What I Look For When I Walk Through My Prairies

Back in August, I posted some questions to readers about what they look for when evaluating their own prairies.  I got some excellent responses, which I really appreciated.  If you missed them, you can re-read that post and those comments here.

Walking around a prairie and getting a read on what's happening is probably the most important part of prairie management.  This is Scott Moats, The Nature Conservancy's Broken Kettle Grasslands, Iowa.
Walking around a prairie and getting a read on what’s happening is probably the most important part of prairie management. Scott Moats, The Nature Conservancy’s Broken Kettle Grasslands, Iowa.

As a follow up to that, here is more detail about what I think about as I walk around my family prairie, or one of our Platte River Prairies.  Of course, sometimes I just hike around and enjoy the day, but this post is about what I focus on when I’m evaluating our management and considering ideas for next steps.  We collect some relatively formal data on some sites, but most of our management decisions are really based on the kind of observation and evaluation I lay out here.  I’m certainly not trying to talk you into doing exactly what I’m doing – especially because what I look for is tied to my particular objectives, not yours.  Instead, I’m hoping that I might spark some ideas you can incorporate into your own decision making processes.

To start with, the basic objective at both my own prairie and those I help manage professionally is the same.  I want to provide a shifting mosaic of habitat structure patches (short, tall, mixed-height, etc.) so that the quilt pattern of those patches looks different each year.  I assume that a dynamic management regime like that will support high plant diversity because it doesn’t allow static conditions that allow a few plant species to become dominant.  I also assume that those shifting habitat patches will facilitate a healthy community of insects, birds, mammals, reptiles, and other life – above and below ground.  These are not blind assumptions; they are based on my own experience and research, along with that of many others.  (You can read more about those assumptions here.)

Grazing can create very important habitat structure such as this short grass/tall forb habitat at our Platte River Prairies.
Grazing can create very important habitat structure, including this short grass/tall forb habitat at our Platte River Prairies.  This habitat allows for easy movement along the ground, but provides plenty of overhead cover as protection from predators and the hot sun.

Not surprisingly, the first thing I look for, then, as I walk around a prairie is the pattern of habitat structure.  I hope to find the full range of variation, from tall and dense vegetation to almost bare ground.  Even more importantly, I want to see some of the important intermediate habitat types – especially short-cropped grass with tall forbs (wildflowers), which is incredibly important for many wildlife and insect species.  If I can find all of those habitat types, and they’re in different places than they were last year, I feel pretty good.

Next, I look at the plant community.  Plant diversity is an important foundation for invertebrate and wildlife diversity, so I want to see a rich diversity of plants as I walk around.  I also want to see that diversity at both large and small scales.  Across the whole prairie, I’d hope to find at least 100-200 plant species (though I certainly don’t count them every time) but I should also be able to count at least 10-15 plant species within arms’ reach if I kneel on the ground.  These numbers vary, of course, based on geography, soil type, etc., so they may or may not be reasonable at your particular site.

As I look at plant diversity, I want to see habitat patches with an abundance of “opportunistic” plants.  These are species that thrive in the absence of competition.  Depending upon your point of view, you might also call them “colonizers” or even “weeds”, but when they are abundant, it means that nearby dominant plants have been weakened.  We try to periodically knock back the vigor of dominant plants (especially grasses) through fire, grazing or mowing, to help less dominant plants maintain a foothold in the plant community.  A flush of opportunistic plants is an indicator of success because it shows that we successfully opened up that space and other plants are taking advantage of it – and not just the weedy ones.  Finding seed heads, and even new seedlings, of slower-to-colonize plant species (purple prairie clover, entire-leaf rosinweed, leadplant, etc.) within those weedy patches makes me feel even better.

Black-eyed susan  is a showy example of an opportunistic plant species that thrives when surrounding vegetation is weakened.  Other species I look for include ragweeds, hoary vervain, annual sunflowers, ironweed, ragwort, annual thistles, and many others.
Black-eyed susan is a showy example of an opportunistic plant species that thrives when surrounding vegetation is weakened. Other  opportunists I look for include ragweeds, hoary vervain, annual sunflowers, ironweed, ragwort, annual thistles, and many others.

In sites where cattle are present, I spend time looking at what they’re eating and not eating, as well as which parts of the prairie are being grazed most and least.  In our patch-burn grazed prairies, we expect most grazing to take place in recently-burned areas, so I check to see if that’s happening.  Often, cattle target their favorite grass species first and then graze wildflowers only if they’ve already eaten the best parts of those grasses.  If I see something other than that pattern, it can tell me a lot about our stocking rate or other issues – not necessarily in a bad way.  There are also a few plant species that our cattle can’t seem to resist (some milkweeds, rosinweed, Canada milkvetch, and spiderworts) and we like to make sure those species get a release from grazing pressure every few years.  As a result, I pay special attention to whether or not – and how intensively – those plants are being grazed.  If I notice that they haven’t been allowed to grow and bloom for a few years, it’s time to change up our management and give them a rest.

The other group of plant species I look closely at is invasive species.  At our sites, invasive grasses such as smooth brome, Kentucky bluegrass, tall fescue, and others get special attention because of their ability to form monocultures, but there are plenty of others to watch as well.  I look not only at the current abundance and density of invasive plants, but also compare what I’m seeing to previous years to see how things are changing.  Finally, I pay attention to whether or not there are conditions that appear to be giving invaders an advantage.  For example, it would be important to know if cattle are grazing all the plants EXCEPT those invaders, allowing them to encroach upon weakened competition.

Siberian elm trees are a major pest in our prairies, and one we track closely and try to keep up with.
Siberian elm trees are a major pest in our prairies, and we have to be careful not to fall too far behind in our control efforts.

Field notes and photos are really helpful when trying to decide whether populations of invasive species are expanding or not.  They can also be helpful when comparing grazing impacts, responses from opportunistic plants, and other interesting phenomena.  I sometimes flip back to last year’s notes while I’m in the field to see if there’s anything I saw then that I should pay attention to.  Then, when I periodically enter my field notes into the computer, I can look at all the notes from other years and look for patterns.  I don’t take extensive field notes, but try to write enough to be useful.  (See here for more on field notes).

As I continue to learn more about the way various animal and invertebrate species see and utilize prairie habitat, I’ve gotten better at looking our prairies through the eyes of those species.  I wrote about wearing “bee goggles” a while ago, but I also try to step back and think about what life would be like in our prairies if I was a grasshopper, mouse, coyote, or other species.  Could I find food all year round?  Are there places to feed/hunt or hide/escape?  If the habitat I’m living in changed dramatically because of fire or grazing, would I be able to find and travel to other habitat nearby?  It’s a really interesting exercise, and helps me think about habitat needs in new ways.

Looking at a prairie through (cute!) eyes of bees or other species is a great way to broaden your perspective.
Looking at a prairie through the eyes of bees or other species is a great way to broaden your perspective.

Finally, I try to look across the fences and note what is happening on neighboring lands.  In some cases, the prairie I’m walking in is the only real prairie habitat in the neighborhood, so it really needs to provide everything for every species living in it.  In other cases, there is more grassland habitat nearby, and I can think about how our prairie can help supplement and complement what’s available in those other sites.  For example, if all the neighbors graze pretty intensively, I might prioritize tall vegetation structure a little more than if that was the predominant habitat in the neighborhood.

So there you go – a quick look inside my head, for what that’s worth.  As I said at the beginning, what you look for should be tied to your objectives, but I also enjoy tagging along when other prairie managers walk their sites because I learn a lot from how they think.  I’d love to hear how similar or different my thought processes are from yours.

Color, Movement and Noise

A couple months ago, I wrote a post asking you how you evaluate your prairies as you walk around them.  I appreciated the thoughtful responses you shared.  This week, I’ll be facilitating a discussion on the same topic at the Nebraska Natural Legacy Conference.  As I’ve been preparing for that discussion, my mind keeps returning to a brief conversation I had at the end of this year’s Patch-Burn Grazing Workshop.

The annual workshop is hosted at different sites each year.  This summer, we hosted it at our Platte River Prairies.  As we were finishing the last tour of our site and walking back to the vehicles, Wayne Copp, of the Tall Grass Bison Ranch in Auburn, Kansas, caught up with me.  He told me how much he had enjoyed the tours and that he thought our prairies looked great.  I thanked him, of course – it’s always nice to hear that.  But then he went on…

“A lot of prairies I visit,” he said, “look pretty dead – there’s not much going on. But your prairies are really alive, and they’ve got the three things I always look for in grasslands.”

“Which are?” I asked.

“Color, movement and noise.”

And there you go.  I’ve not heard a more concise, all-encompassing description of a good prairie.  Even better, you don’t have to be a botanist or ecologist to recognize color, movement and noise.  Anyone, regardless of age or background, can walk through a prairie and judge whether or not that prairie has those qualities.

Color is easy to find in many prairies.  Wildflowers are an obvious source of color, but not the only one.
Color is easy to find in many prairies. Wildflowers are an obvious source of color, but not the only one.
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A closer look at most wildflowers reveals abundant movement – much of it by visiting insects, such as these pollinators on a native thistle.
Birds such as this dickcissel can provide color, movement and noise all by themselves...
Birds such as this dickcissel can provide color, movement and noise all by themselves, but a site needs more than just birds to be a prairie.

Of course, some of you are already asking, “How MUCH color, movement and noise should there be?”

But Wayne’s criteria for judging prairies (at least as I understand them) are not meant to be quantitative.  Sure, more is better, but that’s not really the point.  I think he’s just saying that a prairie without color, movement and noise is deficient.  Clean and simple.

Much of the "noise" in prairies is created by insects, though they are far from the only sources, which can include birds, mammals, wind, and many others.
Much of the “noise” in prairies is created by insects, though they are far from the only sources, which can include birds, mammals, wind, and many others.
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A great deal of the movement, color and noise in prairies can be hidden from those who just drive past at 65 miles per hour.  However, anyone who takes the time to walk out into the prairie will have no trouble finding it.

Sure, we still need other indicators and measures that can help us identify trends in plant diversity or species’ population viability.  We still need to figure out what to look for as we evaluate past management actions and plan the next ones.   And we still need to better understand what factors can indicate whether a prairie is ecologically resilient.

Unfortunately, only those of us who spend the majority of our time working in prairies can get much good out of those highfalutin indicators, measures, and factors.  They are important, but only to a small subset of people.  For everyone else – and us prairie wonks too – Wayne has already figured out the three essential qualities every prairie should have.

Color, movement and noise.

Brilliant.

The Myth of Self-Sustaining Prairies

Here’s a question I get asked occasionally:  “At what point will my prairie become self-sustaining?”

There are lots of ways “self-sustaining” can be defined, of course, but usually the person is hoping that at some point they can just step back and let the prairie do its thing with very little or no human input.  In other words, they hope the prairie will function like a machine.  Once you have it tuned up correctly, it’ll hum along just fine with only occasional inputs of fuel or maintenance.

Ah, that it would be so easy.  Unfortunately, there is a short answer to the question, and it’s a disappointing one.  The answer is, “It just doesn’t work that way.”

Here’s the short explanation of that short answer:

A prairie with no management at all accumulates thatch from each successive year of plant growth, and if not removed, that thatch eventually builds up to the point at which only a small number of plant species can survive.  Unfortunately, the most dominant of those surviving species tend to be either trees/shrubs or invasive plants.  In the eastern half of Nebraska, smooth brome tends to be a primary winner, along with tree species such as Siberian elm and eastern red cedar.

Besides the issue of thatch build-up, there are just too many threats, particularly from invasive species and trees, for prairies to maintain their species compositions and ecological functions without human management.  This is particularly true with tallgrass prairies in an agricultural matrix.  The degree of vulnerability to invasion depends upon soil type and the surrounding landscape.  Some soil types seem favor invasives more than others – oftentimes, high soil nitrogen levels can favor exotic grasses, for example.  The degree of invasive species pressure on a prairie is also influenced by the abundance and proximity of those invaders in the neighborhood around the prairie . However, all prairies (that I’m aware of) have some degree of vulnerability to invasive species.

Active management, such as the application of prescribed fire, is needed to prevent excessive thatch buildup and to help suppress invasive species.

That’s the short answer.  A longer and better answer is that tallgrass and mixed-grass prairies are not “climax communities” in the classic sense.  In my early ecology classes, I learned that terrestrial plant communities move through a process called succession from bare ground to some final stable state – usually a forest.   Bare ground is colonized by opportunistic species, which are eventually pushed out by longer-lived grasses and wildflowers.  Those grassland species are then replaced by various generations of tree species, each topping out the other until a final set of tall long-lived trees becomes dominant and creates a stable community.  Disturbances such as fire or severe weather events might set back succession temporarily, but the process keeps moving toward that climax community.

Prairies don’t fit that successional model very well.  Prairies are maintained (and defined?) by disturbances such as fire, grazing, and drought.  Without some combination of those ecological processes, prairies turn into woodlands.  Because of that, some might argue that prairies are simply an ephemeral stage of the longer successional process, and not really a stable ecosystem.  Others might argue that the whole idea of ecological succession is overly simplistic and not representative of the way all ecosystems function.

Without getting into that larger argument, the real point is that if we agree prairies are important, and we want to maintain them, active management is necessary.  Some people point to expansive prairies in Great Plains landscapes and wonder if those prairies could maintain themselves without humans if given the chance.  After all, lightning-caused fires and roaming herds of bison should be able to take care of things without interference from people, right?  In reality, we don’t have any historical precedent to back that up.  Today’s prairies have only been around since the last ice age –  about 10,000 years (less in the east, more in the west.)  During that entire time, people have been active managers of those prairies.  Fires set by Native Americans were much more abundant and extensive than lightning-caused fires.  Bison herds, and many other herbivores, responded to those fires by focusing grazing in those recently burned areas.  That intensive fire/grazing disturbance interacted with and compounded the impacts of long droughts, floods, and other weather-related events.  Cumulatively, those major disturbances maintained the integrity of prairies.

Along with climate and fire, bison (and other grazers/herbivores) were a major force that shaped prairies. However, people and their activities were also an important component of the process.

There’s really no way (and no reason) to separate people from prairie.  Regardless of the intent or motivation of the people who manage prairies – historically or now – their actions have tremendous impacts.  Similarly, inaction by people who control prairies has tremendous impacts as well.  In the natural resource management world, the phrase “No management is still management” is well-worn but nevertheless true.

Of course, defining the need for continual human management – even in the absence of today’s new challenges such as invasive species – doesn’t solve the problem.  What kind of management is needed?  How do we know when to do what?  The answers to those questions are complex, still being debated, and the primary subject of this blog, my book on prairie management, and myriad discussions among prairie managers around the world.

Some people who agree that prairies require some level of active management still search for a relatively simple management recipe to follow.  Annual haying or burning or two to three-year rotations of fire or grazing are examples of management regimes that are commonly used and advocated for.  This is really just a small step up from the idea that prairies should maintain themselves.  In this case, the argument is that prairies should be able to maintain themselves if we just provide them the right basic disturbance framework.

I’ve given my opinion on simple, repetitive management regimes often within this blog (see my Calendar Prairies post as an example).  I think repetitive management threatens plant diversity because there are always some plant species that are favored in a particular management regime and others who are not.  Over time, those species not favored will inevitably fade out of the community if the same regime is applied over and over.  Perhaps more importantly, animal species – including insects – with fairly specific habitat structure requirements are similarly affected.  Some species thrive under repetitive management if that management consistently favors them.  However, those animals that don’t find what they need in that management system can’t normally survive for many years in suboptimal habitat like many perennial plants can.   Animals without appropriate habitat either move or die – and in fragmented landscapes, or in landscapes where the same management is in place across the entire landscape, moving may not be a viable option.

Annual haying provides good growing conditions for many plants - especially those the bloom and produce seed prior to the haying date. On the other hand, some of the plant species favored by annual haying (including smooth brome) can become invasive. In addition, some desireable native plant species do poorly under annual hay management and eventually disappear from those prairies.

All of this adds up to one conclusion.  Diverse, functioning prairies require active, constant, and thoughtful management by humans.  There’s no getting out of that responsibility.  If we choose not to be active thoughtful managers, we are choosing to let prairies degrade, and we’ll have to live with the consequences (“No management is still management”).  Hopefully, though, most people with influence over the management of prairies will embrace their role, and be active managers – as well as active participants in ongoing discussions about the impacts of various management techniques and systems.

Though active prairie management is time-consuming, and often expensive, it’s also extremely rewarding.  Whether it’s a small backyard prairie garden, a 20,000 acre grassland, or something in-between, every year is a chance to try new things, see what happens, and learn from the experience.  More importantly, the diversity of plant, insect, and invertebrate species in well-managed prairies – large and small – is its own reward.  Who could ask for more than that?