Packhorse Grazing Behavior and Immediate Impact on a Timberline Meadow
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J. Range Manage. 49:546-550 Packhorse grazing behavior and immediate impact on a timberline meadow K.M. OLSON-RUTZ, C.B. MARLOW, K. HANSEN, L.C. GAGNON, AND R.J. ROSS1 Authors are former research associate, Animal and Range Sciences Deparhnent, Montana Stare University, Bozeman, Mont., 59717; associare professor, Animal and Range Sciences Deparhnent, Montana Stare University, Bozeman, Mom., 59717; associate professor, Earth Sciences Department, Montana Stare University, Bozeman, Mont., 59717; associatepro- fessor. Animal and Range Sciences Department, Monrana State Universi& Bozeman, Mont., 59717; and assistant profes- sor, Math and Computer Sciences Department, Montana Tech, Butte, Mont., 59701. Abstract Schreyer 1987). Most grazing literature addressesplant or animal production issues which may not be pertinent to wilderness man- Recreational packhorse grazing is one of many uses of high ele- agement problems (Cole 1987, McClaran and Cole 1993). vation wildland meadows. We quantified the behavior of horses In July 1988 we began a field study to quantify horse (Equus grazing on an upper timberline meadow in southwestern cuballus) grazing impacts on an upper timberline meadow in a Montana and the immediate impact on the plant community. federally designated wilderness. We simulated recreational pack- Horses were picketed on 15-m diameter circles for different horse management by grazing horses on picket circles and tying durations (0,4,8,X3 hours), months (July, August, September), them to a high-line when they were not grazing or being ridden. and frequencies (1 month only, all 3 months) over 3 summers. We quantified horse behavior while on pickets and recorded pro- We recorded the amount of time horses spent grazing or resting, portion of grassesand forbs grazed and plant heights immediately horse movement while grazing, plant height, and grazed plant before and after horses grazed. Comparisons of grazing induced frequency before and after grazing. Grazing was the dominant changes were made with similar measurements taken on nearby activity throughout the trial. After an initial 3-4 hour feeding ungrazed areas and may be useful in assessing horse grazing bout, horses continued to graze intermittently. When not graz- impacts and developing wilderness management guidelines. ing, horses rested more than walked. Horses grazed a higher per- cent of grasses at fmt (4 hour picket duration) but the percent of forbs grazed increased with increased time on picket. After 18 Methods hours of use, or after repeated use on the same picket circle through the summer, more than 50% of the grassesand 20% of the forbs had been grazed and tallest plant material was lessthan Study Site 12 cm tall. Recreational packhorse management should include Grazing experiments were conducted in a 40-50 ha previous training (picket grazing experience), limiting time on meadow/timber complex in the headwaters of Bacon Rind Creek. specific circles to 8 hours or less, and using picket circles only This stream lies within the Lee Metcalf Wilderness of southwest- once each season. em Montana at approximately 111”10’ longitude and 44% lati- tude. The study site is characterized as an upper timberline mead- Key Words: diet selection, forage removal, horse, mountain ow (2,700 m elevation) with fine, textured soils of the Cryoboroll meadow or Cryochrept group (Montagne et al. 1982). The plant communi- ty is classified as a Festuca idahoensis/Elymus trachycaulus habi- Range management practices have been developed largely to tat type (Mueggler and Stewart 1980). While large numbers of enhance or maintain a sustained level of productivity from range- elk (Cervus eluphus eluphus) use the area during summer and lands. Thus, the change in plant community composition induced early fall, records of the Hebgen Ranger District, Gallatin by grazing is usually balanced with economic concerns. Such National Forest, indicate that the area was never part of a live- management philosophy is generally accepted for use on most stock grazing allotment. In addition, there is little recreational rangeland, but it may be unacceptable for Wilderness Areas (Cole horse use in the area because of limited hunting and fishing 1989, McClaran and Cole 1993). Changes in vegetation composi- opportunities. Thus, we considered the plant community at our tion would be unacceptable regardless of the potential economic study site undisturbed by human or domestic animal activity. output because the loss or diminution of the “naturalness” of a wilderness site reduces its value as wilderness (Stankey and Grazing Treatments Horses were constrained to a given area for grazing by a 15 m picket rope. By attaching 1 end of the rope to a horse’s front foot This project as funded by the Intermountain Research Station, Forest Service, USDA, and the hlontana Agricultural Experiment Station. We appreciate the and tying the other end to a metal stake in the ground, each horse advice from David Cole, (USFS, hlissoula, hfonont) and tbe help of all the field grazed a circular area of 175 m’. The grazing treatments were a) workers. We thank John Lacey, hlatt Lavin, Jii Pfiiter, and 2 Journal of Range the duration a circle was grazed (0 = ungrazed control, 4,8, or 18 M7nagemenr reviewers for their comments. hlanuscript accepted 20 Dec. 1995. hours) and b) the month the circle was grazed (July, August, or 646 JOURNAL OF RANGE MANAGEMENT 49(6), November 1996 September). In 1988, there were 4 replicate circles per month by where graze and rest are hourly proportions of the respective duration combination for a total of 48 circles which were ran- behaviors, hour is the actual hour on the picket circle (l-9), domly interspersed on a 3 ha portion of the meadow. month is the month of grazing, and stint is the time the horse was In 1989, we applied the same treatments to a different 3 ha por- on the picket (1 for all 4-hour horses, 1 or 2 for the 8 and 18-hour tion of the same meadow. We included circles which were grazed horses depending on whether the horse was on the circle for the repeatedly during the summer (frequency) to assessthe impact of first or second half of the total duration of grazing). repeated visits to a given site. These circles were grazed for 4 or We tested for a linear and quadratic relationship between 8 hours in July, again in August, and for a third time in hourly grazing observations and time (h) on picket circle (GLM, September (hereafter referred to as JAS circles). All 56 circles SAS 1988) by month of grazing. Number of grazing stations was used in 1989 were regrazed in 1990 with the same month, dura- analyzed in the same manner. tion, and frequency treatment. Plant measurements were recorded before and after horses We used mature Quarter Horses trained to grazing on pickets grazed. Measurements were made in 2 X 5 cm frames at 0.30 m while on pack trips in previous summers. The 4-hour circles were intervals along N to S and E to W diameter transects. Only the grazed a continuous 4 hours. The 8-hour circles were grazed outer 4 m of the E and W transects were measured to avoid over twice each for 4 hours. Horses grazing these circles were placed sampling circle interiors. In 1988 we noted the height class (0, no on the pickets in mornings and again at evening. The 18-hour cir- plant present; l, O-2 cm; 2,2-4 cm; 3,P12 cm; 4,12-24 cm; 5, cles were grazed for 9 continuous hours on each of 2 consecutive > 24 cm) of the tallest plant material. In 1989 and 1990 plant days, beginning in the morning. The horses watered after their height classes were recorded for the tallest of each plant type grazing time, except those grazing for 9 hours which were also (grass and forb) and we noted whether any grasses or forbs had watered mid-way through their 9 hour grazing time. Horses were been grazed within the 2 X 5 cm frame. maintained on a high-line when not on a treatment picket or being To describe the immediate impact of horse grazing on plant ridden. Individual horses were assigned to the same duration of heights, we analyzed both the post-grazing and the change in grazing in ah months. There were 4 to 12 horses grazing at any (post- minus pregrazing) the proportion of plants in each height given time and all grazing treatments were applied over a 3 day class with an AOV. The model had grazing duration, grazing period. month, and vegetation type (grass or forb) as main effects with all 2- and 3-way interactions. There were many significant interac- Horse Behavior and Plant Measures tions, which are hard to interpret. Therefore, we present the mean Picketed horses were observed in 1988 and 1989. Horses were monthly means and standard errors of the proportion of plants in not observed while grazing the repeatedly grazed (JAS) circles. each height class after horse grazing. Beginning l/2-hour after picketing, each horse was watched for The percentage of plants grazed before horses grazed the cir- 15 continuous seconds every 5 minutes for the next l/2-hour. The cles was attributed to elk grazing. To determine how much the l/2-hour observation periods were alternated with l/2-hour of no horses grazed, these pregrazing values should be subtracted from observations. During the 15 second observation we noted whether the percentage of plants grazed after the horses were removed. the horse grazed, traveled, or rested, and the number of grazing However, to contrast the impact of a single grazing with 3 graz- stations used. Grazing stations were defined as areas grazed that ings per summer we had to analyze the percentage of plants were separated by at least 2 steps taken by the horse.