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,

Manipulation of Gambel oak for enhanced rangeland values must be in accord with ecological principles to ensure desired success. Failures in controlling Gambel oak have occurred because the growth patterns, morphological characteristics, and carbohydrate storage patterns of the species have not been taken into account. However, recurrent control will continue to be necessary since grass dominated systems should not be considered to be climax in Gambel oak dominated systems. Existing initial and maintenance control methods appear to offer only short-term solutions, which often result in more troublesome long-term management problems.Gambel oak (Quercus gambelii) is considered a major brush problem species on millions of acres of foothill ranges in Colorado, Utah, New Mexico, and Arizona. Creating open grasslands by removal of mature stands of Gambel oak from these ranges increases watershed values and presents several advantages to the livestock producer (Marquiss 1972). The greatest benefits are an increase in forage produced for livestock and enhanced livestock handling. However, since Gambel oak is a natural part of the vegetation, recurrent treatment is required to retain these advantages.Eradication of Gambel oak is rare by any method, and without complete kill prolific sprouting may occur from roots, rhizomes, and basal stems. Treated ranges many times assume a "thicket"like appearance several years after an initial oak control effort. These sprout thickets differ from the original mature oak stands in both their structure and response to control methods.Range managers are in need of effective control methods on these previously treated areas where abundant oak sprouts are difficult to control with conventional methods and present a major management problem. We suggest here some reasons for the difficulty in controlling Gambel oak and propose some possible alternatives for dealing with the Gambel oak sprouts. Problems in Controlling Gambel Oak Application of Ecological PrinciplesRange scientists recognize that proper and wise management of ranges includes direct manipulation of the ecosystem. Such manipulation should be directed in ways that work in accord with the natural functioning of ecosystems and should be based upon ecological principles, that is, particularly competition and succession (Vallentine 1971). With increasing costs of fuels and herbicides, conventional methods of manipulating oakbrush ranges must continue to be cost effective, as well asenvironmentally sound. Yet, the demand for meat by an expanding world population is sure to place pressure on the livestock producer to increase the productivity of rangelands. Range scientists, in some cases, concede that it is unwise to continually confront natural ecosystem forces by