Native species

Little work was done on the nutrition of the eucalypts until the early 1960s, when it was demonstrated[24] that gains could be made from both phosphorus and nitrogen additions. Thereafter further studies were made and fertilization at planting with these elements and sometimes potassium, became widely used in eucalypt plantations, together with weed control.

Compared with the pines relatively little genetic improvement has been done on the eucalypts in Australia. Some provenance testing has been carried out for commercially important species, notably flooded gum, Sydney blue gum, blackbutt, messmate, mountain ash and shining gum, and superior strains selected for plantation use. The first eucalypt seed orchards were established with seedlings in the early 1970s, by APM for mountain ash in Gippsland and by the NSW Forestry Commission for flooded gum in northern NSW. Vegetative methods for propagation have not been used in Australia to any significant commercial extent in either breeding studies or the production of plantation stock, despite their advantages in reducing both generation interval and variability, but methods based on earlier Australian research on vegetative propagation[25] have been used in large plantation establishment overseas. Recently a small commercial tissue culture operation has started in Australia to produce salt-tolerant river red gum stock for planting in areas of high salinity.

Hoop pine

Hoop pine plantations date back to 1917, with some plantings of open-rooted nursery stock on clear-felled areas in Queensland. Survival rate was markedly improved after 1922, when Deputy Forester Weatherhead of the Queensland Forest Service developed and introduced a technique of planting from metal tubes which helped the young plants withstand the strong weed competition which occurred.[26]

A breeding program was begun in 1951 and a seed orchard in 1957. Propagation proved difficult using conventional grafting methods but in 1959 a new method -bark patch grafting -was developed[27] as a result of research which showed major differences in the biology of the species, particularly in its bud systems, when compared with Pinus species. Two clonal seed orchards were established to produce stock of improved growth rate and stem straightness and this facilitated further genetic improvement.[28] Queensland now has some 40 000 ha of hoop pine plantations and is continuing to extend them. NSW also started to establish hoop pine plantations in the 1930s, but phased them out in the mid-1950s because of high maintenance cost.

Australian Academy of Technological Sciences and Engineering