Isolation refers to the spacing between fields of plants from different genetic origin. The isolation distance for grasses is 165 feet and forbs is 1320 feet. For self-pollinating species no distance is specified. The minimum rotation time period is three years. This means that three years must pass before a different seed source of the same species can be planted on the same field.
Certification is a means of providing information to customers.
Certification is akin to labeling processed food. As such, certification itself does nothing to conserve native plants. It is a tool for informed consumers. It is then up to the customer to decide if the seed source identified on the label meets their needs. Much discussion among restorationists centers around the use of local populations.