How Restored and Remnant Prairies Each Contribute Resources for Pollinators – Research by Hubbard Fellow Emma Greenlee

This post is written by Emma Greenlee, who recently completed her Hubbard Fellowship year here at The Nature Conservancy in Nebraska. Emma is now moving on to graduate school, where she’ll have the chance to study prairies in even more depth than she did with us. As her independent project during her Fellowship, Emma helped us evaluate the way our restored prairies contribute toward pollinator resources. Specifically, she counted the number of flowers and flowering plant species available in both remnant and restored (planted from seed) grasslands at our Platte River Prairies site. She is sharing some of the highlights from her findings in this post:

During my time as a Hubbard Fellow I conducted an ecology research project comparing flowering species community composition and floral resource abundance in remnant and restored prairies at the Platte River Prairies preserve (PRP). The Nature Conservancy has been doing restoration work along the Platte River since the 1990s. That work was initially done in conjunction Prairie Plains Resource Institute, a restoration-focused NGO based in Aurora, Nebraska. Prairie Plains has immense expertise in constructing restorations from a high-diversity of locally sourced native prairie seeds.

The Nature Conservancy’s goal for restoration work at PRP is to increase habitat connectivity among prairie sites. The philosophy with which TNC has approached prairie restoration in this area is not that restored prairies should be exact replicas of nearby remnant sites. They don’t need to have the same species composition as neighboring remnants, they need to contribute to the area’s prairie habitat connectivity. That, in turn, will benefit the native species persisting in today’s fragmented prairie landscape. In my project, I investigated what floral resources for pollinators (aka flowering plants/forbs) look like across these remnant and restored sites.

Orb weaver spider eating a grasshopper on a foggy morning, September 2022. Photo by Emma Greenlee

Although TNC’s restoration practitioners and land managers do not seek to create prairie restorations that are identical to their neighboring remnants, it is important to understand how both compare in terms of the resources they provide to prairie communities. That way, we can assess our restoration and management approaches and alter our techniques if needed. There are so many aspects of a prairie ecosystem that one could measure to determine this, but because I’m really excited about plant community ecology, I chose to approach my project from that direction. In addition, I wanted to address the role plants play in supporting the prairie ecosystem, and thinking about floral resources for pollinators appealed to me as a way to do this (while still focusing my data collection efforts on the plant community!).

Catsclaw sensitive briar (Mimosa quadrivalvis var. nuttallii), July 2022. Photo by Emma Greenlee

I selected five sites at PRP that contain a remnant and an adjacent restored prairie undergoing similar management. Every two weeks, from early May through mid-October, I collected data within a designated sampling polygon in each of the remnant and restored prairie sites I had selected. Collecting data through time in this way allowed me to see how the prairies changed throughout the season, and this was a highlight of my project.

From seeing the first flowers of the year, like fringed puccoon (Lithospermum incisum), to the new plants I learned about throughout the season like catsclaw sensitive briar (Mimosa nuttallii) and Illinois bundleflower (Desmanthus illinoensis), to the bobolinks I heard singing and the cool invertebrates I saw along the way, I noticed something new every time I went out to collect data. Especially satisfying was the day in June when, as if a switch had flipped, the native tallgrass big bluestem had suddenly overtaken the invasive smooth brome that had been widespread in many sites early in the season. Even though my project primarily involved collecting data on wildflowers, it provided me the opportunity to notice so much more.

Monarda (Monarda fistulosa) was particularly abundant in one of my transects on this sampling day, July 2022. Photo by Emma Greenlee


Results and Discussion

In general, my results suggest that floral resources in remnant and restored sites at the Platte River Prairies were similar this year! The flowering species that were available in a given location, as well as their abundances, varied throughout the season, but I found no evidence that remnants or restorations as a group had more or fewer flowers than the other at any point during the growing season.

In fact, some of my results (see graph below) suggest that remnant and restored sites complement each other in terms of the flowering species they provide. This complementarity indicates that there are different floral resources in adjacent remnant and restored sites at a given time, but that remnants and restorations flip-flop throughout the season in terms of which offer more flowering species for pollinators. Because the paired sites I studied were located geographically near to each other, this suggests that insects are able to move between neighboring remnants and restorations to fulfill their needs throughout the season.

Graphs of the number of flowering species in each of my five sites over time. Red lines correspond to remnants, and blue lines to restorations.

Within the above graph, the red and blue lines zigzag many times, with a remnant (or restoration) containing more flowering species, and then its paired restoration (or remnant) overtaking it to have more flowering species the next month, and then vice versa. This should overall be a positive for pollinators who are able to move back and forth between neighboring sites to fulfill their needs at a given time. (If you’re looking for a clear example of the pattern I’m describing, it’s especially visible in the East Dahms NW site (top middle graph) from August through October.)

Additionally, my results suggest that factors apart from a site’s status as a restoration or a remnant are likely responsible for much of the variation in flowering communities found at PRP. Some sites have sandy soils and hilly topography, while others are largely flat with a shallow water table (underground water is fairly near the surface) and wetland sloughs running through them. Variations like these shape the suite of plant species that is able to establish in an area. In the sites I studied it seems likely that factors like these (soils, topography, hydrology…) are important drivers of plant community composition in the patchwork of prairies along the Platte River, regardless of whether a site is a restoration or a remnant (see graph below).

This type of graph is used by community ecologists to simplify many aspects of the communities they’re comparing down to a two-dimensional plot. In my case, it represents the flowering plant species composition and floral abundance of each of my sites! The axis labels aren’t important, they just represent community similarity: the points that are closer together on the graph are more similar in species composition and flowering abundance, and points that are farther apart are less similar.

On the above graph, circles represent remnants and triangles represent restorations, and each remnant/restoration pair is a different color. Most of the color-coded remnant/restoration duos are found close to each other on the graph, indicating floral community similarities. Interestingly, most of the restorations are also grouped fairly near to each other, as are the remnants! This suggests some community similarities among remnants overall and among restorations overall, but it would take more statistics than I accomplished on this project to find out what those might be!

We can’t draw too many firm conclusions from only one year’s data––factors like that year’s weather, the number of sites I collected data from, and each site’s management all may play a role in the patterns I saw. However, this is still useful information that can be built on in the future, or simply serve as a single-year snapshot of a few aspects of prairie community health on the preserve. In general, what I found this year suggests that restoration work at the Platte River Prairies preserve is largely effective in increasing prairie habitat connectivity by the metric of providing floral resources for pollinators. This is encouraging news, and suggests that the methods used here (and in many other places!) of restoring prairies with a diverse mixture of locally sourced native seeds are sound and contribute to the prairie patchwork landscape of central Nebraska.

I learned so much from this project and from the Fellowship more broadly, and I appreciate everyone who has read my blog posts along the way! It’s been a pretty cool privilege having such an enthusiastic audience to share some of what I’ve learned this year with. Next I’ll be pursuing a Master’s degree at Kansas State University studying plant-pollinator interactions in prairie, and I’m very excited for that! I also look forward to finding new ways to share my prairie enthusiasm with a wide audience.

Caption: A snapshot of the floral diversity at the Platte River Prairies, August 2022. Photo by Emma Greenlee
This entry was posted in Uncategorized by Chris Helzer. Bookmark the permalink.

About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.

7 thoughts on “How Restored and Remnant Prairies Each Contribute Resources for Pollinators – Research by Hubbard Fellow Emma Greenlee

  1. Congratulations on the work, Emma. You mention that the prairie restorations were not intended to be a replica of adjacent remnant prairies (this probably makes sense–there are many aspects of remnant prairies that probably cannot be easily replicated in a restoration). But was there an effort to match plant species in the restoration to those present in nearby relics? The reason I ask is that the Sandhills is rather different from prairies along the Platte River. I’m sometimes concerned that generic “native seed mixes” might introduce species that spread out of restored areas and displace unique flora within adjacent relics.

    Also, it looks like the Bombeck site had the biggest difference in overall plat community between the restoration and the remnant (based on point divergence on the NMDS plot). Do you have any hypotheses for why that might be the case, based on your observations?

    Keep up the good work and good luck in graduate school (it was one of the most fun times of my life, so I hope it is for you as well)!

    • Hi Tyler,
      I’ll let Emma answer the questions too, but since I’m the oldster that has context on how the seed mixes were built for these plantings, I’ll chime in on that topic. The target seed harvest lists are built based on a composite of nearby sites. In other words, we pick species we know to be native to similar sites in the area, without picking one or two of those sites to be specific references or targets. Then we create specific mixes for each site based on the soils, topography, soil moisture, etc. We always go a little broader than what we think might be the right fit, though, to leave room for species to surprise us. In other words, we might add some wet species to mesic sites, or even dry sites that might have some pockets of lower ground, etc.

      Bombeck is just a weirdo. Was before we bought it and seeded it, and still is. The remnant is also odd.

      • Hi Tyler! Good questions––it seems like Chris answered your questions thoroughly…I’m glad you asked about the species composition of TNC’s restorations mixes on the preserve! I’ll also say that that outlier Bombeck site has some invasive Siberian elm encroachment problems and that is one of the main focuses of management on that site and probably part of why it seems pretty different from everything else in terms of flowering plant community.

        And thank you very much! I am excited for it and ready to learn a lot and see some new prairies.:)

  2. Fantastic! And wow, the success of the restored sites, the similarities to the remnant sites, and the possibility that they even help each other! Impressive and inspiring. Thanks for your work and your post.


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