Tree Improvement in a Changing Climate
by Brian T. Barber, MA, RPF

Tree improvement, which is the selection, breeding, testing, and production of trees with desirable traits, has a long and successful history in BC. Selection of coastal Douglas fir “plus trees” and superior provenance testing began in the 1960s. Today, there are breeding programs for ten commercial tree species that focus on improving growth, form, wood quality, and pest resistance. The best performing parents in these programs are established in 99 orchards that produce seed for specific seed planning zones and elevation ranges. 40% of these orchards are managed by the private sector, 30% by the BC Forest Service (BCFS), and the remainder through cooperative arrangements. In 2007, 44% of the 273 million trees sown in BC were derived from orchard seed and 6% were from identified superior provenances. This select seed had an average genetic worth of 14%, which represents the expected timber volume increase at rotation as compared with using untested wild seed. Select seed use is projected to increase to 75% of total provincial seed use by 2013, and the average genetic worth (measured in timber value) is forecast to reach 20% by 2020.

The expected benefits of using select seed include an increased long-term timber supply and improved forest health. Since trees planted on Crown land become the property of government, there are few incentives for licensees to invest in long-term tree improvement activities. As a consequence, breeding is conducted by geneticists working for the BCFS and select seed with a genetic worth of 5% or greater, if available, must be used when planting trees to establish a free growing stand. However, there are also shorter-term benefits to using select seed, including reduced time to achieve free growing and relief from harvest adjacency constraints (e.g. visual and hydrological green-up), reduced brushing and weeding costs, and improved nursery recoveries. 

Tree improvement, and other forest genetic resource management (GRM) activities, are coordinated by the Forest Genetics Council of BC (FGC), a multi-stakeholder body appointed by BC’s Chief Forester. The FGC advises the Chief Forester on policy matters, establishes goals and priorities, and allocates public funds from the BC Forest Investment Account to GRM activities.

Climate change was the primary driver identified by members of the GRM community of practice and stakeholders in a recently completed program review undertaken by the FGC. Climate change is also the impetus behind the Chief Forester’s Future Forest Ecosystem Initiative (FFEI). Public expectations for developing responses to climate change are increasing and governments are setting aggressive targets for reducing greenhouse gas emissions. The FGC and BCFS are now grappling with the challenge of incorporating climate change and carbon management into their goals, programs, and operations. GRM activities will play an important role in mitigating some of the potential impacts of climate change on BC’s forests.

In a rapidly warming climate, trees will eventually become maladapted to their environment resulting in reduced productivity and increased susceptibility to extreme weather events (e.g. storms & drought), fire, insects, and disease. Tree populations will have to adapt to these new conditions (through phenotypic plasticity or natural selection), migrate to more suitable areas, or perish. The rate of climate change expected to occur over the next century, however, exceeds the adaptive capacity of most long-lived tree species. As a consequence, one of the few proactive forest management responses to address climate change is to assist or facilitate the migration of species and seed sources through planting.
Researchers at UBC’s Centre for Forest Conservation Genetics, BCFS, and other institutions are developing climate models and tools to assist resource managers in developing adaptive strategies. One of these models produced the “flying biogeoclimatic zones” developed by Hamann and Wang (2006), which were featured in Richard Hebda’s November 2006 article in Canadian Silviculture magazine. Researchers are also using these models, vegetation inventory data, and information from provenance and progeny field tests to project changes in tree species ranges and to identify strategies to reduce losses and increase forest productivity under different climate scenarios (excluding losses due to fires, pests, and weather events, which are expected to increase in frequency).

Although there is some uncertainty about the rate and magnitude of warming and changes in precipitation patterns, especially at regional and landscape levels, these trends are becoming evident and can be improved upon over time. Further development of climate models, combined with applied knowledge of local geography, plant physiology and forest genetics, will assist foresters in selecting species and seed sources more resilient to a changing climate.

Implementing changes to species selection and seed transfer will have implications for a number of forest management and tree improvement policies and practices. These changes could be cumbersome and costly if not appropriately managed and coordinated. For example, public and private forest managers have made significant capital investments in breeding programs, seed orchards, and tree seed inventories. Changes will therefore need to be planned and incremental, yet quick enough to respond to rapid changes in climatic conditions.

The genetic worth (for growth) of select seed may still be realized by moving it into areas where the climate is projected to be similar to areas where it has already been tested. Orchard seed is also as genetically diverse as wild seed (if not more). As such, select seed should be as resilient to climate change as wild seed sources. Nonetheless, forest genetics research will need to place greater emphasis on selecting trees for multiple values, including resilience (i.e. adaptation and pest resistance), and conserving the genetic diversity of our native tree species. 

Climate change could also adversely affect the physiology and reproductive success of trees (e.g. reduced pollination), potentially requiring supplemental management in seed orchards and relocating existing seed orchards. Over time, advancements in genomics and biotechnology could also assist tree breeders and orchard managers in addressing some of these challenges.

Barriers and opportunities for implementing changes to species selection and seed transfer within the existing policy framework also need to be considered. For example, the Forest and Range Practices Act (FRPA) does not explicitly obligate persons to take climate change into account when preparing results and strategies. Forest managers will, nonetheless, need to adjust their strategies (including stocking standards) in response to new information and changes in the environment in order to achieve government’s timber objective of maintaining or enhancing an economically valuable timber supply and addressing long-term forest health.

Changes to seed transfer could be implemented through amendments to the Chief Forester’s Standards for Seed Use. These standards would need to be aligned with species selection guidelines, which reside within the non-legal realm of professional reliance. The potential complexity of climate-based seed transfer may not, however, be easily accommodated in a prescriptive set of seed use rules. Other issues associated with facilitate migration, such as potential increased short-term risks and liabilities, will need to be examined and addressed.

Assisted (or facilitated) migration represents a potential “quick win” for responding to climate change. Implementing this strategy will be challenging, but not insurmountable. The FGC recently struck a committee to oversee the planning and process associated with implementing climate-based seed transfer. This process will involve the assessment of current scientific information and models through policy, operational, and information-management lenses. This project will also be integrated with other BCFS climate-change initiatives, including updates to species-selection guidelines, through the auspices of FFEI. Further information and updates regarding this work will be reported to forest managers and stakeholders in the coming months.

For more information on GRM and climate change activities in BC, please visit the following websites: 
• Tree Improvement Branch, BCFS www.for.gov.bc.ca/hti
• Forest Genetics Section, Research Branch, BCFS 
www.for.gov.bc.ca/hre/forgen
• Adapting to Climate Change, BCFS 
www.for.gov.bc.ca/mof/Climate_Change
• Forest Genetics Council of BC www.fgcouncil.bc.ca
• UBC Centre for Forest Conservation Genetics 
www.genetics.forestry.ubc.ca/cfcg

Brian T. Barber, MA, RPF, is the Assistant Director, Tree Improvement Branch, BC Forest Service and Co-Chair of the Forest Genetics Council of BC. He can be reached at brian.barber@gov.bc.ca.