Forest Genetics Team

Integration of genetics and silviculture

Further development of options for increasing the quantity and quality of wood production while considering other values requires a greater understanding of the integration of genetics and silviculture.

Projects:

Genotype x silvicultural treatment interactions
Incorporating genetic effects into growth models

3.1 Genotype x silvicultural treatment interactions

The research activities of the Forest Genetics Team in the area of genotype x silviculture interactions will focus primarily on continuing research on the interaction of families with different levels of shade (Table 1). We have initiated nursery studies to look at the response of ponderosa pine and hemlock seedlings to different levels of shade using shade cloth, and these studies will be completed. In cooperation with the PNW West-Side Silviculture Team, we have also initiated a long-term field study on the Capitol Forest near Olympia to consider the response of planted Douglas-fir, western hemlock, and western red cedar to a range of different levels of overstory densities. This study has a genetic component that considers the differential response of Douglas-fir families. In addition to the shade studies, we will be working with Dick Miller, formerly of the Silviculture Team, to complete a well-designed study of the response of Douglas-fir families to fertilization at age 14.

Team Principal Investigators: Brad St.Clair and Randy Johnson

Collaborators: Frank Sorensen (retired PNW Genetics Team); Duane Ecker (Ochoco NF); Charlie Cartwright (BC Ministry of Forests); Jeff DeBell (Washington DNR); Leslie Brodie, David Marshall, Bob Curtis and Dean DeBell (PNW West-Side Silviculture Team).

Benefits: Knowledge of family x silviculture interactions, including interactions with shade and with fertilizer, will allow managers to determine the value of testing families from tree improvement programs under different silvicultural regimes for selection and deployment to different regimes.

3.2 Incorporating genetic effects into growth models

Research that provides knowledge of how to incorporate genetic effects into growth models involves exploring the response to silvicultural treatments at the level of the population, in this case, the improved population of selected families. Most genetic trials involve individual tree plots and are not designed to explore per-unit-area yields of a group of selected families in a large plot. Realized gain trials using large block-plots look at levels of genetic gains actually achieved from tree improvement activities, as compared to expected genetic gains based on individual tree performance in progeny tests of all families, not just the selected families. Few improved versus unimproved block-plot realized genetic gain trials have been established throughout the world. The Forest Genetics Team has been working with the Northwest Tree Improvement Cooperative to establish such trials to be used to adjust existing growth models to take into account the effects of genetic improvement (Table 1) (St.Clair 1993). We are also working with the Stand Management Cooperative to establish trials that consider the interactions of improved and unimproved populations with different silvicultural treatments. And we have established a study to look at the effects of intergenotypic competition by looking at the stand response to deploying families in pure blocks versus in mixtures. These are long-term studies; in the meantime, we will be working with the growth and yield modelers to explore the effects on the outcomes from existing growth models using different assumptions of the growth trajectories given what we know from progeny tests.

Team Principal Investigators: Brad St.Clair and Randy Johnson

Collaborators: Keith Jayawickrama (OSU), Greg Johnson (Willamette Industries) and other members of the Northwest Tree Improvement Cooperative; David Marshall (PNW Olympia Silviculture Team); David Briggs (University of Washington and the Stand Management Cooperative)

Benefits: Knowledge of how genetically improved populations grow given a different silvicultural options allow managers to evaluate the value of and tradeoffs among different management options.

US Forest Service - Pacific Northwest Research Station
Last Modified:  Wednesday, 12 January 2011 at 01:31:01 EST