FEASIBILITY OF ALTERNATIVES TO HERBICIDES IN YOUNG CONIFER PLANTATIONS IN CALIFORNIA

Escalating controversy on clear-cutting, herbicides, burning, and graz ing led to a research program with 40 studies, begun in 1980, that com pared most of the vegetation management techniques used for enhancing growth of 1- to 3-year-old conifer seedlings. These include such direc t techniques as manual manipulation, mulching, herbicides, and grazing for releasing conifer seedlings from undesirable vegetation, and seve ral silvicultural practices (broadcast burning, group selection, genet ically improved seedlings) that serve as indirect methods for reducing or avoiding vegetation problems. Manual release and mulching are effe ctive but expensive. Herbicides are effective, applicable to almost al l plant communities, and relatively inexpensive. Grazing is good for c attle and sheep, but does not significantly enhance conifer seedling g rowth. Utilizing the silvicultural practices noted above and emphasizi ng replacement vegetation show promise, but lack sufficient testing fo r us to evaluate feasibility. In most instances, forests cannot be man aged economically without herbicides if the goal is to grow seedlings at the potential of the site and the plant community includes sproutin g hardwoods and shrubs or rhizomatous forbs and ferns. If the goal is to create a forest with several age-classes and variable structure, bu t with slower seedling growth, longer time to harvest, and less specie s diversity in early seral stages, then it is possible to accomplish t his without herbicides and other means of vegetation control.