Breeding strategies for the 21st Century: domestication of poplar

Introduction The goal of plantation culture is the economically and ecologically sustainable production of wood to meet a growing worldwide demand. At the end of the 20th Century, poplar culture has reached a fork in the road to the future, and both paths must be followed in order to achieve the goal of sustainability. One branch of the road leads to poplar forestry, where natural or extensively managed stands have multiple functions in addition to wood and fiber production, such as watershed protection, maintenance of biodiversity, and recreation. Aspen in the boreal ecosystem of North America is an example of a species for which a poplar forestry management strategy seems appropriate. This form of forestry strongly supplements the ecological preservation functions of biological and riparian reservations that include poplars as key species. The other branch leads to poplar agriculture, where "tree farms" are intensively managed with the dominant goal of producing the maximum volume and quality of wood, fiber, and biomass for energy on the smallest possible land base. The best agricultural practices will be used to increase economic yields, including planting on the best available sites; fertilization and irrigation; control of weeds, pests, and diseases; and genetic improvement through conventional breeding, interspecific hybridization, vegetative propagation (cloning), and biotechnology. Examples of poplar agriculture in North America are the large-scale hybrid poplar fiber and energy farms established in the past 20 years, primarily by the forest products industry and government agencies. Increasing the productivity of plantation forests could have many benefits, including providing an alternative crop for farmers and sparing native forests from overharvesting. In this chapter, we