Feasibility of alternatives to herbicides in young conifer plantations in California

Abstract

Escalating controversy on clear-cutting, herbicides, burning, and grazing led to a research program with 40 studies, begun in 1980, that compared most of the vegetation management techniques used for enhancing growth of 1- to 3-year-old conifer seedlings. These include such direct techniques as manual manipulation, mulching, herbicides, and grazing for releasing conifer seedlings from undesirable vegetation, and several silvicultural practices (broadcast burning, group selection, genetically improved seedlings) that serve as indirect methods for reducing or avoiding vegetation problems. Manual release and mulching are effective but expensive. Herbicides are effective, applicable to almost all plant communities, and relatively inexpensive. Grazing is good for cattle and sheep, but does not significantly enhance conifer seedling growth. Utilizing the silvicultural practices noted above and emphasizing replacement vegetation show promise, but lack sufficient testing for us to evaluate feasibility. In most instances, forests cannot be managed economically without herbicides if the goal is to grow seedlings at the potential of the site and the plant community includes sprouting hardwoods and shrubs or rhizomatous forbs and ferns. If the goal is to create a forest with several age-classes and variable structure, but with slower seedling growth, longer time to harvest, and less species diversity in early seral stages, then it is possible to accomplish this without herbicides and other means of vegetation control.

Development of a mixed shrub-tanoak-Douglas-fir community in a treated and untreated condition

“…By the end of the study 20 plant species had been noted. This number is low relative to that found in other studies (17 to 41 species) in our National Administrative Study in young conifer plantations (McDonald and Fiddler 1993).…”

Benefit–cost Analysis of Vegetation Management Alternatives: An Ontario Case Study

“…We found that applying a cutting treatment once, although not as profitable as aerial application of herbicides, is economically viable. However, in some scenarios a single cutting operation may not be sufficient to suppress the competition (MacDonald andFiddler 1993, Heineman et al 2005) and repeated cutting operations are not cost-effective (Comeau and Harper 2009). Although job creation was a major goal of implementing these labour-intensive methods on a large scale, companies now frequently report a shortage of available (willing) workers to carry out mechanical release treatments (Thiffault and Roy 2010;Wyatt et al 2011).…”

Public perceptions of risk and acceptability of forest vegetation management alternatives in Ontario

“…Stimulated by public opposition to herbicides, research efforts in recent years have sought to develop alternatives to herbicide use, especially aerial forms of application (McDonald and Fiddler 1993, Wagner 1993, Comeau et al 1996. Alternatives to aerially-applied herbicides that have been examined include: ground-applied herbicides (tractor-mounted sprayers, granular formulati&, capsule delivery systems, backpack sprayers), biological control (naturally-occurring organisms such as fungal pathogens or phytotoxins derived from natural sources), prescribed fire, mulches (the spreadmg of materials around desired trees to control competing vegetation), heavy motorized equipment for soil scarification or cutting of vegetation, cover cropping (seeding of desirable non-crop plants to suppress or eliminate unwanted vegetation), grazing animals (primarily sheep), and manual cutting with brushsaws.…”