A natural area restoration can not be truly natural unless it uses plants with a genetic makeup (genotype) similar to those that were in that area originally.
This is an excerpt from the Wild Ones Journal
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Of course, this applies to the animals, fungi, bacteria, etc. as well, but it depends on the plants in many ways. All of these organisms are adapted to local conditions and to each other, i.e., they work together as a functioning community. Although it is seldom put into words, we want the animals, the insects and birds, to return to the restoration site. For this to occur, the plants must fulfill their role in the web of life and match the needs of the life forms reliant on them. The scattered science available simply has not been made readily available to the conservationists who could use it.
A genetic perspective
It is well known that different ecotypes (genetically distinct varieties or populations with different genotypes/DNA) often occur within a species (Magurran and May, 1999). Much of this difference is due to local adaptations; however, geographic isolation or habitat separation often create and support these differences.
If needed, it should be possible to use genetic markers to identify and verify local genotypes just as DNA tests can be used to verify human parentage.
Local adaptations
Not only are local plants better adapted physiologically to the local climate and seasonal weather patterns, but they will contain the same structural/physical adaptations and the same spectrum of secondary compounds (organic molecules not involved in the primary functions supporting life) that existed in the original vegetation in that area. These secondary compounds are often involved in the interactions of these plants with animals, microbes and even other plants. The animals that lived in (and often still are scattered around) this area are adapted to these sets of secondary compounds. In other words, the members of a biological community are also adapted to each other. If we recreate the right vegetative community, it will be easier for the animals to return to complete the broader community that we want ultimately to achieve i.e., the local plant hosts will be more hospitable to the animals if they are reintroduced.
Regarding the secondary compounds
Readers of the Wild Ones Journal have already had an introduction to secondary compounds (Whitman, 2011). Secondary compounds mediate plant-animal interactions in many ways, e.g., as feeding cues (deterrents and promoters), as floral scents and pigments and more. They also govern the interactions of plants with microbes, and even other plants. (Harborne 1972, 1993; Iason et al., 2012) Secondary compounds can change over fairly short geographic distances, and these differences in the types and/or amounts of secondary compounds could greatly influence the use of those plants by animals. Many secondary compounds, e.g.., morphine and atropine, are familiar to us as a result of their medicinal uses. In nature, they serve other functions. For example, insects might be attracted to feed on certain plants, or induced to choose certain flowers as nectar sources by one set of secondary compounds, and not attracted or even driven away by another set. The total picture gets very complex very quickly both in terms of the chemical structure and diversity (estimated 200,000-1,000,000) of the secondary compounds out there in our biological communities.
What constitutes local genotype?
When collecting seeds, how far can we stray from the site being restored? This is a discussion in progress; however, foresters have long recommended collecting seeds within 100 miles. This question might better be viewed in terms of ecoregions. Consider for example, the Level III Ecoregions of the Continental United States. SE Michigan contains 3 ecoregions (#s 55-57), and they may cross political boundaries, i.e., state lines. Also, note that many ecoregions extend quite far north and south. It can be argued that getting restoration material from nearby parts of the same ecoregion (or maybe even similar nearby ecoregions) would qualify as local, but material from distant ecoregions (which many restorers use) would not. Distant ecoregions are different environments with different environmental/population histories. Likewise, plants from distant parts (e.g. north-south extremes) of the same ecoregion might also be too different. For restoration of very high value natural areas, many public and private agencies (e.g., The Nature Conservancy) collect seeds/propagules on site, and that seems ideal.
About the diversity of the seeds/propagules used in restorations
It is important to collect from several plants and several locations in order to increase the genetic diversity of the plants produced. This diversity is important not just for long term adaptability but also to enable the plants to establish themselves in the diverse microhabitats on any site. Maintaining genetic diversity also enables a population to adapt to weather/climate fluctuations.
About rare plants
I have to add that it is especially important not to bring in very rare plants from distant sources to locations near residual local plants. An example would be sideoats grama grass (Bouteloua curtipendula), which is common in the Great Plains but rare in Michigan and visibly different from members of the same species further west. Importing large numbers of these plants from the west could overwhelm/absorb the local Michigan genotype, especially if they are planted near remnant local plants.
Local suppliers
The number and capacity of reputable producers of local plants and seeds is increasing, and they offer competitive prices. Suppliers can be found by searching the Internet, for example, see: Michigan Native Plant Producers Association. The Michigan Native Plant Producers Association represents 12 independently-owned nurseries located throughout the state of Michigan.
Native gardens around urban homes and parks?
It is likely that most Wild Ones members would agree that native plants in natural communities offer some significant advantages over nonnative plants and formalized plantings; however, there are some special considerations that need more attention. In urban yards and parks, it may be argued that it is less important to use only local genotypes, unless of course the planting is contiguous to a valuable natural area, or they threaten species that are very rare locally. Nonetheless, local genotypes are best.
Conclusion
I am hopeful that the issues raised above will promote more consideration of local genotypes in community restoration and species conservation. We do not know all that results from mismatches in the very complex web of life in natural communities; however, it seems logical that local genotypes will fit in best.
By Larry Noodén