Tag Archives: prairie

Is Prairie Stewardship Hampered By Our History Goggles?

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23

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 Show Must Go On

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Almost a decade ago, I wrote about two competing metaphors for prairie restoration. I suggested we view prairie restoration like the reconstruction of a city after a disaster rather than like the restoration of an historic building.  We need to concentrate on the roles and functions of prairie ecosystems rather than how closely a restored patch of prairie resembled what it used to be in the past.

Today, I’m hoping to stimulate conversation about the difficult decisions we face as we try to conserve prairies in the face of rapid climate change.  One conservation planning approach is to focus on conserving the stage, not the actors.  It advocates prioritization of sites with geophysical diversity because those abiotic conditions influence habitat heterogeneity, which supports biodiversity.  The hope is that we might be able to conserve “an abiotically diverse ‘stage’ upon which evolution will play out and support many actors (biodiversity).”

The varied topography and the habitat size and connectivity found in Flint Hills of Kansas makes it a ‘stage’ that can potentially sustain biodiversity – but only with thoughtful, persistent, and adaptive management.

I think the ‘conserve the stage’ approach has merit, but it’s just a first step, especially for prairie conservation.  We don’t just want to save the stage; we want to make sure the show goes on.  Thus, I present to you a long (and potentially ridiculous) metaphor for prairie conservation that builds upon the ‘conserve the stage’ approach.

…

Every actor in a theatrical production plays a role that helps tell a story.  Likewise, every species in a prairie plays a role that contributes to the overall functioning of the ecosystem.  In a healthy and resilient prairie, all the key roles in are filled. 

Fortunately, there is a lot of redundancy built into prairie communities.  We have lots of species that provide pollination, seed dispersal, nutrient cycling, and all the other essential functions that keep prairies going.  We have a big cast, or maybe a big actors’ union.

Today’s prairie ‘show’ already looks different than it did in the past.  Prairie landscapes are fragmented, invasive species have joined the cast, and the climate is changing.  Those and other factors mean that some actors who played key roles in the past are no longer part of the show, at least at some venues.  Other actors remain in the cast but don’t play their roles as effectively as they used to.  Despite those changes, there are still really good versions of the prairie show being presented on various stages, though the versions vary quite a bit from place to place.

To keep the show going, we, as producers and directors, have to be creative and adaptable.  We face really difficult decisions, especially when it comes to actors who aren’t well suited for their roles anymore.  Continuing to direct the show with those actors as the main focus can weaken the performance of others and drag the whole production down. 

Making changes to the cast of a show comes with a lot of risk, however.  We don’t have a lot of experience with that process and we’re likely to make mistakes. Fortunately, in most cases, there are existing cast members that have the potential to adapt their roles and take on new challenges.  With some guidance, those actors will find new ways to collaborate with each other and put on a show that might not be exactly the same as we’re used to but will still have a plot we can follow and enjoy.

More frequent and severe flooding is occurring as a result of climate change. That increased flooding will likely affect which plant and animal species will persist in low-lying prairies like this one. Can we predict those changes and help guide them in ways that don’t lead to reduced biodiversity?

If more drastic actions are needed, we might recognize that some actors are on their way out and start training understudies who can gradually take over roles as needed.  If necessary, we might decide to recruit actors that are playing diminished roles on other stages and bring them in to rejuvenate their careers in a more suitable situation.  Similarly, we might help some of our own long-term stars find new opportunities elsewhere, rather than just watching them slowly fade away. 

In some cases, the world around us might force major a rewriting of the show itself.  We might find ourselves directing a shrubland or woodland production rather than a prairie show.  That doesn’t mean the show will stop or become less important, but it will require a different approach, a significantly altered cast, and a lot of adaptation by all involved.  However, if we stick with the mantra of ‘The Show Must Go On’, we’ll need to figure out how to adjust on the fly and sustain as much biodiversity and ecological function as we can.

…

Ok, I have to break away from this tedious metaphor.  The real point here is that we can’t afford to be so invested in current or past versions of our prairies that we don’t allow them to adapt to changing conditions.  At the risk of sliding back into my metaphor, there are lots of old movies and plays that don’t hold up well today.  Jokes that used to be funny 20 or 30 years ago aren’t funny today.  Old references don’t land with new audiences.  In most cases, the basic stories themselves are still solid – they just need to be adapted for today’s world.  Prairies and their species also exist in a different world than they used to, and that world continues to change (very quickly) around them.

The resilience and function of prairies is highly dependent upon biodiversity, which depends upon habitat size and heterogeneity, along with other factors.  Maintaining high biodiversity in prairies that exist in fragmented landscapes comes with huge challenges, which are compounded by a rapidly changing climate.  Plant and animal communities aren’t the same as they were in the past and they’ll continue to change over the next few decades and beyond.  In fragmented landscapes, unless we take an active role, those alterations will largely take place in isolation, with limited opportunities for species to travel between one prairie fragment and another.  Even in landscapes with large contiguous grasslands, we’ll need to be very thoughtful about how we shepherd those prairie communities through the coming years.

These tent caterpillars probably aren’t causing serious impacts to this patch of wild plum, despite appearances. How will climate change, habitat fragmentation, and increased woody encroachment affect this insect species and its impacts on other species in the future? (This is just a random example – I’m not saying tent caterpillars are going to become a major problem!)

It’s really hard to look at the prairies we know best and imagine them with a different composition of species.  We’re used to measuring stewardship success by our ability to sustain the status quo.  Watching the population of a species diminish in size – or disappear entirely – feels like a major failure.  Most of us have also looked skeptically at any new species that show up in a prairie, worrying about potential negative impacts of that species on the existing community. 

I don’t have a lot of answers to the big questions we face.  I’m certainly not ready to lay out a plan or advocate for a particular approach to managing these changing prairies.  As I did in another recent post, I’m mainly trying to get some conversation going on this topic. 

The best I can do right now is offer a few ideas for discussion.  For example, I think we might be smart to reevaluate the way we look at our objectives for prairie management.  Instead of trying to maintain the current composition of plants and animals, maybe we should focus more on biodiversity and less on which particular species are present or abundant within those communities.  (That doesn’t mean we welcome invasive species, by the way.  Any species – plant, animal, or otherwise – that acts to reduce biodiversity is still a problem.)  

I also think we need more serious conversation about when to resist ‘state changes’ like the transition from grassland to shrubland and when to facilitate those transformations, while trying to preserve as much biodiversity and productivity as we can.  Again, I have little to offer in terms of specifics, but it seems clear that we’re not going to be able to stave off those state changes forever in at least some places.  Let’s start thinking about contingencies instead of just waiting for those sites to collapse.

There’s a lot of woody encroachment in this prairie. The number of trees in the surrounding landscape and a changing climate are both spurring that invasion. At what point does the fight against this kind of encroachment become fruitless? What do we do then?

Finally, it’s never been more important to find opportunities to enlarge and reconnect prairie fragments through prairie restoration.  The chances are slim that a small, isolated prairie fragment is going to adapt well to a rapidly changing world.  Growing the size of those fragments by restoring adjacent patches should be a top priority.  Can we find new approaches for creating those restoration opportunities in strategic locations? As we do that restoration work, we should also continue to test and discuss seed sourcing strategies, including the regional admixture approach, to see if we can further bolster the adaptive capacity of those small sites.

We’ll be figuring this out as we go, and we’ll surely screw some things up, but we can’t afford to just continue reacting.  At the very least, we need to be thinking ahead about the changes that are taking place and how those will affect prairies.  In some cases, we should probably be ‘acting ahead’ to guide state transitions, migration of species, or simply changes in species composition within individual prairie sites. 

What we can’t afford to do is live in the past.  We’re hurtling into the future whether we like it or not.  Let’s make sure we bring prairies along with us.