Three-Bar Wildlife Area

Watershed C

AREA: 95.3 ac (38.6 ha)
SLOPE:
ASPECT: North facing
ELEVATION: 3,450 to 4,250 ft (1,050 to 1,295 m)
VEGETATION: Chaparral—Dominant shrubs are shrub live oak, birchleaf mountainmahogany, sugar sumac, and Emory oak (crown cover averaged 60 to 75%).
PARENT MATERIAL: Course granite
GAGE: 90° V-notch
PERIOD OF RECORD: 1956 (partial) through 1980

HISTORY: This is one of the Three Bar watersheds located west of Lake Roosevelt in the Three Bar Wildlife Area, which is maintained cattle-free for game management studies. Stream and rain gages were installed in 1956. Streams were intermittent, flowing about one-third of the time during the first 3 years (1956-1959), and yielding less than 1 inch per year average flow (Hibbert et al 1974). The Boulder wildfire swept over the area in June 1959, topkilling all shrubs (Glendening et al 1961).

OBJECTIVE: To determine how converting chaparral vegetation to grass affects streamflow, erosion and sedimentation, vegetation, and wildlife. Prior to treatment, streamflow form WS B was calibrated against streamflow from the designated control WS D.

TREATMENT: Although the Boulder fire was not intended to be part of the original study, treatment plans were realined to accommodate the burning part of the treatment on watershed C (Hibbert et al 1974). Therefore, treatment on C is properly described as wildfire followed by conversion to grass using chemicals to suppress the shrubs.

Four annual aerial spray treatments of 2,4,5-T (1960 through 1963) on watershed C suppressed shrub regrowth after the fire, but actually killed only 42 % of the shrub live oak and 72 % of the birchleaf mountainmahogany plants. Hand treatment of surviving shrubs in 1964 (pelleted fenuron) and again in 1968 (pelleted fenuron and granulated karbutylate) resulted in much better control (Hibbert et al 1974).

Watershed C was control burned in March 1971. A similar type of burn was made 2 years earlier on a nearby plot with good results (Pase 1971). Topkill of shrub live oak and birchleaf mountainmahogany, the 2 most numerous shrubs remaining on watershed C, was 71 and 68 %. Grass was stimulated to higher production than without burning. There was no evidence of surface runoff or erosion as a result of the control burn.

RESPONSE: By 1969 shrub crown cover on watershed C was reduced to less than 3 %. Grasses and forbs averaged 1,200 lb/arce/year from 1963 to 1968. Ground cover in 1974 was considered excellent over most of the watershed, and surface infiltration rates remained high. The channel area was particularly well vegetated by weeping lovegrass. Cover was pooredt on the upper, steep north exposures where lovegrasses did not do well. Forbs and half-shrubs provide fair ground cover on these sites, which account for about 10 % of the catchment.

SELECTED REFERENCES

Davis, E. A. and P. A. Ingebo. 1973. Picloram movement from a chaparral watershed. Water Resources Research 9:1304-1313.

Davis, Edwin A. and Charles P. Pase. 1969. Selective control of brush on chaparral watersheds with soil-applied fenuron and picloram. USDA Forest Service Research Note RM-140, 4 p.

Glendening, G. E., C. P. Pase, and P. Ingebo. 1961. Preliminary hydrologic effects of wildfire in chaparral. Arizona Watershed Symposium, Proceedings 5:12-15.

Hibbert, A. R. 1971. Increases in streamflow after converting chaparral to grass. Water Resources Research 7:71-80.

Hibbert, A.R.; Davis, E.A.; Scholl, D.G. 1974. Chaparral conversion. Part I: Water yield response and effects on other resources. USDA Forest Service Research Paper RM-17, 36 p. Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Ingebo, Paul A. 1969. Effect of heavy late-fall precipitation on runoff from a chaparral watershed. USDA Forest Service Research Note RM-132, 2 p.

McCulloch, Clay Y. 1972. Deer foods and brush control in southern Arizona. Journal of Arizona Academy of Science 7(3):113-119.

Pase, C. P. 1967. Helicopter-applied herbicides control shrub live oak and birchleaf mountainmahogany. U. S. Forest Service Research Note RM-84, 4 p. Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

Pase, C. P. 1971. Effect of a February burn on Lehmann lovegrass. Journal of Range Management 24:454-456.

Pase, C. P. and P. A Ingebo. 1965. Burned chaparral to grass: Early effects on water and sediment yields from two granite soil watersheds in Arizona. Arizona Watershed Symposium, Proceedings 9:8-11

Pase, C. P., P. A. Ingebo, E. A. Davis, and C. Y. McCulloch. 1967. Improving water yield and game habitat by chemical control of chaparral. XIV International Union for Research Organizational Congress, Munich, September 1967, Proc. V. I., Sect. 01-02-11, p. 463-486.

Smith, Ronald H., T. J. McMichael, and Harley G. Shaw. 1969. Decline of a desert deer population. Arizona Game and Fish Department, Wildlife Digest, Abstract 3, 8 p.