrasses (Axonopus spp.) and low panicums (Dichanthelium spp.) declined linearly. Broomsedge (Andropogon virginicus), wiregrass (Aristida stricta), and bottlebrush 3-awn (A. spiciformis) were eliminated from the site. Above-ground biomass of fortes increased with N (1988 kg ha-1 = 934 + 16.1N and 1990 kg ha-1 = 227 + 60.6N). Grass and grasslike biomass increased linearly as N increased, but N effects were independent of year, which were different (1988 = 1,530 kg ha-1 and 1990 = 2,140 kg ha-1). The plant community at this location became less diverse when the naturally low soil N was increased by 40 kg ha-1 or more. Early successional species replaced later successional species, especially creeping bluestem (Schizachyrium scoparium).

We evaluated the impact of packstock grazing on a dry, upper timberline meadow. Horses were picketed on 15 m ropes for different durations, months, and frequencies over 3 summers. Before horse grazing, we estimated vegetal, bare soil, litter, rock, and moss cover, measured grass and forte plant heights, counted grass and forte stems per area, and determined the percent of plants grazed. These measurements were repeated 1 growing season later. More bare ground and less litter and vegetal cover were recorded 1 year following single 8- or 18-hour grazing events. Single grazing events of 4-hour duration had no effect on cover. Decreases in vegetal cover were associated with reduced stem numbers. Eighteen hour picket durations reduced subsequent year production of grass and forte stems. We discuss the difficulties encountered in this study, including estimates of necessary sample sizes, to help in the design of future studies.

Recreational packhorse grazing is one of many uses of high elevation wildland meadows. We quantified the behavior of horses grazing on an upper timberline meadow in southwestern Montana and the immediate impact on the plant community. Horses were picketed on 15-m diameter circles for different durations (0, 4, 8, 18 hours), months (July, August, September), and frequencies (1 month only, all 3 months) over 3 summers. We recorded the amount of time horses spent grazing or resting, horse movement while grazing, plant height, and grazed plant frequency before and after grazing. Grazing was the dominant activity throughout the trial. After an initial 3-4 hour feeding bout, horses continued to graze intermittently. When not grazing, horses rested more than walked. Horses grazed a higher percent of grasses at first (4 hour picket duration) but the percent of fortes grazed increased with increased time on picket. After 18 hours of use, or after repeated use on the same picket circle through the summer, more than 50% of the grasses and 20% of the fortes bad been grazed and tallest plant material was less than 12 cm tall. Recreational packhorse management should include previous training (picket grazing experience), limiting time on specific circles to 8 hours or less, and using picket circles only once each season.

The objective of this 2 year study was to identify the optimal height to graze Old World bluestem pasture in the Southern Great Plains under continuous stocking during the growing season. We hypothesized that intensely grazing Old World bluestem pasture would increase utilization efficiency by increasing the proportion of live leaf in the pasture, enhance forage quality and animal performance, and animal performance and root biomass would decline if grazing intensity was beyond an optimal level. Pastures were maintained at 3 levels of standing crop using continuous variable stocking. Stock adjustments were made weekly. A disc meter was used to maintain pasture disc heights of short (35-40 mm), medium (41-45 mm), and tall (46-55 mm) levels. Average standing crops of short, medium, and tall pastures were 1,500, 1,900, and 2,400 kg ha-1, respectively. On the short pasture treatments the proportion of leaf and live stem was higher (P < 0.05) and the proportion of dead stem was less (P < 0.05) than that on the tall pasture treatments. There were no significant differences (P > 0.05) in crude protein of forage between treatments during the vegetative growth phase in spring when forage nitrogen levels were fairly high (> 13%). When the grass began to produce reproductive organs and when forage nitrogen levels were lower (< 1.3%), forage crude protein was greater in the short pastures (P < 0.05). Individual animal performance was greater on the tall than on the short pastures (P < 0.10) over all dates. Individual animal performance was greatest when management maximized the proportion of leaf and live stem while minimizing dead stem. Animal performance per hectare was slightly higher on the short and medium height pastures. Both the short and medium height pastures had approximately 70% the root biomass of the tall pastures (P < 0.01) at the end of the trial. These results indicate that intense continuous variable stocking of Old World bluestem increases the utilization efficiency, but increases animal production per hectare only marginally, and reduces root biomass to an extent that production may not be sustained from year to year.

China, with one of the largest grassland and pastoral areas of the world, is placing major effort on sustainable modernization of its rangeland livestock industry. One widely discussed structural change involves development of a cattle feedlot industry with grazing lands oriented to a cow/calf system. However, economic analyses of alternatives have not been carried out. The objective in this article is to evaluate the economic feasibility and benefits to sustainability from shifting from fattening cattle on rangelands in Inner Mongolia to fattening in feedlots in the Beijing area. The method is economic budgeting of costs and returns for both systems combined with comparison of protein and energy requirements for each of them. It is concluded that grazing land producers would obtain more net income from selling weaned calves rather than fattened animals. Furthermore although 14,230 Mcal of metabolizable energy and 738 kg of crude protein are required per 4-year old male sold at slaughter weight by grazing land fattening, a feedlot fattened male would require only 5,670 Mcal of energy and 371 kg of protein Additional evaluations of improved cow/calf systems indicate that considerable advances can be made by improving the efficiency of China's cattle industry.

Cattle have been used to control shrubs following timber harvesting in the Sierra Nevada of California, although their effectiveness varies between sites. Although cattle home ranges, habitat use, and diets are known for many forested ecosystems, the coniferous forests of the Sierra Nevada are different because shrubs are the most common understory species, with fewer herbaceous species than elsewhere in the western United States. As a first step in evaluating factors that influence cattle distribution and their potential effectiveness in controlling competing vegetation in the Sierra Nevada, we used radio-telemetry collars on cows to determine their home ranges and habitat use patterns. Mean home range size was 162.80 ha in 1986 and 278.83 ha in 1987. When choosing home ranges, cattle showed the greatest affinity for riparian habitat, followed by clearcuts, second-growth forest, and burned areas. Distances from streams to cattle locations were significantly (P<0.01) less (average=59.3 m in 1986, and (average = 60.1 in 1987) than were distances from streams to random points (average = 130.4 m). Based on microhistological analysis of fecal fragments, cattle diets included seeded grasses and shrubs mostly from upland sites, but forbs primarily from riparian sites. We suggest the need for water and the relative lack of herbaceous forage in the understory of mixed-conifer forests in the Sierra Nevaa resulted in the strong, summer-long preference for riparian habitats. The effectiveness of grazing in controlling competing vegetation following timber harvest may be related to the proximity of the clearcuts to riparian habitats but this specific hypothesis remains to be tested.