Spring Temperature Fluctuations

Do you remember how excited you were when we had those few days of really warm weather over the march break?  We all felt that spring was coming super early this year and we were going to skip that phase of the spring where it's too warm to ski but too cold to spend time in the back yard.  I will admit to secretly thinking that global warming isn't such a bad thing after all.

Also at that time all over the media, experts were speculating on what repeated ultra early springs could mean for our region.  We could see more insects, more forest fires even more cases skin cancer et cetera.  When it comes to trees, I was thinking about how the spring can be so climatically volatile and an early spring can easily mean severe damage to tender new leaves.

What has been happening over the past week and likely will continue for a few more days is that warm daytime temperatures are helping the trees to expand their leaves.  At night however, we've been experiencing some cold night time temperatures that are freezing the new tissue and causing damage.

Trees will build new leaves late in the summer and keep them in tight buds that are held on the tree over the winter.  In the spring, after the soil and roots thaw, trees send water up to the buds where the pre formed leaves are filled and expanded.  During this process you can tap into that flow on sugar maple trees and make maple syrup.  Usually bud break coincides with the last of the really cold nights where temperatures rarely go below zero and if they do it's only by a couple degrees.

Right now, because of the ultra spring boost, trees are working about two weeks ahead of the weather.  Leaves are out of the buds on many species and filling with water.  The freezing temperatures are turning the water in the leaves and twigs to ice and that expansion is causing plant cells to rupture and burst. 

The net effect of this spring will take a few weeks to reveal itself.  Many tree species will fare just fine but many others, particularly those whose range barely extends this far north, will experience some difficulties.  These problems can range from light leaf scorching to wholesale leaf loss and branch death.

Two springs ago across the Prairies, green ash trees experienced very acute decline from this very phenomenon.

Should these fluctuations in spring weather remain a trend caused by global warming, we will certainly have some challenges to deal with down the road.