"So what we have in red cedar is a species, that has at least some of the characteristics of more traditional invasive species: adaptability to many habitats, suitability as an early successional species, rapid dispersal, ability to crowd out other species by direct competition for resources by altering microclimate and indirectly by allelopathy."Today I received an interesting response from another Kansas Blogger, Gaia Gardener, who took issue with my characterization of Red Cedar as an invasive. Gaia argues:
"I think that labeling this plant as invasive is just an excuse by certain elements of the agricultural community to 1)justify attacking the species with herbicides and 2) to try to shift blame for groundwater and surface water shortages away from human overappropriation and overuse, often by those same agricultural interests.I have lots of sympathy for Gaia's point of view here. But successful weeds are a bit more than plants out of place. Successful weeds often have high reproduction rates, good methods of dispersal, rapid growth rate, often some attribute such as allelopathy that gives them an advantage of other species-exactly the sort of characteristics that we attribute to invasive species. Gaia and I think agree that the root cause of Red Cedar's invasive tendencies is poor land management, especially failure to understand the role of fire in prairie maintenance.
"I know that redcedars are a nuisance, and I've pulled and cut out many a cedar seedling or sapling myself. In fact, we've just bought a new home, complete with a 5 acre pasture that has redcedars speckled liberally throughout it. And we've started cutting them out. But a weed is just a plant out of place, and I love redcedars in their proper place. Let's not put a negative label on a plant that encourages us to "throw out the baby with the bathwater," metaphorically speaking."
The fact is though that human activities are altering the ecosystems of our planet providing opportunities for endemic species with invasive (OK use weedy if you want) tendencies to spread and these species may prove to be less benign than Red Cedar.
For instance consider the diatom, Didymosphenia geminata recently discussed in a Christian Science Monitor report. The report notes that even where the species is endemic and usually a minor component of the flora of cold streams the diatom has become a major problem, prone to major blooms even in warm water streams.
Now outbreaks of this diatom historically occur from time to time, but appears that it's characteristics lend themselves to invasiveness in ecosystems that are excessively disturbed. Perhaps there is normally some keystone species or grazer that keeps this species down. This diatom also has recently invaded parts of the world such as New Zealand where the species is not endemic, as shown to the left.
Image from http://www.biosecurity.govt.nz/didymo showing a young colony of "Didymo".
The United States' EPA has additional background information on this diatom at http://www.epa.gov/Region8/water/didymosphenia/archived/didymosphenia.html
So it seems to me that regardless of whether you call them invasive or weedy or tramp species, the fact is species with characteristics similar to classic invasive species are going to become a greater and greater issue for us as human mismanagement of formerly natural systems gets more intense.
By the way the individual organism is quite beautiful; it is the mats that are the problem. Here is an individual Didymosphenia from the EPA site. Could we have predicted that this individually beautiful diatom would respond to human disturbance as an invasive?Technorati Tags:
didymosphenia
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1 comment:
Much as I've come to love redcedars, I agree with you that they are a (relatively benign) example of a species that is out of balance. And I agree wholeheartedly that human activities/disturbances have created that imbalance.
Furthermore, I completely agree that human activities have created many other species' imbalances as well, on both ends of the spectrum of population numbers.
My biggest concern in the use of the invasive label for endemic species is the tendency of that label to change the focus from "Why is this plant out of balance? What is going wrong?" to "This is a bad plant and should be eradicated, whatever the method or cost." In my experience, that change in focus happens very rapidly.
Once the debate gets framed as the plant being bad, no one looks anymore for the original reason that the plant's numbers increased. Therefore no one tries to address the root problem (no pun intended). They just use the "invasive" label as a reason to spray herbicides or in some other way create even more human disturbance to the ecosystem.
For example, for several years in the past, I acted as a spokesperson for the environment in Topeka and at meetings across the state. In groundwater control meetings, I listened to farmers seriously contend that any tree at all along any stream or river in western Kansas was stealing water from the ground...and therefore taking money out of farmers' pockets...and therefore that all trees should be removed from all waterways in areas where the groundwater was in short supply. Trees were labeled as water wasters, in this instance, and the label was used to try to justify removing as many trees as possible from habitats where trees were always a scarce but important resource.
The "redcedar is invasive" label, especially as written about in the February 10th Wichita Eagle article, reminded me very much of those IGUCA meetings.
When I get right down to it, I guess that I'm just trying hard, in a small way, to keep human mismanagement of our local ecosystems from becoming worse. And since I've learned what a huge impact seemingly simple labels can have in that regard, I'm kneejerking against a label that could be easily misconstrued and misused.
By the way, I agree that Didymosphenia is a beautiful diatom! Thanks for posting that photo...and for letting me weigh in on this topic.
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