Defining Seed Zones

Discrete Zones (two dimensions)

Seed zone boundaries may be delineated from experimental data that identify genetic variation or by analyzing the environmental factors that are most likely to act as selective forces creating genetic variation. Seed zones will vary by species and by geographic location within a region. Seed zone maps should be available locally.

Within the geographic seed zone boundary, elevation guides set limits on transferring seed higher and lower than that it was collected. The limits are determined based on the environmental adaptations. Follow the elevation guides provided locally. When seed is moved too high, seedlings may die during early cold spells to which they are not adapted.

<example of seed zone map>

Continuous Zones (three dimensions)

Continuous zones use regression models to calculate the elevation limits for seed transfer.

Seed transfer expert systems can substitute for the discrete seed zones. These systems incorporate both geographic and elevation guides.