Category Archives: Prairie Restoration/Reconstruction

Lessons from the Grassland Restoration Network

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I’ve been involved with high-diversity prairie restoration (reconstruction) since I joined The Nature Conservancy in 1997, learning the basics from Bill Whitney at Prairie Plains Resource Institute.   We’ve now planted over 1,500 acres of Platte River cropfields to prairie vegetation, using seed mixes of between 150 and 230 species.  Those restorations are being used to enlarge and reconnect existing remnant grasslands along the Platte River.

About 10 years ago, I started reaching out to other sites doing similar work.  Gus Nyberg, then at the Kankakee Sands Restoration in Indiana, and I set up a reciprocal visit between our projects, during which I took some of my staff (and Bill Whitney) to Indiana and the Kankakee staff came to Nebraska.  That experience was really valuable for all of us, and convinced us that we needed to do it more often – and to include as many others as possible.  Thus began the Grassland Restoration Network.

The Grassland Restoration Network (GRN) is a loose affiliation of projects and project staff engaged in the restoration of diverse native grassland communities.  The Network was formed in 2003 by The Nature Conservancy and a wide variety of other conservation organizations, government agencies, and private landowners.  There are three major objectives of the GRN:

  1. Facilitate communication and cross-site learning among large-scale grassland restoration sites.
  2. Identify and close critical knowledge gaps regarding grassland restoration and measures of restoration success.
  3. Foster a “grassland restoration culture” that increases the quantity and quality of grassland restoration.

Grassland Restoration Network workshop participants discuss restoration strategy in a restored Nebraska prairie in 2009.

The Network sponsors annual workshops that are hosted by various restoration projects around the country.  In addition to tours, workshops include presentations and discussions on topics including seed harvest/planting, invasive species control, long-term management, and research and evaluation strategies.  Those workshops have been attended largely by people working in the central United States, but have also included participants from the Pacific Northwest, long-leaf pine ecosystem in the southeast, and even other countries, including Canada and The Netherlands.

GRN workshops differ from other conferences in that the Network focuses on the use of high-diversity restoration as a tool for increasing the ecological viability of prairie ecosystems.  For example, we try to enlarge or reconnect small and/or isolated prairies through the conversion of adjacent cropland to high-diversity grassland communities.  In other words, we are trying to defragment the prairie landscape to increase the effective population sizes of prairie species (plants, insects, vertebrates) and benefit the whole ecosystem.  Success in those cases is measured not only by the establishment of plant species in seedings, but also by whether or not those seedings have increased the viability (long-term sustainability of ecological function) of the remnant prairie(s).

Bringing together people working toward this particular objective has had several benefits.  It has increased communication between sites to the point that we know what each other are doing and are learning from their experiences.  We have also identified common challenges and research questions, and have started several joint research projects to try to address those.  Finally, we have been able to take advantage of the size and experience of the group by collecting a number of “lessons learned” regarding the logistics and mechanics of doing prairie restoration.

Most large-scale prairie restoration sites have found that broadcasting seed (rather than drilling) is the most efficient and effective planting technique.

Several of us who have helped facilitate the Network have summarized many of those lessons in a manuscript that will be published in the upcoming Proceedings of the 22nd North American Prairie Conference.  The organizer of that Conference, the Tallgrass Prairie Center at the University of Northern Iowa, has graciously given me permission to post a PDF of that manuscript here, even though the Proceedings have not yet been published.  (click here to download – GRNLessons2010)

The manuscript covers a wide variety of subjects, including seed harvest and cleaning, planting, invasive species control, and overall project planning.  It also includes a selection of the most pressing research questions facing prairie restoration, as identified by Network participants.  If you’re interested or involved in prairie restoration work, I hope you’ll find the manuscript helpful.

Here is a selection of some of the broader lessons learned, excerpted from our manuscript:

1. Match your methods to your objectives.  The biggest key here is to define specific objectives.  Why are you doing the restoration project?  If your primary objective is to create grassland bird habitat, plant species diversity may not be all that critical, but the particular plant species you select may be.  If, on the other hand, you’re trying to enlarge a small remnant prairie so that all of the plants, insects, and animals in that prairie can have larger population sizes, the species diversity and composition of your seed mix becomes much more important.  (It’s also important to be sure you’re evaluating your success based on those same objectives.  If you’re interested in enlarging a prairie, be sure to measure the response from insects and other organisms – not just plants.)

2. Start slow, and increase the scale of restoration over time.  Many restoration projects, especially those trying to restore hundreds or thousands of acres, feel like they need to start restoring large portions of the total right away.  In almost every case where this has been done, the project manager has regretted it later.  Because every site is different, it’s important to start by spending a few years doing small scale seedings in order to build up a database of seed harvest sites, test the effectiveness of techniques, and gauge the level of invasive species suppression that is needed.  Be sure to experiment with a variety of strategies (seeding method, seeding rates, site preparation, etc.) during those first years so that you can learn as much as possible.  Once you feel like you’ve got a handle on effective strategies, you can start ramping up the scale of the effort exponentially.  This approach helps avoid initial large seedings that fail to produce the anticipated results, and that become management headaches down the road.

3. Restore a site over multiple years, rather than all at once.  This is related to number two, but applies to any site, regardless of scale.  Anyone who has spent many years restoring prairies knows that every seeding is unique.  The relative establishment of plant species, the response of weedy species, and many other factors vary year to year – often for reasons we can’t yet define.  Make that variability a positive thing.  If you have 100 acres to plant, seeding 20 acres a year for five years can produce five unique prairie communities that complement each other and increase overall heterogeneity and diversity of habitat and species composition, rather than one large seeding that looks pretty much the same across the whole site.  Another approach is to “checkerboard” a seeding; break each year’s seeding effort into several locations, scattered across the larger site, and fill in more blanks every year.

4. If you want plant diversity, maximize that diversity in your initial seedings – don’t plant a low diversity mixture with the idea of coming back later to add diversity.  It is much more difficult to enhance the diversity of an established prairie restoration than it is to establish that diversity during the initial seeding process.  Attempts to do so tend to have inconsistent results at best.

Efficient seed harvesting is an important part of prairie restoration when trying to maximize both acres and species diversity.

5. Adapt your technique as you go.  Even if you start small and figure out some apparently effective methods before attempting larger seedings, it’s still important to continue experimenting.  Including a couple small experimental plots (1 acre or so in size) within each year’s restoration work, in which seeding rate or other treatments are varied, can provide tremendous information that can help refine your techniques over time.  Collecting data from those plots can be as simple as visual observation of differences or more intensive, but without those experiments, you’ll never know whether or not you could be doing better restoration work.

6. Develop a plan, and capacity, for dealing with invasive species before you start.  Invasive species are expensive to fight, but the success of that fight is the difference between restoration success and failure.  In fact, when a restoration effort is designed to benefit an adjacent remnant prairie, a seeding full of invasive species can actually put the remnant at greater risk than before.  There are two factors that should drive the number of acres you plant each year: the amount of seed you can harvest to obtain the desired species composition in the seedings, and the number of acres on which you can deal with invasive species.  This is one of the great advantages of starting small – you can evaluate the threat posed by invasive species on small seedings before jumping into large seedings that could overwhelm your available resources.  It’s better to do high-quality, but small, seedings than mediocre (or worse) large ones.

7. Finally, one of the most interesting facets of prairie restoration is that there are many ways to do it successfully.  It is a field full of innovation and creativity, and it’s wonderful to see varying approaches to common problems.  However, through polling participants, we’ve found that there seems to be one set of restoration techniques that is universally successful, regardless of geographic location or other factors.  Excepting extraordinary circumstances, a dormant season broadcast seeding onto Roundup Ready soybean stubble will always establish a diverse prairie plant community.  This doesn’t mean that the Network is prescribing that specific technique – in fact many of us have had great success with other techniques.  But we think it notable that we could identify at least one combination of techniques that consistently produces successful prairie establishment.

Whether you’re creating prairies for educational, historic, aesthetic, or ecological reasons, it can be a rewarding (if challenging) experience.  Because every site responds uniquely to prairie restoration, much of what works for you will likely be learned through experimentation.  However, there is also much to learn from others who have been doing similar work in other places.  I hope this partial summary of that information will help you.

The 2011 GRN workshop has not yet been planned.  Stay tuned to this blog for updates about the date and location.

How Should We Be Preparing Prairies for Climate Change?

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When I wrote my recent book on prairie management, I included a very short section at the end on climate change.  Essentially, my advice to prairie managers was that managing prairies for biological diversity would help them be resilient enough to absorb climate change impacts.  I still think that’s good advice, but it leaves out some other options.

One of the purposes of this blog is to allow me to expand upon the ideas from my book, so I’m taking this opportunity to do that with the issue of climate change.  In this case, I asked for help from John Shuey, Director of Conservation Science for the Indiana Chapter of The Nature Conservancy.  John is a good friend and someone I have tremendous respect for, and I can always count on him to cut through the fog and address issues directly.

What I like most about his ideas is that they are all things we can actually DO RIGHT NOW.  One of the frustrating things about climate change is that it’s hard to design strategies when we don’t really know what climate conditions will be like in the future.  But John suggests strategies that would be good ideas regardless of what the climate does.  It feels good to have a map to follow, and this one points in the right direction – even if we don’t know exactly where we’re going.

Prairie Ecologist:

“What do you see as the major threats to prairie and savannah conservation from climate change in your state?”

Shuey:

“Well, most models predict three key changes in Indiana’s climate change future.  It will likely be hotter, with a slight increase in precipitation, and there will be more frequent severe weather events such as tornados, straight-line winds and ice storms.   The increase in precipitation will be during the dormant season with predicted decreases during the summer.  All that basically translates into three perceived threats: increased drought stress, increased fire frequency and intensity, and increased severe weather damage such as flash flooding and blow downs.”

Cardinal flower and other moist-soil-dependent plants may be particularly sensitive to increases in drought stress.

 

Prairie Ecologist:

 

“The central United States went through the Xerothermic Period between 8,000-5,000 BP, which was considerably warmer and drier than our present climate.  Does the fact that our prairies have already survived that period give us hope for the next phase of climate change?”

Shuey:

“Based on paleobotanical data, expanses of grassland and savanna dominated much of Indiana during the Xerothermic Period, and wooded communities increased in abundance as climates became cooler and moister.  Species compositions in today’s prairies will undoubtedly shift in response to climate change, but appropriate native species should be present at many sites to moderate those changes.  Some species will increase in abundance and others will decrease – even disappear from sites altogether.  The key for biodiversity conservation is to design strategies that will allow those changes to happen while minimizing species loss and preserving ecological functions.  For example, we can help to ensure that the full range of habitat conditions will persist in our conservation areas by designing restoration projects now that meet the future needs of species most at risk from climate change.”

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Prairie Ecologist:

“Fortunately, prairies are pretty resilient communities, but we’ve put a lot of stress on them already – especially in landscapes where prairies are small and isolated from each other.   How does that habitat fragmentation affect our conservation options?”

Shuey:

“The concept that ‘species will have to adjust northward’ as climate changes is very problematic in a landscape that is among the most developed in the world.   Even if it is theoretically possible for species to respond to warming trends by moving northward, fragmented landscapes like those in Indiana will not permit much movement between conservation sites.

Because of that fragmentation, we need to do as much as we can to make habitat patches as internally resilient as possible.  This can be done by maximizing the both the size and physical variation (e.g. slope, aspect, and soil moisture) of our natural areas.  We can increase the size of, and even reconnect, fragmented habitats through restoration of adjacent areas where that’s feasible.  Larger habitats can hold larger populations of species, which gives them a better chance of survival.  In addition, larger sites usually provide more variation in topography and hydrologic gradients, which can increase the chance that species will find the conditions they need to survive somewhere in the conservation area.  For example, shady microhabitats on north facing slopes may partially mitigate the impacts of regional increases of the evapotranspiration rates (a.k.a. drought stress).  Some of the rare species found on these slopes today may not make it through the changes, but those microclimates will likely still be loaded with locally rare species in the future.  Sadly, some of those ‘rare’ species may be abundant today but restricted to narrow ecological creases decades from now.

It’s also important for natural areas and to contain multiple examples of each habitat type, especially those most at risk from climate change – e.g. things like wet prairies and other moist habitats.  This accomplishes two things; it maximizes habitats that are likely to mitigate drought impacts, and it creates a repeating mosaic of ecological gradients that is more likely to support metapopulations (multiple populations interacting with and supporting each other) of species pushed to the brink.  As we design conservation areas and engage with private landowners in priority landscapes, we need to preserve as many examples of each habitat type as we can within regional landscapes. ”

Prairies that include a range of habitat types (wet to dry, shady to sunny, etc.) provide species more opportunities to find appropriate habitat as climatic conditions change. (Griffith Prairie - Prairie Plains Resource Institute)

Prairie Ecologist:

“Talk more about wet prairies and other natural areas that rely on the proximity to groundwater or other hydrological features for their survival.  Increasing drought stress sounds like a big deal for those sites…?”

Shuey:

“First, it’s important to know that many of our wetland systems in Indiana, such as bogs and fens, functioned though the Xerothermic Period in essentially the same manner as they do today.  These sites are literally the source of the pollen records used to re-create paleoclimates such as the Xerothermic.  It seems likely that their water budgets were reduced, and wetlands were probably smaller relative to their presettlement extent in Indiana, but they still survived.

It will be very important to protect groundwater and surface water inputs to natural areas wherever possible.  Groundwater diversion, especially for irrigation, is already a concern at some of our most important sites, and needs to be addressed.  If we really do get more precipitation during the dormant season, that might help recharge surface aquifers.  However, increased droughts may counteract that, so we will need to help develop policies that help moderate surface and groundwater depletions and encourage wetland restoration and protection.

River flows will probably become more flashy because of increased storm intensity.  The prevalence of channelized streams across the Midwest means that most run-off from big rains is lost quickly downstream.  This creates unstable streambeds and increases non-point source pollution in rivers.  It also means that most of that water is not captured in wetlands where it can provide habitat and help contribute to groundwater recharge.  Implementing the increased use of two-stage ditches may be one way to help moderate flood damage while still preserving a more natural stream flow regime.

Finally, restoration of areas adjacent to wetlands and low prairies provides opportunities to improve hydrologic conditions in two ways.  First, wetland restorations in formerly cropped areas can complement the hydroperiod of nearby natural wetlands.  New wetlands can be designed to stay wet longer – or dry up sooner – depending upon what may be missing (or predicted) in existing sites.  That full range of hydroperiod conditions is particularly important for successful breeding by reptile and amphibian populations.  Second, restoring portions of the landscape surrounding small natural wetlands can help buffer them from the impacts of diversion ditches and other hydrologic alterations.”

Prior to converting this Platte River cropfield to prairie, we tried to restore the kind of hydrologic gradients appropriate to a river floodplain wet prairie. Not only did that increase the diversity and resilience of that restoration, it also provided complementary habitats to the existing remnant prairies adjacent to it. (The Nature Conservancy - Nebraska)

Prairie Ecologist:

“Are there other things we need to be thinking about relative to climate change?”

Shuey:

“Three things come to mind.  First, invasive species will be moving into new areas as they, too, adjust to the changing climate.  Unfortunately, invasives are more likely to be able to move around fragmented landscapes than many of our native species, and we need to be prepared for that.  I think that the struggle to manage native grasslands will intensify in the future, and that we can never let our guard down.

Second, we tend to focus on the losers when we discuss climate change.  It’s important to remember that there will be interesting winners as well.  For example, in southern Indiana we are focusing heavily on small glade and barrens habitats surrounded by dense forest.  I expect these glades and barrens – which, structurally, are just prairies that grow on very thin soils and bedrock – to thrive!   We are aggressively restoring these habitats to their pre-fire suppressed condition so that they will be poised to take advantage of future harsh growing season droughts.

And finally, it’s important to remember that the predicted changes are PREDICTIONS.  We have to be flexible in our strategies as we move forward.   My guess is that I understand perhaps half of the future impacts to our sites – enough that we can take good ‘no regrets’ actions (productive strategies regardless of climate change) for the future.  But we’ll need to continue adapting strategies as we learn more.  If we are still following my current prescriptions 10 or 20 years from now we’re probably not paying attention to either changes on the ground or model refinements.”