Tag Archives: conservation

The Show Must Go On

Posted on by
12

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.

The Bench Strength of Prairies in the Face of Climate Change

Posted on by
10

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.