Three-Bar Wildlife Area

Watershed F

AREA: 68.4 ac (26.2 ha)
SLOPE: Upper slopes are steep, often exceeding 60 %
ASPECT: Northeast facing
ELEVATION: 3,900 to 5,100 ft (1,190 to 1,555 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: 1963 through 1983

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 from WS F was calibrated against streamflow from the designated control WS D.

TREATMENT: After the Boulder fire, watershed F (prior to being instrumented????) was seeded with weeping and Lehmann lovegrasses (Eragrostis curvula and E. lehmanniana) and yellow sweetclover (Melilotus officinalis) in July 1959, but the catch was very poor. The watershed was seeded again in May 1960 with weeping, Lehmann, and Boer lovegrasses (E. chloromelas). The resulting fair but spotty catch gradually increased in density where shrubs were controlled.

Watershed F was chemically treated in February 1969 with a broadcast application by helicopter of granular karbutylate to the soil (Hibbert et al 1974). Shrub crown cover was reduced from 55 to 4 % in the first year. The shrubs began to show visual signs of the chemical application by late April. Injury symptoms progressed rapidly during the spring months, and by early June most of the shrubs were either dead or dying. Total shrub kill increased to more than 95 % after 2 years. All grasses and herbaceous plants were killed by the chemical application.

RESPONSE: Phytotoxic residues remained active in the top 6 inches of soil over most of the watershed for the first 2 years, preventing growth of new plants (Hibbert et al 1974). The only exception was along the lower channel area where flow surfaced and became perennial after the treatment. A variety of forbs and grasses dominated by horseweed (Erigeron canadensis) invaded the channel area, where the plants rooted in the bed of the stream or in the moist channel banks. This narrow band of plants ended abruptly where water was not within a few inches of the soil surface.

During the third growing season (1971) forbs and grasses began to appear on interior ridges in the lower part of the watershed, but many of these showed injury symptoms before fall (Hibbert et al 1974). Invasion by forbs and grasses during the fourth growing season finally produced fair cover over all but the upper 10 to 15 % of the watershed.

Additional information on treatments at Three Bar can be found in: Davis and Ingebo 1973, Davis and Pase 1969, Glendening et al. 1961, Hibbert 1971, Hibbert et al. 1974, Ingebo 1969, McCulloch 1972, Pase 1967, Pase and Ingebo 1965, Pase et al. 1967, and Smith et al. 1969.

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.