On a small level, there are many folks that simply do not know what food looks like outside of the grocery store. Even something as basic as an apple, they will worry that it's not edible, or actually poisonous, or "dirty" if it grows outside, etc. Folks may have no idea that hazelnuts are edible and how to collect and use them. Similar to how acorns are viewed now. I think education and hands-on experience needs to be a vital piece of preservation. Get people interested and involved. Share the product, but also where it comes from. Teach children. Hold open house/yard/gardens. Give plants away, etc. Plant the seed and some few will fall in love with the learning and become stewards themselves. Or maybe I'm just an idealist ;)
I've got my son in law eager to turn his backyard into productive space, and my nephew joins me in my urban lot to start seeds, do a "taste-test" tour regularly, and help with the work. He's got his mom getting them a small community garden plot, where he'll have the chance to see and meet other gardeners too, from different walks of life as well. We've gotta raise and teach others to see the value and know HOW to use it and reap the benefits, as much as preserving the land and forests.