Protocols Used to Select Plant Taxa for the Restoration Collection Target List:
The following is an account of how the 544 species compiling the Dixon National
Tallgrass Prairie Seed Bank’s (DNTPSB) Restoration Collection target list were selected.
Using the NatureServe database, a comprehensive list was created of species from 12
ecoregions (Omernik level II) best representing the core of the tallgrass prairie region.
All non-native species, known recalcitrant species, non-vascular species, and cultivars
were removed in attempt to develop a list of species in the region that exhibit orthodox
seed storage behavior and would be good candidates for seed banking. This list of native
species totaled well over 3000 species. Although collection of all orthodox species in the
tallgrass prairie is ideal, a system was devised to select a much smaller group of species
considered important for habitat restoration in the tallgrass prairie region, as a realistic
short-term goal for the seed bank.
Using the ranking system (described below), a core group of 543 species were selected.
One species was added to the list upon request from a seed collector for a total of 544.
Requests for adding species to this target list are encouraged as seed collectors seek ways
to preserve important native plant germplasm in their areas. Some species may be listed
as threatened or endangered in specific areas of the region and should not be collected in
those areas.
Protocols for Selecting and Ranking Species Important for Habitat Restoration
General criteria used to select species important for habitat restoration:
A. Review the literature (floras, vegetation surveys, etc.) for information indicating
the importance of a plant species to common habitats (prairie, woodland, savanna,
marsh, etc.) found in selected ecoregions of the tallgrass prairie region.
B. Review geographic range maps to confirm the primary distribution of a species
occuring within the tallgrass prairie region.
C. Consider other information on a species ease of establishment or overall
performance in habitat restoration projects.
The species selected are ranked with a number 1, 2, or 3 according to the following
criteria:
1. A conservative species that is, according to the literature, considered important to
the most common communities (prairie, savanna, marsh) in the ecoregion.
“Important” can be defined as dominant in, or characteristic of, a community.
2. A conservative species that is, according to the literature, less important (not as
dominant) to a common community (prairie, savanna, marsh), or are less
conservative species but are often used in seed mixes for habitat restoration.
3. A less conservative species that is, according to the literature, considered
important to a common community (prairie, savanna, marsh), or maybe used in
seed mixes for habitat restoration.
Note: Attempts were made to be as objective as possible when designating ranks. Less
objectivity was involved in designating 3’s than for 1’s and 2’s because this designation
represented a “catchall” when a species degree of conservatism, importance in the
community, and/or regional use in habitat restoration came into question. In the literature,
phrases describing habitat with general terms as such as “wet places” were ranked lower
than when a specific term such “prairie swale” or “rocky woods” was used. Also, 3’s
were sometimes given to species known to be conservative in other ecoregions, but
information other than geographic range data was absent. In these instances, since a high
degree of conservatism is assumed, but not confirmed, 1 or 2 designations cannot be
given. The numerical rankings can be changed as more information on a species’
importance in native habitats or habitat restoration is realized.
Selecting the Restoration Target List Based on Data from the Ranking System
Initially, a list of only the top 100 important habitat restoration species in the tallgrass
prairie region was going to represent DNTPSB’s Restoration Collection target list.
However, based on numerical rankings given to select species, 171 species were selected
for this list using the following criteria:
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Include all species designated 1 in at least 5 ecoregions.
Include all species designated 2 in at least 5 ecoregions.
Include all species with at least one designation of 1 and four other number
designations in at least 5 ecoregions.
After reviewing the remaining species not making the list, it was determined the criteria
we used failed to include some important species for restoration, especially those
considered important early successional species. Therefore we revised the criteria to
include all species with at least one number 2 designation, making a total of 543 species.
These species were given a lower collecting status than the top 171 species, however.
Given the inherent subjectivity of selecting species for this list, and the fact that one
person created the list with little on-the-ground knowledge of many areas within this vast
region, this list is not intended to be a definitive record of species important for habitat
restoration across the tallgrass prairie region. We expect the list to change as people who
are familiar with native habitats and floras in their region weigh in on what species
should be preserved in the seed bank context.