is there a general way to know how much nutrients are returned to the soil by decaying natural growth? I know carbon, but what else?

I think I googled nutrient content of weeds once upon a time and found some good info.....Teaweed for example had pretty much the same nutritional value as soybeans. Just keep in mind that there's a lot we probably don't know about native plants and this subject....one thing is pretty certain though in that they were all put here to serve a purpose

Yea, food plots have only been around since the late 80's, so the deer have been relying on native since the beginning of time, except in areas of ag.

I know some weeds mine nutrients from pretty deep in the soil. I have a spot next to a stand that has grapes, honey suckle, green briar, hedge privet, and dew berry briar all in one place.

I believe some varieties of thistle are deep miners