Salt Marshes in Nebraska

Far from any present-day sea shore, saline wetlands are hanging on for dear life in eastern Nebraska.  Fed by saline groundwater – through a process not yet completely understood – saline wetlands are a unique natural community in the middle of the western tallgrass prairie.  However, because of urban expansion and alteration of hydrologic systems, their future is far from certain.

In 2003, The Nature Conservancy helped form the Saline Wetlands Conservation Partnership as a way to work collaboratively among organizations concerned with preserving the last remnants of Nebraska’s saline wetlands.  Most of those remaining wetlands are located in or around the city of Lincoln, with the rest just across the county border to the north.  As the city expands, the threats to the wetlands increase.  Meanwhile, scientists are still struggling to understand exactly why and how the saline wetlands became salty – and, more importantly, how or whether that process can be sustained into the future.

I stopped by the Conservancy’s Little Salt Fork Marsh Preserve last week.  Here are a few photos from the site, along with some background on the ecology of eastern Nebraska saline wetlands.

What looks like sand is really a crust of salt that formed across a “salt flat” at the Conservancy’s Little Salt Fork Marsh Preserve. When the wet soil dries, the concentration of the salts becomes obvious. The houses in the background are an increasingly familiar site along the boundary of the remaining salt marshes. The current and future impacts of the houses, roads, wells, and other associated developments on the hydrology of the saline wetlands are not well understood.

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Saltwort (Salicornia rubra) is one of the few plant species that can grow in the middle of salt flats. Its succulent leaves (like a cactus without the spines) help it to hold on to water even in very saline soils. Saltwort is an annual, so its adaptation to saline soils is an important attribute that allows it to avoid competition from perennial plants.

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Sea blight (Suaeda depressa) is another salt flat plant. This one is growing in a shallow depression made by a cow's hoof. Grazing can be an important strategy for maintaining the open nature of salt flats and surrounding saline wetlands - and for suppressing invasive plant species. Some of the best quality saline wetlands remaining are those with a long history of private lands grazing.

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Hybrid cattails are one of a list of invasive plant species that threaten the remaining saline wetlands. Others include salt cedar, Phragmites, tall wheatgrass, reed canarygrass, and smooth brome. Each invasive species has its own salt tolerance level that determines which portion of the saline wetland landscape it can thrive in, but the cumulative effect is disastrous if left unchecked.

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Saline seeps like this one are the last vestiges of habitat still used by the federally-listed salt creek tiger beetle (Cicindela nevadica lincolniana). The known population of this subspecies is about 300 individuals - all restricted to the small area of saline wetlands around Lincoln, Nebraska.

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Salt flats and saline wetlands have a certain aesthetic charm, but apparently not enough charisma to generate much public support for their conservation. The Saline Wetlands Conservation Partnership has purchased many of the best remaining examples of the natural community, but acquisition may turn out to be the easiest step in the conservation process. Maintaining the hydrology and ecology of the saline wetlands in the face of urban expansion and invasive species will likely be much more difficult.

In Celebration of Annuals

 

When most people think about prairie plants, they think about long-lived perennial grasses and wildflowers.  However, 20-25% of plant species in most prairies are annuals; germinating, flowering, and dying in the same growing season.  Some of those annuals are tiny uncommon species that take advantage of small openings or disturbed areas when they can.  Others are adapted to growing conditions (e.g. saline or alkaline soils) that most other plants can’t grow in, and thrive because of a relative lack of competition.

Eustoma grandflorum is a member of the Gentian family, and is known in Nebraska as "Prairie Gentian". This annual plant has purple to white flowers and can be found in moist prairies throughout much of the Great Plains (we often find it in relatively alkaline soils). Its showy nature has led to the creation of horticultural varieties as well.

Most of the best known native annuals, however – think of annual sunflowers, annual ragweeds, and similar species – are largely considered to be weeds.  Because they can quickly become startlingly abundant, they get lumped in with non-native weeds such as buttonweed, exotic pigweeds, lamb’s quarters, and others, that are cropfield pests.  However, that label of “weed” is unfair for most of those annuals (including some of the non-natives).  A better term is “opportunistic”.  And thank goodness for them.  They fill spaces that are opened when the perennial plants around them are weakened, giving herbivores and pollinators something to eat, providing food and cover for wildlife, and helping to stave off true weeds that can take advantage of the same kinds of conditions. 

 

Plains annual sunflower is on of two annual sunflower species in Nebraska (the majority are perennials).  Plains sunflower inhabits sandier soil than its relative Helianthus annuus.  Both are considered cropfield pests but are also very important components of prairie plant communities.

In our Platte River Prairies, we work to ensure that we harvest seed from as many native annuals as we can each year so they can establish and create a seed bank in our restored prairies.  We do this, in part, because they are native species and part of the prairie community.  However, we also include them because they are a better alternative than some of the invasive species that compete for the same spaces.  We also watch for those annual plants and monitor their ebbs and flows in abundance to help measure whether or not we’re creating open spaces for germination and establish of annual and perennial plants alike.  When I see abundant annuals in our prairie, I know that there are perennials getting an opportunity to spread as well – they’re just not as showy about it.

Woolly plaintain (Plantago patagonica) is an abundant annual in distrubed sandy soils. The small grass seen growing with is is another annual, six-weeks fescue (Vulpia octoflora). We harvest as much seed from both species as we can for our sand prairie restoration work because the two species inhabit the same habitat as exotic annual bromes, and we'd rather have the native species!

These are just a few of the many annuals found in the Nebraska prairies we restore and manage.  They’re not any less interesting than perennial plants – just shorter-lived.  If anything, their short spectacular lives (they HAVE to bloom and produce seed in their single year of life in order to ensure a next generation) with abundant flowers and seeds make them underdogs that are easy to root for.  Go annuals!

Saltwort (Salicornia rubra) is one of several annual plant species that can thrive in very saline soil conditions. In Nebraska it is limited mainly to the saline wetlands around Lincoln, Nebraska and is a state-listed species. It is a succulent plant and tastes like sea water when chewed.

 

Western rockjasmine (Androsace occidentalis) is a tiny annual plant in the primrose family. Found in much of the western 2/3 of the United States and Canada, it is often difficult to see unless one is looking for it. It is relatively common in Nebraska (though usually overlooked) but is a state-listed threatened/endangered species in Indiana, Michigan, and Ohio.

Deer vetch (Lotus unifoliolatus), aka prairie vetch, is a very common native annual legume in our prairies along the Platte River. It becomes very abundant following grazing, summer fire, or drought.