|
Earlier this month was the Loess Hills Cooperative Burn Week, an annual event sponsored by the Loess Hills Fire Partners. Burn Week provides partners with an opportunity to achieve fire management where additional skills and resources are needed to accomplish work at a landscape scale. It is also an opportunity to build relationships with partners, share knowledge and skills, and work within a more complex organizational structure than usual, using the Incident Command System. This year's focus was on the southern Loess Hills and based out of Waubonsie State Park in Fremont County. Nearly 90 participants from nearly 40 organizations participated this year. While weather was not ideal for burning most days, several units were burned on Monday and Tuesday. When conditions did not allow for burning, participants did a variety of trainings and educational sessions both indoors and outdoors. Fortunately several of the partners were able to return to Waubonsie later in April to conduct the planned burn at the park. Learn more about fire in Loess Hills prairies here and here. Check out the photos and videos below to see what this year's burns looked like.  Prescribed fire at Riverton Wildlife Management Area during Loess Hills Cooperative Burn Week 2022. Photo by Lance Brisbois.  Prescribed fire at Riverton Wildlife Management Area during Loess Hills Cooperative Burn Week 2022. Photo by Lance Brisbois.  Prescribed fire at Riverton Wildlife Management Area during Loess Hills Cooperative Burn Week 2022. Photo by Lance Brisbois.  Prescribed fire at Riverton Wildlife Management Area during Loess Hills Cooperative Burn Week 2022. Photo by Lance Brisbois.  Prescribed fire at Riverton Wildlife Management Area during Loess Hills Cooperative Burn Week 2022. Photo by Lance Brisbois.  Oak savanna burn at Wheeler Grove Conservation Area in Pottwattamie County. Photo by Derek Christoffel.  Oak savanna burn at Wheeler Grove Conservation Area in Pottwattamie County. Photo by Derek Christoffel.  Oak savanna burn at Wheeler Grove Conservation Area in Pottwattamie County. Photo by Derek Christoffel.  Oak savanna burn at Wheeler Grove Conservation Area in Pottwattamie County. Photo by Derek Christoffel.  Eastern red cedars burning at Mt. Crescent. Photo by Andrea Porter.  Eastern red cedars burning at Mt. Crescent. Photo by Andrea Porter.  Firefighters walking through a recently-burned woodland at Waubonsie. photo by Andrea Porter  Prescribed fire at Waubonsie. photo by Kody Wohlers.  Prescribed fire at Waubonsie. Photo by Shelly Eisenhauer  Prescribed fire at Waubonsie. Photo by Shelly Eisenhauer  Just-burned prairie at Waubonsie. photo by Shelly Eisenhauer  Group photo by Shelly Eisenhauer.  Information center at Washawtee Lodge. Participants learned about logistics and other important details for the week through this area inside Washawtee Lodge. Photo by Kody Wohlers.  Educational presentation at the Lodge.  When conditions were not adequate for burning, participants did other trainings and activities such as cuttnig trees. photo by Shelly Eisenhauer
0 Comments
updated 2-22-23 The last week of February is Invasive Species Awareness Week, which is "an international event to raise awareness about invasive species, the threat that they pose, and what can be done to prevent their spread." Iowa's landscape has many non-native plant and animals species that can wreak havoc on native plant & wildlife communities, as well as cause economic damage. Invasive species have varying levels of concern depending on their impacts. Some invasive species cause relatively few problems, while others can destroy native ecosystems. Some require action to avoid legal consequences, while others are more a concern to land managers working to restore prairies and savannas. Eastern red cedar (Juniperus virginiana), for example, is one species that can take over and shade out native prairie species, resulting in dense monocultures of coniferous trees where almost no other species can survive. Although they are actually native to the region, removing fire and grazing animals from the landscape has led to their proliferation in recent decades.  Example of a stand of dense cedars (left) and diverse remnant prairie (right) at Loess Hills State Forest. Smooth brome (Bromus inermis) is a grass that was planted in livestock pastures, along roadsides, on terraces and grassed waterways, and elsewhere across the Midwest. While it's not necessarily a problem in every site, it can be challenging to control in prairie restorations and reconstructions. If you have an area where you'd like to restore or create a prairie, you will need to manage the brome. Crown vetch (Coronilla varia) is a non-native legume that was planted for erosion control and ground cover. It has physical similarities to native vetch species but should be eradicated. Reed canary grass (Phalaris arundinacea) prefers wetter areas and has resemblance to some native grasses. These species are problematic in prairies and wetlands because they can crowd out native species. In woodlands, garlic mustard (Alliaria petiolata) is one of the most aggressive understory species. Like cedars, it can take over an area and prevent most other species from growing. Tree of heaven (Ailanthus altissima) was planted as an ornamental and is one of the fastest-growing and -reproducing woody species around. Garlic mustard and tree of heaven can quickly take over a woodland and prevent native species from growing. Some species are listed as noxious weeds and landowners have a legal obligation to remove them. If you have confirmed presence of noxious weeds on your land, you should take action to eradicate them. The links below have full listings of all invasive flora species in Iowa as well as fauna such as insects and aquatic species. If you like the look of certain invasives, plant a native species with similar characteristics instead. Check out the Midwest Invasive Plant Network's Landscape Alternatives for Invasive Plants of the Midwest brochure and mobile app to help find native species. Golden Hills worked with Dr. Tom Rosburg of Drake University on a Common Weeds & Invasive Species virtual program in 2022. View the class recording here or below.  Here are several additional resources to learn more about invasive species in Iowa:
Last week we had the opportunity to visit the Iowa Department of Natural Resources' Prairie Resource Center (PRC). The PRC provides prairie seed to public lands (state wildlife areas and parks) across Iowa. Their operations are primarily located at Brushy Creek State Recreation Area in Webster County, with additional facilities at North Central Correctional Facility in Calhoun County. Staff and volunteers visit remnant prairies in different parts of the state to harvest local ecotype seed. They then clean and store seed, and share it with public land managers within the respective eco-zones. From DNR's PRC website: "A plan was devised to divide the state into 3 zones, the northern 3 tiers of counties, the central 3 tiers of counties and the southern 3 tiers of counties. (This plan is in synchronization with the Iowa Ecotype Project/University of Northern Iowa which works with private seed producers.) For instance, pale purple coneflower is harvested from several prairie remnants in the north zone. Seed is cleaned, grown into 4-6 inch plants in a greenhouse, and planted into a single-species, cultivated row with other plants from northern Iowa. Seed is collected by hand or by use of a small combine and returned to public land in northern Iowa. Native grass seed is collected, planted in larger field situations and harvested with a combine equipped with a unique rice-head stripper. This allows seed to be harvested yet the valuable residue remains as winter cover for a variety of wildlife species." Map of Iowa's eco-zones:  Photos of some of the harvested seed to be cleaned:    A variety of equipment, both large and small, is used to remove seed from hulls, chaff, and other debris, The leftovers are kept separate and returned to fields to provide nutrients to the prairies.     An example of cleaned seed:  In addition to seed harvesting and cleaning, the Prairie Resource Center has a greenhouse where they grow native plants. Most of the plants are used in their seed plots. Seed plots provide an easy way to harvest specific species, planted in rows, versus searching through prairies to find one species and harvesting by hand.    Due to the scale of operations, the DNR uses tractors and combines for some seed harvest, in addition to hand-harvesting remnant prairies.  Below is an example of a seed spreader that is used to sow prairie seed.  Golden Hills would like to thank Laura Leben with DNR for providing the tour.
We recently received a Specialty Crop Block Grant entitled Perennial native seed production for rural resilience. With this project, we will be working with public and private landowners to establish native seed production plots. Project updates will be posted at goldenhillsrcd.org/prairieseed. Email lance@goldenhillsrcd.org with any questions about this project or the PRC visit. December 5th is recognized as World Soils Day. Iowa, perhaps more than any other state, owes its agricultural heritage and economy to some of the most fertile topsoil in the world. The dominant soil order across the region is called Mollisols (dark green in the below map). Mollisols are grassland soils that developed over centuries or millennia within prairie ecosystems.  Within the order of Mollisols, Udolls (green in the map below) are the predominant suborder:  Udolls align closely with the tallgrass prairie region, while Ustolls (another suborder of Mollisols) dominate the mixed- and short-grass prairies:  More than 99.9% of Iowa's tallgrass prairies have been destroyed by human development, and largely replaced with corn. Corn is a plant within the grass family, and like the many types of native grasses, it is well-adapted to thrive in the Udoll soils. The former tallgrass prairie is now aligned closely with the Corn Belt:  Iowa is divided into several soil regions (map below). In western Iowa, you've probably heard the term "loess" before. Besides the Missouri River Alluvium (14), which is floodplain soil on the flat bottoms of the Muddy Mo, most of the region is covered in a layer of loess. East of the alluvial plain are Missouri River Bluffs (13) and Very Deep Loess (12), which includes the Loess Hills landform. The Loess Hills are typically defined as having at least 60 feet of loess, though many of the bluffs adjacent to the Missouri floodplain are much deeper than that, even up to 200 feet deep. Learn more about the Loess Hills here. Loess was deposited through aeolian processes (wind-driven), with prevailing westerly winds dropping the deepest soils closer to the Missouri River. Moving east, the depth of loess gradually decreases over southern Iowa. The Des Moines lobe was glaciated more recently and lacks this loess.  The depth of loess aligns closely with the EPA-designated ecoregions of Iowa. 47d (Missouri Alluvial Plain) is the same as soil region 14 above. Ecoregions 47m (Western Loess Hills) and 47e (Steeply Rolling Loess Prairies) are similar to soil regions 11 & 12.  In the map below, purple areas have Peoria Loess, and green areas are alluvial soils. Most of western Iowa is either purple or green. The Des Moines lobe stands out as not having loess deposits.  Loess is highly erodible. The maps below from USDA show how the deep loess soils of Iowa, along with the loess region of the Palouse in eastern Washington, have some of the worst soil erosion on the continent. Fortunately, however, conservation practices like terraces and grassed waterways have significantly reduced this erosion over the past 40 years.  While many people think of soil as just dirt, there are complex ecosystems living within it. “Essentially, all life depends upon the soil… There can be no life without soil and no soil without life; they have evolved together” - Dr. Charles E Kellogg, Soil Scientist and Chief of the USDA’s Bureau for Chemistry and Soils. Even if you don't farm or garden, the food you eat on a daily basis depends on healthy soils. If soil is treated "like dirt," these webs suffer and soil health declines.  Our agricultural economy, waterways, and wildlife also depend on soils to thrive. Historically, poor soil health has contributed to the collapse of entire civilizations. This is why President Franklin Delano Roosevelt said, “The nation that destroys its soil, destroys itself" following the Dust Bowl. Soil health is becoming increasingly important in agricultural discussions and we should not overlook the humble humus beneath our feet.  In September and October, Golden Hills had funding from The Gilchrist Foundation to continue our Prairie Seed Harvest project in the Loess Hills. We also have funding from Pottawattamie Conservation Foundation to do prairie seed harvest at Hitchcock Nature Center specifically. At each event, Project Coordinator Lance Brisbois provided a brief training on identifying species and ripe seed, then showed how to harvest the seed. Events Summary:
Through these events, we engaged more than nearly 100 volunteers of all ages totaling approximately 187 volunteer hours, worth well over $5,000 of time that would have otherwise been incurred by local conservation agencies with limited time and budgets. The seed we harvested was combined with seed purchased from other sources to be used on prairie restoration projects totaling several hundred acres. All seed collected from state lands was donated to Iowa Department of Natural Resources staff per state regulations. Most seed collected from other areas was given back to local conservation agencies for their prairie restoration efforts. Golden Hills saved a small amount of seed (with written permission) from land owned by county conservation boards for native plant propagation in partnership with Iowa Western Community College. We will grow some of this seed in their greenhouse over the winter and host a native plant sale in spring 2022. Some of the seed has also been saved by Golden Hills to start a small native seed bank. This seed will be stored long-term and added to each year, with the intent of growing a seed bank of local ecotype native species. We thank all the volunteers who helped this year, and look forward to hosting more seed harvest events in 2022. Thank you to The Gilchrist Foundation and Pottawattamie Conservation Foundation for their financial support. As part of this year's Giving Tuesday (November 30), we have a goal of 40 donors and $4,000 to support our Prairie Seed Harvest project. Learn more and donate here.                  Broken Kettle Grasslands, owned and managed by The Nature Conservancy (TNC) in Iowa, recently held their annual bison roundup. Partners and volunteers from throughout the region helped round the bison up to check the health of the animals, weight them, and vaccinate them before releasing them back onto the prairie. Bison were, for thousands of years, an integral component of prairie ecosystems. TNC reintroduced bison to help control invasive species and improve prairie habitat. Broken Kettle, north of Sioux City along Loess Hills National Scenic Byway in Plymouth County, includes the largest remnant prairie and largest roadless area in Iowa. This area is the only known site with a population of prairie rattlesnakes in the state. The bison at Broken Kettle came from Wind Cave National Park and are called genetically pure since they have no cattle ancestry like most other bison found in the country today. The herd totals more than 200 and they spend the rest of the year roaming approximately 1,900 of the preserve’s 3,000 acres.  Rounded-up bison  Scott Moats with The Nature Conservancy observes a bull bison during the roundup  Bison getting weighed and health checkup  Bison corral during the roundup
"Sedges have edges
Rushes are round Grasses have nodes that are easily found (or 'grasses are hollow, what have you found?')" If you've done much plant identification, you may have heard this or a similar expression. Prairies, in short, are grasslands. They are dominated by grasses and grass-like plants such as sedges and rushes, along with abundant forbs (flowers) but only sparse woody vegetation (trees & shrubs). At first glance, especially from a distance, prairies may look like monotonous monocultures. This could not be farther from the truth. A high-quality tallgrass prairie remnant can have more than 300 species, many of which are grasses, or grass-like plants. In our Loess Hills Plant List, which includes many of the species found in western Iowa's natural areas, we have identified 58 species in the Poaceae family, 35 in Cyperaceae, and 4 Juncaceae. In other words, grasses are the most common, followed by sedges and rushes. Overall, there is greater species diversity of forbs (flowering plants), but typically the quantity of grass and grass-like plants exceeds that of forbs in prairies. 
Prairie Plant Functional Groups. Slide from Lisa Schulte Moore's presentation, Iowa's Prairies, from Iowa State University's Master Conservationist Program, Module 2a - Understanding Iowa's Ecosystems: Prairies. https://naturalresources.extension.iastate.edu/programs/master-conservationist
Classification of grasses, sedges, and rushes. Source: http://www.countrysideinfo.co.uk/grass_id/intro2.htm
Grasses, sedges, and rushes are all monocots. Monocots have one seed leaf and share other common characteristics. "Although all grass-like plants are monocots, not all monocots are grass-like plants." Learn more in this short video from Native Plant Trust:
Differences between the three can include stem structure, sheath form, and flower type, This page from Minnesota Wildflowers is an excellent synopsis of the differences. The chart below from Florida also provides a great summary.
Summary of sedge, rush, and grass characteristics. From Erick A. Revuelta's presentation, CENTRAL FLORIDA GRAMINOID IDENTIFICATION WORKSHOP: Introduction to Florida’s Graminoids. Source: https://bugwoodcloud.org/CDN/floridainvasives/2019/Part1-Introduction.pdf
Grasses are commonly sorted into warm-season and cool-season species. According to Missouri Prairie Journal: "Native cool-season grasses are referred to as “C3 grasses” because, during photosynthesis, they use the Calvin-Benson cycle and produce three carbon molecules, while a C4 grass does not directly use the Calvin-Benson Cycle and produces a four-carbon molecule...
These physiological differences allow native cool-season grasses to grow and reproduce in cooler conditions, offering forage in early spring, fall, and part of winter, and seed by early summer, while warm-season grasses continue growing when cool-season grasses are dormant. For more information on comparing these two groups of grasses" (Read more here).
Warm-season grasses include some of the most common grasses in many prairies, such as andropogon gerardii (big bluestem), schizachyrium scoparium (little bluestem), sorghastrum nutans (Indian grass), panicum virgatum (switchgrass), and bouteloua curtipendula (side-oats grama).
Andropogon gerardii (big bluestem) inflorescense. This is a warm-season native prairie grass species.
Native cool-season grasses include elymus canadensis (Canada wild rye), elymus virginicus (Virginia wild rye), and koeleria macrantha (June grass). Many non-native pasture grasses, such as brome and fescue, were planted because they can provide a food source for plants earlier in the season compared to many of the native warm-season grasses.
Elymus canadensis (Canada wild rye) is a cool-season native prairie grass.
Sedges, in the family Carex, are the next most abundant grass-like plants in Iowa's prairies. This blog post by Leland Searles also offers helpful information: "Sedges are an important, often overlooked group of native plants. In Iowa there are at least 125 species belonging to one genus, Carex."
People often remember "sedges have edges" to help identify them while in the field using their stems. 
Sedges have edges! (From In Defense of Plants Facebook page - https://www.facebook.com/InDefenseOfPlants)
Golden Hills worked with Dr. Tom Rosburg to record this Carex Identification class in March 2021. Dr. Rosburg covers some of the more common sedges found in Iowa. A sedge identification key and other resources can be found at goldenhillsrcd.org/plantid.
Dr. Anton Reznicek (Curator of the University of Michigan Herbarium and Research Scientist in the Department of Ecology and Evolutionary Biology)
The charts below show how a grass (andropogon gerardii/big bluestem), a sedge (carex gravida/heavy sedge) and a rush (juncus dudleyi) are
In this video, Bob Lichvar of the US Army Corps of Engineers briefly describes how to field-identify common rushes.
The taxonomic charts below show where three common species fit into into the classification system. Andropogon gerardii (big bluestem) is a grass, carex gravida (heavy sedge) is a sedge, and juncus dudleyi (Dudley's rush) is a rush.
As important as it is to learn native plants, it's also good to identify invasive and unwanted plant species that can harm native prairie, wetland, savanna and woodland ecosystems. Reed canary grass is one of the most aggressive invasive grasses. It can take over large areas in short amounts of time and crowd out native species. Removing it once it is establish can be very difficult, so it's better to identify it early and prevent it from spreading as much as possible. The Grasses of Iowa's Weedy and Invasive Grasses page is a great resource for learning about non-native and problematic species.
Links & Resources for grass & grass-like plant ID and classification:
At the end of winter, sap starts flowing from tree roots back up the trunk. This sap contains the vital nutrients that trees need to survive and thrive. We visited Waubonsie State Park in Fremont County on a warm day in early March to practice tapping trees with Park Manager Matt Moles. Always check with property managers before tapping trees on public lands. We received approval to do this for educational purposes. The process is a lot simpler than many people might expect. Basically you find a tree you want to tap and drill a hole that will fit the size of your spile. The hole should be at a slight upward angle to help the sap drip down the spile. If the sap is flowing, you will likely see it dripping out already. We used inexpensive plastic spiles found online but traditionally the spiles were made of metal.  Example of the spiles we used. Next, attach a tube to the spile and tap the spile into the drilled hole so that it fits tightly and will not fall out of the tree. Measure beforehand to ensure the tubing will fit on your spiles. Below you can see the sap flowing from the spile into the tube. Put the other (bottom) end of the tube into some kind of container like a bucket placed on the ground. You could also hang the bucket on the tree and eliminate the need for the tubing. Make sure to wash the bucket, tubing, and spiles before and after each use, and don't use a bucket that has stored any toxic substances. Depending on the tree, the weather, and other factors, the sap my drip quite slowly or flow fairly rapidly like this one: It's best to cover the bucket to prevent insects, dust, and other debris from settling into the sap. Check the bucket regularly to make sure it doesn't overflow.
Now you've done the easy part! Turning the sap into syrup requires boiling it down until the water evaporates, leaving mostly sugar. Maples generally have higher sugar content than most other trees, which means it takes less boiling to get more syrup. Still, many other species can be tapped. Even with maples, a rough estimate is about 40 gallons of sap boils down to one gallon of maple syrup. For other species, the difference is even greater. If you don't have the right equipment to boil down that much sap, start small and try it out on your stovetop or over an outdoor fire. You can also skip the boiling process completely and drink the sap alone or with other beverages like coffee or tea. Sap, or maple water, as it's been branded, is marketed as a healthy alternative to sugary drinks. It has a slightly sweet taste and includes some nutrients and electrolytes. For more details on tapping trees, check out this recent blog post from Perennial Homestead. National Bison Day, held annually the first Saturday of November, is a "commemoration of the ecological, cultural, historical and economic contribution of a national icon, the American bison." According to the National Bison Association: "The bison, North America’s largest land mammal, have an important role in America’s history, culture and economy. Before being nearly wiped from existence by westward expansion, bison roamed across most of North America. The species is acknowledged as the first American conservation success story, having been brought back from the brink of extinction by a concerted effort of ranchers, conservationists and politicians to save the species in the early 20th century. In 1907, President Teddy Roosevelt and the American Bison Society began this effort by shipping 15 animals by train from the Bronx Zoo to Oklahoma’s Wichita Mountains Wildlife Refuge. Many Native American tribes revere bison as a sacred and spiritual symbol of their heritage and maintain private bison herds on tribal lands throughout the West. Bison now exist in all 50 states in public and private herds, providing recreation opportunities for wildlife viewers in zoos, refuges and parks and sustaining the multimillion dollar bison ranching and production business." While National Parks in the mountain west are typically thought of, bison were once abundant across Iowa. No wild populations remain, but several public and private landowners in the state have bison today. One great way to celebrate National Bison Day is to visit one of several places in western Iowa with public viewing of bison. Botna Bend Park This park is owned and managed by Pottawattamie Conservation and is located in the town of Hancock in eastern Pottawattamie County. It is located within the the Loess Hills Missouri River Region and along the West Nish Water Trail. The park includes bison and elk herds that can be easily viewed from the road. The park has a $3 entrance fee unless you have a Pottawattamie county parks annual pass.  Bison in the winter at Botna Bend Park, Pottawattamie County. Photo by Lance Brisbois Botna Bend even has two white bison, which are extremely rare:  White bison and calf at Botna Bend Park. Photo by Lance Brisbois Broken Kettle Grassland The Nature Conservancy in Iowa owns the largest remnant prairie in the state in Plymouth County along the northern end of the Loess Hills National Scenic Byway, and includes a herd of bison. Because they have a relatively large area to roam, you may not be able to get close. But drive Butcher Road and you may see them in the distance.  Bison roaming Loess Hills prairies at Broken Kettle Grasslands. Photo by Geof Fischer, The Nature Conservancy.  Closeup of a bison at Broken Kettle Grasslands. Photo by Geof Fischer, The Nature Conservancy. Prairie Heritage Center O'Brien County Conservation Board's Prairie Heritage Center, along Glacial Trail Scenic Byway, has a small herd of bison.  Prairie Heritage Center, O'Brien County. Photo from their Facebook page: https://www.facebook.com/PrairieHeritageCenter/  The Prairie Heritage Center's bison are so iconic that they are the image on Glacial Trail Scenic Byway's logo and signage. Learn more at goldenhillsrcd.org/gtsb Swan Lake State Park Located in Carroll County, this park is managed by Carroll County Conservation Board and has a small bison herd. Whiterock Conservancy This 5,500-acre land trust is a short drive from Western Skies Scenic Byway in Guthrie County. Whiterock is open to public visitation and includes dozens of miles of hiking, mountain biking, equestrian trails, camping, paddling, fishing, and much more.  Bison at Whiterock Conservancy. Photo from Whiterock's Facebook page: https://www.facebook.com/WhiterockConservancyIA/ Golden Hills partnered with Raygun to create a WanderLoess bison shirt to support our Loess Hills conservation work.  In a previous post about Western Skies Scenic Byway, we discussed how wind and water shaped the landscape of western Iowa. In addition to natural forces, people have also helped shape the modern landscape. Humans have inhabited the land that is western Iowa for thousands of years, impacting the landscape since the beginning. Indigenous people cultivated crops, built homes, and started regular fires. After European colonization beginning in the late 19th century, the land changed much more dramatically and rapidly. The contemporary landscape of western Iowa would be unrecognizable compared to the vast prairies and wetlands that covered the state prior to colonization. Iowa is the most altered of all 50 states, with the least amount of "wild" or "natural" places. "The state of Iowa has lost 99.9% of its prairies, 98% percent of its wetlands, 80% of its woodlands, 50% percent of its topsoils, and more than 100 species of wildlife since settlement in the early 1800’s. There has been a significant deterioration in the quality of Iowa’s surface waters and groundwaters." (Source: Iowa Code, Section 455A.15 Legislative Findings). The region has some of the best cropland in the world, and prairies and wetlands were converted to rowcrops over only a couple generations. Many of the steeper slopes were converted to non-native pastures. With this vegetation and land use change, the entire ecosystem changed from some of the most biodiversity on the planet to among the least. On top of the vegetative change, nearly all the rivers and creeks in western Iowa were channelized in the 20th Century. Straightening streams shortened their length, which increased the slope and caused the waterways to cut downwards into the deep, highly erodible loess soils. Most streams in the region have severe to extreme bank erosion and are carved 10 to 20 feet (or more) into the surrounding land. The increased stream slope also led to widespread gully erosion, with small waterfalls called knickpoints on many streams. The drastic elevation changes have required streambed grade control structures like spillways and dams to help protect roads, bridges, utilities and other infrastructure.  Channelized streams in Iowa. Source: Hungry Canyons Alliance  Streambed grade control structures in western Iowa. Source: Hungry Canyons Alliance (http://www.goldenhillsrcd.org/hungry-canyons-alliance.html) Due to their silty nature, the deep loess soils are home to the worst soil erosion on the continent. In fact, "loess" is a German word for "loose" and is colloquially called "sugarclay" due its erosiveness. The maps below show rill and sheet erosion in the continental U.S. in 2012 and 1982. While erosion has been reduced from more than 12 tons per acre to 6-8 tons per acre, this is still a concerning erosion rate. Learn about different types of soil erosion here.  1982 erosion map. Source: http://1lbchallenge.com/wp-content/uploads/2018/03/Abreviated-2012-USDA-Natural-Resources-Inventory-Report-on-Sheet-and-Rill-Soil-Erosion-on-Private-Land-in-US.pdf  2012 erosion map. Source: http://1lbchallenge.com/wp-content/uploads/2018/03/Abreviated-2012-USDA-Natural-Resources-Inventory-Report-on-Sheet-and-Rill-Soil-Erosion-on-Private-Land-in-US.pdf  Average soil erosion per acre (Source: https://www.ewg.org/losingground/report/erosion-adds-up.html) Fortunately, agricultural conservation practices, especially terraces and water and sediment control basins, have reduced erosion. Planting rowcrops on contour instead of vertically on slopes also helps to slow erosion rates. These practices are nearly ubiquitous on western Iowa's croplands, further shaping the landscape. The earthen berms reduce rill and sheet erosion and runoff.  Typical western Iowa landscape, with contour rowcrops and terraced slopes. Photo by Lance Brisbois Prior to colonization and subsequent stream channelization, the prairie streams meandered across their valleys with crystal-clear water, as described in some early pioneer accounts. Today the sheet, rill, gully and streambank erosion makes the streams run a muddy brown color. New evidence has shown that phosphorous levels in streams are likely impacted significantly by streambank erosion, as "legacy" nutrients get stored in the soil and enter waterways when riverbanks erode.  West Nishnabotna River in Shelby County, showing streambank erosion and muddy brown water. Photo by Lance Brisbois Some of the poorly-drained areas, especially on the Des Moines lobe in northeastern Guthrie County and some of the larger river valleys like the Missouri in Harrison County, were tiled to convey water off the land and improve agricultural opportunities. Tiling can carry nutrients, sediment, and pollutants into drainage ditches and streams, further decreasing water quality. Tiling is usually invisible above ground, but you may see the end of tile lines going into drainage districts or streams. Learn more about tiling and terracing here.  Drained soils and drainage districts in Iowa (Source: https://scholarworks.uni.edu/cgi/viewcontent.cgi?article=1000&context=other_facpub) Besides agricultural development, humans have built residential, industrial, commercial, and other infrastructure that shapes the land. Most of the communities in the region were founded along rail lines, which were some of the earliest transportation routes before many roads were built.  Source: Iowa DOT (https://iowadot.gov/iowarail/IOWA-FREIGHT-RAIL/RAILROAD-MAPS) Most railroads in this corridor have been abandoned and are no longer active. Some have been replaced by recreational trails like the T-Bone Trail through Audubon County and the Raccoon River Valley Trail in Guthrie County. Many others were removed and have been farmed for decades, with no trace remaining. In some cases, the remnants are visible from satellite imagery and LIDAR, like this area just southwest of Harlan in Shelby County.  Many settlements that began before railroad construction eventually withered into ghost towns. In some cases, a few houses remain, but often there are no visible signs of these ghost towns on the landscape. The highway and road system also greatly contributed to the region's altered landscape and hydrology. For the most part, roadways are built up several feet from the surrounding landscape similar to railroads, and cut into the tops of the hills to reduce slopes. Unlike the railroads, which often followed the path of least resistance, the road system was set up on orthogonal grid system oriented along the cardinal directions, regardless of terrain. Some exceptions to the grid exist, especially in the hilliest parts of Harrison and Guthrie counties. Since the grid does not follow topographic or hydrologic boundaries, the construction of the road system in some cases altered watershed boundaries. Ditches on either side of the roads funnel water into the nearest stream, increasing flash flooding and nutrient runoff.  Roadbed built several feet above the river valley with drainage ditches on either side. Google Streetview Image from Highway 30 in Harrison County.  Example of highway roadcuts through the hills. Google Streetview image from Highway 44 in Harrison County. Next time you drive Western Skies Scenic Byway, try to spot how the land has been sculpted by human development, in addition to natural processes like wind and water.
|
Archives
March 2023
Categories
All
|
RSS Feed