• Packhorse grazing behavior and immediate impact on a timberline meadow

      Olson-Rutz, K. M.; Marlow, C. B.; Hansen, K.; Gagnon, L. C.; Rossi, R. J. (Society for Range Management, 1996-11-01)
      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.
    • Recovery of a high elevation plant community after packhorse grazing

      Olson-Rutz, K. M.; Marlow, C. B.; Hansen, K.; Gagnon, L. C.; Rossi, R. J. (Society for Range Management, 1996-11-01)
      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.