Lacreek National Wildlife Refuge
Mountain-Prairie Region

Habitats of Lacreek NWR

Lacreek National Wildlife Refuge is within the geographic area known as the Northern Great Plains and is classified vegetatively as mixed grass prairie. The refuge lies in the Lake Creek Valley that separates the Nebraska Sandhills on the south from the mid to short grass prairies to the north and west. The refuge has 13 water impoundments and includes over 15 miles of dikes creating nearly 5,400 acres of shallow flooded marsh and open water habitat. The uplands at Lacreek are composed of approximately 4,900 acres of native grasses, 5,450 acres of exotic introduced grasslands, 350 acres of restoration croplands, and 70 acres of non-commercial wood lots and shelter belts. The grasslands occur on rolling uplands, seasonally flooded sub-irrigated meadows, and choppy sandhills. The primary perennial water sources for the refuge include Lake Creek, Cedar Creek, Elm Creek, and several smaller spring-fed creeks that flow from the sandhills.

Wetlands

moist soil plants

Barnyard grass and annual smartweed that grow in the summer provide abundant seeds for the fall and spring migration and high aquatic insect populations when reflooded. Photo USFWS. Tom Koerner

Wetlands on the refuge are managed to provide both resting cover and food resources for migratory birds during spring and fall migrations. Throughout the rest of the year, wetlands serve as production and maintenance habitat for waterfowl, other migratory birds, and resident wildlife. Refuge wetlands are managed using moist soil management techniques. Substantial emergent and submergent vegetation occur in wetlands at the refuge. Cattail, bulrushes, wild rice, smartweed and arrowhead abound, as well as sago pondweed, coontail and duckweed. Extensive mudflats created when wetlands are in the drawdown phase create optimal feeding opportunities for migrating shorebirds and other neotropical species. Improved water quality and stimulated aquatic plant and insect growth occur during drawdowns and provide critical resources for waterfowl, marsh/water birds, shorebirds, and neotropical migrants.

 
spikerush meadown on pool 7

Many areas of the refuge that appear dry during the summer drawdowns, actually are covered by very shallow water. Properly managed, these areas grow species such as spikerush, that remain open and support abundant insect populations. Many species of birds, such as Virginia and sora rails, Wilson's phalaropes, white faced ibis, marbled godwits, willets, blue winged teal, and shovelers find this ideal for raising young.
Photo USFWS, Tom Koerner.

Arrowwood and Bulrush

During the drawdowns, arrowhead and softstem bulrush often establish and grow on portions of the pools. The arrowhead grows very large leaves which capture the summer sun, and store this energy in underground tubers, which are similar to small potatoes. When freezing temperatures return, the above ground stems freeze off and create open water again. The underground tubers remain, and provide the most preferred natural foods for trumpeter swans. The bulrush roots and stems are a preferred food for muskrats, which use them to build winter lodges.
Photo USFWS, Tom Koerner

 
Nuttallssunflower in bloom

Nuttall's sunflower in bloom
Photo: Tom Koerner, USFWS

Wet meadows occur primarily in the valley on the western edge of the refuge and along margins of the wetlands. They are categorized as wet meadows due to the prescence of ground water near the surface. Even during drought, the groundwater provides plenty of water for lush plant growth. These wet meadows contain a variety native forbs, grasses and sedges. The meadows are a glow in late summer with Maximillian and Nuttal's sunflowers, swamp milkweed, joe pye weed, and goldenrods. A wide variety of native grass grows here as well, including prairie cordgrass, Canada bluejoint, and big bluestem. An abundance of sedges can be found in the wettest sites, including Nebraska sedge, slough sedge, aquatic sedge, and bottlebrush sedge. Several species of willows and indigobush also grow here, adding fire tolerant shrubs to the landscape.

 

slough sedge meadow

Slough sedge and other sedges and grasses make up a large part of the plant community in the wet meadows.
Photo: Tom Koerner, USFWS

Wet meadows are managed to maintain the diverse native plant community that exists primarily through grazing and weed control. Grazing in the spring helps to stress non native grasses such as Kentucky bluegrass and smooth bromegrass that tend to establish and invade during long periods when no active management occurs. When the catte are removed, the area regrows and most visitors will not even realize the site had been grazed that year. The grazing also helps with weed control by improving the effectiveness of application. Canada thistle and leafy spurge are the primary concerns.

These wet meadows provide important habitat for many grassland nesting birds, including northern harriers, short eared owls, bobolinks, dicksissels, sharp tailed grouse, and long billed curlews. The sunflower seeds that grow in abundance provide food for thousands of migrating and wintering American tree, Lincoln's, and white throated sparrows. Hundreds of white tailed and mule deer winter in the wet meadows along with concentrations of northern harriers and short eared owls.

 

There are approximately 4,900 acres of native grasses, of which 3,726 acres are in the Nebraska Sandhills. Big bluestem, little bluestem, sand bluestem, prairie sandreed, switchgrass, Indiangrass, Canada wildrye, June grass, sand dropseed, needle and thread grass, western wheatgrass, salt grass, among others and numerous native forbs have all been noted on refuge grassland transects. The Sandhills portion of the refuge contain a diverse component of grass and forb species generally not found anywhere else on the refuge. The refuge contains approximately 5,450 acres of exotic, introduced grass species. Smooth brome and crested wheatgrass are the primary exotic grasses followed by Kentucky bluegrass. During the 1930's, large fields formerly planted to crops were planted to crested wheatgrass to minimize soil erosion. Many of these large, crested wheatgrass fields remain on the refuge.

In the early 1970's, habitat management techniques were developed to provide dense nesting cover for waterfowl. Several areas on the refuge were planted to grass species such as smooth bromegrass and alfalfa. These fields provided good cover for nesting birds, however, the species composition consisted of exotic cool season grasses. Over time, these fields were invaded by Canada thistle, a noxious weed. The refuge has plans to restore these grasslands, along with the crested wheat grass fields, to native grasses and forbs. The native prairie restoration process generally involves cropping the field for several years to eliminate exotic cool season grasses, control Canada thistle and other noxious weeds, and prepare a seed bed for planting native grass seed.

Upland vegetation is maintained to provide nesting habitat for migratory birds (waterfowl and neotropical migrants) and resident bird species. Upland habitats also provide necessary habitat requirements for resident wildlife throughout the year. A variety of management techniques have been implemented to maintain and enhance upland habitat conditions on the refuge including the use of prescribed fire, grazing, haying, native prairie restoration, and invasive species management.

Prairie sunset

The refuges grasslands hold their own subtle beauty.
Photo: Tom Koerner, USFWS

Western wheatgrass

Western wheatgrass, with its characteristic blue green hue, is common throughout the refuges uplands.
Photo: Tom Koerner, USFWS

 

Shrubs and Trees

The mixed grass prairies historically had few trees. Wildfires killed most trees and the only places they could be found were along rivers and streams or where the topography protected them from fire. Fire tolerant shrubs, such as indigobush, willows, leadplant, American plum, and chokecherry were found throughout the prairie in isolated patches. Wildfires limited their dominance, but they could survive a fire and regrow from the roots. It has been shown that in grasslands, tall trees and shrubs (taller than 10 feet) reduce the habitat value to most grassland nesting bird species. The trees provide perch sites for raptors, travel lanes for raccoons and skunks, and increase the amount of nest parasatism by brown headed cowbirds on grassland birds.

The refuge has approximately 70 acres of shrub and tree plantings. Most were planted by the Civilian Conservation Corps in the late 1930s. As these plantings eventually die off, they will be removed and the area replanted to native vegetation. Some of the refuge dikes are lined with wild plum, chokecherry, and willow. The shrubs provide important nesting habitat for Bell's Vireos and many other species of neotropical migrants. Shrubs and trees that cause management problems have been and/or will be removed from most refuge infrastructure. The large mature willows make maintenance of the dikes nearly impossible and do not provide secure firelines for prescribed burning. Native fire tolerant shrubs, such as indigobush, American plum, chokecherry, and willow will be allowed to persist where they do not interfere with other planned management activities.

Last updated: November 2, 2012