Saturday, June 13, 2009

Natural or Introduced?

While botanizing in a St. Joseph County floodplain woods a week ago, I came across a population of Matteuccia struthiopteris, Ostrich Fern, a rare plant in Indiana. Ostrich Fern is often planted as an ornamental fern. It is known (as a naturally occurring plant) from St. Joseph County and adjacent LaPorte County, both from single collections by our own Keith Board. Plants of the Chicago Region (1994) states that it is found in "moist, often calcareous woodlands, either on slopes or floodplains." The woods in which I was botanizing was a floodplain woods with some degradation, but there were no signs a former home site or of this population being an escape from a nearby residence. In fact, one of its associates at this location was Asimina triloba, with which it also apparently grows at a known location in Berrien County, Michigan.

My question is this. With landscaping using native plants as well as well-intentioned "restoration" becoming more widespread, how do we track naturally occurring populations of rare plants versus those that have been introduced, or does it even matter? Specifically, how do I know whether this population was naturally occurring and if I should collect and report it?


Tom said...

Great question- While on Middle Bass Island last week, I ran into some consultants from Maryland that were planting yellow water lily from Wisconsin. The boxes weren't labled, but I'm thinking it could have been Nuphar variegata, an Ohio endangered species, an extremely rare plant in coastal marshes in Lake Erie. They may have just planted tons of it. We'll track it as planted and/or introduced most likely.


Justin said...

As with many things, I have an opinion. I came up with four rough criteria off the top of my head. First, the natural integrity of the site must be in line with the species. If I am at a "from scratch" mitigation site and find a species that exhibits high fidelity to intact natural communities, I should assume it was planted. Second, associated species should be indicative of the habitat of the rare plant. Third, there should be several plants present, not just one or two plants. This comes out my own observation that when rare plants are found, they are rarely single plants. Fourth, there should be evidence that the plant is reproducing (seedlings, for example).

Of course, each of the gross generalizations above have exceptions and short commings. When in doubt, I think you have to assume it is native. It is the old "rather have a guilty man on the street than an innocent man in prison" philosophy.

Lastly, we have to keep in mind that, inspite of our extreme fragmentation of the landscape, plants are still out there colonizing new sites and seed banks prove amazingly resilient. Rare plants are not necessarily relicts.

Scott said...


How would you treat populations of Nuphar variegata that arise as a result of seed from this obviously introduced population? Would there be any way to know if a population that showed up nearby was natural or result of the Middle Bass Island planted population?

Justin, I agree with your assessment. You may remember seeing the restored wetland south of Walkerton, Indiana, where Hypericum kalmianum showed up. It wasn't in a seed or plant mix. Would you assume that to be natural? I'm guessing that based on your assessment, you would consider this Matteuccia struthiopteris population to be natural. Is that the case?

Tom brings up a good point. What are your thoughts on introducing rare plants in restorations?

Justin said...

Having been to the site with Hypericum kalmianum, I would say that it satisfies some of my criteria in that the ecological context is correct and it appears to be reproducing (I think I recall small and large plants). It also sounds as though your Ostrich Fern could very well be native. As for the introduction of listed species to "restoration" sites, I personally don't have a problem with it if it is done right. First of all, it should be conducted by trained ecologist and not well-intending wanna-bees. Introductions should also be conducted with the consent and advisement of a state natural heritage program. Information such as source and amount of seed or other material should be documented and follow-up sampling should be conducted. I'm sure this level of responsible stewardship would scare of the the more timid element. In such cases, said persons obviously would have no understanding of the importance such records in the first place and thus have no business being involved in such an operation. In fact, it would be great if there were such a permit process for all ecological restoration and mitigations. There is way too much slop in such operations.

On a lighter note, I just spent 4 days sampling Hercules Glades Wilderness Area. I saw no exotic species the whole time and countless high quality species and communities. Just life celebrating itself in a symphony ecological and evolutionary splendor.

Brad said...

Scott, the impression you give me is that the Ostrich fern is native. It is a resilient species in Michigan, surviving degradation in its predominantly floodplain habitat. Nativity status matters for tracking rare plant species; as Tom suggested, discovery of an introduced population would be tagged "i" if said population was entered into the heritage database. I am in favor of placing at least skeleton records of such introductions to avoid confusion later on. There appears to be no widespread, standard method for reporting plantings and restorations of listed plant species.

I do not fully understand why people introduce listed species into restoration sites or natural areas, except when that species is truly rare across its entire range, in which case the introduced population may be important for the overall survival of the plant. The conservation community focuses too much attention on planting range-limited "rarities" with the idea that, somehow, planting a listed species in a restoration outside its native context "makes a difference." This may lead me into a favorite rant of late, that of the move towards "bioculture," or the yield-driven management of natural areas for production of "diversity" and rare species. I fear the conservation community is moving away from protecting places with intact biotic communities and ecological processes, and towards hubristic "restorations."

Justin said...

Spot on, Brad.

"Restorationists" often ignore the "work-horse"/"blue-collar" species of natural communities in light of regional rarities. Of course, sites with high species richness offer more resilience in the face of changes in the community and thus more adaptability in the long run, so they certainly should not be ignored. That being said, many sites with of "marginal" floristic quality are left to further degradation by logging, fire supression and such without thought to the fact that they represent the matrix community for the region.

I am sickened when I drive by woodlots, glades and prairie remnants in the Ozarks that are of significant ecological value but are ingored because they fall outside the "Areas of Conservation Opportunity". In short, it seems that ecologist/conservationists have sold-out to the "what is the minimum necessary" philosophy.

Brad said...

Justin, one of the projects I have worked on since starting at MNFI (thankfully, one that is not associated with any more fieldwork) was driven by the question "how much is enough." At the Natural Areas Conference in Tennessee, I brought up this question to a small group of people, mostly colleagues, asking why conservationists seem to be the only ones asking "how much is enough." Do developers see the landscape in that way? I think not. Every other interest group wants it all. We are throwing up our hands and giving up if our drive is to see how little we can protect or manage to potentially ensure (doubtfully, IMO) the continued existence of our biota.

Michael said...

I was at a gardener's workshop a couple of weeks ago where the author of a some top-selling books on naturalized gardens here in Canada suggested planting Stylophorum diphyllum (Wood Poppy). It's native to Ontario but just to a tiny region in the southwest (listed as endangered). Botanists at the University of Western Ontario who are studying the population along a small section of the Thames River have made a good argument for not planting Wood Poppies. Stylophorum seeds for sale here come from states to the south where the plant is abundant and cultivating them may contaminate the distinct genetics of the small, isolated population. This certainly makes recovery, as opposed to introduction, hard to track. With such a huge latitudinal range in Ontario, plants that are native to the far southern region (Carolinian Canada) are enthusiastically planted far from their native range. It is a strange kind of exoticism.
I found a Wood Poppy growing in my town. I was pretty excited and thought I ought to report it. Turns out there are several specimens being grown in a nearby garden and this endangered native species was actually an introduced, dare-I-say, invasive species.

The spirit behind the "native gardening" trend is laudable. Unfortunately the literature written for gardeners and many of the most common sources of plants aren't nearly specific enough about what is locally 'native'.

Scott said...

Thanks for the interesting conversation. I've enjoyed it.

Michael, thanks for visiting and commenting on our blog.