Cooke, J.E.K., Morse, A.M., and Davis, J.M. 2004. Forestry. In: Handbook of Plant Biotechnology. H. Klee and P. Cristou, eds. Wiley, Sussex. 2 vol., 1552 pp. Chapter is 24 pp.
© Copyright John Wiley & Sons, UK, 2004.
Forestry plays a significant role in the global economy. Global trade in the primary commodities produced from harvested timber - solid wood and pulp - was $126 billion (US) in 1998 (FAO 2001). This figure does not include trade in manufactured wood, paper, and fibre products (FAO 2001), nor bioenergy and biofuel products such as ethanol, heat, steam, and electricity (Dinus et al. 2001). Forest trees are also sources for an astonishing variety of commercial natural products such as rubber and taxol. Natural products are discussed in detail in other chapters of this volume, and will not be considered here.
Traditionally, trees have been harvested from natural forests. Increasingly, however, trees are being grown in managed stands, as a consequence of diminishing natural forest landscapes and efforts to increase product yield per unit time (Farnum et al. 1983). Many agronomic practices that are employed in agricultural crop production have been adopted for managed forest tree production. In the most advanced "fibre farms", trees are grown in high-density plantations complete with extensive site preparation, water irrigation, fertilizer amendment, weed and pest control, and sophisticated harvesting mechanisms (Dinus et al. 2001).
Genetic improvement plays a pivotal role in intensive management strategies for forest trees. Contemporary large-scale genetic improvement programmes were established in the 1950's for several commercially important species in North America, Europe, and other regions throughout the world (Zobel and Talbert 1984). Today, there are active genetic improvement programmes for a large number of temperate and tropical forest tree species (White et al., in preparation). Despite the genetic gains that have been realized by these programmes, conventional breeding in forest trees is greatly constrained by long generation times. This is particularly true for temperate coniferous species, which rank among the most commercially important forest trees. For example, after more than 50 years of intensive genetic improvement for loblolly pine (Pinus taeda L.), these programmes are just in the third cycle of breeding (White et al., in preparation). Additionally, many traits of interest exhibit poor correlation between the juvenile and mature phases of growth that are innate to trees (Dinus and Tuskan 1997). Consequently, these traits cannot be reliably evaluated at the morphological level until the tree has entered into mature growth, which may take several years.
Given these constraints to conventional breeding, the use of biotechnology to reduce the time to create and select genetically improved trees could have a significant impact on forest tree improvement and the forest industry. In this chapter, we focus on how biotechnology has been and can be incorporated into forestry.