Hmmm. link no worky. But no matter. The first thing you should know is that since you are planting an evergreen bareroot so late in the season, you will probably experience winter burn on all the trees. Don't worry too much. Even though they may look dead come spring, chances are that only the needles died, and the trees will leaf out again in Late May or June. I am curious though, where did you find bareroot stock this late in the season? I don't think our MN Ag department allows for that.

My vote is mulch yes (but not rock), fabric no. This will mean you need to put down a thicker layer to keep weeds out, but in the end, your trees will love you for it. The mulch will continue to break down and add to the soils' structure, tilth and health. All good things that your trees' roots can grow into. But what happens with fabric? Well, kinda the same thing, but separated from nature's good earth. Tree roots benefit from moisture retention, but benefit minimally from all the other good things happening in that separate layer of forming soil.

I always prefer shredded materials, as opposed to bark bits or nuggets. Shredded stuff weaves into itself and stays put. Nuggets float around, blow around and get picked up by your mower.

Rick

I second the recommendation for lots of good mulch, no plastic, rock, or fabric. You might want to call some local tree service companies and see if you can get a truckload or two (often possible for free).

I agree with the shredded stuff, no fabric. Be sure you keep them well watered until the ground freezes. I'm curious too as to where you found bareroot pines this late in the season. Yes you will very likely have lots of winter burn, unless we're lucky enough to finally get a good snow cover this winter. I'm assuming that if they're bare root pines they're probably not very large and a deep snow cover would give protection from winter burn.