| Area: |
1,349 ac (546 ha) |
| Elevation: |
6,860 to 7,743 ft (2,092 to 2,362 m) |
| Vegetation: |
Ponderosa Pine |
| Parent Material: |
Basalt |
| Years: |
1959 - 1982 |
| Treatment: |
Irregular strip-cut and thin |
| Year Treated: |
1970 |
|
Irregular strip cutting
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| Objective: |
To determine how a strip-cut and thinning treatment of ponderosa pine affects streamflow, erosion and sedimentation, vegetation, and wildlife. Prior to treatment, streamflow from WS 14 was calibrated against flow from the designated control WS 13. |
| Treatment: |
The treatment applied here consisted of irregular strips cut through the forest in 1970. Each strip varied from 9 to 37 m (30 to 120 ft) wide, with pines cleared from one-third of the area. Additional trees were thinned from the stands between the strips to stimulate growth of the remaining trees. In total, half the timber on the watershed was removed. All slash was piled and burned in the cut strips, and seedlings were planted on the higher quality sites. Gambel oaks were left in the cut strips to provide acorns and cover for wild animals, and to soften visual impacts (Brown et al. 1974) |
| Response: |
As on Watershed 9, harvest strips were oriented to direct runoff into drainage channels. Irregular cutting patterns and thorough slash cleanup were designed to make the appearance of these strips better than those on Watershed 9. Visitors polled during research to evaluate esthetic preferences indicated they considered this managed forest to be quite appealing.
This experiment has caused water yield to increase 33 mm (1.3 inches) or 24 % the first year. Increases in water yield decreased steadily until losing significance after the fourth year. Streamflow increase during the fourth year was 18 mm (0.7 inch) or 12 % (Baker 1986). Minor increases occurred in sediment flow. Deer and elk use has increased since treatment.
Scientists have devised a mathematical model that imitates, or simulates, how the forest might respond to various management practices. With this model, scientists can predict future growth rates using available data. If the management method tested on WS 14 were continued, the remaining trees would be thinned again in 1990. Then, in 2010, after trees were well established in the cut strips, new irregular strips covering another third of the watershed would be cut. If WS 14 continues to be managed in this manner, scientist predict the volume of timber harvested in the next 120 years will change from 76 to 228 m3 per ha (1,100 to 3,300 ft3 per ac), a 200 percent increase above pretreatment conditions. |
| References: |
Baker, M.B., Jr. 1986. Effects of ponderosa pine treatments on water yield in Arizona. Water Resources Research 22: 67-73. Brown, H.E., M.B. Baker, Jr., J.J. Rogers, W.P. Clary, J.L. Kovner, F.R. Larson, C.C. Avery, and R.E. Campbell. 1974. Opportunities for increasing water yields and other multiple use values on ponderosa pine forest lands. USDA Forest Service, Research Paper RM-129. |
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