Quality Control in the Production of Forest Planting Stock

Abstract

Plantation performance depends on the outcome of an interaction between the stock planted and its environment. Immediately after planting, it is the degree to which stock is pre-adapted to site conditions (i.e., its phenotype), rather than its genetic potential for adaptation to environment (i.e., its genotype) which has the greatest influence on performance. The purpose of a stock quality control system is to ensure that stock has phenotypic characteristics which adapt it to the planting site. Thus a prerequisite to the creation of an effective quality control system is the definition of stock quality standards which specify the phenotypic characteristics of stock adapted to the conditions of normal use. Physiological principles provide a basis for such standards but they must be refined through trial and error. Thus feedback on the performance of stock conforming to current standards is one key to the development of appropriate stock quality standards. Another is research to determine the causes of unsatisfactory performance. With these sources of information it is possible to modify stock standards or site treatments in a way that improves the cost-effectiveness of regeneration efforts. Culling, the traditional method of quality control, can reduce stock heterogenity, but it cannot transform poor stock into good. Often, therefore, the attainment of a desired quality standard requires an overall improvement in the quality of nursery output. The only practical way of doing this is to modify the nursery environment including cultural and handling practices.