Survival rate will be higher with plug seedlings because the roots are left more intact at planting. But they usually cost a little more and they're harder to plant. The prices at the Itasca site are good, if the source wasn't so far from Tennessee I'd buy some from there next winter. There is a plug dibble bar available but I haven't tried one. They cost roughly twice as much as a standard KBC or OST dibble. They look like they might be difficult to use if the ground isn't really moist. It takes somewhere in the neighborhood of 250-600 trees to re-forest 1 acre, depending on the tree density/spacing you desire & if you are planting in a "grid" or randomly. If money is a major object bareroot state nursery seedlings will almost always be the most inexpensive option just behind direct seeding.
One thing worth mentioning is that most land will eventually turn back into woodland if you leave it alone and keep livestock off it. (Some notable exceptions are certain prairie areas, desert, and some swampland) The point of planting trees is to shave time off the process and improve timber stand diversity. If you don't "jumpstart" the process by tree planting natural progression will pick what grows first, plus there might be erosion problems.
In my area if you let an old field go it will grow up in grass, weeds, maybe briars, and a handful of scattered volunteer seedlings the first year. The volunteers will be whatever is "planted" or excreted by birds/animals/wind. Usually the first tree to show up here is eastern red cedars. It depends on what trees are in nearby forests, but black walnut, sassafras, viburnum, and black cherry are some others that will show up quickly on their own. After 8-10 years the volunteers will be large enough and numerous enough to start choking out the grass/weeds and become a thicketed immature forest. It keeps going from that point on as some of the small quick growing trees get shaded out by larger ones, and some understory trees start to establish themselves. The climax trees will start filling in the canopy and with 20 years you will start to have a real forest. By planting you can shave time off this beginning period, start the natural organic material breakdown process in the soil faster, and decide to some degree what type of timber you want in the stand. There really isn't much old growth forest left in the US, just about everything has been logged recently enough that a true natural ecosystem hasn't been able to fully establish itself. That's changing though ... over the last decade or so alot more trees have been planted than have been harvested.
