Question
Hi there,

I'm dont know where you are, but where i am right now (north of toronto,
canada) we are having something called shinook winds.. Where normally -10
degree temperatures rise to the teen positives for a couple of days and melts
all the snow.. (i think close to 12 inches or more). Usually in a couple of days
the temps return to normal and the snow comes back.

My question is this: what effect does this have on the soil and the
vegetation? I imagine it wouldnt be so good for the trees to have the
surrounding earth absorb all this water then completely freeze again. What
about seeds? Do the get confused, sprout and then die?

Thanks for your time.  

Answer
Hi Lauren, Plants native to your area have evolved with those conditions. Introduced non-native plants may not survive those fluctuations but your natives should be fine.
Unusual warm spells and late freezes do sometimes kill seedlings, but many seed survive and the cycle continues.
Freezing and thawing is good for the soil.  It improves the texture and helps plants grow better.  
Mother Nature has set up a pretty cool system for specie survival.  It's worked for millions of years.  Jim