Known Unknowns

As you may have noticed, I write a blog about prairies.  I post a couple times a week on various topics, ranging widely from basic natural history facts to fairly complex scientific ideas.  I’ve also written a book on prairie ecology and management.  As a result of this, people often assume I know much more than I actually do.

When I write a post, I usually dive into scientific journals (or at least Wikipedia) in order to gather enough information to write something interesting.  Sometimes, I can even retain that new information in my brain for as much as a week or two after I write my blog post.  However, more often than I’d like to admit, I’ll do an online search for information on a particular topic and one of my old blog posts will pop up in my search results!  I then get the surreal experience of learning from my younger self.

The point is, while I’ve been exploring and studying prairies for more than 25 years, I still feel like I’m just getting started.  There’s way more that I don’t know than I do know, and I find examples of this every day.  In today’s post, I’m sharing some of those examples with you.  I’m honestly not sure why you’d want to read about topics on which I have no useful information to share, so I won’t be offended (or even know) if you just stop reading here.

Here goes:

What made that hole in the ground?

There are all kinds of burrows in prairies, and I have no idea what kind of creature dug many of them.  Most of the bigger ones are probably made by badgers as they hunt for ground squirrels, but there are lots of other relatively large animals that dig too, and I don’t really know how to tell their burrows apart from each others.  Smaller burrows are even more mysterious to me.   Little mouse-sized mammals do a lot of burrowing, but I’m not sure which species do or don’t dig their own holes or how to tell them apart.

I’m pretty sure this is a badger hole. Partly because of the diameter of the hole, and partly because the track sure looks like a badger track.  Having that

Sometimes I find even smaller holes lined with silk and I’m pretty confident those have wolf spiders in them, but I don’t even know for sure whether wolf spiders dig their own burrows or just appropriate them from other creatures.  I’m getting better at recognizing burrows made by native bees and wasps because most of them have a little raised lip around the edge, but without seeing the resident come out of the hole, it’s really hard to know if I’m right.  Someday, maybe I’ll take the time to dig deeper into this topic.  Hardee har har.

What kind of insect is that?

I love to photograph insects and other small invertebrates.  When I can, I try to figure out what species I’ve photographed and I usually include those identifications when I put photos up on the blog.  However, most of those identifications come from helpful friends who graciously put up with my frequent emailed photos and queries.  I also take advantage of the excellent Bugguide website, where visitors can either click through images to gradually narrow down possible identifications or submit a photo for experts to identify.  Because I post so many photos of insects with the species name included, people have gotten the impression that I can wander around in prairies ticking off the names of all the insects I see.  Not true.  I can name a lot more than I could 10 or 15 years ago, but I mostly know the common species, or maybe the broad categories (“look, a grasshopper!”).  I try to make up for my lack of knowledge by being extra enthusiastic about what I see.  (“Wow!  Look how cool that little critter is!!”)

I think this is some kind of hopper. Not a grasshopper. It’s sure a neat looking little critter, though, huh?

How does intensive grazing followed by long rest periods affect soil carbon?

Good grief.  I have no idea.  To be fair, though, no one else does either, as far as I can tell.  There is some limited information out there about how grazing can affect soil carbon production and storage, but the science is still far behind on this topic.  Some grazing seems to support more soil carbon than chronic overgrazing or the absence of grazing, but the impact of specific grazing regimes or patterns is still a big mystery.  I can make some educated guesses about what’s happening with soil carbon based on what I know about root responses to grazing, but they’re still just guesses.  Ongoing and proposed research projects should help us understand this topic better in the coming years.

Grazing practices like patch-burn grazing surely have some important effects on soil carbon. Maybe they’re positive, maybe they’re not. I don’t know.

How do various herbicides work?

I managed to get through both my undergraduate and graduate degrees without ever taking any chemistry classes beyond Chemistry 101.  At the time, I was pretty pleased with myself about that, but I’ve come to regret it.  I have a very poor understanding of the various chemical compounds found in herbicides, let alone what their modes of action are in targeted plants.  I’ve also fallen far behind in terms of knowing which herbicides are best for killing which plants, what kind of residual impacts they might have, etc.  Fortunately, I have a father-in-law and several close colleagues who are well-informed on these topics, so I can get pretty quick answers when I have questions – answers I promptly forget as soon as I move on to another project.

Why do bison destroy yucca?

I don’t know, but they sure do.  Both cattle and bison will graze on yucca, especially during the winter when little else is green, but bison seem to have a vendetta against yucca, and I have no idea why.  Managers of bison herds have told me about watching bison violently uproot yucca plants with their horns.  I haven’t yet gotten to see that personally, but I’ve seen the impressive results.  Why do bison work so hard to get rid of a winter food source for themselves?  Are they really trying to kill the plants, or is it just fun?  No one I’ve talked to has seen evidence that the bison eat the roots of yucca or get any other obvious immediate benefit from uprooting the plants.  Regardless, there is usually a sharp fenceline contrast between bison pastures and cattle pastures in terms of yucca abundance, and it’s not due simply to the fact that most cattle pastures aren’t grazed during the winter.

This big clump of yucca was excavated by bison, but still managed to hold on to life. So far.

So, those are some examples of topics I don’t know much about.  I could keep going, but I’ve already written over 1000 words, and that seems more than sufficient since you’re probably not learning anything by reading them.  Sorry about that.  If you’re feeling unsatisfied, you can always go back and read one of the many posts I actually researched ahead of time.  Or you could just go read Wikipedia

This entry was posted in Prairie Management, Prairie Natural History and tagged , by Chris Helzer. Bookmark the permalink.

About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.

21 thoughts on “Known Unknowns

  1. Hi Chris –

    You are hilarious.

    I enjoy your blog.



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  2. The best indication of a person’s wisdom is their willingness to acknowledge that there are things they don’t know.

    • Thanks for sharing this, Lance. Isn’t it fun when we get to use information to care for wildlife from people and places intent on destroying them?

      • makes sense, because the ones trying to destroy them are often the ones who study them the most in order to destroy them more effectively

  3. That is fascinating about the Yucca Attacks! I think there is a horror show in there. It could be made from the Yucca’s point of view.
    About a month ago, I saw a whole string of large holes alongside the road coming down 43 from Bennett. They were big. I am going to check out the link above about holes.

  4. You should know the following. Your blog is the main reason I continue to support The Nature Conservancy. I support The Nature Conservancy even though I don’t get to enjoy the work the TNC does personally. I have only been to one TNC preserve in the last decade. That trip was only because I thought I should at least see what that is being done with the money I send every month. Even when people disagree with you, you still let them have their say. Where I live that does not happen.

  5. Your candor is part of he same thing that makes you so excited about what you see on the prairie. Both of these traits make you a treat to read. Please continue not to be an expert.

  6. Multi-species cover crops planted on crop ground are supposedly increasing soil organic matter rather rapidly compared to conventional no-till agriculture (although I am skeptical because of very few peer reviewed studies show this yet). But a properly managed prairie with even more species, seems to have stagnated with organic matter increases, what’s up with that?

    • I don’t understand all the mechanics of it, but there does seem to be a saturation point in prairies, and that threshold is influenced heavily by annual precip, I think, as well as soil texture and other factors. This topic fits nicely into the overall theme of this post…

      • When changing to multi-species cover crop fields the organic matter has a low starting point compared with native prairie which might explain the claimed increases. As Chris mentioned, prairies do reach a saturation point. What farmers might be observing is an increase in the organic matter in multi-species cover crop fields beyond what occurs in native prairie because of fertilization and irrigation. It is likely the saturation point would increase if people changed the conditions to improve plant growth.

        • When changing a conventional agricultural field to a multi-species cover crop rotation the organic matter has a low starting point. This might explain the large increases that are claimed. Increases in the organic matter in multi-species cover crop fields beyond what occurs in native prairie are probably because of fertilization and irrigation. The saturation point would be expected to increase if people changed the conditions to improve plant growth.


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