From the paper, "Preserving Seed Diversity," possibly the best reasoning I've seen yet to preserve heirloom trees and vegetables by planting them wherever and whenever possible:
Heirloom seeds are incredibly important for the genetic diversity of agriculture. Commercially produced seeds of big agriculture, though high yielding and pest resistant, are genetically uniform and are helping to fuel what Cary Fowler, director of the Global Crop Diversity Trust calls a “mass extinction”. According to Fowler, In 1880 farmers in the United States were growing over 7,000 named varieties of apple and since 6,800 have gone extinct. This is not exclusive to apples, over 100,000 varieties of wheat exist today, but many are in danger of being lost “not in the same way you lose your car keys…losing it in the same way that we lost the dinosaurs,” simply because ease of industrial agriculture relies on uniformity. That uniformity can only be achieved by having genetically identical plants growing at the same height and ripening at the same time. Heirlooms have grown to be locally specific varieties, possessing resistance to the pests alongside which they evolved. The varied genetics often produce interesting colors and shapes as well as more intense flavors. Since heirloom varieties are not focused on easy mechanical harvesting or large fruit to stalk ratios, the plants themselves are larger and have larger leaves leading to an increase in photosynthesis and an increase in sugars produced for the fruit.
To real the entire article on the Food Security website (a clearinghouse of information and resources prepared by the students in Professor Kathleen Morrison's Spring 2012 course, "Food Security and Agriculture: Calumet" at the University of Chicago), follow this link:
http://foodsecurity.uchicago.edu/research/preserving-seed-diversity/
