What is a Watershed? Part II- Invasive Species Removal is Key to Watershed Restoration

Ohio River Foundation (ORF) fights to protect the Ohio River Watershed but many people have no idea what a watershed is and just how important they are to the environment and our drinking water! A watershed is an area of land where all the water drains to a common outlet. Consider that wherever you are at any given moment, and whatever is happening on the land all around you, is also happening to the water. Water runoff from ALL the surfaces around us transports all kinds of good and bad things into our waterways and therefore our drinking water. To learn more, check out What is a Watershed? And What’s Land Got To Do With It?

In recent months the Greater Cincinnati region has experienced drought conditions. 6 Ohio counties were just declared a primary natural disaster area due to drought. In the middle of this ongoing drought, we experienced temporary heavy rains from Hurricane Helene. Although nothing like the catastrophic flooding experienced in the Asheville Watershed and other areas of western North Carolina our local waterways experience very low and then very high-water levels within a short period of time. These extreme fluctuations and fast, powerful moving water cause erosion and floods. Areas where development has replaced permeable, native-dominated forests and wetlands with impervious pavements, grass lawns, and disturbed habitats full of invasive plants make our watershed especially vulnerable to extreme flooding and erosion. In Ohio, only 10% of our historic wetlands remain meaning the hydrology of most of our region has changed significantly and continues to change as more of our landscape is developed. Practically speaking, we won’t be tearing down buildings to put back wetlands. Therefore, it’s critical to protect what is left and minimize the negative effects of loss through better land management.

Because the connection between what is happening across the landscape, near or far from the water’s edge, is affecting the quality of our water ORF is hugely committed to restoring aquatic and non-aquatic habitats. One of ORF’s top priorities is removing non-native, invasive species throughout the landscape and planting native species that have co-evolved with native flora and fauna. Native plant species act as important buffers for our waterways slowing water down and recharging groundwater, stabilizing soil, reducing erosion and flash floods, and trapping and absorbing harmful pollutants and excessive nutrients. Most non-native, invasive plant species cannot provide these important services the way natives can.

Native plants are essential to the survival of a wide range of wildlife by providing habitat and food sources. There are endless examples like the monarch butterflies you see drifting south this time of year and their larval host plant milkweed or the zebra swallowtail butterfly and its larval host tree the paw paw. Non-native, invasives outcompete native plants meaning all the wildlife that has co-evolved to rely on familiar, life-giving plants are left without and the entire food web is affected.

Natives also anchor the soil reducing the risk of erosion caused by wind and water, especially in areas prone to heavy rainfall and strong winds. Native plants have deeper root systems. Deep roots make the soil less compacted and more permeable and allow for the absorption of more water versus sheeting off the landscape and running into sewers and overwhelming waterways. Deeper and fibrous roots grab and hold soil in place far more effectively than shallow roots. Non-native turf grass and invasives like honeysuckle have shallow roots, with a root depth of only a few inches, and the soil underneath is more compacted, causing more water to run off instead of soaking into the ground. Native perennial flowers and grasses easily exceed root depths of 5 or more feet making the soil healthier and more permeable to water. These deeper roots promote important groundwater recharge and reduce drought stress for plants.

Honeysuckle is usually one of the first invasive species that comes to mind and for good reason because it’s everywhere and it’s the perfect example of an aggressively growing, shallow rooting, plant taking over. Honeysuckle even has the advantage of producing toxins in its leaves and berries that impact the growth and survival of plants and animals around it through an amazing process called allelopathy. As we enter into fall and leaves start to fall and enter into waterways sensitive aquatic species like frogs and salamanders will be affected by toxic honeysuckle leaves. Learn more about how honeysuckle is sucking the life out of our water. 

For all of these reasons, ORF spends countless hours removing invasive plants like Amur honeysuckle, Callery pear, teasel, Lesser celandine, etc. from over 40 acres of parklands in Greater Cincinnati. In 2020, Ohio River Foundation began a multi-year project for Deerfield Township to remove and control invasive species at the 40-acre Kingswood Park. A former golf course, the site is already undergoing a native habitat transformation. Hundreds of native trees remain where invasive pear and honeysuckle previously stood nearby. We continue to manage and engage volunteers as a part of this project. This is a monumental task as invasive plants have dominated the regrowth of the old golf course and in order to give natives a fighting chance, acres of invasives must be removed. These are not just river parks located near or next to waterways. Building resilient and native-dominated habitats throughout the entire watershed is key to the health of the Ohio River and its tributaries.