Definitions

An experiment that evaluates genetic differences by growing plants from different seed sources in common environments. A common garden test can be used to infer genetic differences in many different areas of study (both animals and plants), but is most commonly used with small plants and occasionally trees.

Plants that are native to a restricted area. Endemic plants often possess unique adaptations to the area where they occur.

The relative imperilment of species on a global level as determined by NatureServe.

• G1 – Critically imperiled. At high risk of extinction because of extreme rarity.
• G2 – Imperiled. At high risk of extinction because of very restricted range.
• G3 – Vulnerable. At moderate risk of extinction.
• G4 – Apparently secure. Uncommon, but not rare.
• G5 – Secure. Widespread, common and abundant.
• **Clarification needed: would we apply seed zones for plants in G3?

A geographic area defined based on average annual minimum winter temperatures, developed by the USDA Agricultural Research Service to guide movement of perennials based on cold-tolerance. (http://planthardiness.ars.usda.gov/PHZMWeb/). Each zone extends across the country and spans a range of 5° F. These zones do not represent the absolute lowest temperatures that may be reached. Neither do these zones represent the growing season length which is also biologically important, but the two traits are often correlated. The hardiness zones are updated periodically as new weather data become available. These zones have been used to guide the transfer of landscape plants for more than 50 years. They are the basis of some provisional seed zones.

The defined origin of a tree or a group of trees, similar to a seed zone. Typically, provenances are only vaguely delineated and are separated from each other by some distance, while two seed zones may lie right next to each other and share a common border.

A common garden test that compares trees or plants collected from different provenances. Typically provenance tests compare widely separated seed sources. These tests are often designed to study genetic variation across large distances, sometimes the entire range of a species. They are not specifically designed to develop seed movement guidelines, but they are sometimes used to inform their delineation.

A common garden test that is specifically designed to develop seed movement guidelines. These tests generally include closely spaced seed sources from a restricted portion of a species range.

Instructions on how to match seed source to the planting site. Guidelines can be formulated in different ways. They can consist of a seed transfer zone within which seed can be moved at will. They can consist of a distance seed can be moved (e.g. 1° north or south, or 1000’ in elevation up or down). They can consist of a complex formula or computer program that calculates guidelines for specific sites or specific seedlots. Ideally seed transfer guidelines are based on biological data, but they are often based on anecdotal evidence or educated guesses.

In the context of this project, a seed zone refers to a well-delineated contiguous piece of land that represents the origin of the seed. A seed zone may be considered the smallest unit of area for defining locality for plants. When collections are being made in natural populations, this is sometimes referred to as a seed collection zone or a donor zone.

Seed collection zones differ from the planting zones or the deployment zones, the latter two which imply where the seed should be planted. In the past, most foresters have assumed that local sources of native seed were best, implying that seed collection zones and the planting zones were usually congruent. When this is the case, seed zone may refer to both the collection area and the deployment area. This is sometimes referred to as a seed transfer zone. In that case, the assumption is that seed can be transferred throughout the zone. There are situations when local sources of seed may not be best. This could happen when a species recently migrated into the area or when there have been significant amounts of climate change. In that case the seed collection zone could differ from the planting zone.

A particular area broadly delineated by its environment, particularly in terms that affect the type of vegetation that will grow well there. If the species selected for planting on a site is not suited to that site it will perform poorly regardless of the source of seed.