The role of prairie restoration in grassland conservation

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By Chris Helzer and Jill Wells

Those who are familiar with The Nature Conservancy in Nebraska know that one of our strategies is to buy land and preserve it. Many who have enjoyed the beauty of the Niobrara River have visited our 56,000-acre Niobrara Valley Preserve. But in a state where 97 percent of the land is privately held, conserving Nebraska’s natural heritage necessarily and appropriately has to happen on private land. Because of that, the conservancy will only be successful at a meaningful scale if we use and develop multiple strategies, such as prairie restoration, that can be applied to private lands

Prairie restoration used to be largely the realm of academics trying to prove that it was (or wasn’t) possible to re-create prairies from scratch and nature centers and museums trying to show people a glimpse of an historic landscape. People would harvest seeds from prairies and reseed small pieces of land into what were essentially large native plant gardens.

Times have changed. Techniques and research have progressed to the point where prairie restoration is a legitimate tool for large-scale grassland conservation. Row-crop fields can be converted into prairies containing hundreds of plant species. Those high-diversity plant communities are colonized by insects, birds and other animals. And that can happen at a grand scale—there are already several restoration projects in the U.S. that are converting cropland to prairie at the scale of 20,000 acres or more.

The importance of the capacity to work at large scales becomes apparent when you look at the degree of fragmentation across prairie landscapes. Several states have less than one percent of their tallgrass prairie remaining. In other states, like Nebraska, more of that prairie remains, but it is largely arrayed in scattered small pieces.

One of the biggest research questions in grassland conservation right now revolves around those small prairie fragments. In general, small ecosystem fragments tend to have smaller, less stable populations of both animals and plants. Those small populations are vulnerable to being wiped out by disease, drought and other disturbances, and when those populations are isolated by landscape fragmentation, the chance of recolonization is low. That situation, then, can lead to a slow loss of species over time as populations disappear and are not replaced.

One obvious question, then, is “How big do prairies have to be?” in order to sustain biological diversity and their ecological function. In Nebraska, The Nature Conservancy is leading an effort to answer that question in southeast Nebraska. The conservancy is coordinating the research and evaluation focus of the Southeast Nebraska Flagship Initiative, a collaborative conservation effort between the conservancy, Northern Prairies Land Trust, Spring Creek Prairie Audubon Center and Nebraska Game and Parks Commission. The southeast Nebraska research is initially focusing on the status of pollinators and other insects in fragmented prairies. Those insects may be appropriate indicators of whether or not prairie fragmentation has reached a point where ecosystem services and functions have begun to decline. Pilot data was collected in 2008, and graduate students from the University of Nebraska-Lincoln (UNL) and the University of Nebraska at Omaha (UNO) will be at work in 2009.

If we can identify thresholds of fragmentation for prairies, we then have a tool for conservation planning. No one is seriously proposing that we restore the entire tallgrass prairie, or even a large proportion of what has been lost. But, if we could identify the size and/or configuration of prairie fragments that are necessary to sustain viable plant and animal populations and maintain ecosystem services, we would be able to make decisions about where targeted restoration efforts could tip the balance.

There are hundreds of thousands of Nebraska acres enrolled in conservation programs like the Conservation Reserve Program, in which cropland has been converted to some kind of grassland. Most of that enrollment happens in a relatively scattered fashion. If we had the aforementioned data to guide us, we could begin approaching individual landowners who have lands that could be critical pieces of potentially viable prairie landscapes if they were restored to grassland. Landowners should still be able to make the decision about whether or not to participate in programs, but a more targeted approach could make those programs much more effective in terms of their contribution to prairie conservation.

Assuming that we can come up with the data to guide those conservation programs, Nebraska has a wealth of experience in the mechanics of high-diversity, large scale prairie restoration. The state has a number of experienced people in the field of high-diversity prairie restoration, many of them based in the town of Aurora. Bill Whitney was the initial pioneer of high-diversity restoration in Nebraska in the 1980s and the organization he cofounded, Prairie Plains Resource Institute, has planted over 10 square miles of diverse prairie across central and eastern Nebraska since then. The Nature Conservancy’s Eastern Nebraska Project Office in Aurora has helped develop and refine high-diversity restoration methods, and is a national leader in the testing and evaluation of those techniques and the potential contributions of restoration to prairie conservation. Researchers from the University of Nebraska, UNL’s Cooperative Wild­life Research Unit, Kansas State University, the University of Ne­braska-Omaha and others are      collaborating with The Nature Con­servancy on prairie restoration research on conservancy lands in central Nebraska.

Conservancy staff, along with Gerry Steinauer of the Nebraska Game and Parks Commission (also based in Aurora), have pioneered an evaluation method for tracking the floristic quality of restored and remnant prairies over time. Stein­auer, along with conservancy and Prairie Plains staff, also wrote “A Guide to Prairie and Wetland Restoration in Eastern Nebraska,” which is available for free download at www.PrairieNebraska.org and www.PrairiePlains.org. Finally, all three organizations have played critical roles in advocating and facilitating the use of high-diversity restoration techniques on both public and private lands throughout the state. That includes work with other organizations, especially the Natural Resources Conser­vation Service, to fit high-diversity restoration techniques into conservation programs that implement practices on private lands.

The future role of high-diversity prairie restoration in Nebraska and elsewhere is still evolving. Research that identifies the key thresholds in the degree of landscape fragmentation relevant to the viability of wildlife and plant populations is a critical step. It will be important to continue adjusting public policy to facilitate more intelligent and efficient targeting of lands for restoration, so that we concentrate efforts in places where they will have the greatest conservation impact. There are also other challenges, primarily scaling up the commercial availability of locally harvested diverse mixes of prairie seed. While those are daunting needs, the most difficult task is behind us, because we now have the tools and expertise to restore diverse and functional prairie to the landscape. Now it’s just a matter of making it happen.

 

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