Evaluating realized genetic gains from tree improvement.

Abstract

Tree improvement has become an essential part of the management of forest lands for wood production, and predicting yields and realized gains from forests planted with genetically-improved trees will become increasingly important. This paper discusses concepts of tree improvement and genetic gain important to growth and yield modeling, and reviews previous studies of the growth and yield of genetically improved stands. Three types of studies that have been done include: (1) simulations in which assumptions have been made about key inputs into the models, (2) studies of genetic variation in stand productivity at the level of seed sources or families, and (3) actual comparisons of improved versus unimproved stands. Simulation studies indicated that genetic gains are highly likely, but how much gain is realized will depend on height-age trajectories after crown closure. Studies of genetic variation in stand productivity are ambiguous with respect to genetic variation in parameters of the height-age curve. Few studies have been published of actual comparisons of improved versus unimproved stands, although many such studies have recently been established. The design of a study to evaluate realized genetic gains from Douglas-fir tree improvement programs is presented.

Citation

St. Clair, J.B. 1993. Evaluating realized genetic gains from tree improvement. In: Proceedings: IUFRO S4.01 Conference. Blacksburg, VA. Publication FWS-1-93 of the College of Forestry, Virginia Polytechnic Institute: 145-157