Tree improvement is the application of genetic principles to increase the value of tree crops. Each tree species improvement programme is uniquely tailored according to the biology, constraints and the importance of the species to the country’s forestry industry. Tree improvement relies on understanding and using variation that naturally occur in the populations. Tree improvement increases the value of tree species by: 1) Selecting the most desirable tree from natural stands or plantations; 2) Breeding or mating these select tree; 3) Testing the resulting progeny. This three-step process is continuously repeated to further improve the average value of the breeding population. Each interaction of the improvement process is called a generation.
In order to meet the tree planting demands usually a production population referred to as a seed orchard or a group of trees managed specifically for seed production is established. For species which can readily be propagated using cuttings, a hedge orchard or mother garden is managed to produce cutting material. Seed and hedges generated from a tree improvement programme are established from grafts, rooted cuttings or seed of the very best trees in the breeding population. Tree improvement is therefore using genetic variation, and the application of selection, breeding and testing to assess performance of relatives or heritabilities continually improving the value of a population of trees which subsequently are used for the production of adequate quantities of high quality seed and or planting material.
This research programme builds on the long-term species introductions and provenance evaluations undertaken since the beginning of the last century, including both the regional e.g EAAFRO, MONDI, CSIR and international e.g OFI, CAMCORE forest genetic conservation and improvement initiatives.