Section 10

Introduction and Procedure


Introduction

Chemical site preparation differs from mechanical manipulation primarily in that it generally has a much less severe impact upon the environment and in that chemical site preparation is generally much more selective than mechanical site preparation techniques which employ power machinery. It differs from mechanical site preparation, too, in that the active agents, the chemicals, may affect crop as well as target species and may be dispersed beyond the boundaries of the project area. For these reasons, only persons thoroughly conversant with the mode of action of chemicals and with the technology of their distribution should employ herbicides in forest management.

The use of chemicals in vegetation management has been greatly restricted in British Columbia because: a) relatively few compounds are registered for use in the forests; and b) strong resistance to the use of chemicals by environmentally oriented groups. As an example, in the state of Oregon, ca 40,000 ha. have been treated with aerial applications of herbicide each year. In contrast, chemicals have been used less than 10% as frequently in British Columbia (in spite of the fact that B.C. has a much greater area in NSR land) and virtually all the use of chemicals in British Columbia has utilized ground application systems. Given the manpower and resources available to the province, it seems unlikely that much of the current NSR area will be satisfactorily stocked without the use of herbicides. Further, since man's activities have effectively introduced a large reservoir of light seeded endogenous and exotic weed species throughout the commercial forest areas of British Columbia, it is unlikely that successful plantations can be established on much of the current cut-over lands without the most effective vegetation management.

Procedure

Proper use of herbicides to achieve desired vegetation management goals may be a complex operation. This unit will discuss the principal facets of chemical site preparation, i.e., principles of problem analysis and herbicide use, properties of herbicides registered for forestry use, selectivity of herbicides in forest ecosystems, and application systems and drift control.


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