Tag Archives: historic

Is Prairie Stewardship Hampered By Our History Goggles?

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I often think one of the biggest issues we face in grassland restoration and management is that we’re a little too stuck in the past.  This expresses itself in various ways, but I think it’s a nearly universal issue with everyone involved in prairie ecology and stewardship.  To one degree or another, we’re all looking backward.  Let me explain.

We’ve all stood on a hill and stared into the distance, trying to envision what that view would have been a few hundred years ago.

An obvious example of what I’m talking about appears in prairie restoration (reconstruction) when someone’s goal for a prairie planting project is to create a prairie that looks like it used to look a few hundred years ago.  I hear this a lot less than I used to, which is good, given the numerous problems with that goal.  However, even those of us who claim to be focused on more practical objectives can slip up sometimes.  It just feels good to recreate something from the past, especially when the past must have been so great!

The same romanticism for the old days affects our management, too.  Regardless of what our plan says (you’ve all got a clear, written management plan, right?), most of us can’t resist glancing around and wondering what a particular site must have looked like “back in the day”.  It’s real easy to for the resulting mental pictures to start influencing the way we evaluate the condition of a prairie and the direction we try to push things through stewardship actions.  We don’t really think we can get back to what it used to be, and yet…

I see the impact of those “history goggles” all the time, both in my own head and during conversations with other prairie people.  One of the more frequent appearances comes during thinking or talking about plant community composition.  “Oh,” someone will say, “that wildflower used to be much more common before European settlement.” Or, similarly, “Those grass species never used to be as prominent when these prairies were surveyed in the 1920’s”.

Don’t get me wrong – historic plant community composition can be helpful.  It’s nice to know how things have changed because it helps us understand why, or at least helps us ask the right questions.  Answers to those questions can guide us as we devise management strategies.  Where we get into trouble is when we use past conditions as explicit targets for today’s stewardship. 

Our prairies live in a different world than prairies of old.  Habitat fragmentation, rising atmospheric CO2 rates and nitrogen deposition, climate change, and invasive species are just some of the major factors that have changed within last century or two.  We should expect prairies to adapt to those drastic changes.  After all, adaptation is one of their best features!  

Invasive species such as crown vetch (Securigera varia) and many others have drastically changed the competitive environment within prairie plant communities.

History goggles also come into play when we think about prairie management tools and tactics.  How many discussions have you been in that center on the historic frequency and/or season of fire in prairies?  As with plant composition, understanding when and how fires burned in the past can be helpful, but yesterday’s fire frequency shouldn’t automatically be today’s fire frequency.  See above for some of the major differences between historic and present-day prairies.

People who apply grazing to grasslands often wear very thick history goggles.  If I had a nickel for every time someone’s tell me their particular grazing strategy mimics what bison used to do, I’d be swimming in nickels.  I don’t want to swim in nickels.  Even if your approach somehow perfectly mirrors what bison used to do (and it doesn’t), why would that be the best approach for today’s prairies, which aren’t what they used to be?  That applies, by the way, to whatever grazing animal you’re working with – including bison. 

There are lots of great reasons to put bison in prairies, cultural, ecological, and otherwise.  Expecting them to eradicate smooth brome and reverse climate change, though, is going to lead to some big disappointment.  That doesn’t mean bison (or cattle, for that matter) can’t play important roles in today’s prairies.  In many grasslands, especially larger ones, they can manipulate habitat structure, combat the dominance of grasses, and create lots of wonderful messiness.  They can’t (or won’t), however, turn back the clock. 

Bison or other large grazers can play important roles in some prairies, but they can’t suppress rising atmospheric carbon dioxide.

We’ve got to cast off our history goggles and look forward if prairie conservation is going to succeed.  Restoration and management strategies need to be built on creating future prairies, not past ones.  That’s an uncomfortable, even scary, prospect though, isn’t it?  We don’t have any reference points in the future, after all.  It’s easier to look back (or guess) at what used to be and try to aim there.

I don’t have the answers to this dilemma.  I do have ideas.

Prairie communities really are good at adaptation.  Because of that, I think we should be looking for ways to facilitate and guide prairies as they adjust to new conditions.  One way to do that is to help them maintain the resilience they need to adapt.  We do know something about how to do that.  (Remember, ecological resilience doesn’t mean natural communities don’t change.  Instead, it’s a measure of their capacity to adapt.) 

The ecological resilience of prairies relies heavily on two factors: habitat size/connectivity and biological diversity.  The first helps the second persist and the second provides the redundancy of function that means there are species to fill crucial roles no matter what’s a prairie has thrown at it.  Making prairies bigger and better connected comes through restoration (reconstruction) efforts that build new grassland habitat adjacent to and between existing habitats.  We have lots of evidence that prairie species respond well to that kind of restoration.

There are lots of thoughts about how to manage for biological diversity in prairies, many of which seem to work well.  There isn’t a single best way to do it, and the effectiveness of practices and approaches can vary by geography, soil type, prairie size, and many other factors.  The key is to focus on the diversity of the plant community, as well as the more difficult to measure communities of animals, fungi, bacteria, and others. 

The diversity of plant and animal communities (and other taxonomic groups) is a key to the ability of prairie communities to adapt to change.

This is where I think it’s most important to push past our reliance on history.  It’s tempting to judge plant species, for example, by whether we think they used to be part of the plant community at a particular site, or how abundant they might have been.  We’re getting to the point where that may not be very relevant anymore.  That includes non-native plants, by the way. 

Now we’re getting into really uncomfortable territory for some folks but let me be clear that I’m not proposing we stop preventing the appearance or spread of all non-native plants in prairies.  What I am proposing, however, is that the native or non-native status of plants might not be the best metric to apply.  Many of us have already started down this path by looking at natives like Canada goldenrod, for example, as a species that can be problematic if it’s allowed to run rampant.  Why do we care?  Because in some places, it can become dominant enough that it suppresses the diversity of the plant community.  That’s a bad thing for ecological resilience.

Non-native plants that have the same potential to suppress diversity need to be targets for management action.  However, some non-native plants don’t suppress the diversity around them – they add to it.  I think that’s ok.  The immigration of new species into prairie communities is inevitable, so fighting it seems fruitless. 

Yellow salsify, aka goat’s beard (Tragopogon dubius) is an example of a non-native plant that seems to have joined plant communities I’m familiar with in an innocuous, if not helpful, way.

In many places, woody plants – native and non-native – are becoming more abundant in prairies.  Their success is driven largely by rising CO2 levels, which prairie managers have no control over.  That means that in some cases, we’re just going to have to figure out how to manage for biodiversity in shrubby prairies.  We don’t know enough about how to do that yet.  Instead of pouring all our limited resources into resistance, we’d be smart to start learning about how to manage the height and density of shrubs and see how plant and other communities respond.

I could go on, but I think the key point is that focusing on ecological resilience, and thus biological diversity, gives us a target to aim for as we look forward.  We can evaluate the success of our management strategies by whether they lead to increased or decreased plant and animal diversity.  If our prairies are maintaining their diversity, they should have a good chance at adapting to whatever is thrown at them. 

It’s hard to turn away from history as our reference point for success.  You know what else is hard?  Failure.  It’s frustrating to try and try to restrain prairies from moving away from what they used to be.  Why are we subjecting ourselves to that frustration?  Let’s see if we can learn how to support our favorite ecological communities as they flex their adaptation muscles and find ways to thrive in this new world.

The Role of History In Today’s Prairie Management

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Past performance is not necessarily indicative of future results.

I’m no expert in financial investing, but I’d like to retire someday, so I muddle along the best I can.  As I skim through various financial statements and investment newsletters, I often see some variation of the disclaimer above.  The concise statement emphasizes that while history is important, many factors change over time, and we shouldn’t simply assume that what happened previously should drive what we do now.

I was thinking about this statement and its implications while attending the North American Prairie Conference last month.  During presentations and hallway discussions, the topic of history came up frequently.  How often did prairies burn prior to European settlement?  Were bison only abundant in eastern tallgrass prairies after human populations crashed during the smallpox catastrophe?  What was the role of big native ungulates like elk in suppressing woody plants?

Fire

We have reasonably good data on the historic fire frequency in prairies around the U.S.  How should that information drive today’s prairie management?

Questions like those are fascinating to contemplate, and important to our understanding of how prairies have changed over time.  Which of us wouldn’t jump at the opportunity to step into a time machine and go see North American prairies in the 1400’s or other historic times?  Wouldn’t it be fantastic to somehow find and pore over hundreds of years of data on bison population numbers, plant species composition, elk feeding patterns, and lots of other grassland phenomena?  While, that kind historic data is very limited, mining what we do have is fascinating and instructive.

However, just as with stock market investments, we can’t just look to the past to guide what we should do in the future.  The business world has evolved over time.  Simply investing today in the same corporate stocks that were profitable 30 or 60 years ago wouldn’t make a lot of sense.  Instead, we need investment strategies that fit today’s world.  Many companies disappeared over time because their products became obsolete.  Those that are still around, like General Electric, Nokia, and IBM, reinvented themselves.  Why?  The business landscape changed and they changed with it.

The prairie landscape has changed too.  Row crop agriculture and other human developments have replaced grassland across huge swaths of our country, leaving many prairies relatively small and isolated.  Trees and shrubs have flourished in landscapes where they were once scarce, and woody encroachment into small prairies now comes from all directions.  Many new species of plants and animals have found their way into North America, and some have become very aggressive.  Significant amounts of nitrogen from industrial and agricultural sources now enter grasslands by both air and water, changing soil chemistry to favor some plants over others.  Finally, prairies have endured a century or two of impacts from factors such as fire suppression, livestock grazing, haying, and broadcast herbicide use.  Today’s remaining prairies don’t look or function as they did a century or two ago.

corn

Prairies today exist within landscapes that are dramatically different from what they looked like historically.  Row crop agriculture has replaced grassland across much of the Midwest and Great Plains, and trees, invasive species, and many other factors threaten the remaining patches of prairie.

Big changes to prairies and surrounding landscapes mean that land managers face equally big challenges as we try to sustain biological diversity and ecological function.  For most managers, invasive species suppression is our most time consuming and expensive task.  Because of that, we are always searching for new ideas, strategies, and technologies to help us be more effective and efficient.  The herbicides we use to kill invasive plants were not part of the prairie ecosystem a couple hundred years ago, but I can’t imagine trying to do our job without them.  Similarly, brush mowers and the tractors that pull them are certainly not historically accurate, but they are invaluable when creating firebreaks or mowing down large patches of encroaching brush.

Today, land managers’ decisions about when to burn a prairie should be based on the myriad management objectives we face rather than on what the historic average fire frequency might have been at that site.  In many prairies, managers struggle to weigh the benefits of frequent fire to control brush and other invasive species against the potential impacts of frequent fire on vulnerable insects, reptiles, and other species.  Looking at historic fire patterns can help us understand how prairies developed, but today’s fire patterns need to address current challenges and help us sustain our imperiled grasslands.

Similarly, studying the historical population abundance of bison or elk can teach us about how those species influenced prairie communities long ago, but decisions about grazing as a contemporary management strategy need to be made based on today’s objectives and needs.  I wrote last week about the introduction of bison into the Nachusa Grasslands in Illinois, and attempts to capture the impacts of bison grazing at that site.  I’m sure the staff at Nachusa have been in numerous discussions about what historic bison populations were like in what is now northern Illinois.  The decision to bring bison in, however, was not based on history, but rather on defined needs for habitat structure and plant community management.  Nachusa staff are hoping to see more diverse grassland bird communities, for example, and positive effects on a wide variety of mammals, reptiles, and invertebrates.  They also hope bison will help maintain high plant diversity.  In particular, they hope to increase the long-term survival of relatively short-lived plant species that often disappear over time in restored prairie.

bison

Bison and cattle grazing can be useful in meeting some prairie objectives, but is not appropriate for all sites.

Here in Nebraska, The Nature Conservancy uses both cattle and bison to achieve prairie management objectives.  Grazing strategies are designed with specific objectives in mind, and we collect as much data as we can to evaluate the impacts of grazing on plant and animal communities.  Grazing helps us suppress the vigor of both non-native invasive grasses and aggressive native grasses and foster a more diverse plant community.  Plant species that would otherwise be outcompeted by dominant grasses can usually maintain strong populations under various combinations of intensive grazing and long rest periods.  Both cattle and bison can also help us create a wide variety of habitat conditions, including large areas of both short/sparse and tall/rank vegetation and other areas where patches of short and tall vegetation are intermixed.

Just as with fire, mowing, and herbicide use, the value of grazing as a prairie management tool needs to be evaluated not by its historic role in local grasslands but on its potential utility today.  In many prairies, grazing is not feasible or does not fit with management objectives.  For example, grazing is unlikely to make sense in small isolated prairies where wildlife/insect diversity is limited more by habitat quantity than habitat structure, and where plant composition objectives can be met through other means.  At larger sites, however, grazing may allow managers to provide more habitat variety and/or manipulate plant competition in positive ways.  Regardless, decisions about whether or not to graze should be based upon how grazing might help address current management challenges, not upon historic populations of bison or elk.

Prairie management is complicated and we have a lot left to learn.  We can’t afford to be overly conservative or rely too much on what happened long ago.  Imagination and experimentation are crucial components of adaptation, and we desperately need to keep adapting to new challenges if prairies are going to survive.  Companies like General Electric, Nokia and IBM rightly celebrate their history, but they also have to innovate and evolve to keep up with the changing landscape.  Prairie managers need to innovate and evolve to keep up with changing landscapes too.  Let’s learn what we can from the past but keep looking for new ideas and tactics so we can keep prairies healthy and vibrant well into the future.

After all, prairie conservation is worth the investment, right?