in association with chokecherries (Prumis spp.), true mountain-mahogany 

 (Cercocarpus montanus) and serviceberries (Amelanchier spp.). It is also 

 common, and often abundant, in the upper woodland and ponderosa pine types 

 of the Southwest. It is not so drought-enduring as most southwestern oaks, 

 and grows at higher elevations where soil moisture is more plentiful. Al- 

 though often found on coarse or even rocky sites, it prefers the sandy or 

 gravelly loams, and attains its best development in canyon bottoms and 

 sheltered places in rich loam soils, where its extensive roots receive adequate 

 moisture. This species is a good soil builder, and at least a thin layer of 

 black rich soil is usually found beneath an old-established stand of Gambei 

 oak. As a result, a good understory of palatable, herbaceous vegetation, such 

 as bromegrass, bluegrass, lupine, and geranium, frequently occurs under this 

 oak, especially in the more open stands. 



Because of its size, leafiuess, and great abundance, Gambei oak produces 

 a vast amount of herbage, which is usually fair in palatability for all classes 

 of livestock, and also for deer. On some grass ranges where there is a scarcity 

 of palatable browse, it is considered fairly good forage. On the other hand, 

 where palatable shrubs are plentiful this species is regarded as having but 

 little forage value. On overgrazed ranges-, this oak is usually grazed so closely 

 as to form a grazing line, or "high water mark" below which all of the foliage 

 is stripped annually. This is not an uncommon condition along canyon bot- 

 toms where cattle congregate. Gambei oak acorns are relatively sweet and 

 are eaten readily by all classes of livestock, deer, and wild turkeys. 



Forsling and Storm 1 found on a controlled area that heavy use of oak resulted 

 in overgrazing the palatable shrubs and herbaceous species ; furthermore, the 

 cattle grazed made poor gains and slow growth, and the calf crop was unsatis- 

 factory. These experimenters found tlmt oak and other less palatable shrubs 

 were always utilized to some extent along with the more palatable species. 



Experiments by Marsh, Clawson, and Marsh 2 have proven definitely that oak 

 leaves may sometimes produce fatal sickness in cattle. They show, however, 

 that cattle succumb only from an exclusive diet of oak, and that no losses occur 

 where other supplemental forage is available. Gambei oak is an outstanding 

 species in the history of western oak poisoning. Losses are chiefly restricted 

 to cattle, but sheep have also been reported as affected. Oak poisoning has 

 been reported at all seasons where oak leaves are available, but cattle losses 

 have occurred chiefly in the spring and on ranges where grazing was permitted 

 before other forage was available, or on overgrazed range where cattle were 

 forced to subsist on an almost pure diet of oak. There is little or no danger 

 of oak poisoning when the range is grazed properly. The outstanding symp- 

 toms of oak-leaf poisoning are constipation, emaciation, and edema ; the feces 

 contain mucus and blood. 



Gambei oak has been segregated by some modern authorities into a number 

 of species, or forms, based largely on the shape of the acorn au_d the shape, 

 lobing, color, hairiness, and persistence of the leaves. These characters are 

 so variable, that it is very difficult to distinguish between such species as Utah 

 oak (Q. utahen'sis), New Mexican oak (Q. novomexica'na), and Vreeland oak 

 (Q. vreelan'dii). 



Utah oak is very similar to Gambei oak, being segregated chiefly on the 

 basis of the leaf, which is soft-hairy or almost velvety beneath and somewhat 

 reverse egg-shaped in outline. Gambei oak leaves are hairless or only slightly 

 hairy beneath, and usually oblong in outline. The acorns of Utah oak have 

 somewhat thicker scales and are a little larger than those of Gambei oak, 

 being one-half to three-fourths of an inch long; the acorns of Gambei oak are 

 rarely longer than one-half of an inch. Furthermore, Utah oak often grows 

 taller than Gambei oak, occasionally reaching a height of about 30 feet. In 

 economic value these two oaks are practically similar, and hence are seldom 

 differentiated in the field. Sheep losses have been reported in Utah from 

 excessive eating of the acorns of Utah oak. 



1 Forsling, C. L., and Storm, E. V. THE UTILIZATION OF BROWSE FORAGE AS SUMMER 

 RANGE FOR CATTLE IN SOUTHWESTERN UTAH. U. S. Dept. Agr. Circ. 62, 30 pp., illus. 1929. 



2 Marsh, C. D., Clawson, A. B., and Marsh, H. OAK-LEAF POISONING OF DOMESTIC 

 ANIMALS. U. S. Dept. Agr. Bull. 767, 36 pp., illus. 1919. 



