In much of North America, prairies have largely been reduced to isolated fragments of grassland, embedded in a matrix of row crop agriculture. Because it’s difficult to maintain ecological function and species diversity in small isolated prairies, conservation of those prairies in their current state is an uphill battle. The only chance we have for long-term conservation success is to increase the size and connectivity of those prairies. Fortunately, the Conservancy and other organizations know how to do that, and are getting better at it all the time.

 The New Model: Stitching Fragmented Prairie Landscapes Together

 Prairie restoration (AKA, prairie reconstruction — restoring cropland to prairie) has long been seen as more art than science, and thus dismissed by some as an illegitimate conservation strategy. That’s probably a fair assessment in the case of many individual projects. However, a growing number of grassland conservation programs are now using prairie restoration as a critically important tool for the conservation of fragmented grassland landscapes. The old model of prairie restoration often consisted simply of harvesting prairie seed and planting it in relatively small parcels of cropland. The new model applies prairie restoration as a tool to stitch fragmented prairie landscapes back together. This is not your father’s prairie restoration.

 Under the new model, restored prairies are strategically located and constructed so that they enlarge and reconnect prairie fragments, mitigating the top threat to the viability of prairie ecosystems in much of North America. We are using seed mixtures of between 150 and 300 plant species and are so far working on projects ranging in size from 5,000 to 24,000 acres. We are still refining our techniques, but we have been generally successful at creating diverse communities of prairie plants at large scales, and are in the process of assessing how much those plant communities add to the ecological function of the landscape around them.

 For example, we are looking at how well species (from leafhoppers to toads) in remnant prairies make their way into — and through — the restored prairie that now connects those remnants to others. We’re finding it difficult to measure the impact of these restored prairies on ecological processes such as pollination and seed dispersal, but we’re working on that as well. To date, what we have learned has been encouraging, and supports the value of this large-scale, high-diversity restoration effort. Some preliminary findings include:

 • The majority of insect, bird, and reptile/amphibian species in remnant prairies appear to easily colonize adjacent restored prairie habitat.

 •Many insect/plant host and other species interactions observed in remnant prairies are also present in restored prairie. These include gall-forming insects and other invertebrates that require particular plant species as larval hosts, as well as parasitic plants that are able to find and attach to their hosts.

 • Preliminary studies of pollination services have shown that restored prairies have similar abundance and richness of pollinator species as compared to nearby remnant prairies.

 Why Looks Don’t Matter — And Why That Matters

 One of the interesting philosophical changes taking place under the new strategic model is that we’re changing our expectations about the appearance of a restored prairie. Under the old model, the objective was usually to create a prairie plant community that was nearly identical to an historic or current reference site. Many research projects have compared the relative abundance of individual plant and animal species between restored and remnant prairies — and have usually concluded that prairie restoration has failed to meet its objectives. There are plenty of fairly obvious reasons for that failure, including degradation of soil conditions under years of farming, unrealistic notions that a five-year-old prairie will develop the community structure of a 5,000-year-old prairie, invasive species and climate change.

 However, when prairie restoration is used as a way to fill holes in a prairie landscape, the expectations and objectives for individual prairie plantings change drastically. As mentioned above, we want to know how well the restored prairie functions in terms of expanding and connecting habitat for prairie species, and how much it boosts ecological resilience and ecological function across a landscape. Whether or not the prairie looks like a nearby remnant prairie or matches our mental image of what the prairie in that location looked like 200 years ago is irrelevant.

 In most cases, the vast majority of plant species found in nearby remnant prairies are also present in restored prairie, but the relative abundances of those species may be very different. Some of those differences will likely narrow over time — but, just as in remnant prairie, plant-species composition is strongly tied to both soil conditions and management regimes. Restored prairies are obviously different from remnants in both regards. Habitat structure for grassland-nesting birds and other structural-dependent species can be manipulated through management, regardless of plant species composition.

 In some ways, changing expectations with regard to the appearance of restored prairie may seem trivial, but it’s actually very important. We no longer have to figure out how to get less productive soils to support plant communities identical to nearby unfarmed prairies, for example. Instead, we can plant the most diverse mixture of native prairie seeds we can, and let the new prairie establish in a way that conforms to today’s soils and climate. Restored prairies can be allowed to complement — rather than duplicate — nearby remnant prairies. Being freed from unrealistic expectations means that we can focus on suppressing invasive species and improving our ability to restore and measure ecological processes in our restored/remnant prairie landscapes.

 There are multiple challenges facing us as we continue to refine and expand the use of prairie restoration. One challenge is to convince cooperating researchers to measure the ability of restored prairie habitat to functionally enlarge and connect remnants instead of simply comparing the differences in species composition and soil organic matter levels between remnant and restored prairie. We also have some major research questions, including one very big one: How large/connected do prairies have to be in order to conserve the viability of the species and communities within them? Answering that question will take time, but we’re working on it. In the meantime, we can at least be confident that our strategy of stitching together fragmented remnant prairies is working — at least for most prairie species — and keep plugging away.

 Author’s note: In case you’re interested, the Grassland Restoration Network is an informal learning network that TNC began in 2003 to bring together large-scale programs that are using prairie restoration as a conservation tool. Despite losing TNC funding after the first three years, the network continues underground (don’t tell anyone). If you’re interested in joining or learning more about the network, contact me and I’ll see if I can put you in contact with someone who knows someone.

Image: This restored lowland tallgrass prairie in Nebraska differs from nearby remnant prairies in the relative abundance of plant species, but likely functions well as a connector between those other prairie fragments. Cattle grazing is being used to manipulate habitat structure as well as to maintain plant species diversity. Image credit:Chris Helzer/TNC