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.

The Wrong Tiger Beetle

Last week, we had a gathering of biologists out at The Nature Conservancy’s Little Salt Fork Marsh Preserve, a saline wetland we own and manage north of Lincoln, Nebraska.  Saline wetlands are an important ecosystem that are found in very limited numbers in Nebraska – mostly right around the city of Lincoln.  Because the ecosystem is rare in Nebraska, so are many of the species associated with it.  Those species include several plants – including saltwort (Salicornia rubra) and sea blite (Suaeda depressa) – and the salt creek tiger beetle (Cicindela nevadica lincolniana).  The beetle is found only in the saline wetlands around Lincoln and is federally-listed as an endangered species (it’s population is thought to be less than 500 individuals).  To address the conservation needs of the saline wetlands and the species within them, the Conservancy helped assemble local government and conservation entities into the Saline Wetlands Conservation Partnership in 2003.

On this particular day, a couple people spotted some tiger beetles along a saline seep on the creek that runs through our property.  The habitat was ideal for the salt creek tiger beetle, but there has never been a  record of the species being found on our property.  As we tried to get a good look at these tiger beetles, we couldn’t tell which of the dozen or so possible species they were.  I doubted they were the endangered species, but the habitat WAS just what they’re supposed to use, so after the larger group of biologists left, I walked back down to the creek with my camera to see if I could get a better look – and hopefully a few photos.

The seep was only about the size of a compact car, so it wasn’t hard to find the beetles, which were running around hunting and mating.  The trick to photographing them, though, was that the mud in the seep was so soft that it wasn’t possible to step or kneel in it without sinking quickly.  I had to wait for the beetles to come close enough to the edge for me to photograph them – something they were reluctant to do.  The temperature was in the 90’s and the nice breeze that had earlier made the day tolerable didn’t reach down into the stream bank where I was kneeling in the mud.  There were some diffuse clouds that provided good light, but didn’t do much to cut down on the heat of the sun.  Oh, and I forgot to mention the mosquitoes.

The longer I waited and sweated in the heat, the more I talked myself into the idea that these just had to be the endangered salt creek tiger beetes.  I even saw a couple of burrows in the vertical bank of the stream, which fits the profile of where the tiger beetle larvae hang out.  At long last, after about 20 minutes, one of the beetles finally came within range, and I was able to get a few photos before it scurried off again.  Relieved, I decided to stop supplementing the salinity of the wetlands with my own sweat and head home.

The final result of my hot and sweaty efforts to get a tiger beetle to come within range of my camera.

When I got home, I pulled up my photo and compared it to those on the excellent Tiger Beetles of Nebraska website to confirm that I had just gotten some photos of a very rare insect.

…And I was wrong.

It looked relatively similar, but the insect I’d sweated for was actually the twelve-spotted tiger beetle (Cicindela duodecimguttata) – an uncommon but fairly widespread species.

I’m sure the twelve-spotted tiger beetle is a very nice species, and probably has an extremely interesting natural history story to go along with it.  I’m sure some day I’ll take the time to look it up and learn all about it.  I’m sure I’ll be really glad I took the time to photograph it.

I’m sure that’ll happen.

But not yet.