USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 49 



bordering the swales, 0.8 to 1.1; rolling slopes with few rock outcrops, 

 trees, or shrubs, 1.25 to 1.75; rolling to steep slopes with numerous rock 

 outcrops, trees, or shrubs, 2.0 to 3.0; and steep slopes with numerous 

 rock outcrops, trees, or shrubs, 3.0 to 5.0. The lowest grazing capacity 

 was found on steep north slopes with a heavy canopy of trees and shrubs. 



Ranch stocking must also consider the characteristic yearly fluctuations 

 in herbage production. On granitic soils at the experimental range, in 

 the 2 years with near-average total precipitation (16 to 20 inches), 

 herbage yields were average or greater. In wet years (more than 20 

 inches of precipitation), total yields were somewhat similar to those in 

 average years; most of the excess moisture was lost through seepage. 



In dry years (12 to 16 inches of precipitation), rapid plant growth 

 during a short interval of favorable weather in the spring produced yields 

 that were only about 9 to 27 percent below the estimated 13-year average 

 of 1,640 pounds per acre. The effects of the occasional extreme drought 

 year (with less than 12 inches total precipitation) were not encountered 

 during the studies. 



Fluctuations in the quantity of forage make advisable some adjust- 

 ments in livestock numbers nearly every year. The extent of needed 

 adjustments can be judged in late spring after most of the plant growth 

 for the year is complete. Changes in number of livestock will depend on 

 the average stocking and type of operation at each ranch. 



Adjustments can be made by several measures in a mixed breeding-cow 

 and feeder operation. Enough cows and replacements can be carried to 

 utilize the herbage produced in dry years. The extra herbage in years of 

 average production is utilized by weaners. In years of above-average 

 production the increased yield can either be utilized by bringing in 

 outside animals or be left on the ground to replace any litter that may 

 be lost during dry years. This type of operation will permit the necessary 

 adjustments in livestock numbers in all except the occasional years of 

 extremely low forage production. 



Most fluctuations in individual forage species exert relatively minor 

 effects on range stocking. The amount of grass in the plant mixture, 

 however, is of special importance on ranges grazed from summer until 

 winter. In years of very low grass production, stocking should be re- 

 duced from average or hay should be provided in addition to the short 

 supply of dry grass. 



A reserve of range forage cannot be carried over from year to year 

 because dry herbage of annual plants is ruined by leaching during the 

 winter. It appears desirable and feasible, therefore, to keep a reserve of 

 hay above usual yearly needs. 



Selecting most efficient degree of grazing. — Overstocking foothill range 

 lowers efficiency of production from a cattle breeding herd, according to 

 the conclusion of animal husbandmen of the University of California, 

 in charge of the livestock phases of the cooperative grazing-intensity 

 experiment. The objectives of efficient production — high calf crops 

 and optimum weaning weights — could not be met in the pasture under 

 heavy stocking for about 6 months (February to August), even with 

 moderate stocking for the remainder of the year. In the pasture stocked 

 slightly heavier than moderate, production was also reduced for unsupple- 

 mented cows but was not lowered for cows fed supplements during the 6 

 months they were out of the grazing-intensity pastures. Cattle produc- 



