Forests Ontario

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Genetics, Climate Change, and Your Forest

Posted: February 9, 2017

by Steve D’Eon, Forest Stewardship Council

Climate change is rapidly becoming a topic forest owners cannot ignore.  Genetics is a topic most foresters have spent their career trying to ignore.  Your forest is something you should never ignore.  So what do the three have to do with each other?

Diversifying the genetic basis in your forest can be a solution for the variability a changing climate is bringing.  But how to

Ontario seed zone map.

create genetic diversity?

First and simplest concept is to keep the tree species you have; your current native tree species diversity.  Never totally eradicate a native tree even if it currently isn’t something you want.  It might be the species that survives the next catastrophic event so keep a small population around just in case.

Add some new native species.  Look around your property and tally up all the tree species you have.  Then look down the sales list from your local reputable nursery (or a nursery slightly further afield) and see what native species they are selling that you don’t have growing.  Do a bit of research and see if you have suitable sites to try out a new species or two.  Especially try some species from further south.  Purchase a dozen or a hundred seedlings, plant them in micro sites where you think they will survive taking into account light levels, soils, and moisture regimes.  Monitor how they do over a few years.  If you get decent survival and growth then the new species might be a good bet for a larger planting program on your property.  In this way you can slowly and cautiously add native tree species to diversify your forest.

The more complicated concept is to diversify the gene pool of the species you have.  A suite of research in the past showed that local populations of trees were best adapted for local sites; a “local is best” approach.  Along this principle Ontario established tree seed zones where nuts and cones collected in a zone were deemed suitable for planting within that zone.  Tree seed collectors and the entire native tree seedling industry uses seed zones to identify locally adapted stock and where it is suitable for planting.

So what do seed zones have to do with climate change and your forest.  The best defense in the ‘we do not know for sure what the future will bring’ is to diversify.  Diversity equals a better chance that some part of your collection of trees and genes will be adapted to this changing but unknown future.

The Forest Gene Conservation Association recommends planting 50% with your local seed zone, 25% with one zone to the south, and 25% with two zones to the south for each species you are planting.  In this way you are safely betting local is good but also importing a gene pool that is more in tune with a southerly and slightly warmer climate, presumably closer to your future climate.  If you want to diversify a tree species you already have order and plant some of the one and two zone to the south stock.  To diversify even further, order your seedlings from two or more different nurseries and/or plant over several years.  This will add even more genetic diversity as the seedlings will most likely come from different seed lots (collections of tree seed) within the local and one zone to the south/two zones to the south formula.  Slowly but surely you will diversify the gene pool of the tree species in your forest.

The best bet in an unknown future is a hedged bet.  Hedge your bet by diversifying your forest through some simple and fairly inexpensive plantings.