Everything old is new again… at least along the south stream of the Platte River.
Starting in 1988, the Conservancy's Nebraska Program purchased several tracts of land now known collectively as the “Dahms/Derr complex” – part of the Platte River Prairies. The Conservancy knit together 1,253 acres in hopes of restoring farmland and an old sand and gravel pit to the kind of habitat that is welcoming to wildlife such as sandhill cranes, whooping cranes, mallards, pintails, Northern river otters, regal fritillaries, grasshopper sparrows, native fish and freshwater mussels.
Restoration efforts are critical in this landscape. Over 80% of the native grasslands and wet meadows associated with the Platte River have been lost to agricultural production. The remaining grasslands and meadows are subject to encroachment by invasive or nonnative plants and trees. This change has resulted in a reduction in the quantity and quality of cover for wildlife.
Two examples of these efforts are:
From Irrigated Crop Field to Grassy Mosaic
In 1994, the Conservancy converted the 100-acre Dahms pivot from an irrigated crop field to prairie vegetation. The project was a demonstration of the concept that cropland could be transformed into grazing land and wildlife habitat. As an experiment, a small portion of the site was seeded with a high-diversity mixture of prairie seeds by Prairie Plains Resource Institute, including more than 100 prairie plant species.
Since 1994, grassland/wetland restoration techniques have become much more refined, and high diversity seedings and wetland slough creations have become more commonplace. Thanks to an award from the Nebraska Natural Legacy Project, the Conservancy is initiating a process to improve upon our initial efforts. The grant will fund the enhancement of the first half of the site (with the second half to come later) – a process that will entail adding 3,800 linear feet of slough wetlands, and reseeding approximately 50 more acres with a 120-150 species seed mix.
Higher diversity seedings provide better habitat for at-risk and other wildlife species and provide a more resilient and functional ecological community. The addition of created wetlands (seeded with a high-diversity wetland seed mixture) adds additional habitat as well as making the restored site – and the surrounding landscape – more resilient and able to adapt to rapid climate change.
From Sand and Gravel to Otters and Mussels
Less than a mile south of the Platte River, a meandering stream flows through the Platte River Prairies. Known locally as the “clam channel”, this clear water stream is home to more than eight species of freshwater mussels, along with a variety of fish and other aquatic species. In addition, the strong connection to groundwater keeps the stream and its adjacent wetlands from freezing quickly in cold weather. This makes it valuable for ducks and geese, along with other animals that rely on open water habitat during the winter.
Between the 1920’s and 1980’s, a long stretch of that channel was mined for sand and gravel, leaving a series of deep lakes and tall sand piles behind. By the time the Conservancy acquired the property, some of the lakes had filled in with sediment from upstream, but there were still large deep pools of 5 to 9 feet in depth, surrounded by steep sandy slopes. In 2001, the Conservancy began a restoration project consisting of clearing trees and pushing the old spoil sand piles into the deep water to recreate shallow wetlands and a meandering stream channel. With financial help from the U.S. Fish and Wildlife Service and Ducks Unlimited, the Conservancy completed the first half of the project and seeded the area with a high-diversity mixture of grassland and wetland seeds.
Ten years later, the Conservancy is finishing the job, with help from the same two partners. “We did the cheap half of the project in 2001”, said Chris Helzer, Eastern Nebraska Program Director. “Then we had to wait to find sufficient funds to do the harder part and fill in the deeper pools.” With the help of a grant from the North American Wetlands Conservation Act, the hard part was completed this fall. The remaining lakes were filled in and multiple stream channels and wetland areas were created.
“We have just set the stage,” said Helzer. “We have created some raw channels through the sand that water can flow through. As soon as we get a couple of high water events, the water will take over from there and the shape of those channels and wetlands will change from year to year.
The shallow slopes and absence of trees along the creek and wetlands create a relatively unique and valuable habitat type in the Platte Valley. The portion of the site that was restored in 2001 has been heavily used by ducks, shorebirds and other water birds, along with river otters, muskrats, and many other wildlife species. Now that the entire restoration project is completed and the steep banks have been knocked down, it’s likely to get even more attention from wildlife, including sandhill and whooping cranes. The Conservancy’s job now will be to stay on top of invasive species such as reed canarygrass, Phragmites, and purple loosestrife that will be a constant threat to the species and habitat quality at the site.
Photographer Michael Forsberg has set up a time-lapse camera at the sandpit restoration in order to record the transformation as the bare sand and water establish into a full blown vegetated and dynamic wetland. This will help showcase the beauty of the site, but also track the changes in the water levels, wildlife use patterns, and shape of the channels and wetlands through years of high and low water levels.
“This is the kind of comeback story it’s easy to root for”, said Helzer. “We essentially played around in a big sandbox and ended up with fantastic habitat. How fun is that?”