Tree Breeding and Genetics of Exotic Conifers in Canada

Abstract

The most commonly planted exotic conifers in Canada are Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) Norway spruce has its highest potential on acid soils in high precipitation areas where it is more productive than the local spruce and fir mixture. Extensive plantations of Norway spruce have not been established because of its susceptibility to attack by white pine weevil. A number of provenance experiments have been established, and selection and breeding for resistance to the white pine weevil appear promising.Scots pine has not been favoured for timber production in Canada mainly because most early seed imports came from poorly formed stands in western Germany. Rapid early growth and green foliage in early winter led to extensive cultivation of these German types for Christmas trees. A limited number of stands from Poland and White Russia, and nearly all the Scots pine from Estonia-Latvia (Riga Pine) are well formed and are recommended for timber production, but not for the growing of Christmas trees. On less fertile sites, Scots pine grows more rapidly than red pine but, at least in the first 20 years, it does not grow as well as jack pine. Selected provenances of Scots pine hold much promise in the prairie region and in the boreal forest.Other exotic spruces have not been widely planted in Canada so very little is known about their silvicultural potential and ecological amplitude. Combined species and provenance trials have been planted recently to remedy this situation. A hybrid between Serbian and black spruce growing at Chalk River, Ontario has grown more rapidly than either parental species. Other species hybrids have been made, but are not yet assessed.In an attempt to develop a hard pine of wider ecological amplitude than red pine, species hybrids have been made between Scots pine, Japanese red pine and varieties of Pinus nigra. These are promising on rich soils in southern Ontario and might be extended further to the north and to poorer acid soils by using selected provenances for the breeding work. Pitch pine has been successfully crossed with P. taeda and P. radiata in an attempt to improve the productivity and potential of pitch pine.