Section 10

Objectives

Upon the completion of this section and assigned material, you should know the advantages and disadvantages of chemical site preparation and be able to answer questions such as the following:

Vegetation Inventory. The first step in the problem analysis necessary to properly prescribe chemical treatments is an inventory of the principal weed species present on the area and estimation of their present and future potential for reducing crop seedling growth and survival (in essence this tells the regeneration forester what the problem is that the chemical treatment must correct). Such an inventory should include data describing the plant community, i.e., is the plant cover solid or clumpy? Is the vegetation short or tall, herbaceous or woody, sprouting or non-sprouting? Are seedlings of desired crop species present? Is the stocking of crop seedlings good? Well-distributed or confined to small areas?

The tables in the appendix of this section summarize the characteristics and uses of herbicides commonly employed in forestry. It should be apparent that a good inventory of competing vegetation is necessary to prescribe the chemical treatment necessary to prepare the site for regeneration or to release established crop seedlings.

Click me for a view of Mac Forest (North Zone) vegetation type maps

Click me for a view of Mac Forest (Central Zone) vegetation type maps

Click me for a view of Mac Forest (South Zone) vegetation type maps

Site Evaluation. The use of chemicals in vegetation management is frequently criticized on the grounds of potential impact upon non-tree growing uses of the project area. Before recommending herbicide applications, the forester should investigate the possibility of alternate methodology, i.e., will the terrain permit the use of tractors or other machinery, and if so, would the use of such equipment have a significant detrimental impact upon the site or surrounding property? It should be determined also whether the use of chemicals will conflict with other land uses such as production of high quality water or of endangered plants or animals. The forester should assess the probable effects of chemical techniques upon adjoining properties and estimate the extent to which the proposed application of herbicide can be confined to the target area. Obviously, he should follow legal requirements with regard to posting the property and notifying neighbors.

Animal Populations. During the site examination, evidence of animals should be noted and, if possible, the major species should be identified. Knowledge of the food and cover requirements of resident animal populations will permit an estimation of the effect the use of herbicides may have upon the number and species of animal and upon the potential for animal damage to seedlings of crop species. Certainly, it would be counter- productive to apply herbicides to an area if such action modified cover to support a larger population of animals known to destroy seedlings of a crop species.

Seedling Requirement. Finally, the site examination should include an estimation of the degree of site preparation necessary to permit seedling survival and of the seedling type (both species and stock type) required to produce a successful plantation.

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