Badgersett Research Farm has some interesting commentary on chestnuts and hazlenuts, specifically their hybrid varieties that bear heavily beginning at 2 years and respond well to coppicing. While this is interesting on its own, several features of the chestnut/hazlenut arboriculture potentially mesh very well with what I've previously written on Creating Resiliency & Stability in Horticulture and on Tuscan Hilltowns and Hamlet Topology.
To start with, chestnuts have been a traditional staple crop of much of Italy (Tuscany and Sicily still harvest significant quantities) where they have been successful partners with localized human culture for several millenia. Second, the hybrid species of chestnut and hazlenut in development by Badgersett bear heavily, early, and very consistently year on year--even in drought--as tall shrubs (~12') rathern than towering trees while simulaneously producing excellent quality and quantity of coppiced fuel wood. Finally, the two nuts complement each other quite nicely from a nutritional and practical stanpoint:
Hazlenut is very high in fat, about 70%, and produces a very high-quality, light oil for use in cooking, as fuel, etc. And its excellent flavor and versatility in cooking make it a welcome part of any horticulture scheme.
Chestnut is almost the exact opposite of the Hazlenut, with about 1% fat and primarily carbohydrate (78%). While it spoils quickly when fresh, it can be dried out to last for years, and makes a gluten-free flour that is a common part of vernacular Italian cooking. The lack of gluten (unlike all cereal flours) means that it has the same health advantages touted by the paleo-diet concept, but without the gluten it is best in unleavened breads, cakes, muffins, pastries, etc. Because the dried nuts can be stored for years, the surplus from one harvest can be stored and made into flour to compensate for any future shortfalls in horticulture-system productivity.
Both hybrid species of the Chestnut and Hazlenut appear to work well in Zone 4 (having survived winters to -40F), so this pairing may be a viable alternative in most temperate zones. Dryfarming these species seems to work best with 30"+ of annual rainfall, but this can likely be extended into drought-prone regions by use of mulch basins, rain-collection basins, swales, or a variety of other techniques.
Add a permanent green-manure/forage cover-crop and a flock of chickens to the pairing of chestnut and hazlenut and a very small area (1/2 acre) could likely meet the nutritional and fuel-wood needs of four people, consistently and sustainably, and with very minimal labor input--in fact, I think that such a system could rival the low labor requirements of even the most favorable hunter/gatherer systems... even if this is a stretch, it seems like a very good component of a more diverse horticultural system.