>>1746309Basal area doesn't work like that.
So imagine you are looking at a cutaway of the stump of the tree, the basal area is the area in square feet per acre of that stump. This is a fast and dirty explanation but it works.
In the good ol days you would use pic related to determine when you needed to apply different silvicultural treatments to forests depending on what you wanted to do; also bear in mind that these stocking charts are different for each individual species. When you sample the stand and come up with the basal area you use this stocking chart, in combination with your growth projections, to predict what the basal area is going to be in the future.
This is most useful if you're growing trees to harvest, but the method can be used for general forest growth. If they have invasive species in the forest (which the PDF said was the primary reason for the operation) then the shelterwood would make perfect sense. If you're wanting to clear out the invasives its best to have a plan for what comes next after you take them out, because SOMETHING is going to fill the space. By selectively thinning out the overstory then you can allow more light to reach the forest floor and stimulate regeneration. Also a good thing to remember is that during a selective cutting they are selecting the best of the remaining trees to be the genetic material for the new growth. So the resulting saplings (in theory) will be healthier and have better form. This is one way that you can manipulate forest genetics to improve it over time without having to resort to clearcutting and planting genetically improved planting stock, granted that's way fucking faster and works better.
They could just leave it alone and let nature take it's course, but you would be dead before those trees were big and beautiful, also there's no guarantee that the resulting forest would be resilient or healthy.
