Three-Bar Wildlife Area

Watershed B

AREA: 46.5 ac (18.8 ha)
SLOPE:
ASPECT: North facing
ELEVATION: 3,300 to 4,200 ft (1,005 to 1,280 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 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 form WS B was calibrated against streamflow from the designated control WS D.

TREATMENT: After the Boulder fire, watershed B 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.

Shrubs on northeast-facing slopes (40 % of watershed B) were hand treated with chemicals (pelleted fenuron and granular picloram) in 1965 after 6 years of recovery following the wildfire. Surviving shrubs were again treated in 1968. Browse plants of highest wildlife value were not treated; these species made up only about 5 % of the total shrub cover, and included hollyleaf buckthorn, desert ceanothus, and false-mesquite (Calliandra eriophylla).

The remaining 60 % of watershed B (untreated portion) was treated in January 1972 in the same manner as the 1965 treatment, except that the chemical applied was karbutylate formulated as 50 % active ingredient tablets spaced a foot or so apart on the ground surface around each shrub. After 2 growing seasons the treatment appeared successful.

RESPONSE: The chemical treatment in 1965 reduced shrub cover to about 8 %. In spaces between shrubs, damage was light to forbs and grasses, which responded to release from shrub competition. Grass and forb production averaged 690 lb/acre/year on the treated areas (through 1973), but only 300 on the untreated slopes (Hibbert et al 1974).

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, P.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.