In an exciting development for TWI’s Smart Wetlands program, staff ecologists have taken a step toward better understanding the evolving vegetative makeup of our farm-based Smart Wetlands sites, designed to improve water quality. Beginning in 2023, plant surveys were conducted at the sites for the first time. The surveys add to an existing body of water, soil, and nutrient data already collected for the purpose of better understanding, monitoring, and improving the Smart Wetlands going forward.
Vegetation plays a critical role in the ecosystem services provided by natural wetlands, and the same is true for the six constructed wetlands installed on Illinois farmland by TWI in recent years. Since 2015, TWI has partnered with farmers to construct small, precisely-placed wetlands on their property with the purpose of intercepting and removing nitrogen and phosphorus from agricultural runoff associated from tile-drained cropland. Considering that Illinois is the number-one contributor of agricultural runoff to the Mississippi River system, these small, nutrient-removing constructed wetlands hold the potential to make a powerful positive environmental impact!
Plant surveying helps TWI ecologists to develop a detailed picture of the species currently inhabiting the Smart Wetlands sites, which in turn helps to ensure the projects’ future success. Plant survey data provides a window into the plant community makeup of each individual Smart Wetland, which is an important indicator of how well the wetland is functioning as a healthy ecosystem. The data also helps illuminate the success of efforts to establish various native plant species at the sites via seeding and plug planting. Our ecologists also went into the surveying process with a healthy dose of curiosity, seeking to answer the question: Do different species of plant dominate in areas with native wetlands soil, which has high water content, versus non-wetlands soil, which has lower water content?
The results of the plant surveys indicate that a few native species stood out as the most dominant plants among all Smart Wetlands sites. These included common water plantain (Alisma subcordatum), common arrowhead (Sagittaria latifolia), prairie cordgrass (Spartina pectinata), and rice cutgrass (Leersia oryzoides). Despite not having been planted by TWI staff, various species of cattail (Typha sp.) found their way to our wetland sites and proliferated as well!
A TWI ecologist gets some assistance with surveying one of TWI’s Smart Wetlands sites.
Due to recent drought conditions in Illinois, native species with stronger, rhizomatous root systems were found to have outperformed native wetland forbs and sedges with weaker root systems. As a result of this finding, TWI plans to supplement the sites with seeds and plugs of these weaker-rooted species, which include swamp milkweed (Asclepias incarnata), monkeyflower (Mimulus ringens), and bottlebrush sedge (Carex hystericena), to restore their populations and increase biodiversity.
The surveys also identified several invasive plant species present at some Smart Wetlands sites, including common reed (Phragmites australis), watercress (Nasturtium officinale), and hybrid cattails (Typha × glauca). Armed with this knowledge, our staff plans to target the sites for invasive species management this spring.
Native swamp milkweed (foreground) and hybrid cattail were identified in the recent surveys.
With this new information at hand, ecologists at TWI plan to move confidently forward with the work necessary to increase function and efficiency at our Smart Wetlands sites. We will conduct annual site surveys in the future so that we can proactively manage vegetation and maximize nutrient removal efficiency of the sites. Not to mention, maintaining healthy vegetation at the sites also bolsters their secondary benefits, which include stormwater absorption, carbon sequestration, and serving as wildlife and pollinator habitat. Our hope is that this is just the beginning of a long tradition of maintaining and growing the Smart Wetlands program for the betterment of wildlife, farmers, and the environment alike!