Newbie wants advice on nitrogen fixer

Hello all! My name is Jessica and I live in Qc, Can. I made a plan of my next little project: tiny orchard. You can look at my plan and leave comments, but what I am really looking for is help to find the best nitrogen fixers for my project. The chosen one (ones) should be about the same size than my fruit trees (all of them would be on small to semi-standard size rootstock, between 2.5 and 3.5 meters tall) and offer the possibility to be pruned into a good support-tree for grapes or kiwis to climb onto. Of course, attractive blossoms to beneficial insects and edibility would be bonuses. So... any experience with the followings? Any tips, advice, etc...? Note: a lot of plants (legumes, flowers and herbs) would be planted too, but I didn't draw them because I want to be able to focus on the trees. Thank you!

I recall someone on here making an excellent point about nitrogen fixers here on permies a while back.  They pointed out that EVERY tree can be a nitrogen fixer, if you allow beans to use the trunk and branches as a trellis.  I thought that was an excellent 'outside the box' suggestion.  

For a bush, look into Seaberry trees.  I believe they do well in the north.  What zone is Quebec?  4?  I am not familiar with that end of the spectrum.  Don't forget Black Locust trees and cut/pollard/trim them to the size you want; and let them copice.  

Hi Jessica,

I am from Québec too.  We are in the Beauce region zone 3b/4a.  Where are you located and what zone are you in?

We are currently planting over 100 sea buckthorn (seaberry) as a hedgerow and small orchard . They are great nitogen fixers for our cold climate.  

We also have planted apple trees, cherry trees, kiwi, haskap, gooseberries, grapes, blueberrys, raspberries etc... More to come....

@Jack - Since Québec is very large and some regions are mountainous, the zones are from zone 5 in the southwest to zone 2 way up north.

@Jessica - Maybe we can be friends on Facebook.  maybe echange some cuttings, plants & seeds.... https://www.facebook.com/michelle.bisson.37