Why There Is No Cookbook for Restoring and Managing Prairies

From Anne Stine, Hubbard Fellow:

My big goal for this fellowship is to learn how to make a prairie from scratch.  I also want to know enough about prairie restoration/management that I can evaluate a prairie’s condition and then prescribe treatments to fix it.  For these first few months with The Nature Conservancy, and especially at the Grassland Restoration Network workshop (July 16-18, 2013 in Columbia, MO), I’ve been asking questions about the problems and solutions common to prairie restorations.  My naïve desire is to develop some sort of prairie restoration cookbook.  When I asked Chris why this didn’t exist, he laughed and said “If that were possible my book would’ve been a lot shorter.”  I built my flowchart anyway.

This blog post will be a bit different- I’m going to share the “Patch-Burn Grazing Flowchart” I developed.  Then Chris will respond and explain why the cookbook method doesn’t work.

(Click on the flowchart to see it as a larger image)

PBGbigfcResponse from Chris:

I give Anne credit – it’s clear she’s paying attention and learning a lot during the first couple months of her Fellowship experience.  Her flow chart includes very appropriate treatments for issues that pop up in prairies, and it’s a nice guide to some of those options.  However, prairie restoration and management is a more complex and dynamic process than can be easily captured in a flowchart (or even in a book).  That complexity can seem daunting to some, but is really what makes prairies fun and interesting to work with.  The trick is to accept the complexity and roll with it.

I've been working to rejuvenate our family's prairie south of Aurora, Nebraska for well over a decade.  It's getting there, but it's been anything but a straightforward process.  Every year brings new challenges and surprises.

I’ve been working to rejuvenate our family’s prairie south of Aurora, Nebraska for well over a decade. It’s getting there, but it’s been anything but a straightforward process. Every year brings new challenges and surprises, and we continue to tweak our management strategies.

When I wrote my book on managing prairies, I purposefully stayed away from prescribing any particular management regime (or recipe), and instead tried to provide some background on how prairies work and some guiding principles for managing them.  You can find a partial compilation of those ideas by going to PrairieNebraska.org and clicking on the “Prairie Management” or “Prairie Restoration” tabs at the top of the page.  There are lots of reasons I didn’t prescribe particular management recipes.  Here are a few of them:

1. Every prairie has its own unique species composition (plants, insects, animals, fungi) and that composition drives the way it responds to weather and management.  In some ways, prairie management is like parenting – each prairie (and child) has its own personality and needs to be treated in ways that match that personality.  The best parenting books are the ones that suggest general philosophies and offer tips to try in various situations.  Anyone who has been a parent knows that there is no cookbook for how to do it well.

2. Every year is different.  Last year was the driest on record for our Platte River Prairies.  This spring was very cool and wet, followed by a hot dry July, followed by a cool and wet August (so far).  Prairies respond very differently to fire, grazing, seeding, herbicide treatments, and other techniques due to weather conditions.  Countless times, we’ve applied a treatment to part of a prairie and were excited to see how it worked.  The next year, we applied the treatment in exactly the same way and things would turn out very differently.  We try to tailor our management and restoration to the weather, but we know we’ll be surprised by how things turn out.  Those surprises are what I look forward to most each year.

During the drought of 2012 this sandhill prairie was burned and grazed pretty intensively.  By late summer, it was looking pretty tough.

During the drought of 2012 this sandhill prairie was burned and grazed pretty intensively. By late summer, it was looking pretty tough.  The same burn timing and grazing stocking rate in a wet year would have resulted in a very different impact.

After adjusting our management plans to account for last year's drought, the prairie was grazed briefly this spring and - thanks to some good spring rains - looked lush and green by early June.

After adjusting our management plans to account for last year’s drought and grazing, the same sandhill prairie shown above was grazed briefly this spring and – thanks to some good spring rains – looked lush and green by early June.

3. Prairie restoration is not very predictable either.  We have developed and tested seeding rates, seeding methods, site preparation, and other techniques that seem to work well at our particular sites, but those same techniques wouldn’t necessarily work somewhere else.  One of the big pieces of advice shared each year at Grassland Restoration Network workshops is that when starting a large restoration project, the best plan is to spend several years experimenting with various techniques on small portions of the overall restoration site to figure out what works best at that particular location.  Once you figure out what seems to work best, start planting larger and larger areas each year.

However, even when the exact same techniques are applied, results can still vary from year to year.  Jeb Barzen and Richard Beilfuss did a great experiment at the International Crane Foundation in the early 1990’s in which they seeded 1 acre a year for five years, using the same seed mix and the same techniques.  Even though all the seedings were in the same crop field, each turned out very differently from each other.  The same thing happens everywhere.  Differences are partially tied to the rainfall and other weather that occurs in the early stages of the seeding, but there are many more factors that are difficult to understand or control.  This isn’t a bad thing, it just means that you have to relax your expectations a bit, and embrace the idea of variability.  Why would you want to create multiple prairie plantings that look exactly the same as each other anyway?

4. Invasive species are always a major challenge, and (you’ll not be surprised at this) have to be handled in unique ways depending upon the species and the site.  Every invasive species has its own growth and reproductive strategies, so an approach to controlling one won’t work well on others.  There are general approaches to controlling each species that have been tested and can be useful, but those approaches will work differently from year to year and from site to site.  One of most important aspects of invasive species control is prioritization, something Anne’s flowchart covers pretty well, and more information on that can be found here.

5. Finally, one of my guiding principles for prairie management is that diverse prairies require diverse management.  Doing the same thing every year means always favoring the same group of species – and, by default, managing against another group.  Eventually, that kind of repetitive management can reduce overall species diversity by eliminating plants or animals that can’t thrive under that management.  It’s good to mix things up to allow all the species in a prairie to have a good productive year now and then.

If a prairie is large enough, splitting it into multiple management units each year can help ensure that animals and insects can always find what they need for habitat (it’s more difficult to do that in very small prairies).  However, it’s also important to avoid simply splitting a prairie into the same three or four pieces and rotating management between them in a repetitive pattern – even those patterns can restrict species diversity over time.

Many prairie insects and animals have fairly specific habitat needs.  Grasshoppers, for example, tend to thrive best in prairies with patchy vegetation structure that allows them to move easily back and forth between shade and sun.  Splitting prairie into multiple management units each year can help provide the kind of habitat variety needed to maintain high species diversity.

Many prairie insects and animals have fairly specific habitat needs. Grasshoppers, for example, tend to thrive best in areas with patchy vegetation structure that allows them to move easily back and forth between shade and sun. Splitting prairie into multiple management units each year can help provide a variety of habitat conditions and maintain high species diversity.

During the next couple of months, Anne and Eliza will be part of our annual management planning process here in the Platte River Prairies.  Each fall, we go around to each of our prairies and go through a basic evaluation process.  How does the prairie look this year?  What were the impacts of weather and management this year?  What challenges, including invasive species, are we facing?  What kinds of management have occurred over the last several years?  What does the monitoring data from the last couple of years tell us about how past management has been working (sometimes we have hard data, but we always have field notes and other observations to consider).

We walk around, look at maps, and talk about ideas.  Then we sketch out a plan for the next season based on all of those factors.  We try to make sure it’s different from what we’ve done over the last year or two, but that it addresses the challenges the prairie is facing.  Most importantly, we make sure that we’re learning from and adapting to what we’ve tried in the past and the ways the prairie has responded.

I suppose I could capture that process in a flowchart.  It would look something like this:

Helzer Flowchart

That’s probably not exactly what Anne was hoping for, is it?

It’s Bee Week!

Thanks to a return visit by Mike Arduser of the Missouri Department of Conservation, it’s bee week in the Platte River Prairies.  Mike came out to our sites a year ago to help us start thinking about our prairies from the perspective of bees and other pollinators.  This year, he made a return visit and we’ve given him a full plate of activities.

Mike Arduser (right) talks about bees with Sam Summers and Anne Stine earlier this week.

Mike Arduser (right) talks about bees with Sam Summers and Anne Stine earlier this week.

On Monday, Mike and I spent the day inventorying bees at several of our prairies, assisted by Anne Stine (Hubbard Fellow) and Sam Summers (TNC volunteer).  We are building upon the initial list of 57 bee species we found in 2012.  Several new species have already been added to the list, and more are likely as we continue to look.

We hosted a pollinator ecology workshop on Tuesday, attended by about 40 people – mostly biologists who assist private landowners with habitat projects or who manage conservation lands.  The objectives were to have Mike help us better understand basic pollination ecology and the needs of pollinator species – particularly bees, and to help us better incorporate bee habitat into our prairie restoration and management strategies.  It was a great day, and everyone had their heads buzzing (sorry) with new information and ideas.

At our pollinator workshop on Tuesday, we spent time talking about prairie restoration and management strategies, as well as general pollinator ecology.

At our pollinator workshop on Tuesday, we spent time talking about prairie restoration and management strategies, as well as general pollinator ecology.

On Wednesday and Thursday, Mike is leading a smaller group of us through an intensive bee identification workshop.  I’m looking forward to peering closely at the faces and private parts of bees through microscopes, and learning to differentiate between Melissodes, Colletes, Lasioglossums, and all the other bees in our prairies.

Less than a month ago, we saw Mike at the Grassland Restoration Network workshop in Columbia, Missouri.  He gave a presentation in which he talked about a variety of pollinator-related topics, including some potential ways to use bees to assess the success of prairie restoration projects.  One of Mike’s suggestions was to see what percentage of bee species in a prairie are specialist pollen feeders (oligolectic bees) and compare that percentage between restored (reseeded) and remnant (unplowed) prairies.

Pollen specialist bees feed only on pollen from one to a few flower species, whereas pollen generalists can feed from a wide variety of plant species.  Specialists tend to be less common in small isolated prairies than in larger prairies, in part because they need a certain minimum population size of their host plants, which can be difficult to obtain in small prairies.  Restored prairies might also lack that population size threshold, especially during the early establishment phase of a new seeding.  In addition, restored prairies that are isolated from remnants might be missing specialist bees simply because the bees in those remnants can’t find them.

According to Mike, a couple of recent surveys in Iowa found that about 20% of the bee species in remnant prairies are pollen specialists.  However, some early data from re-seeded Iowa prairies is showing much lower percentages of specialist bees – especially when those sites are isolated from large remnant prairies. If pollen specialists are not easy to attract to restored prairies, comparing the percentage of specialist bees in restored prairies to the percentage in nearby remnant prairies might be an important way to assess restoration success.

This bee is (probably) Lasioglossum pruinosum, which is a generalist pollen feeder.  It's not suprising to see it in a restored prairie.  Pollen specialist bee species seem to be more sensitive to habitat fragmentation, and may be less likely to occur in restored prairies - especially if those restorations are isolated from large remnants.

This bee is (probably – according to Mike) Lasioglossum pruinosum; a generalist pollen feeder. It’s not suprising to see it in a restored prairie. Pollen specialist bee species, however, seem to be more sensitive to habitat fragmentation, and may also be less likely to occur in restored prairies – especially if those restorations are isolated from large remnants.

Mike suggested that another useful metric could be the number of cleptoparasitic bee species present in a prairie.  Cleptoparasites, or cuckoo bees, are the cowbirds of bees – they lay their eggs in the nests of other bee species.  Because each cleptoparasitic species tends to specialize on the nests of certain species or groups of bees, their presence could another interesting indicator of restoration success.

From our 2012 bee inventory data, I can make some preliminary, and very tentative, conclusions about the number of pollen specialists and cleptoparasites in our prairies.  Of the 38 species we found in remnant prairies last year, 10 (26%) are pollen specialists and only 1 (3%) is a cleptoparasite.  By comparison, of the 47 bee species we found in restored prairies, 12 (26%) are pollen specialists and 7 (13%) are cleptoparasites.

Those data are encouraging, but pretty sketchy because we were really just doing broad inventory work – not collecting data in a way that would allow for a good comparison.  In addition, it clumps all our prairies together, so we can’t look at each one individually.  Anne Stine (one of our two Hubbard Fellows) is going to help remedy that during the next couple months by conducting a short study.  She do some standardized collection of bees from a variety of remnant and restored sites and then compare the percentages of specialists and cleptoparasites between those prairie types.  That should give us a better feel for what’s going on.

In the meantime, it looks like a relatively high percentage of the bee species in our restored prairies are pollen specialists.  That probably reflects positively on both the plant species diversity in those restored prairies and the fact that they are adjacent to remnant prairies – making bee colonization pretty easy.  Since the main objective of our prairie restoration work is to enlarge and reconnect our remnant prairies, those early results are very promising.  …But let’s see what Anne finds before we get too excited.

Now if you’ll excuse me, I have to go learn to tell the difference between Melissodes agilis and Melissodes desponsa.  Wish me luck…