Quality and Yield of Forage as Affected by Chemical Removal of Blue Oak (Quercus douglasii)

It is estimated that 6.5 percent of the land area in California is of the grass-woodland cover type. Blue oak (Quercus douglasii), a major tree species of this type cover, modifies both yield and composition of the herbaceous understory. It has been demonstrated that oak trees lower forage production and affect the flow of water from springs and watersheds (Harvey, Johnson, and Bell, 1959; Biswell and Schultz, 1958). Johnson et al. (1959) conducted a 1-year study of yield and quality of range forage following chemical treatment of oak trees by the cut-surface method. Though significant results were obtained, rather wide fluctuations in forage yield and composition are known to occur from year to year on the annual type range in California. The present study is concerned with forage yield over a sevenyear period and botanical composition for a 10-year span. Trees were chemically killed past the mid-point of the yield measurements and at the beginning of botanical evaluations.