Why Does Plant Diversity Matter? Help Us Figure It Out!

How important is plant diversity in restored prairies?

Are diverse prairies more resistant to drought and invasive species than less diverse prairies?

How does plant diversity influence invertebrate communities and their ecological functions?

These kinds of questions have been the focus of multiple research projects in our Platte River Prairies over the last decade or so.  We have numerous restored (reseeded) and remnant (unplowed) prairies that provide excellent field sites, and have also established two sets of experimental research plots to help focus specifically on questions related to plant diversity.  Those plots are 3/4 acre (1/3 ha) in size and represent varying levels of plant diversity, allowing us to investigate the functional differences between them.  Researchers from the University of Nebraska, Kansas State University, the University of Illinois, and Simpson College have been involved in data collection efforts so far.

2013 photos from

2013 photos from our experimental research plots.  The plots from left to right were planted to a monoculture (big bluestem), a low diversity mixture (mostly grasses and a few late season wildflowers) and a high diversity mixture (100 plant species).  We are investigating functional differences between these kinds of plant communities.

Craig Allen, Leader of the Nebraska Cooperative Fish & Wildlife Research Unit, and I are hoping to take the next step in these efforts by bringing on either a PhD or Post-Doctoral Research Associate.  We have data to build upon, including some intriguing results regarding invasive species and insect herbivory rates at varying levels of plant diversity, but want to greatly expand upon those data.  If you or someone you know is interested in these kinds of questions, please read below and contact Craig or me with questions.

Here is the official description of the position:

Ph.D. or Post-Doctoral Research Opportunity:  Grassland diversity, restoration and resilience

Ph.D. graduate research assistantship or Post-Doctoral Research Associate.  Available starting in May 2015, to investigate the relationship between grassland restorations and ecosystem services and resilience.  The assistantship (or Post-Doc) is with the Nebraska Cooperative Fish and Wildlife Research Unit, in the School of Natural Resources at the University of Nebraska, working closely with the Nature Conservancy scientists and resource managers.   The research project will include a synthesis of literature to identify prominent knowledge gaps related to the restoration of grasslands and resilience.  In addition to synthesis, field work will occur on a suite of restorations in central Nebraska.  Some questions of interest are listed below, but ultimately, successful candidates will be expected to develop a specific research project(s).  The candidate could approach this project from a broadly ecological, or botanical, or entomological frame.

The successful applicants will be highly motivated, with a strong work ethic, strong and demonstrated writing skills, a passion for field work, and the ability to work in collaboration.  Experience in restoration ecology is helpful, but not required.  Ph.D. applicants should possess a M.S. in Wildlife, Biology, Zoology, Botany, or Entomology, or a related field and have a valid driver’s license.  Post-doctoral applicants should possess a Ph.D.

Interested applicants should send a cover letter, names and emails of 3 references, GPA and GRE scores, and an updated CV as an electronic PDF or Word document to Craig Allen, allencr@unl.edu

Review of applications will begin March 15 and continue until a qualified candidate is identified.  For more information on the Nebraska Coop. Unit and the University of Nebraska-Lincoln please visit us at:


Applicants should also review:


Specific projects could include all or part of the following:

Relationship between restoration diversity and ecosystem services, such as invasion resistance and herbivory; interactive effects that might mediate some resilience properties; responses to multiple disturbances; how invasions might weaken the ability to cope with disturbance; microbial diversity and ecosystem function and services; response to pulse and press disturbances and mechanisms driving responses; functional trait diversity and redundancy and resilience.

Photo of the Week – June 7, 2013

Prairies demonstrate their resilience regularly, but usually in a fairly subtle way.  They tend to adjust their plant composition after fire, grazing, or drought in ways you might not notice unless you were a botanist.  Once in while, however, prairies take it to the next level and really show off.

A profusion of penstemon in restored sandhill prairie at The Nature Conservancy's Platte River Prairies.

A profusion of penstemon in restored sandhill prairie at The Nature Conservancy’s Platte River Prairies.

Last year was the driest year on record for this area.  We had less than half of our average annual rainfall, and most of that came early.  By late August, very little green was left in most of our sites.  The prairie shown above had been burned in the spring and grazed most of the season.  Many people seeing it for the first time would have assumed it was dead and gone (see photo below).

This is the same portion of prairie shown in the first photo, but this images was taken August 24, 2012 after a year of fire, grazing, and severe drought.  Most of the green in the photo is western ragweed and a little goldenrod.

This is the same portion of prairie shown in the first photo, but this images was taken August 24, 2012 after a year of fire, grazing, and severe drought. Most of the green in the photo is western ragweed and a little goldenrod.

I’ve written about the ecological resilience of prairies before, and have presented long-term data showing how our prairies fluctuate in plant composition over time in response to drought, grazing, fire, and various combinations of those factors.  Many plant species rise and fall in abundance as conditions change (opportunistic species) and others tend to maintain a steady population size, though they may be more or less visible in particular years.  It’s one thing to see that in graphs and tables, but it’s also fun to see a spectacular green-up and explosion of wildflowers in person, especially after a long dry (brown) year.

In the sandhill prairie shown above, last year’s drought caused most of the perennial plant species to enter dormancy by July – effectively giving up on that season’s growth and reproduction potential and saving their remaining energy for the next year.  Before they went into dormancy, however, the perennial grasses had already been weakened by relatively intense grazing, reducing the size of their root masses and opening up space for opportunistic species to take advantage of.  One of those opportunistic species is the short-lived perennial shell-leaf penstemon (Penstemon grandiflorus) which is obviously thriving this season.  Shell-leaf penstemon has been generally increasing in abundance since this prairie was seeded in 2002, but it took a gigantic leap forward this year.  Based on what I’ve seen in other prairies, I expect it to decline in abundance over the next couple of years as the dominant grasses and other long-lived perennials recover from last year’s stress.  In the meantime, we’re happy to enjoy the prairie’s flamboyant demonstration of resilience.

Junegrass (Koeeria macrantha) is also having a great year, and provides a beautiful counterpoint to the penstemon in this photo.

Junegrass (Koeeria macrantha) is also having a great year, and provides a beautiful counterpoint to the penstemon in this photo.

If you’re in the area, now is a great time to come hike our trails.  Both the upland and lowland trails through the Platte River Prairies cut right through huge patches of penstemon.  If you’ve never been to our trails, you can find directions and more information here.

The mowed hiking trail through sandhills provides excellent exposure to the penstemon profusion this season.

The mowed hiking trail through the sandhills takes you right through penstemon profusion this season.