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West, this species was selected for study. The investigations were designed to determine its response to various intensities, frequencies, and seasons of herbage removal under favorable (artificially watered) and unfavorable (arid) environment. The responses were evaluated on the basis of forage yield, chemical composition of herbage, apparent vigor, seed production, root yield, and root reserves. • REVIEW OR LITERATURE The effect of frequency and intensity of clipping on the yield and vigor of various pasture and range plants has received considerable study. These investigations have dealt with a great variety of conditions and methods and in general they show that yield and vigor decrease as frequency or intensity of clipping is increased (

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Highlight: A high degree of Gambel oak control can be attained with a combination of mechanical treatment followed by a system of goat grazing. This type of control program can result in significant increases in the amount of forage available for livestock production. Mechanical treatment of the oak is necessary to attain maximum benefit from goats. High stocking rates and the proper time of browsing are important management considerations. Gambel oak (&ercus gambelii) is an important component of several million acres of foothill rangelands in Arizona, Colorado, New Mexico, and Utah. It is found growing from the pinyon-juniper zone to the aspen-spruce zone. The value of Gambel oak on rangelands is questionable. Control studies have indicated that significant increases in soil moisture, forage production, and beef production can be expected in areas where Gambel oak is controlled (Marquiss, 1972). Goats have been used successfully in the southern part of the United States to control a number of oak species, including live oak (Quercus virginiana), post oak (Quercus stellata), Spanish oak (juercus falcata), and blackjack oak (Quercus marilandica) (King, 1956; Magee, 1957; Norris, 1968). Studies in several countries indicate that goat browsing may cause certain detrimental effects to other types of vegetation, but that the goat is of considerable value for brush control and utilization of herbage not normally taken by other stock (Campbell et al., 1962). The success of goat browsing in an oak control program is largely dependent on animal grazing preference and the physiology of the plants themselves. The preference of goats for the leaves and buds of brushy species has been noted in a number of areas (Campbell et al., 1962; Norris, 1968). Oak-sprout kill by goat browsing is a result of continued defoliation and subsequent reduction of carbohydrate reserves. Results from studies on defoliation on total available carbohydrate (TAC) storage levels substantiate this (Donart and Cook, 1970; Trlica and Cook, 1971). The effect of defoliation becomes more pronounced if repeated at frequent intervals and at the critical times of the year when carbohydrate reserves are normally low (Cook, 1966). A twelve-year study on oakbrush by Shepherd (197 1) revealed Authors are senior research technician and research technician,