The discipline of forest tree propagation

Propagation, generally by stem cuttings, is part of clonal forestry. Approaches to the common technical problems (especially variation in initial survival and rooting ability of cuttings) are open to criticism, hindering progress. For example, the concept of rooting promotors and inhibitors has led to undue emphasis on the ultimate mechanism of adventitious rooting, and the application of the term ‘juvenility’ to propagation is confusing and largely erroneous. The actually important (if local) sources of variation determining propagation ability deserve more study. Limited generalities are required for predicting and improving propagation ability, and for developing efficient propagation systems, in practice.