• Decision-analysis approach to brush management planning: ramifications for integrated range resources management

      Scifres, C. J. (Society for Range Management, 1987-11-01)
      Simulation, optimization, and other modeling paradigms for systems ecology and economics have not been broadly applied to development of models for range resource management in real-world settings. The lag in emergence of applicable management models may be attributed to the lack of a conceptual context for their application. Recent appreciation of the decision-analysis approach to natural resource management and the general availability of high-speed computing capabilities have provided viable bases for using increasingly sophisticated analytical tools to solve management problems. Decision models may be used to generate proforma contrasts of selected management alternatives for multi-enterprise firms and implementation protocols for the selected management program(s). Such models, operating from a computer-managed information base, become decision-support systems (DSS) for approaching specific management problems; Integrated Brush Management Systems (IBMS) is one example. These DSS are proposed at the first step toward creating comprehensive decision-making models for total resource management (i.e. Integrated Range Resource Management or Integrated Range Resource Analysis). The next generation of models will link qualitative information and rules-of-thumb (heuristics) with hard (experimentally derived) data. These knowledge-based or expert systems, one facet of the growing field of artificial intelligence, hold great promise as vehicles for achieving Integrated Range Resource management. Bringing Integrated Range Resource Management Systems to fruition can be expedited by interdisciplinary research and educational programs for potential user groups.
    • Optimal economic timing of range improvement alternatives: southern High Plains

      Ethridge, D. E.; Pettit, R. D.; Sudderth, R. G.; Stoecker, A. L. (Society for Range Management, 1987-11-01)
      Profit maximizing combinations of livestock enterprises, plant control practices, and grazing management systems for ranches in the southern High Plains were examined. A typical ranch and a multi-period linear programming model were used to determine the combinations and timing of improvement practices and enterprises to maximize discounted net income with different investement capital constraints, cattle prices, and discount rates. All solutions included chemical control of sand shinnery oak (Quercus havardii) and a rotation grazing system. Timing of improvements and net income were affected by size of investment capital constraint.
    • Seasonal diets of herded sheep grazing Douglas-fir plantations

      Leininger, W. C.; Sharrow, S. H. (Society for Range Management, 1987-11-01)
      Use of livestock for biological weed control in timber plantations is gaining popularity in the United States and elsewhere. Efficient use of livestock to control unwanted brush relies upon knowledge of livestock feeding habits. A study was conducted during 1981 and 1982 to determine seasonal diets of herded sheep grazing cutover Douglas-fir (Pseudotsuga menziesii) forests in the Coast Range of Oregon. Study sites included both 4- to 6-year-old non-grass-seeded and 2-year-old grass-seeded plantations. Sheep grazing was monitored in spring, summer, and late summer. Forage on offer ranged from 764 to 2,459 kg/ha. Vegetational composition of sheep diets varied by year, season, and plantation age class. Averaged over the 2 years of grazing, graminoids and forbs were nearly equal, at approximately 40% each, in sheep diets in older plantations. In contrast, diets of sheep in young grass-seeded plantations averaged 70% graminoids and only 16% forbs. Ferns were a minor component (<2%) of sheep diets in both plantation age classes. Browse averaged 15 and 12% of sheep diets in old and young plantations, respectively. Douglas-fir was most palatable to sheep in spring soon after bud break. It was generally avoided, however, and never comprised more than 3% of sheep diets. Our data suggest that sheep can be most effectively used for biological control of unwanted brush species during summer and late summer when differences in relative preference indices for target brush species and Douglas-fir are greatest.