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Understanding the Importance of Genetics

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There has been a growing awareness recently of the importance of plant genetics in restoration projects. Genetic variation within plant species can influence their long-term chances of survival and growth. Sometimes specialized ecotypes within a species develop that are adapted to specific local environmental conditions. An ecotype is a certain population of plants within a species that, due to different genetics, has a different form (height, leaf size, etc.), flowering time, or hardiness that is adapted to certain environmental conditions. Plant ecotypes are not different species because they can still interbreed. Taking plant species that are of one ecotype and moving them to an area with environmental conditions different than the ones that the plant is adapted to, such as different freezing stresses or different moisture levels, can result in poor growth or death.

These types of genetic concerns have been recognized for quite a while in the forestry industry. Tree seed zones have been developed for specific tree species based on an understanding of their genetic variation across the landscape. Seeds are only planted in the same tree seed zone they were collected from, in order to increase the plants’ chances of survival and adaptability. However, it is only recently that some scientists have begun to examine the genetic variation of herbaceous or shrub species across the landscape. Consequently there is very little information available yet about what might be the appropriate distance to relocate native plant species.

In addition to concerns about the ability of the planted species in restoration projects to survive and adapt, some people are concerned that the introduction of new genetic material in an area can damage local populations of native species. The thought is that new genetic material could result in the weakening of local populations’ ability to survive and adapt to environmental pressures. This particular concern is still being debated. However it is clear that without a better understanding of the genetic variation of the species, it is a safer option to avoid as much as possible introducing non-adapted genetic material that may have unanticipated detrimental effects.

Depending on the genetics, there may be very different strategies for the appropriate places to collect propagation material for specific species. A general rule to follow is, if information is not available on the plant species’ genetic variation, try to use local genetic sources for plant material whenever possible. There is no universal agreement as yet on the exact guidelines for “local” sources, however some factors to consider include whether the plant sources’ genetic origin:

is in the same watershed
is in the same ecoregion
has similar soil type
has similar elevation
has similar slope
has similar aspect
has similar rainfall
has similar temperature patterns
has similar frost dates
has similar associated vegetation

Because this is a fairly new concern in the restoration field it may be difficult to get plants that are from as local a genetic source as you would like. However, a broad guideline to follow is to ensure that they are at least from the same ecoregion. There are a few different ecoregion classifications of the United States that have been developed. One popular classification is Bailey’s ecoregions, a product of a cooperative effort of a number of different federal resource agencies and The Nature Conservancy. These regions are areas that have been defined as having similar natural communities, geology, and climate.

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