Festuca paradoxa and why we know we know nothing

The mention of fescue often brings to mind tough, stringy, silica-laden strands of grass being pulverized by the broad molars of cattle, cudding its way through the four steamy stomachs of the beast only to be expelled in a watery, brownish-green ooze of hot acrid defecation upon an overgrazed, cracked and sore, field that once harbored an intricate assemblage of native organisms but that is now reduced to a monoculture of fescue. Or at least it does to me. But there are good fescues in the world. Ones whose histories are not synonymous with the death knell of Midwestern natural systems. Folks with a remedial knowledge of Midwestern natural communities are aware of Festuca subverticillata (Nodding Fescue); a native species commonly found in woodlands and forests of decent remnant natural integrity. Others might be surprised to know there is another native fescue in our midst. I am writing, of course, of Festuca paradoxa.

Festuca paradoxa resembles F. subverticillata in gross morphology but is generally larger and occurs in more open habitat. Here is mediocre photo of the overall habit of F. paradoxa:
Festuca paradoxa also has more spikelets on the lower branches of the inflorescence than F. subverticillata (8-20 vs. 2-7).
Both of the afore mentioned native species can be differentiated from the exotic F. arundinacea (aka F. elatior, Schedonorus arundinaceus and S. phoenix) by having leaves that are distributed evenly along the stem (basal distributed in F. arundinacea) and by lacking finely ciliate auricles.

The spikelets of F. paradoxa (below) are very typical of fescue wherein the glumes are about as long as the lemmas which are elliptic in outline with acuminate tips. Members of the genus Festuca typically have fewer florets per spikelet (3 to 10) than grasses with a similar morphology.
To the field botanist, who relies heavily on the vegetative characters of grasses for identification, fescue venation is quite distinct. The adaxial leaf surface has many raised nerves which give it the texture and appearance of a vinyl record.
The auricle of F. paradoxa is creamy white in coloration and contrasts with the yellow-green of the leaf blade and sheath.
The auricle of F. subverticillata is green or sometimes tinged with purple, while the auricle of F. arundinacea (below) has a pronounced yellowish coloration in stark contrast to the dark green of the blade (note the ciliate margins which are indicative of F. arundinacea).
Festuca paradoxa is a bit of an enigma. Geographically, it occurs in the eastern regions of the Great Plains states (Texas, Kansas, Nebraska….), east to Pennsylvania and Georgia and north to Minnesota and Wisconsin. However outside the east-central portions of the Tallgrass Prairie Ecoregion and the Ozarks, its distribution is very spotty. It is listed as a species of conservation concern in ten states and potentially extripated from three. On a county by county basis, Missouri has the most occurrences of F. paradoxa, but even here it is rarely encountered. When it is encountered one usually finds but a few stems or a single patch in areas where suitable habitat abounds. Why?

(WARNING: the following is theoretical ramble based on general assumptions and oversimplifications serving ultimately to illustrate a point that the author concedes may itself be an overgeneralization of the facts).

In any given flora there are species whose occurrences within the landscape are infrequent and seemingly patternless. These plants exemplify the difficulty inherent to our human understanding of the structural, temporal and compositional complexity of natural systems; the plethora of biotic and abiotic influences over the evolutionary histories of species as they assemble into natural communities and disassemble as influences change. In most cases the ranges of species are either expanding or contracting depending on the abundance of suitable habitat and their ability to disperse into said habitat; where suitable habitat is defined as the proper biotic and abiotic conditions necessary to colonize, persist and reproduce. Climate change (non-human induced, for these purposes) is one of the larger factors involved in the ebb and flow of the geographical ranges of species. As the availability of suitable habitat decreases in a region, species become isolated in the fragments of habitat. Pleistocene relict species are classic examples of this phenomenon. Such relicts are usually edge of range species associated with regionally rare habitats. Other major factors include a missing pollinator or seed disperser which can ultimately result in a fragmented range but usually is not primarily associated with a fragmented habitat. In this case, plenty of habitat exists but the species does not seem to be able to colonize it successfully. Of course, all of this is further complicated by the fact that subtle changes in climate or the achieved evolutionary potential of competitors, predators or symbionts can lead to local or global extinctions.

But how does this relate to F. paradoxa? Ultimately, all that can be said is that because it is found in small, isolated populations across its range despite the availability of seemingly suitable habitat it best fits the pattern of a species with a contracting/fragmenting distribution. As is the case for many such species with similar distributions, this is where our knowledge runs out of gas. Such scenarios illustrate the ignorance of science as it relates to a functional understanding of individual species; as such knowledge relates to the reality of species distributions. Yet outside the realm of federally threatened species you never hear botanist discussing these strange distributions. Which make me wonder how can we protect potentially imperiled species or manage natural communities with nothing more than a basic understanding of regional phytogeography?

Here is good example of what I am talking about. A few years ago I collected data pertaining to the herbaceous and woody ground flora in several natural areas in the Chicago region. The research was directed at demonstrating the effects of deer browse. These preserves were being managed as black oak savannas and each had numerous acres of very large trees most of which were black oaks (Quercus velutina). Land surveyor notes as well as the matrix flora of these sites verified that these sites were likely black oak savannas historically. While collecting quadrat level data throughout the region at these flagship preserves we started noticing that several of the sites had no oak seedlings in the understory. We then noticed that there were no oak saplings, nor any young trees. None. Just large 150 to 300 year old oak trees. When we brought it up to the scientist in charge we were met with blank stares and some on-the-fly explanation the boils down to a “burn it and they will come” philosophy. A more likely explanation, based on my own speculation, is that these sites have been changed such that they no longer favor black oak colonization even though there are tons of acorns raining into the seed pool annually. These sites were heavily grazed for over a century. It seems likely that anything ranging from soil compaction to changes in mycorrhizal interactions (little is known about invasive/exotic soil fungi) could have killed these savannas decades ago in terms of population structure. The situation is akin to visiting a retirement home, not noticing the disproportionate number of elderly people and instead convincing ourselves that they have the potential to be a flourishing community if we can only rehabilitate them. I fear such ignorance is rampant when dealing with floristic shift that take decades, centuries or even millennia to unfold.

This brings us back to F. paradoxa and species like it whose distributions we can’t explain or worse, that no one is trying to explain. If we are to successfully preserve, restore or, god forbid, recreate natural systems, we should be able to answer questions regarding species assemblages. Otherwise we are practicing science based on blind-guesses and the active application of assumptions about past systems that may or may not apply to current scenarios. It seems to boil down to the Socratic Paradox in that “All we know, is that we know nothing”.
So the next time you encounter F. paradoxa, waving gracefully in the breeze, admire its current station in the modern landscape and remember to ponder what missing pieces of the puzzle it could provide if we only knew the relevant questions.

Comments

  1. I love this post and the philosophizing! I am preoccupied with rarity. For me our current wave of extinctions is almost all due to human overpopulation. What can be done about it?

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  2. Don't forget Festuca saximontana, another native fescue found throughout western and northern North America. I've never seen F. saximontana or F. paradoxa, but I keep an eye out for both of them.

    I agree with Alan about human overpopulation being the cause of the current wave of extinctions, and I wish I could help with an acceptable solution. I wonder, though, about the hypothesis that F. paradoxa is a species with a range that is contracting. The ranges of all species, plants and otherwise, are not static, in my opinion. But is it possible that some species are just "rare" wherever they occur? I don't know the answer, I just raise this as a simplistic possibility for an explanation of the distribution of F. paradoxa and other "rare" species. Aren't some species less competitive than others, simply by nature? Just because the above ground habitat seems suitable doesn't mean that below ground conditions are appropriate. As you state, there is so much that we don't know. If the hypothesis that you raise is correct, wouldn't there be someplace in the world where F. paradoxa is (or at least was) common? And maybe there is... I don't know. Is there evidence that it once was more widespread or abundant? Have you looked through herbarium specimens? I wonder if there are many misidentifications of old specimens of F. paradoxa in F. subverticillata folders. Deam (1940) points out that F. paradoxa "is easily recognized in the field but herbarium material is difficult to determine."

    I also agree that it is a serious problem that more research on the ecology of species that are not charismatic is not being conducted. (In the same sense, C-values are becoming seriously misused, as I've seen too many times recently where restoration ecologist want all high C-value plants seeded in their projects because they have the incorrect perception that seeding high C-value plants will result in a "high quality" restoration; this is a topic for another post and another time.) I don't, however, think that all restoration work should cease until we figure out the ecology and requirements of every species; restoration science needs to adapt as new information becomes available, assuming that there is someone to do that research. Restorationists also often have an attitude that they know everything they need to know about restoration; some humility once in a while wouldn't hurt. It is points like the one that you make in this post that need to reach restorationists to let them know that there are species they know nothing about (and in most cases have never heard of). How does this happen? I'm not sure that enough restoration ecologists will be looking for answers in the blogosphere. To me, this all boils down to one conclusion: you should really consider publishing and presenting more.

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  3. I couldn't agree more with you gentlemen regarding the problems associated with overpopulation, though most of these problems have yet to rear their ugly heads. Of course, human overpopulation is the result of modern efficiency mixed with a hunter-gatherer’s mentality. The only hope resides in how quickly we can redirect our exploitation-based perspective of the natural world. Can a leopard change its spots? If only Lamarkian evolution was accurate.

    That being said, there are few rare plants that are rare because of modern human exploitation, at least in North America. Most rare species were rare prior to European colonization. Most others are rare within political boundaries but secure across their range (edge of range rarity is not real rarity, IMO). Many other species will certainly become rare or extinct due to the alteration of landscape scale dynamics. The fact that there is no longer a Tallgrass Prairie Ecoregion will have a huge impact. As for the modern distribution of Festuca paradoxa, it does actually fit that of a species with a contracting range. Somewhere in history it was likely common across its range, and possibly beyond. The hallmark of a species with a contracting range is hyper-fragmentation where populations become increasing isolated; like water droplets drying on a windshield. The potential reasons are numerous and fascinating in and of themselves. Investigating these reasons would unearth a goldmine of ecological information and it the primary focus of my complaint. Of course, some of the fragmented populations of F. paradoxa could eventually witness regional speciation and we could end up with many infant species of Festuca, thus is the resiliency of nature.

    I also don’t believe that restoration activities should cease, but I cringe every time I encounter the same formulaic application of “solutions” without regard to site specific conditions or appropriateness. I would qualify this with my belief that anyone conducting “restoration” that has not collected baseline data and that does not periodically resample is operating a faith-based inititive not a scientifically justifiable project.

    Unfortunately, there is no real arena for the publication of complaints. Also, I am not really driven to push my complaints because I ultimately understand that most conservations and ecologist are doing the best they can with limited resources in a society that has no understanding, appreciation or interest in what they are trying to do. They don’t need some one else riding them down. I mainly post my ramblings because I think science always needs to be paranoid, cautious and questioning. The blogosphere is as good a place as any for that.

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  4. Although you may see your post as a complaint (and I agree that the blogosphere is a good place for that), I see it as educational and useful for restoration practitioners. You could easily transform your complaint into a manuscript for a restoration-focused journal. There are plenty of people in restoration positions that unfortunately lack the knowledge to perform the science correctly. There are as many (or more) loud-mouths that think they know what they're talking about that lack the knowledge that you possess. Unfortunately, impressionable people listen to loud-mouths. But they may also read scientific journals.

    By the way, I saw Ted MacRae's plug for your blog in the most recent Flower Pusher. Congratulations! Hopefully you get the viewership that you deserve.

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  5. Perhaps you are right. I am going to have to write down the "impressionable people listen to loud mouths" line. That's gold, Scott, gold. What is the Flower Pusher? I feel like I'm out of the loop.

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  6. Flower Pusher... ha! I meant Petal Pusher, the newsletter of the Missouri Native Plant Society.

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  7. Huh. I haven't seen it. Is it possible that you recieved a new one in Indiana before I did in MO. Regardless, I'll be sure to thank him.

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