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    On a medium site in northern California, a tanoak-mixed shrub community was given several treatments (manual release two and three times, a combination chainsaw and cut surface herbicide treatment, two foliar herbicides, and a tank mix of the two herbicides) to study its development in both a natural (control) and treated condition. The herbicides were 2,4-D, Garlon 3A, and Garlon 4, each applied two times. Survival of planted Douglas-fir seedlings was recorded for 11 years and growth was quantified for 9 years after the last treatment application. In addition to Douglas-fir, data are presented individually for the two most abundant species (tanoak and snowbrush), for greenleaf manzanita, and for the hardwood tree and shrubs combined. At the study's end in 1992, combined vegetation in the control had a mean density of 1,800 plants per acre, foliar cover of 23,700 ft² per acre, and height of 11.2 feet. In contrast, combined tree and shrubs in the most effective treatment for controlling them—cut and spray Garlon 3A—had a mean density of 150 plants per acre, foliar cover of 150 ft² per acre and height of 5.9 feet at study end. And because competition for site resources was low, Douglas-fir seedlings developed best in this treatment. Mean Douglas-fir diameter was 4.6 inches at 12 inches above mean ground line, height averaged more than 21 feet, and mean foliar cover was 39,850 ft² at the end of the study. The cost was $227 per acre. The treatment response data, cost information, and plant community relationships provide the forest land manager with knowledge on how to attain some specific plant communities in the future, and their developmental potentials.

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    McDonald, Philip M.; Fiddler, Gary O. 1996. Development of a mixed shrub-tanoak-Douglas-fir community in a treated and untreated condition. Res. Paper PSW-RP-225. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 16 p


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    Douglas-fir seedlings, manual and chemical release, northern California, shrubs, tanoak sprouts

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