Ecotypes: Considerations in Restoration

How important is it to use plants from local sources when working to restore damaged or compromised ecosystems? How is “local” defined? These were two of the questions that were explored in the afternoon session of the Economics and Ecotypes workshop put on by the Association of Florida Native Nurseries (AFNN) in Kissimmee last month.

The University of Florida sent down a fleet of professors from their Consortium for Horticultural Application in Ecosystem Conservation. These passionate folks had some very interesting research to share as the crowd wrestled with both the ethical and the practical problems that restoration can pose. The Consortium works to provide science-based information to meet the needs of the native plant industry called in to supply the plants for restoration work.

Dr. Carrie Reinhardt Adams lead off with an explanation of ecotypes. She noted that  there can be distinct and separate genetic composition within a plant species resulting from adaptation to local environmental conditions. Within each species then, some plants can be better adapted for certain conditions. Individuals are capable of interbreeding with other ecotypes within the species.

Questions arise when plants begin to be moved around by people; although certainly there are valid reasons for doing so. Substitutions of ecotypes can sometimes lead to genetic pollution. One way this type of pollution can happen is by replacement of local genotypes with less fit genotypes, leading to a decrease in genetic diversity.  Lower genetic diversity, which makes plants more susceptible to disease, arises when plant material originates from just a few genotypes. One importance of diversity is that  it provides the mechanism for evolution.

Pickerelweed in bloom

 Pickerelweed, Pontederia cordata is a wetland plant widely distributed up and down  the east coast and many of its  original habitats are now disturbed. It is also widely used in restoration work. The Consortium conducted an experiment using eight different ecotypes of pickerelweed, five from Rhode Island, Pennsylvania, and North Carolina, and  and three from Florida. The plants were grown out under exactly the same conditions in a greenhouse. Over the course of plantings that occurred during 13 different times of year, it was found that the southern plants grew in a much more upright form. Northern plants grew in more lateral form, no matter what the season, perhaps in an attempt to avoid freezing. The variation of the plant’s response suggested distinct ecotypes, and illustrated the complications of introducing plants not properly suited for local conditions.

Note corm on grass pink

Philip Kauth noted that identifying ecotypes is important for both conservation and commercial purposes. He chose the orchid for some of his research partly because “it is the polar bear of the plant species.” He told us about experiments he had conducted in growing the orchid Calopogon tuberosus. The Calopogon, commonly called ‘grass pink’ because its leaf looks like grass, is native from Florida to Newfoundland, but its home lands are under duress everywhere. It's an indicator species, meaning its sensitivity to the environment can cause it to act as an early warning signal of changes like the presence of disease, species competition, or differences in climate. It grows in full or partial sunlight and one of its characteristic features is the formation of a corm, a swollen underground stem which stores energy to help it survive winter or drought.

Kauth’s experiment centered around the question “Does growing season matter?” In Michigan, where the orchid is growing in a compressed season, Calopogon puts a lot of its early growth into the corm. In Florida, where the growing season for the orchid is 365 days a year, its corm is very small, more biomass is allocated to the leaf and the shoot.


Kauth put Calopogons from Michigan, South Carolina, North Florida and Central Florida into petri dishes in the greenhouse and grew them out under exactly the same conditions. What he found was that the orchids from the north, even in petri dishes, sent their biomass to the corm very early. Plants from SC in the dishes all the way to week 20 had very low biomass in the corm; they were growing more shoots, roots and leaves instead. The Michigan orchids at week 20 were almost almost all corm with very little growing shoot. The questions he next wants to answer is “Can the plants adapt to different ranges? What differences will be caused by new temperatures, seasons, and dormancy conditions?”  Good questions.

Wiregrass on the Wade Tract Preserve

Hector Perez’ research was on Aristida stricta, the native bunchgrass so vital to the ecology of our beloved and vastly diminished longleaf and slash pine savannahs. Aristida is native to coastal plains up into North Carolina, and is known to have several ecotypes. Data indicate that while individuals within each population are genetically diverse, there seemingly are barriers to gene flow across populations leading to their divergence. He showed us a map displaying two distinct ecotype populations that occurred in areas from a four-state region that included NC, SC, Georgia and Florida. The two populations were in clusters that grew near one another within all four states. Meaning that one type might have a closer match in another state than from right around the corner. Details of this particular research can be found at:

http://www.springerlink.com/content/n1g765444360w202/

The results of his work, along with previous studies that presented evidence for local adaptation and phenotypic differences among populations, suggest that there is sufficient differentiation among populations of this species to warrant: (1) maintenance of the existing genetic diversity at individual sites, and (2) use of local seed and plant sources for conservation projects. But, he added, decisions about how material should be selected and moved are still in the formative stages.

Sea-oats prevent erosion on beachfront

Michael Kane gave us the last example of ecotype variation using sea-oats, Uniola paniculata.
Dune restoration, providing the first line of defense against storms, is a popular project these days, but the geographic source and genetic diversity of these plants present a real dilemma of choices.  It turns out that there is a big difference between the ecotypes that grow on the east and west coasts of Florida, with no genetic crossover between the two sides. Along the east coast, where gene flow is fairly continuous, sea-oats are virtually the same ecotype. But along the west coast, significant variety is found. The west coast types were generally taller, with more leaves and different root structures. On one evaluation plot, after a three-year trial the west coast types exhibited a higher rate of survival. Dr. Kane noted that problems with seed availability, lack of consensus on a definition of the meaning of ‘local,’ and of course, cost, are among the present challenges to dune restoration. Perhaps even more significantly though, he stated that most dunes today are no longer “real” places or natural areas.

These fascinating presentations set the stage for break-out sessions on brainstorming solutions. The professors urged our group to help them understand the problems so they could focus research on helpful answers. The debate was loud and passionate; as you can imagine this room was full of people who care greatly about restoration and conservation. In fact, that might be one of the problems, see the post on Economics!

The time remaining was not nearly long enough, but some of the major problems were listed as;

• lack of flexibility on distance limitations for obtaining an ecotype match, as we have seen, geographic limitations may not be the defining paradigm

• lack of reliability on part of  some providers, in other words, honesty sometimes a problem

• verification of source location sometimes not possible, for instance when big lots of plants from different places were mixed together

• insufficient time to obtain or grow the required plants was a major problem

One grower told of being asked to provide plants for a restoration project that needed to be installed in 9 days. This was upped by a grower who had been asked to provide material for an installation "tomorrow!"

The next big question of the day, “Where do we go from here?” was answered with these solutions:

• educate politicians
• better communication among those directly involved
• more native plant awareness

Lastly, a quote from Romeo LeBlanc, on his first day as Governor General of Canada,  was offered.

“When we only talk among ourselves, all we get back

are echoes. But when we talk with others of a different

mind, we are made to think. And it is in thinking that

we learn, and in learning that we grow.”

Many thanks to the AFNN and to the professors from U. of Fl. for this informative day.

by Sue Dingwell