Choosing Your Destination Before You Choose Your Mode of Transport

Last week, I attended a science and stewardship conference of The Nature Conservancy in Madison, Wisconsin.  It was an inspiring and thought-provoking week.  There were a lot of topics that will provide fodder for future blog posts, but I wanted to start with an issue that came up in several sessions.  The topic had to do with setting appropriate objectives for conservation strategies, and for land management in particular.  In short, it’s really important to make sure we’re not setting objectives that are focused on strategies rather than outcomes.

This mixed-grass prairie is managed with both prescribed fire and grazing.  However,  neither fire nor grazing is the objective, they are tools that are strategically employed to create desired outcomes.  Gjerloff Prairie – Prairie Plains Resource Institute

Here’s an illustration of what I mean.  If I was planning a vacation for next summer, I probably wouldn’t start with the following question: “What mode of transportation should I take on my vacation next year?”

Clearly, it’s tough to answer that question without knowing more about the ultimate objectives of the vacation.  Where do I want to go?  What time of year am I going?  How many people are going with me?  If I’m planning to travel from Nebraska to Ireland, I probably won’t be able to do that by bus.  I could conceivably travel by motorcycle (if I had one) to the Rocky Mountains, but probably not if I was going during the winter or planning to take little kids with me.

It seems silly to start by thinking about how to get somewhere before deciding where to go, but as land managers, it’s easy to fall into exactly that mindset.  We sometimes set objectives about using fire or grazing, for example, instead of first defining the outcome we want and then thinking about what tools and strategies might get us there (which may or may not include fire or grazing).  In this post, I’ve provided examples of how this trap can present itself, both to managers of conservation land and private landowners, and some thoughts about how to avoid the trap.

Significant research has helped us understand the kinds of fire and grazing patterns under which North American prairies developed.  For example, in many places, we have a pretty good idea how often a particular site burned, on average, before European settlement.  We also have reasonably good information on the presence, abundance, and behavior of historic grazers.  Based on that information, a land manager could decide that the best management for their prairie would be to reinstate, as closely as possible, the timing and intensity of historic fire and grazing that site likely evolved under. 

Historically, prairies in this region probably burned on an average of every 4-5 years.  However, within that average range, there would have been wide variation.  More importantly, this prairie sits within a very different landscape today, with challenges not faced by those historic prairies.

Patch-burn grazing is often described, for example, as “mimicking historic fire and grazing patterns.”  Mob grazing advocates trumpet (though I’m skeptical) that their system replicates the way bison moved across a landscape.  Some in the Upper Midwest region of North America point to research showing high populations of indigenous people and scarce evidence of abundant bison and argue that their prairies should be managed only with fire.  We can argue about all three of those examples – and many more – but the bigger point is that none of those arguments should determine our management strategies.  Again, we shouldn’t be setting objectives about the strategy we want to use without first identifying the outcome we want.

To make a clunky return to my vacation travel analogy, it would be silly of me to choose horseback as my preferred mode of transportation across the Great Plains to the Rocky Mountains just because it’s what worked several hundred years ago.  Today’s landscape is broken up into countless fenced off private land parcels, which would make cross-country horse travel difficult, to say the least.  In addition, there is a pretty nice set of modern opportunities (roads and vehicles) I can take advantage of nowadays.

Likewise, our prairies exist within a different world today, with a new set of challenges and opportunities.  Mimicking historic disturbance regimes won’t necessarily keep prairies in good shape in a world with habitat fragmentation, massive invasive species pressure, climate change, nitrogen deposition, and other factors.  And speaking of good shape, our first and primary concern should really be to define what “good shape” is, right?  Are we managing for plant diversity or a few rare plants?  Are we trying to sustain diverse bird populations?  Habitat heterogeneity? Is ecological resilience the goal?  If so, what are the factors driving resilience, and how to we sustain those?  There are countless reasonable goals for land managers to choose from, many dependent upon scale, but those goals should be based on the outcome we want.

This annually-hayed prairie maintains high plant diversity but provides only one type of habitat structure for nesting birds and other wildlife species.  Depending upon the objectives for the site, that could be fine, but it very much depends upon what the manager wants to accomplish.

I feel it’s important to say this here:  I am a big proponent of both fire and grazing as management tools – you can find myriad examples of that by searching through my previous blog posts.  However, while I think combining fire and grazing can create some fantastic results, those strategies/results don’t fit all objectives.  More importantly, your particular site may or may not respond well to those kinds of fire and grazing combinations.

Let’s say your primary objective is to provide habitat for as many species of grassland birds as possible.  First, you’ll need a pretty big swath of land – many bird species have minimum habitat size requirements.  Assuming you’ve got sufficient land, the major factor grassland nesting birds respond to is habitat structure.  Some birds prefer tall thatchy structure, others like short/sparse vegetation, and others want something in-between.  A reasonable outcome-based objective might be that you want to provide all three of those habitat types across your prairie each year (and you’ll want to make sure the habitat are being successfully used by a diverse bird community).  Perfect.  Now, how will you create those habitat types?

 Grasshopper sparrows tend to nest in prairies with relatively short structure, but with some thatch (which they use to build nests) along the ground.  Some of the highest abundances of grasshopper sparrows around here are found in relatively heavily-grazed prairie.

Fall or spring fires can create short habitat structure that some birds really like to nest in.  However, some bird species (e.g., grasshopper sparrows) usually like short habitat with a little more thatch in the ground layer than is usually found in recently burned prairies.  Also, while burned areas are short and unburned areas are tall, it’s difficult to create in-between height/density habitats using only fire.  This is where other tools such as mowing and grazing might be helpful.  Mowing can reduce the height of tall vegetation and create short or mid-height structure that grasshopper sparrows, meadowlarks, and other species prefer.  Grazing can do the same and can have the advantage that cattle or bison are selective grazers, eating some plants and leaving others.  This can create structure with both tall and short vegetation mixed together and can also help suppress grasses and allow for greater expression of forbs (broadleaf plants) – something birds such as dickcissels often prefer.

Upland sandpipers prefer to nest where vegetation structure is short, but often move to sites with strong forb cover and a little patchier structure when their chicks become active.

If we’re trying to create optimal bird habitat, then, fire, mowing and grazing might all be useful tools to consider.  It’s important to understand how each tool can be used to affect habitat structure, as well as the potential risks of using each (fire can sometimes kill aboveground animals and stimulate invasive plants, grazers can sometimes target vulnerable plants and create issues via trampling).  With all of that information, you can start putting together strategies that employ the right tools, and then test those strategies against the OUTCOMES you desire.  Notice that the process I’ve just described is independent of the kinds of historic fire returns for your area or whether or not you think grazing was a significant factor in the evolution of regional plant communities.  Define your objective by the outcomes you want and test/adapt strategies based on that objective.

Other examples: At my family prairie, we aren’t using prescribed fire because we’ve been able to use grazing to meet our objectives of habitat heterogeneity and increasing plant diversity, and we use loppers/herbicide to successfully control woody invasion.  In small prairies where preserving particular plant species is the objective, a strategy using only fire or mowing could be most appropriate.  If that small prairie has rare insects or reptiles that are especially vulnerable to fire, maybe mowing is the best tool.  Regardless, the right tools and strategies depend upon the outcome-based objective.

This photo was taken in the burned patch of a patch-burn grazed prairie at Konza prairie, near Manhattan, Kansas.  The grazing created varied habitat structure because of the selective grazing by cattle.  Leadplant and other ungrazed forbs contrast with surrounding short grasses.

For ranchers and farmers who manage prairies, this same objective setting process should apply, but of course those prairies also have to help provide sufficient income to keep a family or business thriving.  Even in those cases, however, it’s still important to start with outcome-based objectives.  Those objectives can include a certain amount of needed income but should also include specific habitat or other ecological objectives.  Once you’ve decided, for example, that you really want to manage in a way that provides a certain amount of quail habitat or provides consistent pollinator resources through the season, you can look for ways to accomplish that while still providing the needed income.  When a conflict between income and habitat objectives arises, you can make the decisions that make sense to you, but at least you’re making those decisions with all the information needed to fully consider the options.

Prescribed fire can be a great tool for accomplishing some objectives, but it can also be difficult to implement for some managers.  While it is an important ecological process in prairies, employing prescribed fire should still be seen as a tool/strategy, rather than as an objective in and of itself.

There are plenty of reasonable prairie management objectives to choose from, but they should be based on outcomes rather than on tools and strategies.  Employing more frequent prescribed fire is not a good objective.  However, using more frequent prescribed fire might be a great strategy to reach a particular outcome.  (It could also be a terrible strategy, depending upon your objective.)  Don’t fall into the trap of choosing your transportation method before you know where you want to go. 

P.S. I’m sure some of you are thinking it, so let me address what might appear to be a weakness of my vacation transportation analogy.  Yes, it’s perfectly fine to start vacation planning by deciding that you want to take a cruise ship or motorcycle if the OUTCOME you really want is to ride on a ship or motorcycle.  If you don’t care where you go, the destination isn’t the outcome, it’s just a by-product of your mode of travel.  Fine.  But I think you understand what I was trying to say, right?  Sure, you could argue that conducting prescribed fires could be your objective if all you want is a legal way to light things on fire and watch them burn.  If that’s your objective, though, you’re not managing prairies, you’re lighting things on fire – and there’s a big difference.  Ok?  Ok.

A Closer Look at Prairie Roots

One of the biggest jobs of a prairie steward is to manage the competition between plants, ensuring that no species becomes too dominant and no species is pushed out of the community.  In our prairies, much of our effort is directed toward some of the stronger grass species, including big bluestem, indiangrass, smooth brome, and Kentucky bluegrass.  Left unchecked, those grasses (and a few others) can monopolize both light and soil resources and reduce plant diversity.  Our management targets those grasses with fire and grazing, often using season-long defoliation by cattle or bison to weaken the competitive ability of those grasses, opening up space and resources for other plants to flourish.  Our long-term plant data show that we’ve been able to maintain species richness and a full complement of plant species with this kind of management.

When those major grasses are weakened, one of the most obvious responses is a flush of “weedy” vegetation that quickly takes advantage of the soil and light resources that have become available.  Research has shown that growing season defoliation temporarily causes grasses to abandon some of their roots (until defoliation stops and the grasses recover), opening up space for nearby plants to grow larger and more abundant.  However, there are still many questions about the actual physical responses of grass roots to defoliation, and gaining a better understanding of that could be really important to prairie managers.  Researchers at Kansas State University are actively working on those questions right now.  Dr. Jesse Nippert, in particular, has done a lot of work on this subject, including some work on prairie shrubs that I wrote about a few years ago.

Last week, a couple of Jesse’s graduate students, Seton Bachle and Marissa Zaricor, were at our Platte River Prairies, collecting data on roots under grazed and ungrazed conditions.  In addition, Seton brought along a nifty tool called an air spade, which uses compressed air to dig into prairie soil with enough force to expel soil particles, but not so much that it tears apart the roots of plants (with the exception of the tiny rootlets at the tips).  Seton and I started talking about a year ago about the possibility of getting the air spade up here so we can look for visual evidence of grazing impacts to roots.  Marissa and Seton are both doing very in-depth (ha!) measurements of plant root responses, but I also wanted to see what’s those roots really look like.  The air spade seemed like a great way to do that.

Here is our sampling area, as seen by our drone. The bottom right portion was burned this spring and has been grazed fairly intensively since. The top left portion is unburned and has had very little grazing pressure.

Dust erupts out of the ground as Seton excavates with the air spade.

For this initial trial, we chose a part of the prairie that was burned this spring and was being grazed intensively by cattle as part of our patch-burn grazing management.  Abundant rain this year has meant that the cattle aren’t keeping the grasses as short as we’d really like, but we were still able to find some big bluestem plants that have been cropped pretty short.  As a comparison, we went across the burn line to part of the prairie that hasn’t had much grazing pressure in recent years and, because it is unburned, hasn’t had much attention from cattle this year either.  As a result, we were (ok, Seton was) able to excavate around the roots of big bluestem plants that had been grazed off to just a few inches of leaf height, as well as ungrazed plants with leaves around 12 inches high.

Here is the excavation spot in the burned/grazed patch.

Here is the unburned/ungrazed excavation site.

As Seton started blowing soil away from the roots (and I photographed the process with my camera and our drone), one of the first things that became obvious was the relatively shallow depth of the main root mass.  The work of J.E. Weaver and others has shown that prairie plants, including grasses, have some very deep roots.  However, more recent work, including that of Jesse Nippert of Kansas State, Dave Wedin at the University of Nebraska, and others, has shown that those grasses don’t appear to actually use those deep roots for much.  In fact, grasses tend to concentrate the vast majority of their root masses in the top foot or so of the soil profile, effectively monopolizing most of the moisture and nutrients there.  Forbs tend to pull most of their resources from below that, and shrubs work at even greater depths.  I’ll write about this more in a future post, but for now, just trust me when I say that this is abundant evidence for this (and many more questions being pursued).  Prairie grasses can have deep roots, but it’s the incredible root density at shallow depths that they most rely on, even during drought.

With the air spade, we could pretty easily see that most of the big bluestem roots were in that shallow depth, and only a few extended down below that.  However, as Seton pulled out fully-excavated clumps of big bluestem shoots and roots, my initial reaction was one of disappointment.  There didn’t seem to be any obvious difference in the density of roots or size of the overall root mass between the grazed and ungrazed plants.

Marissa and Seton examine the roots in the partially excavated grazed site.

Seton examines some of the roots dug out of the burned/grazed site.

My immediate thought was that because these plants had only been exposed to grazing for about a month, maybe there hadn’t been enough time to see changes in their root masses.  In addition, it might be that some of the roots were no longer active, but were still connected to the root mass for now.  We’ll be repeating this excavation process later in the season, and might see differences then that aren’t yet obvious.  In addition, we’ll look at some roots of grasses that were heavily grazed all of last season and see what those look like.  Still, I was a little disappointed not to see a bigger visual difference.

However, when Seton and Marissa looked at the roots, they pointed out something I hadn’t initially seen because I was so focused on root length and density.  The diameter of most of the roots of the ungrazed bluestem appeared to be considerably larger than those of the grazed plants.  We were working with a small sample size, but among all the plants we dug up, that size difference seemed to be pretty consistent.

An ungrazed clump of big bluestem on the left and grazed on the right.  You can’t see the length of all the roots in this image (they were similar between plants) but the ungrazed roots are noticeably thicker than the roots of the grazed plant.

Here’s another look at the difference in root thickness between the grazed plants (top) and ungrazed (bottom).

Marissa explained that thicker roots have more carbohydrates stored in them.  Plants that have been defoliated, and are trying to regrow shoots, have to pull carbohydrates from their reserves to do so – pulling them out of their roots and putting them into aboveground growth.  Whether those roots kind of deflate as the carbohydrates are pulled from them or stressed plants just create skinnier roots is something Marissa and Seton are hoping to learn from their work.  Regardless, carbohydrate storage plays into competitive ability.  Grasses rely on their storage capacity to fuel growth and withstand further stress, so differences in root diameter could be part of the answer to why grazed grasses are less competitive.  Seton and Marissa plan to examine some cross sections of the roots we dug up to see if they can see more under a microscope than we could by just looking at the roots with our naked eye.

Seton and Marissa’s actual scientific explorations will give us much better answers to questions about grazing impacts on grass roots than simply looking at a few samples, but it was fun to see the actual roots themselves.  While the differences between grazed and ungrazed plants weren’t as stark as I’d expected, I’m still looking forward to our next effort later this summer – especially because all I have to do is photograph the results of the hard work Marissa and Seton are doing!

If you’re interested, here is a short 1 minute drone video showing the excavation process.  You can also check out Seton’s science website here.

Special thank you to the Nebraska Environmental Trust for funding our drone purchase through a PIE (Public Information and Education) minigrant, administered through the Nebraska Academy of Sciences.

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

The Bench Strength of Prairies in the Face of Climate Change

In case you hadn’t noticed, the climate is changing.  Things are getting weird, and they’re going to get weirder.  Here in central North America, we’re expecting more and more intense storm events and drought periods in the coming decades.  Scientists are scrambling to figure out how to predict and facilitate the inevitable changes those crazy weather events will bring to natural systems, including prairies.

Fortunately, prairies have been training for this for a very long time.  A few months ago, I wrote a post about the resilience of prairies, and how that resilience is built largely upon the diversity within their ecological communities and the size and connectivity of prairie habitats.  Prairies that are relatively big and still have the majority of their potential plant and animal species are going into this encounter with rapid climate change with what you might call solid bench strength.

Diversity of plants and animals is the keystone to ecological resilience. The Nature Conservancy’s Nachusa Grasslands, Illinois.

In sports, teams want to have lots of available players that represent a broad diversity of skills.  Each opponent they face will have its own individual mix of power, endurance, speed, and other attributes.  A successful team can build a roster for each game that counters their opponent’s strengths, no matter what they are.  The number and quality of their players is a team’s bench strength.

Healthy prairies have great bench strength too.  No matter what gets thrown at them, they can adapt by changing their roster of species.  The speed at which they can drastically change the makeup of their “team” is impressive.  Anyone who has spent many years watching the same prairie has seen this in action, but none of us have seen prairies go through what Professor John Weaver saw back in the 1930’s and 40’s.

Weaver, one of the best known prairie ecologists of all time, had been studying 30 “large typical prairies” across parts of Nebraska, Iowa, Kansas, and Colorado prior to the start of the Dust Bowl era.  His baseline data gave him an invaluable opportunity to document the dramatic changes to the plant communities of those prairies during and after the droughts of the 1930’s.  What he recorded, along with his former student F.W. Albertson, was an incredible testimony to the dynamism and resilience of those prairies.  Their 88 page 1944 publication, entitled “Nature and Degree of Recovery of Grassland from the Great Drought of 1933 to 1940”  encapsulates the bulk of their findings in one place, and is worth a read if you have the time.

In 2012, we got a small glimpse of what Weaver and Albertson saw in the 1930’s, but our drought – while severe – only lasted one year here in Nebraska.

In 2013, the response of the prairie to the 2012 drought included some explosions of wildflowers, including shell leaf penstemon (Penstemon grandiflorus).

One of the biggest plant community shifts Weaver and Albertson documented was the widespread and dramatic death of grasses such as big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), and Kentucky bluegrass (Poa pratensis), and the subsequent rise of other grasses such as prairie dropseed (Sporobolous heterolepis), sand dropseed (Sporobolous cryptandrous), porcupine grass (Stipa spartea), and most of all, western wheatgrass (Pascopyrum smithii).  Western wheatgrass populations exploded throughout the mid to late 1930’s, to the point where many prairies were completely dominated by it, to the near exclusion of other plant species. In fact, in a 1942 publication, Weaver said the following, “The large area of drought-damaged true prairie and native pasture now dominated by western wheat grass and the harmful effects of the successful competition for water of western wheat grass with species of greater forage value present a problem of much scientific interest and great economic importance.”

In other words, as they made massive substitutions within their lineups, prairies were changing so much they became almost unrecognizable, even to those who knew them best.  Weaver and Albertson watched waves of forb species they’d always considered to be of little value become stars on the field, and they and others didn’t quite know how to react.  Daisy fleabane (Erigeron strigosus), Missouri goldenrod (Solidago missouriensis), and heath aster (Aster ericoides) were all examples of wildflowers that suddenly rose to prominence in new and major ways.  The two dismayed scientists described how heath aster, a “nearly worthless native forb,” formed near monocultures across wide swaths of prairie, to the extent that it “ruined many of the prairies…for the production of hay, because of its brush-like growth.”  Others were out of their depths on this too, and Weaver and Albertson reported that “considerable native sod was broken because of the seriousness of this pest.”  In the following sentence, however, they begrudgingly added a short sentence, “Of course, it did protect the soil.”

While Weaver and Albertson considered heath aster to be “nearly worthless” it plays an important role in the prairie, and is an important food source for pollinators in the fall.

Exactly.  While the strategy was foreign and frightening to those who hadn’t seen prairies dealing with these kinds of conditions before, those prairies were just doing what they’ve done many times before – making whatever roster adjustments were necessary to keep functioning at a high level.  In addition to forb species they denigrated as weeds, Weaver and Albertson noted that many wildflowers with “large storage organs”, including bulbs and corms, also greatly expanded their population size during the dust bowl years.  This included species like Violet wood-sorrel (Oxalis violaceae), bracted spiderwort (Tradescantia bracteata), windflower (Anemone caroliniana), and wild garlic (Allium canadense).  Those species and others increased the size of the patches they’d occurred in previously, but also were found “in many new locations.”  Other native forbs that became superabundant in some prairies, especially early in the dust bowl years, included prairie ragwort (Senecio plattensis), white sage (Artemisia ludoviciana), and yarrow (Achillea millefolium).

Windflower (Anemone caroliniana) was one of the wildflowers with “large storage organs” that proliferated during the droughts of the 1930’s.

As rains started to return in the early 1940’s, Weaver and Albertson watched with amazement and renewed optimism as plant communities started “recovering”, which of course meant they were returning to a composition more familiar to the people observing them.  Grasses were often the first to rebound in prairies, including big bluestem, which initially formed large and lush monocultures in many places.  Wildflowers that hadn’t been seen for seven years or more, suddenly appeared everywhere, including blue-eyed grass (Sisyrinchium campestre), which grew “more thickly than if the stands of 7 normal years had been combined.”  Downy gentian (Gentiana puberula), which had been considered rare prior to the big droughts, became much more common in the early 1940’s than Weaver and Albertson had ever seen before, with abundances of “15 or more plants in a space of a few rods”.

Stiff sunflower (Helianthus pauciflorus) returned fairly quickly to “normal abundance” by 1943, as did many others, including silverleaf scurfpea (Pediomelum argophyllum), cream wild indigo (Baptisia bracteata), and buffalo pea (Astragalus crassicarpus).  Prairie violets (Viola pedatifida), pussy toes (Antennaria neglecta),  and others came back more slowly, but returned nevertheless.  Importantly, those returning species didn’t appear to be traveling from long distances.  Instead, they simply re-emerged, either from seeds or underground buds, from where they’d been sitting on the metaphorical bench, awaiting the call to step up to the plate again.

Buffalo pea (Astragalus crassicarpus) and many other wildflowers recovered from the long droughts at a speed that amazed Weaver and Albertson.

The prairies we know today have been through a lot.  In Nebraska and surrounding states, we have specific documentation of the kinds of extreme roster changes prairies can and have made to adjust to the world around them, thanks to the work of John Weaver and F.W. Albertson.  If you have a favorite local prairie, and I hope you do, it’s important to remember that the way it has looked for as long as you’ve known it is only a small sample of what it’s capable of.  Smart teams don’t reveal their secrets before they need to.

As we work to keep prairies healthy through this period of rapid climate change, it’s both useful and reassuring to remember what they’ve been through before.  Today’s prairies certainly have additional challenges to deal with today, compared to the dust bowl days (more invasive species, more landscape fragmentation, etc.), but many should still have sufficient bench strength to make the adjustments they’ll need to make in the coming years.  Our responsibility is to provide management that helps prairies sustain their plant and animal diversity, as well as to protect prairies from additional conversion to cropland or other land uses.  Where possible, restoring prairie habitat around and between prairie fragments can also help build resilience.  In short, we have to allow prairies to do what they do best – adapt and adjust.  Prairies are wily veterans and they’ve been in this game for a long time.  It’s a good bet they’ve still got a few tricks up their sleeve.

Measuring Our Influence as Conservation Scientists

I am a conservation scientist.  Like any other scientist, I develop and test hypotheses, trying to figure out how the world works.  Once I learn something, I publish my results in academic journals where other scientists can evaluate and build upon what I’ve learned.  Because I’m a conservation scientist, however, I also need make sure the people who directly impact prairie conservation (ranchers, land managers, policy makers, etc.) get my information and use it to improve the way grasslands are managed and restored.  If I fail to influence the actions of others in positive ways, I fail as a conservation scientist.

It doesn’t matter how much we learn about employing prescribed fire effectively if we’re not able to help others use the lessons we learn.

In science, keen observational skills and creativity often spark innovations, but rigorous collection of data is required to see whether a great idea actually makes sense or not.  While I’ve had some good ideas, I’ve also come up with plenty of grassland management and restoration strategies that turned out to be duds.  In each case, I learned a little more about prairie ecology and our land stewardship improved as a result.

I’m proud of the work I’ve done over the years to develop new and better ways of restoring and managing prairies.  I know those strategies are effective because I’ve spent a tremendous amount of time testing them, through both observation and rigorous data collection.  My computer is full of spreadsheets and graphs showing how prairie species and communities respond to various treatments.

I’m also proud of the work I’ve done to share what we’ve learned with others, but until recently, I’ve done very little to evaluate the effectiveness of that work.  I’m not alone – most of my colleagues in the world of conservation science do a great job of measuring the natural world and its responses to human activities, but do very little to evaluate whether their work is actually influencing conservation.  It’s fairly ridiculous when you think about it.  We would never think of devoting ourselves to a new invasive species control technique without testing its effectiveness, but for some reason we’re satisfied to rely on blind optimism that our outreach strategies are changing the world.

Come on, folks!  We’re scientists!  We love data, and we’re good at developing and testing ideas.  Why do we apply that passion and aptitude to only part of our work?  Why aren’t we testing whether our ideas are reaching the intended audience and influencing on-the-ground conservation work?  How can we adjust and improve our outreach strategies if we don’t have any data to work from?

To be fair, measuring outreach impacts requires a very different kind of scientific approach than most of us are comfortable with.  Instead of counting plants or observing behavior of birds, bees or bison, we have to assess the attitudes, motivations, and actions of people. Many of us took our career paths because we prefer the company of birds, bees and bison to people, but that doesn’t give us leave to just ignore people altogether – especially when the success or failure of our work hinges upon their actions.

Fortunately, we don’t have to work alone.  There are lots of scientists who are already good at studying people, and many of them are happy to work with us.  I’ve had very enthusiastic responses from those I’ve asked advice from, and their input has been very helpful.

We should probably take some of the energy we spend studying animals and put it towards studying the way people respond to our outreach efforts.

Whether you’re a scientist who actively shares your results with your target audience, or someone who relies on others to translate and transmit that information, there are some basic questions we should all be trying to address.  This is far from a comprehensive list, but it’s a start.

Defining Audience and Message

What lessons and messages from my work are most important?

Who is the audience for those?

What messengers/media will best reach the audiences?

What are the current attitudes/actions of my audience?  What are the main drivers of those those attitudes and actions?

Who are the credible voices my audience looks to for guidance?

How can I reach those credible voices?

Evaluating Success

Are my messages reaching my target audience?

How many people in that audience am I reaching?

Are my messages changing attitudes and/or actions?

At what scale, and to what degree am I making a difference?

Which messages, messengers, and media are most effective for reaching each of my audiences?

Many of us host field days, at which we can share what we’re learning with others.  How many of us are assessing the effectiveness of those field days and other outreach strategies?

I’ve spent a lot of time thinking about audiences and messages, and it’s really helped me focus both my research and outreach more effectively.  Recently, I’ve also started trying to answer some of the questions in the above “Evaluating Success” category.  I’m making some progress, but I need to do much more.

I can tell you how many presentations I’ve given over the last two years (40) and how many people were in those audiences (3,447).  I’ve also been keeping track of calls and emails asking for advice on prairie restoration and management.  Unfortunately, while I have a lot of numbers, I can’t easily translate them into acres of improved management or enhanced habitat quality.

I have, however, made at least some progress toward measuring conservation impact on the ground.  Much of that success came from survey work by one of our first Hubbard Fellows, Eliza Perry.  Eliza conducted interviews with some land managers and private lands biologists who had attended field days at our Platte River Prairies.  Among her many findings were that almost all respondents said what they learned from us had influenced their work, and they conservatively estimated that over 330,000 acres of land had been restored or managed differently because of that influence.  Beyond that, Eliza was able to identify key factors that led to our success and suggest ways to improve our effectiveness.

In addition, Eliza surveyed readers of The Prairie Ecologist Blog and I conducted a follow-up survey three years later.  Those surveys helped quantify the demographics of readers (e.g., about 2/3 of respondents have direct influence on prairie management).  The surveys also measured the degree of influence the blog has on readers’ understanding of prairies and approach to managing or restoring prairies (when applicable).  We even got a rough estimate of the number of acres on which management had been influenced by the blog (over 300,000).

Being able to quantify outreach impact, even when the numbers are fuzzy and incomplete, has been really helpful.  It helps me justify my job, for one thing, and assures both me and my supervisor that the time I spend writing, giving presentations, and consulting with others has value.  Most importantly, it helps me assess what is and isn’t working and adjust accordingly.

While it’s still not fully within my comfort zone, I’m trying hard to make sure I’m measuring the effectiveness of our outreach efforts, just as I do our prairie management and restoration work.  I would love to hear from people who are trying to do the same thing, especially if you’ve found effective evaluation strategies.  As more of us focus on measuring the success of our outreach work, we’ll be able to learn from each other and establish some common metrics.  Hopefully, we’ll also become more effective at translating what we’re learning into large scale and meaningful conservation impact!

Pondering Winter Wildlife Cover From My Comfy Couch

It’s a good ol’ fashioned blizzard here today.  As I’m sitting snugly in my warm house, I’m feeling a little badly for some of wildlife out there in the snow and wind.  The boys went outside to play in the snow for a little while, and both of them spent most of their time building shelters from the weather.  Many wildlife species, of course, migrate to warmer places or find/build themselves underground burrows to overwinter in, but there are some animals out there in the prairie right now, and this has to be a bad day for them.

Calvin was able to dig out a little shelter in a drift. He was still pretty glad to come in and get some hot chocolate a few minutes later…

Sitting here on my comfortable couch, I’ve been thinking about the prairies I manage or help with, trying to remember what kind of cover is out there.  Overall, I feel pretty good about the situation.  Our shifting habitat mosaic approach involves providing a wide range of vegetation structure types in each of our prairies, including everything from short sparse vegetation to the kind of thick dense cover wildlife are probably seeking out today.  Nelson  (our Platte River Prairies land manager) and I have periodic conversations in which we try to envision ourselves as creatures that prefer various habitat types.  How far would we have to travel to find cover?  If we burn one patch of dense cover, where is the next closest patch of similar cover, and what would animals have to travel through to get to it?  We have a lot of factors to consider and balance as we discuss management plans each year, so it’s always helpful to see the world through the eyes of the various species that will have to live with (literally) the decisions we make.

To be completely honest, I probably don’t think enough about winter cover as I’m trying to consider the perspective of various creatures.  I’m more often thinking about nesting habitat for birds, breeding cover for small mammals, or sunning areas for invertebrates and reptiles that need to thermoregulate during the growing season.  Days like today are a great reminder that while all those considerations are important, at least some species will probably live or die based on what kind of shelter they can find during winter storms like the one roaring outside right now.

Many parts of our family prairie have pretty short vegetation structure during the winter, but we always try to leave some patches of taller grass as well.  This is kind of in-between.  It’s not really dense enough to provide great cover from the wind, but has places for small animals to hide while they’re out feeding.

I’m thinking today about meadowlarks, for example.  As I’ve walked our prairies during the last month or two, I’ve seen a lot of meadowlarks flying around in small groups.  My understanding is that meadowlarks that breed around here head south to Kansas or Oklahoma, and the ones we see during the winter come from up in the Dakotas.  In other words, meadowlarks don’t migrate en masse to one general destination.  Instead, each bird just goes a little southward from where they spent the summer.  I wonder if they each wait until they start seeing birds from the north show up and then head south to get away from the crowd…

Regardless, birds like western meadowlarks need some kind of shelter out in the prairie on days like this.  We know a lot less about the winter habitats used by grassland birds than we do about summer habitat use, and as far as I know, no intrepid biologist has yet gone out to see where meadowlarks or other birds are hanging out during blizzards.  (If you’re an intrepid biologist who HAS done this, please let me know!)  I think it’s fair to assume that most birds (and any other wildlife who aren’t underground) try to get out of the wind during this kind of storm.  It’d be interesting to know whether they stay in open grassland and look for tall dense vegetation or venture into brushy or wooded areas where they might not normally go.

Somebody is apparently sheltering in place under the snow here.  Probably not a meadowlark…

Not knowing much about individual wildlife species and how they each choose to shelter from winter storms, I guess the best strategy is to provide as many habitat types as possible so they can all find what they need.  That way, meadowlarks can forage in short or “weedy” areas during pleasant sunny days, but move to a nearby patch of dense grass (or whatever other cover they like) when they need to nestle in thatchy vegetation and get out of the wind.

Here in our comfy house, we’ve been talking about trying to fix the drafty corner of our kitchen, where one of our walls needs a little better insulation.  Our poor little feet get cold when we’re making toast on windy winter mornings!  It’d be really nice to get that fixed.  On the other hand, it’s just the kind of hardship that helps me understand what meadowlarks are going through on days like this.  I bet their feet were cold at breakfast time too…

 

Meadowlarks could learn from opossums, who either take over abandoned burrows from other mammals or find a nice wood pile to shelter in during cold weather and blizzards.

Why Would Bison Have Done That??

I have an honest and earnest question:  What do we actually know about the movement and grazing patterns of historic bison herds in North America?

I’ve heard many similar versions of a story about the way in which historic bison herds moved across the North American prairie in pre-European days, but I’ve never been able to find someone who can substantiate it.  I’m not sure where the story (legend?) came from, but it seems to have become canon among many people in the grazing world.  It is particularly used by advocates of intensively managed grazing rotations, who say their grazing strategies mimic what bison did historically.

The most common variation of the story goes something like this: Back in the old days, bison herds were constantly on the move across the plains, grazing and stomping down the prairie as they went.  A bison herd would move into an area, stay briefly, and then move on – leaving behind short-cropped and trampled vegetation, which would get plenty of time to recover before another herd passed by.  The constant movement of bison was driven by humans, wolves, and other predators, who were constantly nipping around the edges of herds, picking off weak animals and keeping the herd moving.

I’m not saying the story is wrong, but I’m fairly skeptical.  Based on both observations and an impressive array of data from around the world, large grazing animals show a strong preference for recently burned and/or recently grazed vegetation.  The lush regrowth of grasses that have been recently burned or grazed is usually the easiest, tastiest, and most nutritious available, especially relative to undisturbed plants that are more mature.

This small area (a few hundred acres within a 12,000 acre pasture) of regrowth from a 2015 hay cutting became a predictable spot to find grazing bison during the remainder of that year and through 2016.  The animals visited the patch often, re-grazing many of the same plants over and over.  The Nature Conservancy’s Niobrara Valley Preserve.

In studies of patch-burn grazing, where cattle or bison are given access to both burned and unburned patches of vegetation, they graze spend something like 70% of their time grazing recently burned areas (and they stay on those areas most of the growing season), even when those burns make up a small percentage of the overall pasture.  The same pattern occurs in both small (a few hundred acres or less) and large pastures (10,000 acres or more).  These results are not coming from a few studies here and there; this is a large and comprehensive body of scientific research.  Bison and cattle are very good at optimizing their own diets, and when they are given the opportunity to regulate their own movements, without cross fences in the way, their optimal diet comes largely from recently burned and/or recently-grazed vegetation.

Given what we know about how bison and cattle (and many other large grazers) select their diets and grazing locations, how can that fit with the story I shared at the beginning of this post?  Why would bison have moved away from burned prairie into unburned/ungrazed grass that was more mature and less nutritious?  If they were forced to move from a particular place, why wouldn’t they have later circled back to graze the regrowth?  Many historic prairie burns, whether set by people or lightning, must have been of considerable size – probably plenty big to keep a herd of bison content for a full season, even if they were constantly bouncing around that burned area to stay ahead of predators.  No?  I just have a hard time imagining large areas of attractive, nutritious vegetation being sampled briefly by large herbivores and then abandoned and allowed to grow uninhibited for the remainder of the growing season.

I understand that much of our research on grazing patterns today is lacking the kind of predator pressure bison might have been under a few hundred years ago, and even a 10,000 acre pasture restricts the ability of bison to freely move across the landscape.  Given that, I’m open to the idea that movement patterns were different long ago than they are today.  Even so, I have a hard time imagining that bison wouldn’t have done everything they could to return to areas they knew contained high quality forage, even if they were being constantly pursued.  Can anyone provide some evidence to support that story?

In historic prairies, many patches of high-quality forage would have been transient (e.g., burned areas that were grazed for a season or so and then allowed to recover as bison switched to newer burns), but prairie dog towns might have represented a consistent supply of high-quality regrowth, and likely hosted fairly frequent visits from bison.

Even assuming (and I’m not) that bison herds were constantly on the move, never circling back to where they’d been earlier, it still seems unlikely that recently burned prairie would have been grazed for more than a few days and then just allowed to grow uninhibited for the remainder of the season.  Surely those burned areas (and later in the season, burned and previously grazed areas) would have been magnets for any other herd wandering nearby, and would have been grazed repeatedly (by a succession of nomadic herds) throughout the growing season?

Why does all of this matter?  In a way, it really doesn’t, other than for the sake of curiosity.  As I’ve discussed before, the way we design prairie management strategies should be based on today’s world, challenges, and objectives.  For example, it doesn’t make any sense to burn a prairie every three years just because we know that was the average historic fire frequency in that landscape.  The same is true with historic grazing patterns.  With increased levels of nitrogen deposition, woody plant encroachment, and habitat fragmentation, not to mention invasive species and climate change, today’s world is not the same as it was at whatever mystical point in history we might choose to try to replicate.  We have to manage today’s prairies in ways that make sense today.

Having said that, history does matter when it helps us understand how plant and animal species used to respond to the world around them, and what current adaptations and traits they have as a result.  That understanding can help us design and evaluate contemporary management strategies that fits with those adaptations.  It doesn’t mean we try to replicate history, it just means that we incorporate our understanding of it as we move forward.

Cattle seem to exhibit the same preferences for grass regrowth as bison.  These cattle are grazing in a burned patch in our Platte River Prairies this year.  That burned patch was grazed repeatedly and intensively all season while adjacent unburned areas were only lightly grazed.  The cattle were very selective, grazing mostly on their favorite grasses because of a moderate stocking rate.

If we’re going to incorporate a historic context into today’s strategies, however, we should make sure we’re as accurate as we can be about that history.  As I mentioned earlier, advocates of management-intensive grazing (and/or mob grazing, small cell grazing, and other similar strategies) mention the historic bison story often as a reason for managing cattle as they do today.  Because they contend that bison moved quickly across the historic landscape, never staying long in any one place, they propose that we manage cattle herds in that same way today.  I’m not saying those rapid rotation systems are right or wrong, I’m just wondering whether the historic context used to justify them is accurate.  I can’t understand why bison would have done what they’re supposed to have done, and would love to see evidence either way.

Even if bison were pushed off of areas they preferred, why wouldn’t they have returned later to take advantage of the nutritious forage?

I personally prefer the way prairies and wildlife respond to the kind of shifting mosaic approach we (mostly) employ on the sites I’m involved with, but that’s because I have a particular set of objectives, and I measure success based on those.  My personal guesses and extrapolations about how historic bison herds might have interacted with the landscape play a role in why I like our current approach, but they’re not really a major factor.  If I find out that historic bison acted very differently than I think they might have, I’ll appreciate that knowledge, but I’ll still evaluate our current strategies based on the objectives we have for today.  I will, though, pay closer attention to hints that species or natural communities might be showing stress due to exposure to conditions they’re not well adapted to.

Mostly, I’m just curious, and tired of listening to the same old story without knowing if it’s true.  Can anyone help me?

ADDENDUM:  Since writing this post a couple people directed me to this excellent article by Richard Hart that addresses my question fairly well.  Thanks to those of you who shared it!

Open Gate Rotational Grazing

An alternative approach to facilitating wildlife and plant diversity in grazed prairie.

Based on the last 20 years of experience and data collection, the shifting mosaic approach to habitat management seems to support plant and animal diversity and foster ecological resilience in our prairies.  One of the most important parts of our shifting mosaic management is that each patch of prairie goes through a progression of season-long intensive grazing, followed by a multi-year recovery period.  At any time, only part of a prairie is in each phase of the system (intensive grazing, early recovery, late recovery), so there is always a variety of habitat structure available (short, “weedy” and tall) for wildlife.  In addition, as that grazing/recovery progression occurs, plant species experience a different set of growing conditions each year.  Regardless of its competition ability or strategy, each plant is ensured favorable conditions for its growth and reproduction at least once every few years.  Based on our long-term data sets, our management has sustained plant species richness, and both conservative and opportunistic plant species are persisting in our prairies.

A fenceline contrast at our family prairie shows the kind of habitat heterogeneity found in a shifting mosaic approach to prairie management.

Patch-burn grazing is one way to create a shifting mosaic, but it’s certainly not the only way.  While patch-burn grazing has some attributes that make it easy to implement (no need for cross fences or moving animals during the season), it does require regular application of prescribed fire, which can be difficult for some landowners.  In addition, patch-burn grazing is very different from the kinds of rotational grazing systems many ranchers are comfortable with and have set up their pastures for.  We’ve been experimenting with an approach to creating a shifting mosaic that keeps many of the wildlife and diversity-friendly attributes of patch-burn grazing but might fit better within the comfort zone and logistical framework of many ranchers.

For lack of a better idea, I’m currently calling this approach “Open Gate Rotational Grazing”.  It is not a rigid prescribed grazing system, but rather a general and adaptable way of managing multiple grazing paddocks within a prairie.  It’s similar to a traditional deferred grazing strategy, but with one big difference.  In most rotational grazing systems, cattle are moved from one pasture to the next, closing the gate behind them to allow the previous paddocks to rest.  In the open gate system, when cattle are presented with their next paddock, the gate behind them remains open – allowing the cattle to continue grazing the initial paddock even as they have access to new grass.

In a traditional rotational grazing system, cattle are progressively moved through a series of paddocks, closing the gate behind them.  In a deferred rotational system, at least one paddock is usually rested for the season.

Under an open gate approach, gates are left open when new paddocks are made available, allowing cattle to graze both the new paddock and the one(s) they had been grazing before.

The idea started one year when we weren’t able to get a burn done in a prairie under patch-burn grazing management.  Since we didn’t have a burned patch to focus cattle grazing, we instead used electric fence to concentrate the cattle in the area we’d hoped to burn.  We kept them in the enclosure until they had it grazed pretty short.  Then we removed the electric fence and allowed cattle to access to the whole site.  For the remainder of the season, the cattle continued to focus most of their grazing in that former enclosure, attracted by the tender regrowth.  As a result, the overall grazing pattern was fairly similar to what we’d expect with patch-burn grazing.  Seeing how strongly cattle were drawn back to where they’d grazed earlier provided the seed for the open gate rotational system.

On my family prairie, I’ve been using the open gate approach for the last several years.  I have four paddocks, and I basically think of the gates between those paddocks as relief valves.  We start with the cattle in one paddock, and when they have grazed most of the grass down in that pasture, I open the gate to an adjacent paddock so they have more options.  The cattle can keep grazing the regrowing plants in paddock #1, but they aren’t forced to eat more than they want to in that paddock because they have another whole paddock available to them.  If the cattle graze down most of the plants in the second paddock, I can open a gate to a third paddock and provide them with even more options.  I keep the fourth paddock closed off for the entire season so it can rest.  I choose a different paddock to start with each year.

The result of an open gate approach is that one paddock is grazed all season long, one is rested all season, and the others have intermediate levels of grazing.  This results in heterogeneity of habitat structure as well as a wide range of growing conditions for plants.  Each year, grazing starts in a different place, shifting the disturbance regimes among the various paddocks.

The open gate approach can be used with just about any rotational grazing system, as long as there are adjacent paddocks that can be opened up.  One key component of the open gate approach is that paddocks grazed early in the season continue to receive grazing pressure for the rest of that season without forcing cattle to eat progressively lower quality forage as the season goes on.  Instead, cattle can regulate their diet freely, choosing between previously grazed areas and those they haven’t yet grazed.  Typically, when cattle are given that kind of choice, they eat very little other than grasses.  This works out well for pollinators because it means many wildflowers are allowed to grow and flower amongst grazed grasses.

At our family prairie, the open gate approach seems to be helping with our continuing quest to increase plant diversity in areas formerly dominated by grasses.  New plants are introduced via overseeding (after a season of intensive grazing), and then persist under our grazing management.

In the open gate system, there is great flexibility about when, and how intensively, each paddock is grazed each year, though some of that flexibility depends on how the paddocks are arranged.  Ideally, all the paddocks would be connected through a single hub so the manager can choose to open any gate to any pasture, as needed.  However, my family prairie doesn’t provide that amount of flexibility (the four paddocks are arrayed in a donut-like loop, with no way to connect them through the donut hole) and the approach still works.  Most of the time, the paddock grazed most intensively one year gets complete rest the next.  However, the pattern of grazing each year always depends upon how I think recovery from previous years’ grazing is going.

I think there are great benefits to longer grazing periods and longer rest periods than are typically found in rotational grazing systems.  Certainly, those prolonged grazing and rest periods can provide a greater variety of wildlife habitat conditions, especially on the shorter and taller ends of the vegetation structure spectrum.  In most rotational grazing systems, cattle are moved out of a pasture before grasses are grazed very short, allowing them to recover quickly.  In addition to reducing habitat heterogeneity, that approach can favor strong grass dominance at the expense of wildflowers and plant diversity.

Even when grazing pressure is intense within each paddock of a traditional rotational system, short duration grazing may not foster habitat heterogeneity.  For example, if a paddock is grazed hard in May, it might suppress cool-season grasses, but warm-season grasses won’t be much affected, and once cattle are removed, summer vegetation will fill in quickly, resulting in vegetation structure of moderate to tall height.  The same can happen with summer grazing bouts followed by fall growth of cool-season grasses.  By maintaining grazing pressure for the entire growing season, two things happen.  First, there is sustained short vegetation structure for wildlife that need it.  Second, and perhaps more important, all dominant grasses are weakened by that long term grazing, leading to a fairly long recovery period (1-3 years, depending upon grazing intensity and geographic location), during which wildflowers and other plant species are temporarily released from that grass competition.  That long recovery period creates terrific wildlife habitat and also helps sustain plant diversity.

While prescribed fire isn’t necessary in open gate rotational grazing, it can certainly be incorporated.  The paddock to be grazed all season could be burned before the season starts, for example, which would further add to its attractiveness to livestock (and remove eastern red cedar trees, excess litter, etc.).  At my own prairie, I haven’t been using fire for a variety of reasons, including that I’m so busy burning for work I don’t have time/energy to burn my own place.  So far, I’ve been happy with the way the prairie is responding in the absence of fire, but if I can get myself better organized, I wouldn’t mind doing some burning.  If nothing else, it would mean less time cutting little cedar trees with loppers.

Prescribed fire is not a strategy all ranchers are willing or able to include in their operations.  The open gate approach provides options for creating a shifting habitat mosaic without relying on regular prescribed fire.

I don’t have many years of experience with this open gate approach, or much data to help me understand all the nuances of its impacts on flora and fauna.  However, what I’ve seen from early experiments seems promising.  I’m sharing the idea and our experiences so far, not because I’m endorsing the open gate approach as the next big thing, but because I hope others might find ways to try it and report back.  Because the basic idea is as simple as not closing a gate when opening a new paddock, it can be employed in many different scenarios if people see potential for it.  Also, I’m not trying to claim or patent the idea, and I’d be shocked if there aren’t people reading this that have already tried it in various forms.  If so, I’d love to hear about it.

A Hopeful Metaphor for Prairie Managers

Recently, I listened to a conference presentation by Doug Ladd, the Director of Conservation for The Nature Conservancy in Missouri, and one of the smartest people I know.  Doug talked about the importance of conserving biodiversity, habitat diversity, essential ecological processes, and irreplaceable habitats and species, and stressed the need to better connect people with nature.  It was an excellent talk, and I could spin many of his points into entire blog posts.  For now, however, I want to focus on one short phrase he uttered, which relates to something I often think about.  The phrase was “There is no endgame in conservation.”

The importance of that phrase might not strike you immediately, but for those of us who dedicate much of our lives to prairie conservation, it’s an idea we need desperately to come to terms with.  No matter how much time and effort we put into restoring or managing prairies, we won’t ever reach a place where we can stop and just let nature handle the rest.  Many people harbor the romantic notion that if we could make prairies big enough and provide them with their full complement of species – including everything from soil microbes to bison, we could step away and the system would run itself without human intervention.  Unfortunately, that’s just not the way it works.  Nature relies on people just as much as we rely on nature, and it’s really not even fair to mention nature and people as if they are two distinct entities.

Even in places like the Nebraska Sandhills, with roughly 12 million mostly contiguous acres of prairie, the role of humans is still critically important and necessary.

Because there is no endgame in prairie conservation, we need to develop an appropriate mindset. Most importantly, we have to be able to look at the future without despair.  As an example, it’s easy to look at many grasslands and wonder how we can possibly deal with all the invasive species threatening the site today, let alone all the new ones that will inevitably join them.  It can feel like trying to hold back a river with a garden hoe.  Issues like habitat loss and fragmentation, nitrogen deposition, and climate change just make the picture even more bleak.  Knowing that our prairies won’t ever be able to stand on their own might seem the same as knowing that we can never win.  All we can do is stave off loss for as long as possible.  That’s seriously depressing.

Since this is the life I’ve chosen for myself, I’ve thought a lot about the idea that there is no endgame in conservation, and I’ve come up with a metaphor that makes me feel a lot better about it.  I don’t see myself as a hopeless defender of prairies, trying to stave off inevitable destruction.  Instead, I see myself as part of a long series of mechanics.  I inherited the prairies I work with from prior mechanics, and someday I’ll hand those prairies off to future mechanics.  As such, my job isn’t to save the prairie, it’s to keep it running until the next mechanic takes over.  The metaphor applies to an individual manager and a single prairie, but it also applies to each generation of conservationists and the earth we’re all working to maintain.  Success is being able to hand off a functioning prairie, biome, or earth to the next generation of mechanics.

To understand my metaphor, you have to move away from the idea that most mechanics are only able to keep a particular car, for example, running for a certain period of time before it inevitably dies and goes to the scrap heap. While that is the way it usually works, it doesn’t necessarily have to be.  Imagine starting out in 1908 with a brand new Ford Model T automobile and giving a series of mechanics the charge to keep the vehicle functional forever.  For a while, keeping the car running just means replacing fluids and parts that break or wear out.  Eventually, however, there will be needed updates to parts, and even changes to the overall design of the car, so it can be adapted to keep up with a changing world.  Over time, because of changes in road design, safety and fuel efficiency rules, and needs of drivers, the car will have to be made to drive faster, brake more efficiently, use different fuel, and evolve in numerous other ways.  As each generation of mechanic finds innovative ways to keep the vehicle on the road and running well, the vehicle will be continually and repeatedly transformed.  Today’s version of the vehicle would be nearly unrecognizable to the mechanic who first worked on the Model T.  Very few original parts would remain, but today’s version of the vehicle would still perform the same essential function of transporting people and/or goods from place to place.

Prairies and other ecosystems are both easier and harder than cars to maintain over time.  On the one hand, prairies are infinitely more complex than cars, and come with many more challenges (though auto mechanics might argue that last point).  On the other hand, prairies consist of networks of living organisms, which can adapt as individuals and as communities to evolving challenges.  That inherent adaptability means that the prairie manager’s job is really to help the prairie maintain its resilience – its ability to retain its essential functions – as the world changes around it.

Just as the vehicle in my mechanic metaphor is constantly transforming, prairies and other ecosystems have to do the same, and land stewards have difficult choices to make as those changes occur.  As an example, many of today’s prairies have numerous and abundant species that weren’t even on the continent a few hundred years ago.  A profusion of introduced plants have entered the scene, some of which are apparently innocuous, and others that have dramatically changed the balance of power within plant communities.  In addition, white-tailed deer have become superabundant across most prairie regions, pollinator populations are crashing, and many other changes to animal communities have severe impacts on ecological processes.  Belowground, non-native earthworms and pill bugs are just two examples of species that have fundamentally altered the soil fauna in ways we don’t really understand.  Habitat fragmentation, high levels of nitrogen deposition, and a rapidly changing climate all combine to further drive important transformations in prairie species composition.

Yellow bedstraw (Galium verum) is a yellow flowered plant that seems to be invading low meadows in portions of the Nebraska Sandhills.  Making decisions about whether and how to address invaders like this can cause a lot of anxiety for land managers.

Fortunately, our job as land stewards is not to prevent our prairies from changing; our job is to help prairies preserve their character and function as they change, and then hand those prairies off to the next generation of stewards.  How do we do that?  We can manage for plant diversity and habitat heterogeneity to maintain ecological resilience.  We can prevent or suppress invasive species that have serious negative impacts on that resilience and diversity.  We can enhance the viability of small isolated prairies by restoring adjacent habitats and making those prairies larger and more connected.  As time goes by and conditions change, prairies will transform in ways that might make them nearly unrecognizable to land stewards of previous generations.  Rather than a sign of failure, those transformations are a sign of success, as long as they preserve the components and processes that are characteristic* of prairies.  After all, a 2017 Tesla Model 3 is a far cry from the 1908 Ford Model T, but which would you rather drive through today’s world?

*Defining the essential characteristics of prairies is something we don’t discuss nearly enough.  It seems like a simple enough exercise to outline what makes a prairie a prairie, but if you believe that, give it a shot…

Prairies like this are surely very different today than they were in the past or than they will be in the future. Change is good and healthy, as long as we can preserve the essential components and processes that define and sustain prairies and prairie communities.

Trying to Create Something Different in the Nebraska Sandhills

At our Niobrara Valley Preserve (NVP), we’re experimenting with prairie management techniques to see if we can create a wider range of habitat conditions than is found throughout much of the Nebraska Sandhills.  On many Sandhills ranches, pastures look fairly similar to each other in terms of vegetation structure.  That’s because Sandhills ranchers tend to be careful in their grazing management to avoid wind erosion that can cause “blowouts” of bare sand.  As a result, pastures are rarely grazed intensively enough to create wide expanses of bare ground.  If intensive grazing does happen, it’s usually on a small scale and/or for short periods of time, which allows for quick recovery of grasses.

The Nebraska Sandhills have tremendous innate heterogeneity.  Just in this photo, you can see areas of bare sand created by pocket gophers and/or other animals, habitat structure created by various kinds of plants, including grasses, wildflowers, yucca, and shrubs.  Vegetation height varies greatly across small areas.

Overall, the ecology of the Nebraska Sandhills seems very healthy.  It’s a huge and mostly intact grassland landscape, and because of the dry sandy soils, topography and diversity of vegetation, there is quite a bit of habitat heterogeneity that is independent of management.  As you walk across most Sandhills pastures, you will move through both short/sparse vegetation and taller/dense vegetation, and occasionally come across other structural components like yucca plants or plum thickets.  Wildlife and insect species can often find the habitat structure they need somewhere in that pasture, though it might be in a small patch surrounded by other habitat types.  That seems to be true even for many bird species, which have relatively large breeding territories.  As an example, in pastures with fairly tall vegetation, we often see and hear horned larks that are (apparently) nesting in a few small and scattered patches of the short vegetation structure they prefer.  Those patches of short habitat often occur in gravelly flat areas or in favorite feeding areas for cattle, where grass growth is weak because of frequent grazing.

This late July photo shows a portion of our west bison pasture that was burned this spring and has been grazed intensively by bison all year. Because bison are in the pasture year round, they had immediate access to the burned area and started grazing regrowth as soon as it was available.

We’re trying to figure out more about how management with patch-burn grazing or other similar grazing systems affects Sandhills ecology.  Patch-burn grazing has part of the management of our bison pastures at NVP since the early 1990’s.  Because of that, we know Sandhills vegetation can recover from fires that are followed immediately by season-long intensive grazing.  However, we still don’t know much about how many animal species might respond – positively or negatively – to the kind of large patch heterogeneity created by this kind of management.  Instead of pastures with interspersed small areas of tall and short vegetation, we’re trying to create large patches (500-1000 acre patches within 10,000-12,000 acre pastures) of each habitat type and then shift the location of those patches between years.

Plains sunflower (an annual) often becomes very abundant after fires because it germinates well in exposed soil and then thrives in the absence of strong competition from perennial grasses.  This is the current year’s burn patch in our east bison pasture, where plains sunflower tall and blooming, surrounded by short-cropped grasses.

Creating large patches of various habitat types could bring both advantages and disadvantages to different species.  As an example, large patches could create an abundance of resources that support larger and more viable populations of some animal species. On the other hand, a vole who likes thatchy habitat could wake up in the middle of a 1000 acre burn, and it would have to make a long dangerous trip to find a more suitable place to live.  Trying to evaluate those potential costs and benefits is a big challenge for us.

This landscape shot shows the abundance of plains sunflower across the entire burned patch.

One possible advantage of the kind of shifting mosaic of habitat approach we’re trying is that it helps avoid risks that come from having the same habitat conditions in the same place year after year.  Just as crop rotation can help avoid buildups of pests and pathogens, shifting habitat types from place to place could have important benefits.  For example varying the location of habitat types from year to year could limit disease outbreaks and help prevent predators or herbivores from building up large and potentially destabilizing populations.

Showy evening primrose, aka fourpoint evening primrose (Oenothera rhombipetala) where the prairie was burned in 2015 and grazed intensively in both 2015 and 2016.  This opportunistic biennial is taking advantage of a long period where grasses are weakened by prior intensive grazing and haven’t yet recovered.

The most intriguing part of our experimentation for me, though, is the idea that we could create large ‘recovery patches’ where grasses have been weakened by a full season of intensive grazing and the plant community is temporarily dominated by opportunistic, mostly short-lived plant species.  That combination of short grasses and tall ‘weedy’ wildflowers can provide excellent brood-rearing habitat for some birds and important structure for reptiles and invertebrates that need to regulate their body temperature by moving quickly from sun to shade as needed.  Studies in other landscapes have shown that this kind of recovery patch habitat creates pulses of high insect biomass, which could have numerous impacts – including the provision of an awful lot of food for wildlife.  In addition, if an abundance of opportunistic plants include species beneficial to pollinators, that could provide quite a bonanza of resources for bees, butterflies, and other insects.

Zoomed out

In most of the Sandhills, patches of  ‘weedy’ habitat tend to be in small, static and widely scattered locations such as around windmills or other places where cattle or bison frequently congregate.  We’re wondering what might happen if we created big patches of the same habitat type and shifted their location from year to year.  In our Platte River Prairies, patch-burn grazing (and similar strategies) has sustained prairie plant diversity over many years, but we haven’t looked closely for similar responses in the Sandhills.  In addition, we know a little about how birds respond to patch-burn grazing in the Sandhills, but not much about impacts on other species like lizards, pollinators, small mammals, or invertebrates.  Now we’re trying to collect data on the responses from all those different organisms.

The lesser earless lizard is often found in and around sand blowouts or other habitat patches with abundant bare sand.  Will they respond positively to much larger patches of sparse vegetation?  Can they successfully shift their population locations as we burn/graze new sites?

Will pollinators such as this plasterer bee (Colletes sp) benefit from higher abundances of flowering plants in big patches of Sandhills prairie that are recovering from season-long intensive grazing?

This is part of our east bison pasture that hasn’t burned since 2012, and has been only lightly grazed during that time period.  It should support a different array of wildlife and allow different plant species to thrive than more recently-grazed areas.  Providing a wide range of habitat types across the prairie seems beneficial for biological diversity, but we still need to test that idea in the Sandhills.

I’ve really enjoyed digging into all the questions we have about our attempts to create more habitat heterogeneity in the Sandhills.  We haven’t had time to answer many questions yet, but we feel like we’re at least creating something different than what exists throughout most of the Sandhills landscape.  A few years from now, we might conclude that the heterogeneity we created didn’t really result in any significant positive or negative impacts compared to what exists elsewhere.  If that’s the conclusion, we’ll move forward with that in mind.  On the other hand, we might find that there are some important positive (and/or negative) impacts of the shifting mosaic approach we’re testing.  In the meantime, it’s exciting to have the opportunity to try something different and watch what happens.  Stay tuned…

If nothing else, huge populations of Plains sunflower like this one in our west bison pasture provide a different (and I think beautiful) look to parts of the Sandhills landscape at the Niobrara Valley Preserve.