Anyone who has watched a prairie seeding go through its first several years of establishment will appreciate and identify with this post. For those of you who haven’t, the best analogy I can come up with is that the experience is a little like watching your son or daughter go off into the world on their own. You can spend tremendous energy planning ahead, preparing a site, and harvesting and planting seed, but at some point, you have to just stand back and let the new prairie stand or fall on its own. Sure, you can jump in and knock back the weeds a little now and then, but eventual success or failure depends upon many factors beyond your control, and it can be hard to predict the result during the first few years.
In February and March of 2016, we planted about 60 acres of land with a seed mixture of around 140 prairie and wetland plant species. The site had been cropland for many years, and then was converted to a mixture of native grasses and used as pasture. Eventually, the site became heavily invaded with tall fescue, smooth brome, and Kentucky bluegrass. A few years ago, we decided to kill off the existing vegetation and try to establish a much more diverse plant community. Although it had been farmed, the site still had some remnant wetland swales that had been farmed through and partially filled, but still had some wetland hydrology. Restoring this 60 acres feeds into our larger restoration objectives of enlarging and reconnecting remnant (unplowed) prairies in the area.
Volunteers hand broadcast wetland seed on frozen wetlands during February 2016.
This “drop spreader” was used to plant the majority of the site.
We used a combination of herbicide application and tillage to get rid of the grasses and prepare a seed bed. In addition, (under the appropriate permits) we had a contractor with a big scraper come in and deepen/widen the degraded wetland swales. Using seed we harvested from nearby prairies and wetlands, a couple different groups of volunteers hand-planted the wetland swales and low sandy ridges created by excavation spoil, and we used a broadcast seeder behind a UTV to plant the remainder of the site. (Thank you to the U.S. Fish and Wildlife Service, Nebraska Natural Legacy Project, and Nebraska Environmental Trust for funding this project.)
During the 2016 growing season, I visited the site very rarely, and didn’t spend much time there when I did. Early in the season, there wasn’t much germinating and growing except the kinds of “weeds” you’d see in an abandoned crop field (foxtails, pigweeds, ragweeds, annual sunflowers, etc.). Later in the season, those weedy plants had grown so tall and thick, it was physically difficult to walk through them.
This photo shows the kind of weed cover that grew during the first growing season. Lots of tall ragweed and annual sunflowers were joined by some perennial sunflowers and other plant species we had seeded. This is pretty typical of what we see during the first year of our restored prairies.
I walked around this site on Monday of this week and tried to capture what I saw with my camera. As I explored, I experienced a roller coaster of emotions. Some areas are looking way ahead of schedule, with a nice diversity of prairie and wetland plants coming in, while others don’t look like they’ve even started, or have problematic plants that we might eventually have to deal with. On the whole, I feel good about the progress of the restoration, though we do have some trees to control, but my overall confidence comes mainly because I’ve been through this process many times. We’ve had restored prairies look like junk for 4 or 5 years before finally kicking into gear, and others that look like a prairie after two years. Very rarely have we seen plantings fail. Regardless, it’s way too early to guess how this planting will turn out.
For what it’s worth, here is what I saw and thought about during my walk around this prairie at the beginning of its second field season.
The first thing I saw as I walked into the new prairie was a pretty good sized patch of 3-4 foot tall cottonwood trees (Populus deltoides). The parent trees can be seen in the background. We’ve been getting smarter about removing those kinds of seed sources before starting projects, but these trees are growing along a public road and we didn’t have the authority to remove them. We’ll have to evaluate our options for controlling the young cottonwoods in our new prairie.
A skeleton of an annual sunflower from the initial season shows how big some of those pioneering species were last year. Many of the sunflowers were over 12 feet tall.
Biennial wildflowers, like this prairie ragwort (Packera plattensis) germinated last year and are blooming this year. Hopefully, this one will start a colony that will help support spring-flying bees and other pollinators in future years. A pair of crane flies are mating on top of this one.
I was excited to see quite a few sedges blooming in only their second year. We don’t always get quick establishment of sedges from seeds. This one (Carex craweii) was in a patch of maybe 10 plants along the edge of a wetland, and I found at least three other species growing elsewhere in the site.
To balance out the excitement of seeing lots of sedges, I also found quite a few areas where there wasn’t much yet growing from our seed. This big patch of marestail (Conyza canadensis) was representative of maybe 30% of the planting. I think this is a soil issue – in our alluvial soils, prairie plant communities can vary dramatically from place to place, based on the soil deposits beneath them. Restored prairies establish with great variation for the same reasons.
Canada milkvetch (Astragalus canadensis), hoary vervain (Verbena stricta), goldenrod (Solidago gigantea), and Canada wild rye (Elymus canadensis) make up a very nice patch of new prairie plants.
The wetland swales are filling in quickly with wetland plants, including lots of spikerushes, grasses, rushes, and a few forbs and sedges. Much of that vegetation came from our seed, but I think some also came from the seedbank.
We purposefully designed the wetlands to vary in their depth to groundwater so that we’d have some areas of standing water most of the time, but also many other areas that go dry each summer.
Some of the wetland pools had tadpoles in them, likely from the Woodhouse’s toads that have already colonized the area. I also saw leopard frogs hopping around. In addition, numerous snails, and aquatic insects were moving around in the water, and dragonflies and damselflies were buzzing around above it.
This section of wetland had standing water a few weeks ago, but has now gone dry, leaving great habitat for shorebirds (but also for young cottonwoods). The vegetation along the margin of this wetland is mostly native colonizing plant species such as fleabane (Erigeron annuus), yarrow (Achillea millefolium), and Canada wildrye.
Sweetclover (Melilotus sp) is abundant across much of the new site. Experience shows that sweet clover (though I don’t like it) doesn’t seem to actually affect plant diversity much in our restored prairies, so we’ll just let it go until the site is established well enough to support fire and cattle grazing. At that point, the cattle will keep the sweet clover suppressed because it’s one of their favorite plants to eat.
In addition to areas of strong native plant growth and others dominated still by non-native or “weedy” plants, there were also areas where bare ground was still plentiful. Again, alluvial soils make all of this really interesting because the soils vary greatly from place to place and strongly regulate plant growth.
Last year’s seed pods of Illinois bundleflower (Desmanthus illinoensis) show that this native perennial legume established and bloomed in its first year at the site.
Duck and raccoon tracks joined the tracks of many shorebirds along the edges of the restored wetlands. It’s really encouraging to see how quickly wildlife and insect species colonize these sites, even while the plant community is still young.
I’ll probably return to walk through this site numerous times this season because I can’t help myself. Apart from working on cottonwood trees and a few musk thistles, however, it’s unlikely that we’ll actually do anything else here, so my visits will be mostly out of curiosity rather than to stimulate management. As with this trip, I’ll see things on future walks that will encourage me and others that will make me wonder if the planting will end up as a disaster, even though I know it’s too soon to know anything.
Within the next few years, we’ll try to burn the new prairie whenever we can, and when the major grasses start to assert their dominance, we’ll begin grazing the site in ways that support a diversity of plants and animals. Typically, that grazing begins when the site is between 5 and 8 years old. In the meantime, there’s really nothing to do but wait. (But I’ll still peek in now and then anyway.)
I was really glad to see coyote tracks along the edge of the site. The presence of these (relatively) large predators will be key to the long-term success of the ecological community in this restored prairie.
For those of you with technical questions about our restoration methods, we didn’t test our seed for viability, but based on previous experience, our seeding rate for this planting was probably about 2-4 lbs PLS/acre, about 2/3 of which was grasses and 1/3 was forbs, sedges, etc. We typically broadcast our seed into recently harvested soybean fields, so this planting was a little different, but not that different. We don’t mow weeds during the first season based on trials that have shown no difference in long-term establishment (sandy soils help keep weed densities low enough to still allow sufficient light to hit the ground, despite what it looks like in the 2016 photo in this post). We don’t cultipack or harrow seeds in either. We’re fortunate not to have much trouble with aggressive perennial invasive plants in our early plantings, which makes our weed control pretty easy. Deciduous trees are the main exception to that, especially cottonwoods (as shown above) and Siberian elms (not too bad at this site). Later, we see invasion by perennial cool-season invasive grasses, but we suppress those with fire and grazing.
The Prairie Ecologist 