By Nelson Bennett
As the northern hemisphere experiences earlier, hotter, drier summers and heavier precipitation in the winters, due to global warming, natural selection should eventually result in trees naturally adapting to changing climatic conditions.
Tree varieties that thrive in warmer, drier southern parts of the province, or on lower slopes, are likely to gradually shift further north and further up mountain slopes.
Scientists and foresters in B.C. are already beginning to give them a gentle nudge through assisted migration – one of the topics this morning at the University of British Columbia’s ongoing three-day Commonwealth Forestry Conference.
Using a variety of scientific tools and experiments, like genomics and provenance trials, scientists have already been able to identify which tree varieties have naturally evolved certain traits, like cold hardiness, disease resistance and drought tolerance, in different geographic regions.
Climate data can be matched with tree phenotype data to identify which trees will be best suited to climate conditions in the coming decades. Genomics is an additional tool that helps scientists identify key genetic characteristics.
These tools are used to develop seed lots that foresters can use to replant trees in a given area that are the same species, but different varieties that have traits that make them more suitable to a climate that is changing rapidly.
Interior varieties of Douglas fir, for example, are more cold hardy than coastal varieties. And Sitka spruce from California grow longer and bigger than ones that grow in Alaska. They are the same species of tree, but are different varieties that have naturally adapted to their particular environments.
Scientists and foresters are already using these tools to identify which varieties might fare better in certain areas, and use them in what is called “assisted migration” using a climate-based seed transfer program.
To date, the climate based seed transfer program in B.C. has been optional, but will become mandatory next year, said Sally Aitken, a forestry scientist at UBC’s department of forest and conservation science.