Normally I wouldn't make such a specific ID based just on pictures, but yours show enough to do so. I've been seeing a lot of these where I live (northern Alberta). I've also collected some and examined them closely, and ID'd them to species, so the spider is familiar to me.

I printed out your pictures and compared them with the specimens I have and they match. Most especially, the epigyne is visible in your 2nd picture, and I can see the characteristic scape and the bulge of one of the lateral sclerites to the side of it clearly enough to recognize it as a female Cyclosa conica (Araneidae). The shape of the abdomen, with the tubercle at the back, and the shape and placement of the spinnerets, and the coloring all match.

This is an orb web spider. It builds a small circular web a few feet off the ground, often near spruce trees. Through the center of the web it weaves a line of debris (the remains of prey, etc) and sits in the middle of that line where it blends in. It's hard to pick it out from the stuff around it! When disturbed the spider will often vibrate itself and its web vigorously. When it does this it becomes a standing blur in the middle of the web. Very fascinating to watch!

An interesting thing I'm noticing this early in the season is the line of debris in the web is often short or even non-existent. I'm finding many webs that only have some short silken stabilimentum where the line of dead prey would normally be. I believe the spider has to kill and eat a few bugs first before it can build up it's characteristic string of corpses it normally hides among. As the season progresses, I expect to see longer debris lines (the result of more meals by the spider).

Nice pictures.