Effect of Chemical and Manual Release on Live Oak Sprouts and Other Vegetation in a Ponderosa Pine Plantation on a Poor Site

In their quest to increase vegetation management alternatives, managers continue to test new treatments and to apply old ones to different species. In this northern California study, the new treatment was undiluted Velpar applied with a spot-gun; the old treatments were Garlon 3A, Garlon 4, and manual release; and the different species was canyon live oak (Quercus chrysolepis). Principal categories of vegetation in the new plantation were hardwoods (mostly live oak root-crown sprouts), shrubs, forbs, and grasses. Planted 2-yr-old ponderosa pine (Pinus ponderosa var. ponderosa) seedlings were part of the plant community. Eleven growing seasons after treatment (1988–1998), hardwood sprouts in the untreated control averaged 1,850/ac, combined shrubs over 3,600/ac, forbs 5,900/ac, and grasses more than 19,500/ac. Mean hardwood height in 1998 was significantly shorter when treated with Velpar and Garlon 4 than in the control. Significantly longer needles for pines in the Velpar and manual release treatments in 1989 forecast a significant difference among treatments that was realized in 1994, when mean stem diameter of pines at 12 in. above ground was significantly larger in all treatments than in the control. Stem height and diameter of pine did not differ significantly among treatments in 1998, but needle length again indicated that it would in the near future. Ten years may not be enough time to fully evaluate release treatments on poor sites with hard-to-control species. West. J. Appl, For. 18(1):22–28.